mud pump pressure formula made in china

As shown in the figure: (0) is the slush pump body. (1) be the slush pump main shaft, power from then on axle passes into. (2) be the push-and-pull dish, it is driven by two parallel oil cylinder rice. (3) be driver plate, itself and main shaft (1) spline joint, when main shaft rotated, it also and then rotated, and driver plate is moving by the push-and-pull dribbling, Can be along the segment distance that moves axially of main shaft. (4) be rolling bearing. (5) be shaking tray, driven by driver plate, can rotate to an angle. (6) be radial spherical roller thrust bearing. (7) be balance, it is supported by center sphere (8), and take the balance center as fulcrum, any point can move left and right on the balance, but balance can not rotational angle. (9) be piston rod, the one head is connected with balance, and the other end is connected with piston (10). (11) be cylinder body, identical cylinder body can have 7.

This switching mechanism is work like this, when the end face of balance is vertical with the spindle axis line, at this moment prime mover drives main axis rotation, main shaft connects the drive dial by spline and rotates, and dial drives shaking tray again and rotates, at this moment, because of balance vertical with the spindle axis line, so during the balance transfixion, piston is also just motionless, pump duty is zero.If the control oil cylinder makes dial when main shaft moves any segment distance backward, shaking tray and balance just form certain angle with spindle centerline.When main shaft and dial rotation, shaking tray is and then rotation also, because the effect of shaking tray end force, balance just centers on the right swing of center sphere carries left, and piston rod drives piston and moves back and forth in cylinder body.The movement locus of seven pistons carries out successively, promptly above left, following moves right, and carries out in turn in week in a garden.When angle increased, promptly the amount of swinging of balance increased, and the corresponding increase of piston stroke is so the flow of pump increases.Because of angle can progressively increase to certain certain value from zero, so the flow of pump also can progressively increase to maximum value from zero.To have realized the mud pump for petroleum drilling of permanent power control stepless variable.

Bit speed is relevant with the slurry pump pump pressure, the pump pressure height, and then speed is fast, and expensive few, cost is low, the economic benefit height, slurry pump pump pressure of the present invention can reach 340 barometric pressure, and rated pump pressure reaches 250 barometric pressure, so discharge capacity is big, and volume is little, and is in light weight, about 5 tons; If separate unit moves, can satisfy the hydraulic parameters needs of high-pressure jet drilling fully, especially with the supporting use of turbodrill, more can realize the technological requirement of high-pressure injection formula drilling well; Can control with computer, realize permanent power control and stepless variable, bore well depth and need not change cylinder sleeve.

RIGCHINA Stand Pipe Gauges provide a quick, accurate display of pump pressure. Main applications are for standpipes and to be mounted on mud pumps. This style of gauge has been in service for many years and has proven to be a tough, dependable and reliable way to monitor pump pressure.

The mud pump piston is a key part for providing mud circulation, but its sealing performance often fails under complex working conditions, which shorten its service life. Inspired by the ring segment structure of earthworms, the bionic striped structure on surfaces of the mud pump piston (BW-160) was designed and machined, and the sealing performances of the bionic striped piston and the standard piston were tested on a sealing performance testing bench. It was found the bionic striped structure efficiently enhanced the sealing performance of the mud pump piston, while the stripe depth and the angle between the stripes and lateral of the piston both significantly affected the sealing performance. The structure with a stripe depth of 2 mm and angle of 90° showed the best sealing performance, which was 90.79% higher than the standard piston. The sealing mechanism showed the striped structure increased the breadth and area of contact sealing between the piston and the cylinder liner. Meanwhile, the striped structure significantly intercepted the early leaked liquid and led to the refluxing rotation of the leaked liquid at the striped structure, reducing the leakage rate.

Mud pumps are key facilities to compress low-pressure mud into high-pressure mud and are widely used in industrial manufacture, geological exploration, and energy power owing to their generality [1–4]. Mud pumps are the most important power machinery of the hydraulic pond-digging set during reclamation [5] and are major facilities to transport dense mud during river dredging [6]. During oil drilling, mud pumps are the core of the drilling liquid circulation system and the drilling facilities, as they transport the drilling wash fluids (e.g., mud and water) downhole to wash the drills and discharge the drilling liquids [7–9]. The key part of a mud pump that ensures mud circulation is the piston [10, 11]. However, the sealing of the piston will fail very easily under complex and harsh working conditions, and consequently, the abrasive mud easily enters the kinematic pair of the cylinder liner, abrading the piston surfaces and reducing its service life and drilling efficiency. Thus, it is necessary to improve the contact sealing performance of the mud pump piston.

As reported, nonsmooth surface structures can improve the mechanical sealing performance, while structures with radial labyrinth-like or honeycomb-like surfaces can effectively enhance the performance of gap sealing [12–14]. The use of nonsmooth structures into the cylinder liner friction pair of the engine piston can effectively prolong the service life and improve work efficiency of the cylinder liner [15–17]. The application of nonsmooth grooved structures into the plunger can improve the performance of the sealing parts [18, 19]. The nonsmooth structures and sizes considerably affect the sealing performance [20]. Machining a groove-shaped multilevel structure on the magnetic pole would intercept the magnetic fluid step-by-step and slow down the passing velocity, thus generating the sealing effect [21–23]. Sealed structures with two levels or above have also been confirmed to protect the sealing parts from hard damage [24]. The sealing performance of the high-pressure centrifugal pump can be improved by adding groove structures onto the joint mouth circumference [25]. The convex, pitted, and grooved structures of dung beetles, lizards, and shells are responsible for the high wear-resistance, resistance reduction, and sealing performance [26–28]. Earthworms are endowed by wavy nonsmooth surface structures with high resistance reduction and wear-resistance ability [29]. The movement of earthworms in the living environment is very similar to the working mode of the mud pump piston. The groove-shaped bionic piston was designed, and the effects of groove breadth and groove spacing on the endurance and wear-resistance of the piston were investigated [30]. Thus, in this study, based on the nonsmooth surface of earthworms, we designed and processed a nonsmooth striped structure on the surface of the mud pump piston and tested the sealing performance and mechanism. This study offers a novel method for prolonging the service life of the mud pump piston from the perspective of piston sealing performance.

The BW-160 mud pump with long-range flow and pressure, small volume, low weight, and long-service life was used here. The dimensions and parameters of its piston are shown in Figure 1.

A mud pump piston sealing performance test bench was designed and built (Figure 3). This bench mainly consisted of a compaction part and a dynamic detection part. The compaction part was mainly functioned to exert pressure, which was recorded by a pressure gauge, to the piston sealed cavity. This part was designed based on a vertical compaction method: after the tested piston and the sealing liquid were installed, the compaction piston was pushed to the cavity by revolving the handle. Moreover, the dynamic detection part monitored the real-time sealing situation and was designed based on the pressure difference method for quantifying the sealing performance. This part was compacted in advance to the initial pressure P0 (0.1 MPa). After compaction, the driving motor was opened, and the tested piston was pushed to drive the testing mud to reciprocate slowly. After 1 hour of running, the pressure P on the gauge was read, and the pressure difference was calculated as , which was used to measure the sealing performance of the piston.

To more actually simulate the working conditions of the mud pump, we prepared a mud mixture of water, bentonite (in accordance with API Spec 13A: viscometer dial reading at 600 r/min ≥ 30, yield point/plastic viscosity radio ≤ 3, filtrate volume ≤ 15.0 ml, and residue of diameter greater than 75 μm (mass fraction) ≤ 4.0%), and quartz sand (diameter 0.3–0.5 mm) under complete stirring, and its density was 1.306 g/cm³ and contained 2.13% sand.

The test index was the percentage of sealing performance improvement β calculated aswhere and are the pressure differences after the runs with the standard and the bionic pistons, respectively ().

Figure 4 shows the effects of stripe depth and angle on the sealing performance of mud pump pistons. Clearly, the stripe depth should be never too shallow or deep, while a larger angle would increase the sealing performance more (Figure 4).

Both the standard piston and the bionic striped piston leaked, which occurred after 84 and 249 minutes of operation, respectively (Figure 5). Figure 6 shows the pressures of the two pistons during testing. Clearly, the sealing pressure of the standard piston declined rapidly before the leakage, but that of the bionic piston decreased very slowly. After the leakage, the reading on the pressure gauge in the standard piston declined to 0 MPa within very short time, but that of the bionic piston decreased much more slowly.

The piston lips and the cylinder liner were under interference contact, and their mutual extrusion was responsible for the lip sealing. Thus, a larger pressure between the piston lips and the cylinder liner reflects a higher lip sealing effect.

The bionic striped piston with the highest sealing performance (h = 2 mm, α = 90°) was selected for the sealing mechanism analysis and named as the bionic piston. The 3D point cloud data of standard piston were acquired by using a three-dimensional laser scanning system (UNIscan, Creaform Inc., Canada). Then, the standard piston model was established by the reverse engineering technique. The striped structure of the bionic piston was modeled on basis of the standard piston.4.1.1. Contact Pressure of Piston Surface

The standard piston and the bionic piston were numerically simulated using the academic version of ANSYS® Workbench V17.0. Hexahedral mesh generation method was used to divide the grid, and the size of grids was set as 2.5 mm. The piston grid division is shown in Figure 8, and the grid nodes and elements are shown in Table 3. The piston cup was made of rubber, which was a hyperelastic material. A two-parameter Mooney–Rivlin model was selected, with C10 = 2.5 MPa, C01 = 0.625 MPa, D1 = 0.3 MPa−1, and density = 1120 kg/m3 [32, 33]. The loads and contact conditions related to the piston of the mud pump were set. The surface pressure of the piston cup was set as 1.5 MPa, and the displacement of the piston along the axial direction was set as 30 mm. The two end faces of the cylinder liner were set as “fixed support,” and the piston and cylinder liner were under the frictional interfacial contact, with the friction coefficient of 0.2.

Figure 9 shows the pressure clouds of the standard piston and the bionic piston. Since the simulation model was completely symmetrical and the pressures at the same position of each piston were almost the same, three nodes were selected at the lip edge of each piston for pressure measurement, and the average of three measurements was used as the lip edge pressure of each piston. The mutual extrusion between piston and cylinder liner happened at the lip, and thereby the larger of the lip pressure was, the better the sealing performance was. The lip pressure of the standard piston was smaller than that of the bionic piston (2.7371 ± 0.016 MPa vs. 3.0846 ± 0.0382 MPa), indicating the striped structure enhanced the mutual extrusion between the bionic piston and the cylinder liner and thereby improved the sealing performance between the lips and the cylinder liner. As a result, sand could not easily enter the piston-cylinder liner frictional interface, which reduced the reciprocated movement of sand and thereby avoided damage to the piston and the cylinder liner.

Figure 10 shows the surface pressures from the lip mouth to the root in the standard piston and the bionic piston. The surface pressure of the bionic piston surpasses that of the standard piston, and the pressure at the edge of each striped structure changes suddenly: the pressures at the striped structure of the bionic piston are far larger than at other parts. These results suggest the contact pressure between the edges of the striped structures and the cylinder liner is larger, and the four edges of the two striped structures are equivalent to a four-grade sealed lip mouth formed between the piston and the cylinder liner, which generates a multilevel sealing effect and thereby largely enhances the sealing effect of the piston.

The piston surface flow field was numerically simulated using the CFX module of the software ANSYS® Workbench V17.0. The side of the lips was set as fluid inlet, and the other side as fluid outlet, as shown in Figure 11. The inlet and outlet were set as opening models, and the external pressure difference between them was 0 Pa. The moving direction of the piston was opposite to the fluid flow direction. The fluid region was divided into grids of 0.2 mm, while the striped structures were refined to grade 2.

To better validate the sealing mechanism of the bionic striped pistons, a piston’s performance testing platform was independently built and the sealed contact of the pistons was observed. A transparent toughened glass cylinder liner was designed and machined. The inner diameter and the assembly dimensions of the cylinder liner were set according to the standard BW-160 mud pump cylinder liners. The sealing contact surfaces of the pistons were observed and recorded using a video recorder camera.

(1)The bionic striped structure significantly enhanced the sealing performance of the mud pump pistons. The stripe depth and the angle between the stripes and the piston were two important factors affecting the sealing performance of the BW-160 mud pump pistons. The sealing performance was enhanced the most when the stripe depth was 2 mm and the angle was 90°.(2)The bionic striped structure can effectively enhance the contact pressure at the piston lips, enlarge the mutual extrusion between the piston and the cylinder liner, reduce the damage to the piston and cylinder liner caused by the repeated movement of sands, and alleviate the abrasion of abrasive grains between the piston and the cylinder liner, thereby largely improving the sealing performance.(3)The bionic striped structure significantly intercepted the leaked liquid, reduced the leakage rate of pistons, and effectively stored the leaked liquid, thereby reducing leakage and improving the sealing performance.(4)The bionic striped structure led to deformation of the piston, enlarged the width and area of the sealed contact, the stored lubricating oils, and formed uniform oil films after repeated movement, which improved the lubrication conditions and the sealing performance.

The bionic striped structure can improve the sealing performance and prolong the service life of pistons. We would study the pump resistance in order to investigate whether the bionic striped structure could decrease the wear of the piston surface.

The feasibility of applying delay pressure detection method to eliminate mud pump pressure interference on the downhole mud pressure signals is studied. Two pressure sensors mounted on the mud pipe in some distance apart are provided to detect the downhole mud continuous pressure wave signals on the surface according to the delayed time produced by mud pressure wave transmitting between the two sensors. A mathematical model of delay pressure detection is built by analysis of transmission path between mud pump pressure interference and downhole mud pressure signals. Considering pressure signal transmission characteristics of the mud pipe, a mathematical model of ideal low-pass filter for limited frequency band signal is introduced to study the pole frequency impact on the signal reconstruction and the constraints of pressure sensor distance are obtained by pole frequencies analysis. Theoretical calculation and numerical simulation show that the method can effectively eliminate mud pump pressure interference and the downhole mud continuous pressure wave signals can be reconstructed successfully with a significant improvement in signal-to-noise ratio (SNR) in the condition of satisfying the constraints of pressure sensor distance.

In measurement while drilling (MWD), various downhole signals will be transmitted to the surface in real time for instructing the drilling operation. One of the most common methods of transmitting the measured downhole information to the surface is through mud pressure pulses produced by mechanical modulation of a mud siren in MWD tools and transmitted at acoustic speed in the mud flow. The mud siren generates mud continuous pressure wave signals with complex modulation methods to produce higher data rates. When transmitting the mud pressure signals, there will be a lot of pressure noise and interference, among which the mud pressure fluctuation generated by the mud pump contributes to the largest influence. The mud pump pressure interference is related to the pump stoke rate which includes fundamental component and harmonic component. When the mud pump is in imbalance operation mode caused by sealing problem or in abnormal working status, some higher harmonic amplitude will become very large. Although the pressure dampers are equipped on mud pump pipe, the pressure fluctuation generated by mud pump reaches or exceeds the downhole signal strength detected in the stand pipe [1]. These higher harmonics will enter the frequency band of mud pressure signal and thereby create great interference that cannot be eliminated by conventional signal processing method, leading to the great decrease of signal-to-noise ratio (SNR) of signal and affecting extraction of the MWD signals. Many studies had been done to eliminate the pump interference. Marsh and others proposed the matched filter method which treated mud pump interference as random noise and calculated the autocorrelation coefficient to eliminate the mud pump pressure interference [2]. However, the pump interference is a kind of system interference rather than random noise, so the conclusions of the method needed further discussion. Brandon and others proposed an adaptive compensation method which uses extracted interference component in the signal and automatically adjusts strength of the interference component to eliminate the pump pressure interference impact on the signal [3], but the effect was limited. Some literatures [4–7] introduced the delay pressure detection technique and built a mathematical model, being fitted to the single-frequency signal with pressure sensors distance of quarter signal wavelength, for eliminating the mud pump pressure interference. Because components of many frequencies are contained in mud continuous pressure wave signals, the mathematical model presented in those literatures cannot be applied in reconstruction of actual mud continuous pressure wave signals. Based on transmission path analysis of mud pump pressure interference and downhole mud pressure signals, the authors established the mathematical model in time domain for processing mud continuous pressure wave signals according to the fundamental mathematical principle of delay pressure detection method and then studied the reconstruction method of mud continuous wave signals in both time domain and frequency domain and constraints of the distance between pressure sensors.

The delay pressure detection method uses two pressure sensors being some distance apart on the mud pipe to detect and process the mud pressure signal; Figure 1 shows the schematic figure of mud pressure signal detection system. Two pressure sensors, A and B, having distance between each other, are equipped in a straight pipe between wellhead and mud pump. The pressure signals received by two sensors contain downhole signal (mud pressure signal) , downhole random noise , and mud pump pressure interference . The transmission direction of pump pressure interference is opposite to that of downhole signal. Suppose that the propagation velocity of the mud pressure wave is and the pressure wave transmission time between sensors A and B is .

Suppose that is unit impulse response of the linear system . When the signal is being transmitted through the linear system [8], signals received by the pressure sensors A and B can be expressed as

According to (5), the time-domain solution of the system frequency response can be described as the reconstruction of the downhole signal after the delay pressure detecting signal is passed through a signal recovering system with frequency transfer function .

Considering that the maximum frequency of mud continuous pressure wave signal in transmission will be dozens of hertz (Hz), the signal frequency is lower and limited. In limited frequency band, the signal attenuation in amplitude will keep unchangeable when mud continuous pressure wave signal passes the straight pipe between pressure sensors A and B, so the pipe can be seen as an undistorted transmission system and regarded as an ideal low-pass filter. The frequency domain transfer function of the system can be described as

Equations (13) and (11) have the same structure, so the essence of signal reconstruction process in time domain is to make the delay pressure detecting signal pass through a closed-loop delay feedback system with recursive structure.

The straight pipe between pressure sensors A and B will cause pressure signal attenuation. According to the transmission characteristics of mud pressure wave [11], the attenuation coefficient of pressure signal or the amplitude ratio of mud pipe can be described as

where is the pipe length between pressure sensors A and B, is the attenuation index, is the volume fraction of gas in mud, is the volume fraction of solids in mud, is the bulk modulus of gas in mud, is the bulk modulus of liquid in mud, is the bulk modulus of solid in mud, is the bulk modulus of the mud pipe, is the internal diameter of the mud pipe, is the wall thickness of the mud pipe, is the Poisson’s ratio of the mud pipe, is the kinematic viscosity of mud, and is signal frequency.

Suppose that the mud is water-based mud. The computational conditions are listed as follows [12]: internal diameter of the mud pipe is 108.6 mm, wall thickness of the mud pipe is 9.2 mm, the mud kinematic viscosity is 20 mPa·, the pipe Poisson’s ratio is 0.3, volume fraction of gas in mud is 0.5%, volume fraction of solid in mud is 15%, the mud pipe bulk modulus is 210 GPa, and bulk modulus of water in mud is 2.04 GPa, bulk modulus of solid in mud is 16.2 GPa. If signal frequency of mud continuous pressure wave is , when the distance between pressure sensors A and B is less than , the pressure signal attenuation coefficient will be by numerical calculation. This means that transmission loss of mud pressure wave signal is very small and the attenuation coefficient will be close to 1 when the two sensors are nearer to each other.

If the maximum frequency of mud pressure signal spectrum is , there is . When the corresponding pole frequency falls into the passband of ideal low-pass filter, the pole frequency will be very likely to enter signal spectrum and generate great interference in the reconstruction of downhole signal. To avoid such situation, all the pole frequency values should be greater than the passband frequency of ideal low-pass filter. That is, .

Propagation velocity of the mud pressure wave in the mud pipe can be calculated according to the literature [13]. Take the mud pressure DPSK (differential phase shift keying) signal with carrier wave frequency of 24 Hz for example, the maximum frequency of signal spectrum is 36 Hz. When  Hz, we have  s. Furthermore, if the mud pressure wave velocity is  m/s, the corresponding distance between pressure sensors is  m.

The numerical simulation takes mud pressure DPSK signal as an example. According to the mathematical model of mud pressure DPSK signal [14], the signal can be formulated as . In the formula, carrier frequency is  Hz, signal amplitude is  Pa, and data code is . By analyzing the power spectral of mud pressure DPSK signal, the maximum frequency of signal spectrum is  Hz and the signal power is . Mud pump interference simulates multifrequency pressure pulsation generated by triplex pump with pump impulse rate 64 r/min, and the fundamental wave frequency is with harmonic orders 2 to 9. Therefore, the frequency changing range of pump interference is from to . Suppose that the fundamental wave and every harmonic wave amplitude are . The corresponding power density of fundamental wave or every harmonic wave is an impact function and the average power of the pump interference is

Figure 2 shows the signal waveform and the signal spectrum mixed with mud pump interference. It can be seen that the mud pressure DPSK signal is completely submerged in the pump interference in time domain and the signal spectrum is completely covered by mud pump interference frequencies.

Suppose that the signal acts on the at , has zero state response only, and the system output before is . Simulation result of the reconstructed signal by MATLAB programming is shown in Figure 3. It can be seen that the mud pump interference is eliminated after delay pressure detection from Figure 3(a); the reconstructed signal in Figures 3(b) and 3(c) are consistent with the mud pressure DPSK signal in Figure 2(a). In Figure 3(b), the numerical calculation result shows that the SNR of reconstructed mud pressure DPSK signal under condition of  ms is 72.4, which is about 657 times higher than that of existing pump interference. Numerical calculation and analysis show that the SNR of reconstructed mud pressure DPSK signal will be affected by the delayed time in time domain and the influence is listed in Table 1. The reason is that the set value of , participating in the recursive computation in (11), will be increased with the delayed time , but the influence is not notable. In Figure 3(c), the reconstructed mud pressure DPSK signal based on inverse Fourier transform method has no distortion in whole waveform and is better than the signal reconstructed by time-domain differential equation method in quality. However, both reconstruction methods can reconstruct downhole signal effectively.

(1) Theoretical analysis and numerical simulation show that delay pressure detection method can effectively eliminate mud pump interference and realize reconstruction or recovery of mud continuous pressure wave signals with greater SNR.

(2) To avoid the pole frequency entering into the signals frequency band in signal reconstruction, the distance between pressure sensors should be determined according to the highest signal frequency and the minimum wave velocity.

(3) According to the mathematical principle analysis of delay pressure detection method, it is only applied to eliminate special interference (mud pump pressure interference) whose transmitting direction is opposite to that of the downhole signal. For mud continuous pressure wave signal which is seriously affected by mud pump interference, this method has some inspiration effect on solving the problem of mud pump pressure interference.

Positive displacements pumps are generally used on drilling rigs to pump high pressure and high volume of drilling fluids throughout a drilling system. There are several reasons why the positive displacement mud pumps are used on the rigs.

The duplex pumps (Figure 1) have two cylinders with double acting. It means that pistons move back and take in drilling mud through open intake valve and other sides of the same pistons, the pistons push mud out through the discharge valves.

When the piston rod is moved forward, one of intake valves is lift to allow fluid to come in and one of the discharge valve is pushed up therefore the drilling mud is pumped out of the pump (Figure 2).

On the other hand, when the piston rod is moved backward drilling fluid is still pumped. The other intake and discharge valve will be opened (Figure 3).

The triplex pumps have three cylinders with single acting. The pistons are moved back and pull in drilling mud through open intake valves. When the pistons are moved forward and the drilling fluid is pushed out through open discharge valves.

On the contrary when the piston rods are moved backward, the intake valve are opened allowing drilling fluid coming into the pump (Figure 6). This video below shows how a triplex mud pump works.

Because each pump has power rating limit as 1600 hp, this will limit capability of pump. It means that you cannot pump at high rate and high pressure over what the pump can do. Use of a small liner will increase discharge pressure however the flow rate is reduces. Conversely, if a bigger liner is used to deliver more flow rate, maximum pump pressure will decrease.

As you can see, you can have 7500 psi with 4.5” liner but the maximum flow rate is only 297 GPM. If the biggest size of liner (7.25”) is used, the pump pressure is only 3200 psi.

Finally, we hope that this article would give you more understanding about the general idea of drilling mud pumps. Please feel free to add more comments.

Mud pump valve body and mud pump valve seat were produced according to API Specs as well as ISO9001 quality system by our company, were used high quality alloy steel 40CrNiMo、20CrMnTi, processed with overall forging and carburizing, the surface hardness HRC≥60; They were produced under accurate calculation and numerical control lathe, which makes dimensions of valve body and seat perfectly match each other, also were used many times by land and offshore platforms. The service life of valve body and seat are 4-5 times more than ordinary ones, which improves the working efficiency and decrease the cost and working strength.

Mud pump valve assy include valve body, valve seat, valve insert (valve rubber ). As to valve insert (valve rubber) material, we can provide Nitrile rubber (NBR) valve insert, polyurethane (PU)valve insert, compound polyurethane and HNBR.