，形成合理、高效的固控流程，可以清除钻井液中的有害固相，保留有用固相，满足钻井工艺对钻井液性能的要求。 Drilling fluid solid phase control (abbreviated as solid control) system is to control harmful solid phase particles in drilling fluid. By scientifically arranging solid control equipment , a reasonable and efficient solid control process can be removed to remove harmful solid phase Retain useful solid phase to meet drilling fluid performance requirements.
The deep well drilling fluid solid control system uses five levels of solid control. The solid control process is as follows:
First-level solid control-remove large particles. The drilling fluid returned through the bottomhole circulation contains larger cuttings. The drilling fluid enters the vibrating screen through the connection pipe from the wellhead to the 1 # tank. The vibrating screen is used to screen out the cuttings with a particle size greater than 74 μm. First-level solid control.
Secondary solids control-remove gas. The vacuum degasser is a special drilling fluid processing equipment used to remove the gas invading the drilling fluid during the drilling process. It can quickly and effectively remove the gas (including air) contained in the drilling fluid. The degasser is useful for recovering the drilling fluid. It plays an important role in preventing the occurrence of potential blowout and well collapse danger.
Three-level solid control-remove larger particles. 中，除砂器将钻井液较大的砂粒(粒度44μm～74μm)分离出来，完成除砂过程，即为三级固控。 The drilling fluid that has been processed by the vibrating screen enters into the sand remover . The sand remover separates the larger sand particles (grain size 44μm ～ 74μm) of the drilling fluid, and completes the sand removal process, that is, three-level solid control.
Four-level solid control-remove small particles. The drilling fluid treated by the sand remover enters into the desilter, and the small mud particles (grain size 15μm ～ 44μm) of the drilling fluid are separated by the desilter, and the desilting process is completed, which is the four-level solid control.
Five-level solid control-remove smaller particles. The drilling fluid treated by the desilter enters the centrifuge. The centrifuge separates the smaller sand (grain size 2μm ～ 15μm) of the drilling fluid, and completes the centrifugation process, which is the five-level solid control.
All of the five-level solid control are mainly used for complex well conditions and demanding well conditions. In actual use, according to the needs of drilling operations,
Adopt one or more levels of solid control processes. 后的钻井液固相含量，可以完全达到国内钻井作业对钻井液质量的要求。 The solid phase content of drilling fluid after five-level solid control equipment can fully meet the drilling fluid quality requirements of domestic drilling operations.
The cut point is used to indicate the separation characteristics of the solid control equipment at a given time. In the evaluation of separation point data, it is necessary to consider not only the performance of solid control equipment, but also the performance of drilling fluid. The separation point curve can be drawn based on the collected data, which characterizes the probability of a specific size solid phase passing through or being removed by a solid control device at a certain determined time when the data is collected. Therefore, the separation point curve is a function of the physical properties of the solid phase (such as density), the particle size distribution of the solid phase, and the condition of the solid phase equipment (such as sealing ability) and the performance of the drilling fluid.
The separation points of all solid control equipment can be determined by comparing the mass flow rates of solid phases of different sizes discharged from the solid control equipment and the mass flow rates of solid phases of the same size entering the equipment. When testing specific solid control equipment, you should know the injection flow rate of the solid control equipment and the discharge and underflow flow rates of the solid control equipment. Obviously, the sum of the mass flow rate of the equipment discharge must be equal to the mass flow rate of the equipment injection. Typically, part of the effluent stream is discarded, while another part remains in the drilling fluid. Before measuring the solid phase size of various liquid flows, you should first check whether the mass balance equation is satisfied, that is, the volume flow rate balance and the mass flow rate balance.
The solid control equipment only removes a part of the solid phase in the drilling fluid entering the equipment. For example, a 4-inch cyclone in a desilter has a processing capacity of 50 gal / min, but can only remove about 1 gal / min solid phase material. The ratio of the discharged solid phase material to the treated amount is so small that it is difficult to measure the difference between the retained liquid and the injected stream. Therefore, in order to obtain a more accurate concentration of the injected solid phase, the concentration of the solid phase in the discharged stream plus the concentration of the solid phase in the bottom stream is used to calculate the solid phase concentration in the injected stream.
In order to determine the mass flow rate of a specific size solid phase in an injection stream and the mass flow rate of particles of the same size in a waste stream, the flow rate and solid phase concentration need to be measured. Although the waste volume flow rate is generally relatively low, measuring the injection flow rate requires the use of a flow meter or metering pump.
For a drilling fluid shaker , the flow rate of the shaker is equal to the rate of drilling fluid in the annulus of the wellbore. The drilling fluid pump displacement can be controlled to provide accurate injection flow rates. When drilling, move the drilling pump from the suction mud tank to the weighted mud tank, and measure the descending speed of the drilling fluid weighted mud tank. Drilling fluids in weighted mud tanks contain liquids and gases. Therefore, the volume of gas must be subtracted from the volume of drilling fluid that is drawn when the mud tank is weighted. The gas volume fraction is obtained by dividing the difference between the pressurized drilling fluid and the non-pressurized drilling fluid by the volume of the pressurized drilling fluid and multiplying by 100. If the desilter or drilling fluid centrifuge uses a sand pump as the slurry pump, other types of flow meters are needed to accurately measure the flow rate. The anemometer can be replaced by a large scale container and a stopwatch. Due to the high particle content in the underflow of centrifugal sand pumps, it is difficult to measure the underflow volume flow rate of the equipment. Draw a calibration line inside the container for volume measurement. Inject a large amount of water into the mud tank and connect the mud tank to a centrifuge installed on the top of the mud tank. When the drilling fluid in the mud tank flows into the drilling fluid centrifuge, the stopwatch starts timing and you can observe the change in water level. Divide the known volume between the two lines by time to get the discharge volume rate. Typical samples of underflow or high-density drilling fluid are used for underflow density measurement. Once the mass and volume flow of the confidence measurement is balanced, the particle size in waste and underflow can be determined.
Measuring the rate of drilling fluid shaker and desilter injection and discharge flows requires larger vessels, and their volume cannot be directly weighed or measured. Remaining in the drilling fluid must use typical samples to determine the mass of particles of different sizes.
For drilling fluid centrifuges and desilters, micron-scale instruments must be used to measure the size of the solid phase. Drilling fluid vibrating screens can be measured using screens because the separation point range is within the screen level determined by the American Society for Measurement Experiments (ASTM). Different diameters require different instruments for measurement. Smaller diameter particles must be measured with more accurate experimental equipment. The laboratory needs a laser.
Solid and liquid phases contained in waste drilling fluid samples. For the waste stream of drilling fluid shakers, the mass of particles left on the ASTM test screen can be measured directly by weighing the dried solid phase. For desilter underflow and underflow (heavy drilling fluid) waste fluid from a drilling fluid centrifuge, the density of the solid phase must be used to determine the mass fraction of the particles.
Using a series of standard drilling fluid shakers, the separation point of the drilling fluid shaker can be measured by measuring the solid phase particle size in the injection stream, the waste stream, and the underflow. Once the flow rates of the bottom stream of the injection stream and the waste stream are determined, the mass flow rate of the particles in each screen discharge liquid of each stream is different from the mass flow rate of particles of the same size in the injection solution.
With this method, the sample injected into the flow is only a small part of the total flow, because errors can lead to unconserved mass. A better method is to use the waste stream and the underflow as samples, and combine the particle distribution in the two streams to establish a more accurate separation point curve. This method can be used for solid control equipment where the flow rate of the injected liquid is much greater than the flow rate of the waste liquid.
Take waste liquid and underflow samples from solid control equipment for analysis. Measure the density of all streams. The volume flow rate of the waste liquid stream is measured by placing all waste liquid in a container, which is a part of the trench intact in the working state of the drilling fluid shaker waste section. The mass flow rate of the waste fluid divided by the density of the waste fluid or the drilling fluid density is the volume flow rate of the waste fluid. The displacement of on-site drilling solid control equipment is the injection volume flow rate. The injection mass flow rate is used to clean the excess drilling fluid from the liquid phase of the drilling fluid, thoroughly dry the screening sample, and the measurement is the injected volume flow rate. The injected mass flow rate is calculated by multiplying the drilling fluid density by the circulating fluid velocity. Use a series of widely distributed sieving wet samples, clean excess drilling fluid with the liquid phase of the drilling fluid, thoroughly dry the sieved samples, measure the mass of solid particles under the sieve, and calculate the flow rate of the injected waste and underflow . To determine the screen separation point curve, the amount of particles of a particular size in the waste stream must be compared to the amount of particles of the same size entering the screen. Although all waste streams can be collected, the mass of all waste-specific particles can also be determined. However, while the waste stream is being collected, it is impractical to try all the fluids of the cell phone screen. For example, if the circulating flow in the wellbore on site is 500 gallons per minute and the mobile phone wastes the sample for 3.5 minutes, then the exhaust flow through the drilling fluid shaker should be 1750 gallons. If the drilling fluid density is 9.2 lb / gal, it means that 16,100 lb drilling fluid passes through the drilling fluid shaker. The total solid phase processed by the drilling fluid shaker in 3.5 minutes was 113.75 gallons (6.5% of 1750 gallons). It is considered impractical to collect and screen such a large amount of solid phase, so it is more practical to determine the particle concentration and size distribution of the drilling fluid shaker through the bottom fluid oxygen pump of the drilling fluid shaker as a sample. The flow rate of the underflow sample and the mass of the solid phase of each screen must be measured. The flow rates of the above dry solid phase are only used for calculation, not for the reason of collecting all particles in a specific time.
The mass flow rate of the injection stream corresponding to each screen cloth can also be determined, and the flow rate of the waste liquid stream and the injection stream of the underflow screen cloth can determine the percentage of the waste solid phase in the solid control equipment. The size of the solid phase is plotted against the percentage of solid phase removed.
The separation point curve shows the fraction of solid particles of various sizes entering and being removed by the solid control device. For example, the D50 separation point is the intersection of a 50% point on the Y axis and the corresponding particle size on the X axis of the separation point. This separation point indicates that there is a 50% chance that the particle size injected into the solid control equipment will pass through the equipment and a 50% chance that it will be excluded from the equipment. Usually the solid phase distribution curve is incorrectly marked as the separation point curve. The separation point curve indicates the classification of the particles of different sizes that are separated. They largely depend on the drilling fluid parameters and indicate the performance of the solid control equipment at the time of mobile phone data. The separation point of solid control equipment depends on the performance of the equipment and the performance of the drilling fluid.
The following distribution introduces the method of analyzing particle size and calculates the separation point using the separation point curve. Then, the drilling fluid shaker is taken as an example to describe how the data is collected and processed, and a lot of useful information is obtained from the example. This method is most suitable for the analysis of the separation point of the drilling fluid vibrating screen. Since the drilling fluid vibrating screen cannot be very fine, it can be analyzed to the API 400 mesh screen.
The non-screening method should be used to draw the curve of the separation point of the cyclone in the desilter and the sand separator and the centrifuge in the drilling fluid. Approximately 635 mesh sieve measurement of solid phase particle size is the limit of sieving analysis.
Installation of mud cleaner in drilling system
In drilling systems, mud cleaners are often co-located with the desilter. Desilter or hydrocyclone (mud cleaner) is usually used to treat unweighted drilling fluid mud. Drilling fluid vibrating screen is required to handle drilling fluid containing barite or hematite. The size of the solid phase filtered by the hydrocyclone is usually larger than that of barite, and the smaller size is returned to the drilling fluid together with the liquid phase. Tips for use, if barite is added, drilling fluid shaker should be used.
Another method of replacing the drilling fluid mud cleaner with a main drilling fluid shaker is commonly used in offshore drilling processes. Use a linear or translational elliptical drilling fluid shaker to process the fluid in the upper wellbore, and use less drilling fluid shaker to treat fluids with reduced wellbore size and increased drilling fluid mud density. Some adjustments are needed on site, and up to 20 4-inch hydrocyclones can be installed on the drilling fluid shaker. Feed and overflow of a hydrocyclone under normal conditions. In general, all the desilter removes the underflow of the non-weighted drilling fluid and is discarded, while the drilling fluid shaker processes the drilling fluid from the overflow pipe. This is usually the maximum flow rate. As the depth of the well continues to increase, heavier drilling fluids need to be used, at which time the flow rate will decrease. After adding barite, close the valve to prevent drilling fluid from flowing into the shaker. When the underflow of the desilter is transferred to the shaker, the drilling fluid shaker becomes a mud cleaner.
Operation of drilling fluid mud cleaner.
For the first time, a mud cleaner is used in a well site to handle heavy drilling fluids, and the mud cleaner should be turned off. Large amounts of barite are removed during the first cycle. In practice, this indicates that the drilling fluid mud tank is not installed vertically.
The drilling fluid mud gun draws back the drilling fluid from the addition or suction part to the removal tank. A large portion of API-compliant barite will still be removed by a 200-mesh screen (74 microns). If the barite can pass through the drill nozzle, the barite will be dispersed and not removed by the screen.
It is often heard that the aggravating drilling fluid initially passes through the mud cleaner and "all barite will be removed." Why is this so? The density of drilling fluid decreases, and it is necessary to add an extra normal amount of barite to maintain the density. When the solid phase (barite or drill cuttings are removed from the drilling fluid, the density of the drilling fluid will decrease. In fact, regardless of whether these relationships are drilling Swarf, barite, gold, silver, or diamond, removing all solid phases larger than 74 microns is very useful for reducing drilling accidents because these solid phases will form a dense mud cake, which will cause stuck drilling. Mud cleaner removal The solid phase situation is similar to the drilling fluid centrifuge processing of heavy drilling fluid or underflow. Although it seems that a lot of barite will be removed, tests have shown that this is not the case.
The API stipulates that 3% by weight of the barite can be greater than 74 microns. For 100,000 lbs of barite, 3,000 barites are filtered by API200 sieve. For this reason, drilling fluid mud in the feed compartment should not be circulated from the upper stream, and the main drilling fluid shaker will also remove most of the barite with a size larger than API200 mesh. The effect of barite is not obvious because the quality of the drilling fluid usually determines the amount of shaker screen removal.
The principle of removing the solid phase from drilling mud by a mud cleaner is similar to that of a solid phase separated by a drilling fluid centrifuge. The solid phase concentration is about 60% and the liquid is about 40%. In the beginning, large amounts of liquid seemed unreasonable. Researchers frequently take sand to check the oil recovery process under various conditions. If the gap of the sand cylinder reaches 33% ~ 35%, the sand cylinder is very tight. Such as sand on the beach, when the tide recedes, they are 40% water, and they can form a dune without drainage. The drilling fluid mud passing through the drilling fluid mud cleaner screen contains the same liquid volume percentage as the mud water from the drilling fluid centrifuge underflow.
Mud cleaners can continuously process drilling fluids just like drilling fluid shakers. The screen of the mud cleaner can prevent larger cuttings particles from entering the drilling fluid system. Occasionally stopping the mud cleaner can also keep the solid phase in the drilling fluid system. When these larger solid phases are ground to smaller sizes, it is more difficult to remove. A drilling fluid centrifuge can remove smaller solid phases from the weighted drilling fluid, but it cannot handle all drilling fluids. If a slurry cleaner is used continuously, the solid phase can be removed before the larger solid phase is ground.
Note again that drilling fluid mud cleaners and drilling fluid centrifuges are complementary and not mutually exclusive. Mud cleaners are used to remove solid phases that are larger than barite, and drilling fluid centrifuges are used to remove those smaller than barite.
Other uses of mud cleaners
Additional uses of mud cleaners are for tunneling, non-excavation and shield engineering. . The sites of these projects are mainly below roads, at the bottom of lakes or rivers, etc., and are used as gas pipelines, fiber optic cable channels, or other installation sites for circulating drilling fluids. Mud configuration and handling is often a tricky issue in these projects. Therefore, for these small drilling systems, a mud cleaner is installed on the first mud tank of the circulation system. The screen of the mud cleaner removes the solid phase, and the remaining drilling fluid mud is returned to the mud tank. The size of the screen and the diameter of the wire used here are larger than those used in the drilling of oil fields. The purpose of using these screens is to remove water from the cuttings and return as much liquid phase as possible to the drilling fluid mud. The solids produced by these engineering excavations are less destructive than the solids produced in oilfield drilling compared to drilling fluid muds. Therefore, the opening sizes of these screens in mud cleaners are larger than those used in oilfield drilling Size of the opening.Read More »
In order to ensure that the bottom cuttings are carried to the surface, the drilling fluid must have sufficient up-speed. To this end, the displacement of the drilling pump must be determined based on the diameter of the well and the capacity of the rig. 必须从要清除的固相颗粒范围和处理量两方面考虑。 The choice of solids control equipment must be considered from both the range of solid phase particles to be removed and the throughput.
- Drilling fluid vibrating screen: Drilling fluid vibrating screen is the first-level equipment to remove solid phase from drilling fluid and must be used throughout the drilling process. 的清除范围由所使用的筛网决定，而其处理量由于筛网规格有关。 The removal range of drilling fluid vibrating screen is determined by the screen used, and its processing capacity is related to the size of the screen. The larger the screen mesh number, the smaller the processing capacity, the smaller the mesh number, the smaller the solid control particles to be removed, and the more solid phases to be removed.
- Vacuum degasser: The vacuum degasser is used to remove the gas from the gas invasion drilling fluid, and its processing capacity should reach the full flow rate. The vacuum degasser must be placed after the drilling fluid shaker before the sand pump to process the drilling fluid. Because when the drilling fluid contains gas, cavitation will occur in the sand pump. Cavitation not only reduces the performance of the sand pump, generates noise and vibration, shortens the life of the sand pump, but also makes the sand pump inoperable or damaged in severe cases.
The function of the vacuum deaerator is twofold:
The first is to ensure the relative stability of drilling fluid performance, prevent blowouts and well surges, and ensure drilling safety;
The second is to ensure that the cyclone can work normally. When drilling deep, wells and gas-bearing oil wells, vacuum degassers must be provided.
- Sand remover and desilter: The sand remover and desilter are both composed of a set of hydrocyclone and a fine mesh vibrating screen. The sand remover should be used as the second-level solid control equipment after the drilling fluid shaker to remove solid particles from 44 to 74 μm; and the mud remover should be used as the third-level solid control device to remove 15-44 μm solids. Phase particles.
- Drilling fluid centrifuge: as the final stage
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在泥浆净化处理的时候需要对不同阶段的泥浆进行逐步的清理。 The solid control equipment needs to gradually clean up the mud at different stages during the mud purification process.
When gas invasion occurs in the drilling mud, the mud purified by the drilling fluid vibrating screen enters the grit silo of the mud purification tank, and then the suction effect of the deaerator vacuum pump is used to cause negative pressure in the vacuum tank to make the mud in Atmospheric pressure enters the deaerator for separation. The separated gas is vented to the top of the derrick, and the degassed mud is discharged into the mud tank under the drive of the venting cavity rotor.
When the mud in the solid control equipment is aggravated, the centrifuge will not only remove the harmful solid phase, but also remove the barite, the weighting material in the mud, which will cause the specific gravity of the mud to decrease quickly and increase the weight of the material. A large amount of loss, in order to avoid the loss of material and achieve the purpose of removing harmful solid phases, two centrifuges need to be used in series. The medium-speed centrifuge's liquid supply pump lifts the slurry from the slurry tank through the centrifuge to process it. After the mud into the mud purification tank.
中的泥浆中没有气体的情况下，我们可以将除气器作为大功率的泥浆搅拌器使用，然后保持净化罐内的泥浆不沉淀，在通过振动筛得到净化的泥浆。 In the case that there is no gas in the mud in the solid control equipment , we can use the deaerator as a high-powered mud agitator, and then keep the mud in the purification tank from sedimenting, and obtain the purified mud through a vibrating screen. The discharged underflow is discharged into a special tank at the lower part of the medium-speed centrifuge. It is pumped into the second-stage high-speed centrifuge by a special slurry pump for re-separation. After separation, the slurry containing heavy crystals is returned to the slurry purification tank and maintained. The performance of the mud is stable.Read More »