mud pump flow loop schematic made in china

Mud Pump Pulsation Dampener is usually installed on the discharge line to reduce the fluctuation of pressure and displacement of the drilling mud pump.

Mud Pump Pulsation Dampener is a pneumatic device built into the outflow line of each UUD pump to dampen the pressure fluctuations resulting from the action of the pump. Although presented as a surge tank, this device is really a device that can be tuned to greatly diminish the output pulsations transmitted downstream from the mud pump. Unfortunately, the effectiveness of the pulsation dampener is a function of both output pump pressure and frequency of the pump pulsations.

The piston is one of the parts that most easily become worn out and experience failure in mud pumps for well drilling. By imitating the body surface morphology of the dung beetle, this paper proposed a new type (BW-160) of mud pump piston that had a dimpled shape in the regular layout on the piston leather cup surface and carried out a performance test on the self-built test rig. Firstly, the influence of different dimple diameters on the service life of the piston was analyzed. Secondly, the analysis of the influence of the dimple central included angle on the service life of the piston under the same dimple area density was obtained. Thirdly, the wear of the new type of piston under the same wear time was analyzed. The experimental results indicated that the service life of the piston with dimples on the surface was longer than that of L-Standard pistons, and the maximum increase in the value of service life was 92.06%. Finally, the Workbench module of the software ANSYS was used to discuss the wear-resisting mechanism of the new type of piston.

The mud pump is the “heart” of the drilling system [1]. It has been found that about 80% of mud pump failures are caused by piston wear. Wear is the primary cause of mud pump piston failure, and improving the wear-resisting performance of the piston-cylinder friction pair has become the key factor to improve the service life of piston.

Most of the researchers mainly improve the service life of piston through structural design, shape selection, and material usage [1, 2]. However, the structure of mud pump piston has been essentially fixed. The service life of piston is improved by increasing piston parts and changing the structures of the pistons. However, the methods have many disadvantages, for example, complicating the entire structure, making piston installation and change difficult, increasing production and processing costs, and so on. All piston leather cup lips use rubber materials, and the material of the root part of the piston leather cup is nylon or fabric; many factors restrict piston service life by changing piston materials [3]. Improving the component wear resistance through surface texturing has been extensively applied in engineering. Under multiple lubricating conditions, Etsion has studied the wear performance of the laser surface texturing of end face seal and reciprocating automotive components [4–6]. Ren et al. have researched the surface functional structure from the biomimetic perspective for many years and pointed out that a nonsmooth surface structure could improve the wear resistance property of a friction pair [7, 8]. Our group has investigated the service life and wear resistance of the striped mud pump piston, and the optimal structure parameters of the bionic strip piston have improved piston service life by 81.5% [9]. Wu et al. have exploited an internal combustion engine piston skirt with a dimpled surface, and the bionic piston has showed a 90% decrease in the average wear mass loss in contrast with the standard piston [10]. Gao et al. have developed bionic drills using bionic nonsmooth theory. Compared with the ordinary drills, the bionic drills have showed a 44% increase in drilling rate and a 74% improvement in service life [11]. The present researches indicate that microstructures, like superficial dimples and stripes, contribute to constituting dynamic pressure to improve the surface load-carrying capacity and the wear resistance of the friction pair [12–21].

In nature, insects have developed the excellent wear-resistant property in the span of billions of years. For instance, the partial body surface of the dung beetle shows an irregularly dimpled textured surface with the excellent wear-resistant property that is conducive to its living environment [7, 8, 22]. The dung beetle, which is constantly active in the soil, shows a body surface dimple structure that offers superior drag reduction. These dimples effectively reduce the contact area between the body surface and the soil. Moreover, the friction force is reduced. Therefore, the dung beetle with the nonsmooth structure provides the inspiration to design the bionic mud pump piston. This paper proposed a new type of piston with dimpled morphology on its surface and conducted a comparative and experimental study of different surface dimpled shapes, thus opening up a new potential to improve the service life of the mud pump piston.

A closed-loop circulatory system was used in the test rig, which was built according to the national standard with specific test requirements. The test rig consisted of triplex single-acting mud pump, mud tank, in-and-out pipeline, reducer valve, flow meter, pressure gauge, and its principle, as shown in Figure 1. Both the pressure and working stroke of the BW-160 mud pump are smaller than those of the large-scale mud pump, but their operating principles, structures, and working processes are identical. Therefore, the test selected a relatively small BW-160 triplex single-acting mud pump piston as a research object, and the test results and conclusion were applicable to large-scale mud pump pistons. The cylinder diameter, working stroke, reciprocating motion velocity of piston, maximum flow quantity, and working pressure of the BW-160 triplex single-acting mud pump were 70 mm, 70 mm, 130 times/min, 160 L/min, and 0.8–1.2 MPa, respectively.

The mud pump used in the test consisted of water, bentonite (meeting the API standard), and quartz sand with a diameter of 0.3–0.5 mm according to actual working conditions. The specific gravity of the prepared mud was 1.306, and its sediment concentration was 2.13%. Whether mud leakage existed at the venthole in the tail of the cylinder liner of the mud pump was taken as the standard of piston failure. Observation was made every other half an hour during the test process. It was judged that the piston in the cylinder failed when mud leaked continuously; its service life was recorded, and then it was replaced with the new test piston and cylinder liner. The BW-160 mud pump is a triplex single-acting mud pump. The wear test of three pistons could be simultaneously conducted.

The mud pump piston used in the test consisted of a steel core, leather cup, pressing plate, and clamp spring. The leather cup consisted of the lip part of polyurethane rubber and the root part of nylon; the outer diameter on the front end of the piston was 73 mm, and the outer diameter of the piston tail was 70 mm, as shown in Figure 2. We proceeded in two parts during the design of the dimpled layout pattern because the piston leather cup consisted of two parts whose materials were different. The dimples at the lip part of the leather cup adopted an isosceles triangle layout pattern, and the dimples at the root part were arranged at the central part of its axial length, as shown in Figure 3(a). Dimple diameter (D, D′), distance (L), depth (h), and central included angle (α) are shown in Figure 3. The dimples on the piston surface were processed by the CNC machining center. Since then, the residual debris inside the dimples was cleaned.

Schematic of dimpled piston: (a) dimpled layout of piston, (b) dimpled array form diagram, (c) cross section view of the piston leather cup, and (d) original picture of dimpled piston.

Table 1 shows that average service lives of L-Standard, L-D1, L-D2, and L-D3 were 54.67 h, 57.17 h, 76.83 h, and 87.83 h, respectively. Therefore, the mud pump pistons with dimples provide longer service life than the L-Standard piston. As the dimple diameter increases, the piston service life was improved, and the largest percentage increase of the service life was 60.65%. The service life of the L-D4 piston was about 81.17 h, which increased by 7.94% compared with that of the L-D2 piston, indicating that the piston with dimples at the leather cup root could improve piston service life.

Figure 4 illustrates the surface wear patterns of pistons with different dimple diameters in the service life test. Figures 4(a) and 4(a′) show wear patterns on the surface of the L-Standard piston. This figure shows that intensive scratches existed in parallel arrangement on the piston leather cup surface, enabling high-pressure mud to move along the scratches from one end of the piston to the other easily, which accelerated the abrasive wear failure with the abrasive particles of the piston. Figures 4(b), 4(b′), 4(c), 4(c′), 4(d), and 4(d′) show the wear patterns of the leather cup surfaces of L-D1, L-D2, and L-D3 pistons, respectively. Figures 4(b), 4(b′), 4(c), 4(c′), 4(d), and 4(d′) show that the scratches on the leather cup surface became shallower and sparser and the surface wear patterns improved more obviously as the dimple diameter increased. If the piston leather cup surface strength was not affected to an extent as the dimple diameter increased, the reduced wear zone near the dimple would become greater and greater, indicating that the existence of dimples changed the lubricating status of the leather cup surface, their influence on nearby dimpled parts was more obvious, and they played active roles in improving the service life of the piston.

Figure 5 displays the wear patterns of the leather cup root parts of the L-D4 and L-D2 test pistons. The wear patterns of the nylon root parts of the L-D4 pistons are fewer than those of the L-D2 pistons, as shown in Figure 5. When the leather cup squeezed out high-pressure mud as driven by the piston steel core, it experienced radial squeezing while experiencing axial wear. Therefore, the area with the most serious wear was the piston leather cup root part, and the friction force at the leather cup root was much greater than that at the other areas. The rapid wear at the root decreased the piston load-carrying capacity and then affected the service life of piston. The dimples at the piston leather cup root could reduce the wear of the piston leather cup root and improve the service life of piston.

Figure 6 shows the surface wear patterns of the L-S1 and L-S2 test pistons. In Figures 6(a) and 6(a′), the scratches on the piston leather cup surface became sparse and shallow in the dimpled area. Figures 6(b) and 6(b′) show that the wear was slight in the area close to the dimples. The farther the scratches were from the dimpled area, the denser and deeper the scratches would be. The L-S1 piston had a small dimple central included angle, which was arranged more closely on the piston surface. The lubricating effects of oil storage in each row of dimples were overlaid very well, which was equivalent to amplifying the effect of each row of dimples in Figure 6(b), making the wear on the whole piston leather cup surface slight, preventing the entry of high-pressure mud into the frictional interface, and lengthening the service life of piston.

During the operation of the mud pump piston, the outside surface of the piston leather cup comes in contact with the inner wall of the cylinder liner and simultaneously moves to push the mud. The lip part of the piston leather cup mainly participated in the piston wear and exerted a sealing effect, while the piston root part mainly exerted centralizing and transitional effects. In the mud discharge stroke, the lip part of the piston experienced a “centripetal effect,” and a gap was generated between the lip part and the cylinder liner. The greater the contact pressure between the lip part and cylinder liner of the piston was, the smaller the gap was, and the entry of high-pressure mud into the contact surface between the piston and cylinder liner was more difficult. The piston root easily experienced squeezing under high pressure, and the smaller the equivalent stress caused by the piston root was, the more difficult the squeezing to occur. Hence, the contact pressure at the lip part of the piston and the equivalent stress at the root were analyzed, and they would provide a theoretical basis for the piston wear-resisting mechanism. The ANSYS Workbench module was used to perform a comparative analysis between the contact pressure at the lip part and the equivalent stress at the root of the three kinds of pistons (i.e., L-Standard piston, L-S1 piston, and L-D1 piston). The service life of the L-S1 piston exhibited the best improvement effect, whereas that of the L-D1 piston demonstrated the worst improvement effect. The piston adopted a 1 mm hexahedral grid, and the grid nodes and elements are as shown in Table 4.

The lubricating oil on the mud pump piston surface could reduce the wear of piston and cylinder liner and improve the service life of pistons with the reciprocating movement. The lubricating oil would eventually run off and lose lubricating effect, which would result in piston wear. The finite element fluid dynamics software CFX was used to establish the fluid domain model of the dimpled and L-Standard pistons and analyze the lubricating state on the piston surface. The piston surface streamlines are shown in Figure 10. This figure shows that the lubricating fluid did not experience truncation or backflow phenomenon when passing the surface of the L-Standard piston. When the lubricating fluid flowed through the surface of the dimpled piston, it presented a noncontinuous process. Its flow velocity at the dimpled structure slowed down obviously because it was blocked by the dimpled structure.

Figure 11 shows the piston cross section streamline. This figure shows that the existence of dimples changed the distribution status of the lubricating flow fields on the contact surface between the piston and cylinder liner. The lubricating oil entered the dimpled structure in a large quantity, and the flow velocity slowed down. The dimpled structure on the piston surface enlarged the storage space of the lubricating oil and made it difficult for the lubricating oil inside the dimpled structure to be taken away by the cylinder liner to improve the lubricating conditions of the friction pair interface, reduce the frictional resistance between the piston and cylinder liner, reduce wear, and improve the piston service life.

When the piston moved in the cylinder liner, a small quantity of solid particles in mud entered gap of piston and cylinder liner and participated in abrasion. The dimpled structure on the piston surface could store some abrasive particles (as shown in Figure 6(a′)) during the piston wear process to prevent these particles from scratching the piston and cylinder liner and generating gullies, thus avoiding secondary damage to the piston and cylinder liner and improving the piston service life.

This paper presented a dimpled-shape mud pump piston; that is, the piston leather cup surface had a dimpled array morphology in regular arrangement. The experimental results can provide the basic data for design engineering of the mud pump piston with a long service life. The comparative analyses of service life and wear patterns for dimpled mud pump pistons and L-Standard pistons were conducted. The main results and conclusions were summarized as follows:(1)The service life of the mud pump piston with dimpled morphology on the surface improved in comparison with that of the L-Standard piston, and the service life increase percentages were from 4.57% to 92.06%.(2)The piston service life would increase with the dimple diameter under the same dimpled arrangement pattern, and the maximum increase in the value of service life was 60.65%.(3)The service life of the piston with dimples increased by 7.94% in comparison with that with none.(4)Under the same dimpled arrangement patterns and area densities, the tighter and closer the dimples were arranged on the piston surface, the longer the service life of piston was, and the maximum increase in the value of service life was 92.06%.(5)Under the same wear time, the wear of the dimpled piston slightly decreased in comparison with that of the L-Standard piston, and the minimum value of wear mass percentage was 3.83%.(6)The dimpled shape could not only change the stress state of the piston structure, improve piston wear resistance, and reduce root squeezing, but also increase oil storage space, improve lubricating conditions, and enable the accommodation of some abrasive particles. Furthermore, the dimpled shape was the key factor for the service life improvement of the mud pump piston.

When two (or more) pumps are arranged in serial their resulting pump performance curve is obtained by adding theirheads at the same flow rate as indicated in the figure below.

Centrifugal pumps in series are used to overcome larger system head loss than one pump can handle alone. for two identical pumps in series the head will be twice the head of a single pump at the same flow rate - as indicated with point 2.

With a constant flowrate the combined head moves from 1 to 2 - BUTin practice the combined head and flow rate moves along the system curve to point 3. point 3 is where the system operates with both pumps running

When two or more pumps are arranged in parallel their resulting performance curve is obtained by adding the pumps flow rates at the same head as indicated in the figure below.

Centrifugal pumps in parallel are used to overcome larger volume flows than one pump can handle alone. for two identical pumps in parallel and the head kept constant - the flow rate doubles compared to a single pump as indicated with point 2

Note! In practice the combined head and volume flow moves along the system curve as indicated from 1 to 3. point 3 is where the system operates with both pumps running

In practice, if one of the pumps in parallel or series stops, the operation point moves along the system resistance curve from point 3 to point 1 - the head and flow rate are decreased.

The Made-in-China F series mud pumps have same reliable quality and performance as other USA products. Now, F series mud pumps (from F-500 to F-2200) have been produced in batches and sold to many abroad oilfields. Your order for F series mud pumps is cordially welcome.

Huaxin"s export-orientated mud pump parts, including liners, pistons, piston inserts, valve inserts, oil seals, rod packing, fluid ends etc. All of them meet or exceed DIN and API standards and have been exported to U.K., Germany, USA, Canada, Pakistan, Middle East, and so on.

Researchers have shown that mud pulse telemetry technologies have gained exploration and drilling application advantages by providing cost-effective real-time data transmission in closed-loop drilling operations. Given the inherited mud pulse operation difficulties, there have been numerous communication channel efforts to improve data rate speed and transmission distance in LWD operations. As discussed in “MPT systems signal impairments”, mud pulse signal pulse transmissions are subjected to mud pump noise signals, signal attenuation and dispersion, downhole random (electrical) noises, signal echoes and reflections, drillstring rock formation and gas effects, that demand complex surface signal detection and extraction processes. A number of enhanced signal processing techniques and methods to signal coding and decoding, data compression, noise cancellation and channel equalization have led to improved MPT performance in tests and field applications. This section discusses signal-processing techniques to minimize or eliminate signal impairments on mud pulse telemetry system.

At early stages of mud pulse telemetry applications, matched filter demonstrated the ability to detect mud pulse signals in the presence of simulated or real noise. Matched filter method eliminated the mud noise effects by calculating the self-correlation coefficients of received signal mixed with noise (Marsh et al. 1988). Sharp cutoff low-pass filter was proposed to remove mud pump high frequencies and improve surface signal detection. However, matched filter method was appropriate only for limited single frequency signal modulated by frequency-shift keying (FSK) with low transmission efficiency and could not work for frequency band signals modulated by phase shift keying (PSK) (Shen et al. 2013a).

In processing noise-contaminated mud pulse signals, longer vanishing moments are used, but takes longer time for wavelet transform. The main wavelet transform method challenges include effective selection of wavelet base, scale parameters and vanishing moment; the key determinants of signal correlation coefficients used to evaluate similarities between original and processed signals. Chen et al. (2010) researched on wavelet transform and de-noising technique to obtain mud pulse signals waveform shaping and signal extraction based on the pulse-code information processing to restore pulse signal and improve SNR. Simulated discrete wavelet transform showed effective de-noise technique, downhole signal was recovered and decoded with low error rate. Namuq et al. (2013) studied mud pulse signal detection and characterization technique of non-stationary continuous pressure pulses generated by the mud siren based on the continuous Morlet wavelet transformation. In this method, generated non-stationary sinusoidal pressure pulses with varying amplitudes and frequencies used ASK and FSK modulation schemes. Simulated wavelet technique showed appropriate results for dynamic signal characteristics analysis.

As discussed in “MPT mud pump noises”, the often overlap of the mud pulses frequency spectra with the mud pump noise frequency components adds complexity to mud pulse signal detection and extraction. Real-time monitoring requirement and the non-stationary frequency characteristics made the utilization of traditional noise filtering techniques very difficult (Brandon et al. 1999). The MPT operations practical problem contains spurious frequency peaks or outliers that the standard filter design cannot effectively eliminate without the possibility of destroying some data. Therefore, to separate noise components from signal components, new filtering algorithms are compulsory.

Early development Brandon et al. (1999) proposed adaptive compensation method that use non-linear digital gain and signal averaging in the reference channel to eliminate the noise components in the primary channel. In this method, synthesized mud pulse signal and mud pump noise were generated and tested to examine the real-time digital adaptive compensation applicability. However, the method was not successfully applied due to complex noise signals where the power and the phases of the pump noises are not the same.

Jianhui et al. (2007) researched the use of two-step filtering algorithms to eliminate mud pulse signal direct current (DC) noise components and attenuate the high frequency noises. In the study, the low-pass finite impulse response (FIR) filter design was used as the DC estimator to get a zero mean signal from the received pressure waveforms while the band-pass filter was used to eliminate out-of-band mud pump frequency components. This method used center-of-gravity technique to obtain mud pulse positions of downhole signal modulated by pulse positioning modulation (PPM) scheme. Later Zhao et al. (2009) used the average filtering algorithm to decay DC noise components and a windowed limited impulse response (FIR) algorithm deployed to filter high frequency noise. Yuan and Gong (2011) studied the use of directional difference filter and band-pass filter methods to remove noise on the continuous mud pulse differential binary phase shift keying (DBPSK) modulated downhole signal. In this technique, the directional difference filter was used to eliminate mud pump and reflection noise signals in time domain while band-pass filter isolated out-of-band noise frequencies in frequency domain.

Other researchers implemented adaptive FIR digital filter using least mean square (LMS) evaluation criterion to realize the filter performances to eliminate random noise frequencies and reconstruct mud pulse signals. This technique was adopted to reduce mud pump noise and improve surface received telemetry signal detection and reliability. However, the quality of reconstructed signal depends on the signal distortion factor, which relates to the filter step-size factor. Reasonably, chosen filter step-size factor reduces the signal distortion quality. Li and Reckmann (2009) research used the reference signal fundamental frequencies and simulated mud pump harmonic frequencies passed through the LMS filter design to adaptively track pump noises. This method reduced the pump noise signals by subtracting the pump noise approximation from the received telemetry signal. Shen et al. (2013a) studied the impacts of filter step-size on signal-to-noise ratio (SNR) distortions. The study used the LMS control algorithm to adjust the adaptive filter weight coefficients on mud pulse signal modulated by differential phase shift keying (DPSK). In this technique, the same filter step-size factor numerical calculations showed that the distortion factor of reconstructed mud pressure QPSK signal is smaller than that of the mud pressure DPSK signal.

Study on electromagnetic LWD receiver’s ability to extract weak signals from large amounts of well site noise using the adaptive LMS iterative algorithm was done by (Liu 2016). Though the method is complex and not straightforward to implement, successive LMS adaptive iterations produced the LMS filter output that converges to an acceptable harmonic pump noise approximation. Researchers’ experimental and simulated results show that the modified LMS algorithm has faster convergence speed, smaller steady state and lower excess mean square error. Studies have shown that adaptive FIR LMS noise cancellation algorithm is a feasible effective technique to recover useful surface-decoded signal with reasonable information quantity and low error rate.

Different techniques which utilize two pressure sensors have been proposed to reduce or eliminate mud pump noises and recover downhole telemetry signals. During mud pressure signal generation, activated pulsar provides an uplink signal at the downhole location and the at least two sensor measurements are used to estimate the mud channel transfer function (Reckmann 2008). The telemetry signal and the first signal (pressure signal or flow rate signal) are used to activate the pulsar and provide an uplink signal at the downhole location; second signal received at the surface detectors is processed to estimate the telemetry signal; a third signal responsive to the uplink signal at a location near the downhole location is measured (Brackel 2016; Brooks 2015; Reckmann 2008, 2014). The filtering process uses the time delay between first and third signals to estimate the two signal cross-correlation (Reckmann 2014). In this method, the derived filter estimates the transfer function of the communication channel between the pressure sensor locations proximate to the mud pump noise source signals. The digital pump stroke is used to generate pump noise signal source at a sampling rate that is less than the selected receiver signal (Brackel 2016). This technique is complex as it is difficult to estimate accurately the phase difference required to give quantifiable time delay between the pump sensor and pressure sensor signals.

As mud pulse frequencies coincide with pump noise frequency in the MPT 1–20 Hz frequency operations, applications of narrow-band filter cannot effectively eliminate pump noises. Shao et al. (2017) proposed continuous mud pulse signal extraction method using dual sensor differential signal algorithm; the signal was modulated by the binary frequency-shift keying (BFSK). Based on opposite propagation direction between the downhole mud pulses and pump noises, analysis of signal convolution and Fourier transform theory signal processing methods can cancel pump noise signals using Eqs. 3 and 4. The extracted mud pulse telemetry signal in frequency domain is given by Eqs. 3 and 4 and its inverse Fourier transformation by Eq. 4. The method is feasible to solve the problem of signal extraction from pump noise,

These researches provide a novel mud pulse signal detection and extraction techniques submerged into mud pump noise, attenuation, reflections, and other noise signals as it moves through the drilling mud.

The drilling fluid circulating system is like a close loop electric circuit through which drilling fluid (i.e. mud) can travel from the surface to all the way downhole and back to its initial point (i.e. mud pit).

Drilling fluid (i.e. mud) goes from the mud pits to main rig pumps (i.e. mud pump), and then major components including surface piping, standpipe, kelly hose, swivel, kelly, drill pipe, drill collar, bit nozzles, the various annular geometries (annulus means space between drill pipe and hole) of the open hole and casing strings, flow line, mud control equipment, mud tanks, and again the mud pit/mud pump (Figure 1). It is obvious that the rock cuttings must be removed from the borehole to allow drilling to proceed. This is done by pumping drilling fluid down the drill-string, through the bit and up the annulus.

The cuttings are then separated from the mud, which is then recycled. The circulating system (i.e. drilling fluid) also enables to clean the hole of cuttings made by the bit; to exert a hydrostatic pressure sufficient to prevent formation fluids entering the borehole, and to maintain the stability of the hole by depositing a thin mud-cake on the sides of the hole.

The main components related to the circulating system are mud pumps, mud pits, mud mixing equipment and contaminant removal equipment (Figure 2). The detailed equipment list for this system is shown in Figure 1 and Figure 2. Drilling fluid is usually a mixture of water, clay, weighting material (barite) and chemicals. A variety of mud are now widely used (i.e. oil base, invert oil emulsion).

The mud must be mixed and conditioned in the mud pits, and then circulated by large pumps i.e. sludge pumps (Figure 3). A schematic diagram illustrating a typical rig circulating system along with its flow direction is depicted in Figure 3. The mud is pumped through the whole cycle as mentioned in Figure 3. Once the mud comes back to the surface again, the solids must be removed and the mud is conditioned prior to be re-circulated. These solids and some other contaminants are removed using shale shaker, desander, desilter, and vacuum degasser (Figure 5).

The mud pit is usually a series of large steel tanks, all interconnected and fitted with mud agitators to maintain solids in suspension (Figure 6). Some pits are used for circulating (i.e. suction pit) and others for mixing and storing fresh mud. Most modern rigs have equipment for storing and mixing bulk additives (i.e. barite) as well as chemicals (both granular and liquid). The mixing pumps are generally high volume, low discharge centrifugal pumps (Figure 2). At least two sludge pumps are installed on the rig. At shallow depths, they are usually connected in parallel to deliver high flow rates.

Positive displacement pumps are used (reciprocating pistons) to deliver high volumes at high discharge pressures. The discharge line from the mud pumps is connected to the standpipe, a steel pipe mounted vertically on one leg of the derrick. A flexible rubber hose (i.e. kelly hose) connects the top of the standpipe to the swivel via the gooseneck (Figure 7). Once the mud has been circulated around the system it will contain suspended solids, perhaps some gas and other contaminants. These must be removed before the mud is recycled. The mud passes over a shale shaker, which is basically a shaker screen. This removes the larger particles while allowing the residue (underflow) to pass into settling tanks. The finer material can be removed using desanders, desilter, vacuum degassers, and decanting centrifuges.

If the mud contains gas from the formation it can be passed through a degasser that operates a vacuum, thereby separating the gas from the liquid mud. Having passed through all the mud processing equipment the mud is pumped to settling traps prior to being returned to the mud tanks for recycling. Another tank which is useful for well monitoring is the possum belly tank. This is calibrated to measure the fluid displaced from hole while running in. If the level varies significantly from the expected level a pressure control problem can be identified and necessary actions take place.

The Yellow River is known as the Huang He in China. Because the river level drops precipitously toward the North China Plain, where it continues a sluggish course across the delta, it transports a heavy load of sand and mud from the upper reaches, much of which is deposited on the flat plain.

After it reaches the North China Plain, the Yellow River I is slow and sluggish along most of its course and some regard it as the world"s muddiest major river, discharging three times the sediment of the Mississippi River. It gets its name and color from the yellow silt it picks up in the Shaanxi Loess Plateau . The Yellow River flows in braided streams, a network of smaller channels that weave in and out of each other. In each channel silt slowly builds the riverbed above the surrounding landscape and gives the river its devastating habit of breaking its banks and changing course.

The flow of the Yellow River is channeled mainly by constantly repaired manmade embankments; as a result the river flows on a raised ridge fifty meters or more above the plain, and waterlogging, floods, and course changes have recurred over the centuries. Traditionally, rulers were judged by their concern for or indifference to preservation of the embankments. In the modern era, the new leadership has been deeply committed to dealing with the problem and has undertaken extensive flood control and conservation measures.*

The Yellow River originates on Tibet-Qinghai plateau and flows for 5,464 kilometers (about 3,400 miles) through seven present-day provinces and two autonomous regions — (from west to east): Qinghai, Gansu, Ningxia, Inner Mongolia, the border of Shaanxi and Shanxi, Henan and Shandong — before it empties into Bo Hai Gulf in the Yellow Sea. Initially flowing northeast from its source, the Yellow River follows a a somewhat winding path toward the sea with a large chunk of it running through the Loess Plateau, one of the historic center of Chinese civilizations, where its pick up a lot of silt that gives its yellowish-brown color.

Where the Yellow River begins, source tributaries drain into Gyaring Lake and Ngoring Lake in the Bayan Har Mountains of Qinghai. In the Zoige Basin along the border of Qinghai and Gansu border, the Yellow River loops northwest and then northeast before turning south, creating the "Ordos Loop", and then flows generally eastward across the North China Plain to the Gulf of Bohai. Major cities along river include (from west to east) Lanzhou, Yinchuan, Wuhai, Baotou, Luoyang, Zhengzhou, Kaifeng, and Jinan. The mouth of the Yellow River is located at Kenli County, Shandong. [Source: Wikipedia]

The Yellow River is commonly divided into three stages: 1) the Upper Section. roughly northeast of the Tibetan Plateau; 2) the Middle Section at the Ordos Loop; and 3) the Lower Section in the North China Plain. Tributaries of the Yellow River listed from its source to its mouth include: White River, Black River, Huang Shui, Datong River, Daxia River, Tao River, Zuli River, Qingshui River, Dahei River, Kuye River, Wuding River, Fen River, Wei River (the Wei River is the largest of these tributaries), Luo River, Qin River, Dawen River, Kuo River,

From time to time parts of the Yellow River change their routes and courses, sometimes with profound impacts. For example, the river Huai He, a major river in central China and the traditional border between North China and South China, traditionally cut through north Jiangsu to reach the Yellow Sea. However, from 1194 the Yellow River further to the north changed its course several times, running into the Huai He in north Jiangsu each time instead of its other usual path northwards into Bohai Bay. The silting caused by the Yellow River was so heavy that after its last episode of "hijacking" the Huai He ended in 1855: the Huai He was no longer able to go through its usual path into the sea. Instead it flooded, pooled up (thereby forming and enlarging Lake Hongze and Lake Gaoyou), and flowed southwards through the Grand Canal into the Yangtze. The old path of the Huai He is now marked by a series of irrigation channels, the most significant of which is the North Jiangsu Irrigation Main Channel, which channels a small amount of the water of the Huai He alongside south of its old path into the sea.

From time to time the Yellow River overflows its banks and fills huge plains with large amounts of water. Floods sometimes occur when blocks of ice block the Yellow River. About once a century these floods reach catastrophic levels.

In a tactic intended to halt the southward movement of Japanese soldiers from Manchuria before World War II, Chiang Kai-shek ordered his soldiers to breach the levees of the Yellow River and purposely divert its flow. At least 200,000, maybe millions, died, millions more were made homeless and the Japanese advanced anyway.

Sometimes when the Yellow River floods it becomes like a flowing mudslide. The river normally carries an enormous amount of silt and the amount increases when it floods. During a 1958 flood sediment levels were measured at 35 pounds per square foot, causing the river surface to become “wrinkled.

Each year 1.5 billion tons of soil flows into the Yellow River. Sometimes there is so much sediment in the river it looks like chocolate milk. Three fourths of this silt ends up in the Yellow Sea, with the remainder settling in the river beds, causing the level of the river to rise. Over the centuries the river has risen between 15 and 40 feet above the surrounding plains, in some cases with silt blocking off natural drainage channels and making areas more prone to flooding.

The middle section of Yellow River in the Loess Plateau supplies 92 percent of the river"s silt. The large amount of mud and sand discharged into the river makes the Yellow River the most sediment-laden river in the world. The highest recorded annual level of silts discharged into the Yellow River was 3.91 billion tons in 1933. The highest silt concentration level was recorded in 1977 at 920 kilograms per square meter. These sediments are mostlt deposit in the slower lower sections of the river, elevating the river bed and creating the famous "river above ground"

Today, the Yellow River is above the landscape for much of its last 800 kilometers (500 miles) to the sea and the river continues to rise at an alarming rate of four inches a year. If a levee breaks, larger tracts of the countryside are vulnerable to flooding. Much of the silt, sand and mud carried by the Yellow River originates in the faster-flowing upper reaches but is largely deposited on the flat plain, where the river flow is much slower.

Artificial embankments that channel the flow require constant repair. In some places the river flows on a raised ridge that is 50 meters (164 feet) m) or more above the plain. Still enough sediment reaches the sea, where deposits have created a kind of continental shelf (a Distal Depocenter) around the Shandong Peninsula in the Bohai Sea extending to the North Yellow Sea and South Yellow Sea.

The Yellow River has dried up more than 30 times since 1972, when it ran dry for the first time in recorded history. It ran dry all but one year in the 1990s. In 1994, it ran dry for 122 days along a 180-mile section in Shandong, not far from where it empties into the Yellow Sea. In 1996 it ran dry 136 days. In 1997, for 226 days, denying water to 7.4 million acres of farmland and producing a dry riverbed that stretched more than 372 miles. The outflow o the river is just 10 percent of what t was in the 1940s. Timely releases of reservoir water kept it from drying up in the 2000s.

The Yellow River"s problems begin at its source where droughts in the Tibetan plateau have reduced the amount of water flowing to the river. But the main reason the river runs dry is because between 80 to 90 percent of its water had been taken upstream for urban areas, industry and agriculture. Decline of water caused by global warming and the melting of Tibetan glaciers could make the situation worse.

A lot of water is wasted. Agriculture swallows up 65 percent of the Yellow River"s water, with more than half lost to leaky pipes and ditches, with rest swallowed up by industry and cities. Twenty major dams punctuate the Yellow River and another 18 are scheduled to be built by 2030. Dams are particularly damaging on the Yellow River because they exacerbate silting and pollution. The reduced flow cause by dams causing silt to settle and prevents the flushing out if pollutants.

To keep the river flowing efforts are being made to distribute water more equitably and use it more efficiently. In August 2006, new laws were passed to better manage and reduce fights over the Yellow River. Beijing gave broad authority to the Water Resources Ministry to oversea management of the river in 11 provinces and municipalities and gave it a mandate to impose stiff fines and sanctions on officials that don"t comply with the rules or take more than their share of water.

According to the National Palace Museum, Taipei: “In the north covered in loess and yellow earth, the flowing Yellow River gave birth to the splendid ancient Chinese culture. Inhabitant in this area excelled in pottery with patterns of multi-colored twisting and turning patterns. Compared to the animal motifs popular among the inhabitants in the coastal area to the east, they instead created simple yet potent jade objects with geometric designs. Their circular pi and square "ts"ung" were concrete realization of a universal view, which saw the heavens as round and he earth as square. The segmented pi disk and large circular jade designs may represent the concepts of continuity and eternity. The existence of edged jade objects in great numbers seems to bear out what is recorded in the annals of the Han Dynasties: "In the times of the Yellow Emperor, weapons were made were made of jade." [Source: National Palace Museum, Taipei npm.gov.tw \=/ ]

More than 80 percent of the Hai-Huaih Yellow River basin is chronically polluted. Four billion tons of waste water — 10 percent of the river"s volume — flows annually into the Yellow River. Canals that empty into it that were once filled with fish are now purple from the red waste water from chemical plants. The water is too toxic to drink or use for irrigation and kills goats that drink from it.

In October 2006, a one kilometer section of the Yellow River turned red in the city of Lanzhou in Gansu Province as result of a “red and smelly” discharge from a sewage pipe. In December 2005, six tons of diesel oil leaked into a tributary of the Yellow River from a pipe that cracked because of freezing conditions. It produced a 40 mile long slick. Sixty-three water pumps had to be shut down, including some in Jinan, the capital of Shandong Province.

Emsco、Gardner-Denver, National oilwell, Ideco, Brewster, Drillmec, Wirth, Ellis, Williams, OPI, Mud King, LEWCO, Halliburton, SPM, Schlumberger, Weatherford

Because the online rotational Couette viscometer is easily blocked, Vajargah [31], Magalhães [27], Sercan Gul [32], Knut Taugbøl [33,34], Hansen [2], Krogsæter [35], and Frøyland [36] used pipe viscometers to test drilling fluid rheological properties. According to Ahmed and Miska [37], the reliability and accuracy of pipe viscometers often outweigh rotational viscometers. Figure 4 shows a schematic example of the pipe viscometer. The test equipment requires a variable pump, a flow meter, mud with a known density, and a differential pressure sensor to measure the pressure difference in the test section of the straight pipe. Because screw pumps have no pressure pulsation and Coriolis flow meters can measure density and flow rate, pipe viscometers usually use a screw pump and a Coriolis flow meter. Pipe viscometer can measure drilling fluid rheological properties under laminar, transitional, and turbulent flow conditions. The data in the laminar flow state is calculated to characterize the rheological constant of the non-Newtonian fluid. The data obtained in transitional and turbulent conditions can be used to calculate the critical Reynolds number and friction factor in real time. Figure 5 shows the velocity profile in pipe laminar flow. The drilling fluid’s rheological properties can be obtained from the follow equations.

According to Equation (7), the slope of the “flow curve” (ln τw vs. ln(8v/D)) represents the generalized flow behavior index, N. Once N is obtained from the flow curve, the shear rate at the wall can be calculated by using Equation (8). Subsequently, rheological parameters for any desired rheological model can be obtained by plotting the shear stress vs. shear rate at the wall and applying a proper curve fitting technique. The Herschel–Bulkley model (Equation (3)) exhibits an acceptable accuracy for the majority of drilling, completion, and cementing fluids and is therefore usually used to fit rheological curves.

μ, dynamic viscosity; K, consistency factor; n, flow behavior index; τ0, fluid yield stress; AV, apparent viscosity; PV, plastic viscosity; YP, yield point; MSE, mean square error.

The pipe viscometer designed by Sercan Gul et al. [32] has the test sections of the flow loop 1.25 m and 3.80 m long with an outside diameter of 2.54 cm. A comprehensive system calibration was achieved by circulating water at different flow rates through the flow loop. Excellent agreement was observed between the measurement results and the theoretical results. The mean absolute percentage error (MAPE) was calculated by taking the mean of the absolute percentage error (APE) for each single data point, as shown in Equations (11) and (12). The maximum APE was 3.5%, the MAPE was 1.6%, and the coefficient of determination (R2) was 0.99. In experimental verifications, a total of fifteen tests were performed using various water-based mud and oil-based mud formulations at 25 °C, 50 °C, and 65.5 °C. It showed the precision and robustness of the pipe viscometer method and that it could be used to provide a quality and frequent fluid characterization for field muds. In field testing, the pipe viscometer measurements of both PV and YP were a perfect match to the data reported in daily mud reports by the mud engineer.

Some methods have the same theory as the pipe viscometer. Compared with the abovementioned pipe viscometers, these methods are convenient and do not take up much space. A novel downhole sensor was developed by Rondon et al. [39]. It can be inserted into the drill string to measure the rheological properties of fluids in real-time. The mixtures of glycerin and water were used to test and calibrate this sensor. Real crude oil samples were also used to test the performance of this sensor. The error between the designed sensor’s measurement value and the standard measurement value was within 2%. However, drilling fluids need further testing to evaluate the performance of the sensor. This sensor needs to further consider the flow rate and viscosity range of the drilling fluid and optimize the dimensions of the sensor. Carlsen et al. [40] measured the pressure at various positions in the drilling fluid’s circulation system. Various flow rates and pressures were used to measure the friction coefficient of the drilling fluid. The results show that it can also be used to calculate other drilling fluid rheological properties such as shear stress and viscosity. Vajargah et al. [41,42] proposed a method to determine rheology in real time from downhole measurements of pressure drop and temperature, considering the well as an annulus pipe viscometer. It can directly obtain the ECD of the well. The results were compared to offline data taken from an offline high-pressure, high-temperature rheometer. It can estimate the gel strength by peak pressure loss. However, the time-dependent behavior of the drilling fluid theory needs to be developed through this method. We think, with the development of measurement while drilling (MWD) technology, it is a good method to obtain the rheological properties of drilling fluid by measuring downhole pressure. This method does not require further surface measurements, which can greatly simplify the rheological measurement methods and equipment and eliminate the labor required for operation and maintenance.

Pipe viscometers usually use a round pipe, the sensor installed in the round pipe may affect the flow rate, resulting in inaccurate pressure measurement. Therefore, Liu et al. [43] developed a rectangle pipe viscometer. During the test, a 5% bentonite slurry with a density of 1.03 g/cm3 was prepared, and 0.1% polyacrylamide glue solution, 0.1% polyacrylonitrile ammonium, and xanthan gum was added successively. The pipe viscometer continuously recorded the change process of the rheological properties of the drilling fluid, the measurement results were the same as the standard viscometer measurement results, and the error was small. Sun et al. [44] developed a type of altered-diameter rectangle pipe viscometer to realize continuous online monitoring. Through altered-diameter pipes, different flow rates can be generated under constant flow. Fresh water and bentonite drilling fluid are tested in the laboratory. Compared with the standard viscometer, the results show that the error of AV and PV are both within the allowable range. The field test results show that the performance of the tested data was stable and reliable. Compared with the API standard method, the error was within the allowable range.

While a pipe viscometer takes up a lot of space, Sercan Gul [45,46] developed a helical pipe viscometer to measure rheological properties. The system included four test parts (two horizontal straight pipes and two vertical spiral pipes), four differential pressure sensors, a 40 L liquid storage tank, a Coriolis flowmeter, and a variable frequency drive screw pump. It tested the rheological properties of 20 polymer-based fluids. These fluids were based on water and added xanthan gum to increase the viscosity. The equivalent straight pipe pressure losses needed to be calculated accurately by using the pressure loss data obtained from a helical pipe viscometer. However, none of the papers [47,48,49] reported correlations of PL fluids were valid for Herschel–Bulkley fluids. Thus, a random forest regression model was used to predict the friction coefficient with friction pressure loss, the mean absolute error was 0.803 × 10−3, and the mean absolute percentage error was 4.55%. The algorithm was developed using the trained machine learning model and the pipe viscometer equations. The rheogram results matched the standard Couette viscometer.