A downhole drilling fluid density measuring device

Abstract

The present application discloses a downhole drilling fluid density measurement device, which is used to simulate the measurement of drilling fluid density under the condition of water loss and wall building. The present application includes: a driving motor, a motor output shaft, a displacement piston, a liquid cylinder, and a filter disc; the driving motor is connected to the first end of the motor output shaft; the displacement piston is connected to the second end of the motor output shaft; a simulated cavity is provided inside the liquid cylinder, and the simulated cavity is used to place the drilling fluid to be measured; a displacement opening is provided at the first end of the simulated cavity; the displacement piston is located at the displacement opening of the liquid cylinder, and the displacement piston is adapted to the size of the displacement opening; a simulated opening is provided on the side of the simulated cavity; the filter disc is provided at the simulated opening; the filter disc is used to simulate the water loss and wall building state.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of formation development, and in particular to a downhole drilling fluid density measuring device. Background Art

[0002] Nowadays, well collapse, leakage and oil and gas layer protection are the three major technical problems that restrict the smooth progress of drilling projects. For formations with developed bedding and fissures, in order to prevent well collapse and leakage and reduce damage to the oil and gas layers, the drilling fluid is required to have strong plugging properties, effectively plug the formation bedding and fissures, and prevent the drilling fluid and its filtrate from entering the formation, so as to achieve the purpose of improving the pressure bearing capacity of the formation, stabilizing the well wall, preventing leakage and protecting the oil and gas layers.

[0003] Downhole, the density of drilling fluid will change. This change comes from the effects of high temperature and high pressure. Under the effects of high temperature and high pressure, the density of drilling fluid will change due to the phenomenon of "thermal expansion and contraction" and "pressure compression of volume". Under the effect of pressure, the drilling fluid is squeezed and the water in the drilling fluid penetrates into the well wall, resulting in the phenomenon of "water loss and wall formation", which causes the density of drilling fluid in the well to change.

[0004] In the process of managed pressure drilling, the density of the downhole drilling fluid is a very important input parameter. If the true density of the downhole drilling fluid is not known, the well control pressure may be too high or too low, resulting in safety accidents such as well leakage and blowout. Therefore, a device is needed to simulate the high temperature and high pressure environment downhole and the water loss process of the drilling fluid under this environment, and measure the density of the drilling fluid under this condition.

[0005] Secondly, drilling fluid may also encounter the situation of "water loss and wall formation". Water loss and wall formation mainly occurs when the free water in the drilling fluid penetrates into the cracks or voids of the well wall rock under the pressure difference between the drilling fluid column and the formation pressure. In this process, some solid particles in the drilling fluid adhere to the well wall to form mud cakes, which will prevent or slow down the water in the drilling fluid from continuing to invade the formation. At present, there is no equipment for simulating the density detection of drilling fluid in the case of water loss and wall formation. Utility Model Content

[0006] The application discloses a downhole drilling fluid density measuring device, which is used for simulating the drilling fluid density measurement under the condition of water loss and wall building.

[0007] The first aspect of the present application discloses a downhole drilling fluid density measuring device, comprising:

[0008] Driving motor, motor output shaft, displacement piston, liquid cylinder, filter disc;

[0009] The driving motor is connected to the first end of the motor output shaft;

[0010] The displacement piston is connected to the second end of the motor output shaft;

[0011] A simulated cavity is provided inside the liquid-filling cylinder, and the simulated cavity is used to place the drilling fluid to be tested;

[0012] A displacement opening is provided at the first end of the simulated cavity;

[0013] The displacement piston is located at the displacement opening of the liquid-filling cylinder, and the displacement piston is adapted to the displacement opening in size;

[0014] A simulated opening is provided on the side of the simulated cavity;

[0015] The filter disc is set at the simulated opening;

[0016] The filter disc is used to simulate the water loss and wall building state.

[0017] Optionally, the downhole drilling fluid density measuring device further includes an end cover;

[0018] The second end of the liquid filling cylinder is provided with an input port for the drilling fluid to be tested;

[0019] The end cover is installed on the input port.

[0020] Optionally, the downhole drilling fluid density measuring device further includes a pressure sensor and a temperature sensor;

[0021] The pressure sensor and the temperature sensor are arranged on the end cover.

[0022] Optionally, the motor output shaft is an electric cylinder output shaft, a linear motor output shaft, a ball screw or a worm gear.

[0023] Optionally, the liquid-containing cylinder is provided with a pipeline thermal simulation module;

[0024] The pipeline thermal simulation module is a non-contact heating cylinder or a built-in heating rod.

[0025] Optionally, the downhole drilling fluid density measuring device further includes a displacement sensor;

[0026] The displacement sensor is installed at the connection between the motor output shaft and the displacement piston.

[0027] Optionally, the downhole drilling fluid density measuring device further includes a sand bed tube and a measuring medium;

[0028] The sand bed cylinder and filter disc are detachably connected;

[0029] The sand bed tube is provided with a formation simulation groove, and the measuring medium is placed inside the formation simulation groove;

[0030] The sand bed cylinder is provided with a transparent window, and the material of the transparent window is sapphire or sapphire glass;

[0031] The sand bed cylinder is fixed by a supporting seat.

[0032] Optionally, a pressure cylinder and a vibration propulsion cylinder are provided inside the sand bed cylinder;

[0033] The shape of the pressure cylinder is adapted to the inner wall of the sand bed cylinder;

[0034] The first end of the vibration propulsion cylinder is fixed to one end of the sand bed cylinder, and the second end of the cylinder is fixed to the bottom of the pressure cylinder.

[0035] Optionally, the pressurizing cylinder is also provided with a pressurizing air hole;

[0036] The pressurized air holes are evenly arranged on the bottom surface and inner side surface of the pressurized cylinder;

[0037] The pressurized air hole is connected to an external air pump.

[0038] Optionally, the downhole drilling fluid density measuring device further includes a measuring cylinder;

[0039] The measuring cylinder is detachably connected to the filter disc.

[0040] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0041] In the present application, the downhole drilling fluid density measuring device includes a driving motor, a motor output shaft, a displacement piston, a liquid-filling cylinder, and a filter plate. The driving motor is connected to the first end of the motor output shaft, and the displacement piston is connected to the second end of the motor output shaft. The driving motor and the motor output shaft control the displacement piston to move to compress the liquid-filling cavity. A simulated cavity is provided inside the liquid-filling cylinder, and the simulated cavity is used to place the drilling fluid to be measured. A displacement opening is provided at the first end of the simulated cavity, and the displacement piston is located at the displacement opening of the liquid-filling cylinder. The displacement piston is adapted to the displacement opening in size, and a simulated opening is provided on the side of the simulated cavity, and a filter plate is provided at the simulated opening. Among them, the filter disc is provided with neatly arranged simulated gaps and simulated holes. The filter disc, simulated gaps and / or simulated holes can help simulate the formation of the loss-of-water wall-building state, and the initial volume and initial weight of the tested drilling fluid in the liquid-filling cylinder are determined before the test. In the loss-of-water wall-building state, water is discharged outward from the filter disc, and the current residual volume is determined by displacing the piston. The density of the discharged water in the current loss-of-water wall-building state is determined by looking up a table, and the mass of the discharged water is determined. The current residual mass of the drilling fluid in the liquid-filling cylinder is inferred from the mass of the discharged water, and finally the density in the current loss-of-water wall-building state is calculated from the residual mass and residual volume of the drilling fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0043] Figure 1 This is a schematic diagram of the overall structure of the downhole drilling fluid density measuring device of the present application;

[0044] Figure 2 This is a schematic diagram of a top view of the structure of the downhole drilling fluid density measuring device of the present application;

[0045] Figure 3 This is another overall structural schematic diagram of the downhole drilling fluid density measuring device of the present application;

[0046] Figure 4 A schematic cross-sectional structure diagram of a downhole drilling fluid density measuring device of the present application;

[0047] Figure 5 Another cross-sectional structural schematic diagram of the downhole drilling fluid density measuring device of the present application;

[0048] Figure 6 Another cross-sectional structural schematic diagram of the downhole drilling fluid density measuring device of the present application;

[0049] Figure 7 This is a schematic diagram of the overall structure of the pressurized cylinder of this application. DETAILED DESCRIPTION

[0050] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0051] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0052] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0053] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0054] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0055] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0056] In the prior art, the density of drilling fluid will change underground. This change comes from the effects of high temperature and high pressure. Under the effects of high temperature and high pressure, the density of drilling fluid will change due to the phenomenon of "thermal expansion and contraction" and "pressure compression of volume". Under the effect of pressure, the drilling fluid is squeezed and the water in the drilling fluid penetrates into the well wall, resulting in the phenomenon of "water loss and wall formation", which causes the density of the drilling fluid in the well to change.

[0057] In the process of managed pressure drilling, the density of the downhole drilling fluid is a very important input parameter. If the true density of the downhole drilling fluid is not known, the well control pressure may be too high or too low, resulting in safety accidents such as well leakage and blowout. Therefore, a device is needed to simulate the high temperature and high pressure environment downhole and the water loss process of the drilling fluid under this environment, and measure the density of the drilling fluid under this condition.

[0058] Secondly, drilling fluid will also encounter the situation of "water loss and wall formation". Water loss and wall formation is mainly caused by the pressure difference between the drilling fluid column and the formation pressure, and the free water in the drilling fluid penetrates into the cracks or gaps in the rock of the well wall. In this process, some solid particles in the drilling fluid adhere to the well wall to form mud cakes, which will prevent or slow down the water in the drilling fluid from continuing to invade the formation. At present, there is no equipment for simulating the density detection of drilling fluid in the case of water loss and wall formation.

[0059] Based on this, the present application discloses a downhole drilling fluid density measurement device for simulating the drilling fluid density measurement under the condition of water loss and wall building.

[0060] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0061] See also Figures 1 to 7 The present application provides an embodiment of a downhole drilling fluid density measuring device, comprising:

[0062] Driving motor 1, motor output shaft 2, displacement piston 3, liquid filling cylinder 4, filter disc 5;

[0063] The driving motor 1 is connected to the first end of the motor output shaft 2;

[0064] The displacement piston 3 is connected to the second end of the motor output shaft 2;

[0065] A simulated cavity is provided inside the liquid-filling cylinder 4, and the simulated cavity is used to place the drilling fluid to be tested;

[0066] A displacement opening is provided at the first end of the simulated cavity;

[0067] The displacement piston 3 is located at the displacement opening of the liquid-filling cylinder 4, and the displacement piston 3 is adapted to the displacement opening in size;

[0068] A simulated opening is provided on the side of the simulated cavity;

[0069] The filter disc 5 is arranged at the simulated opening;

[0070] Filter disc 5 is used to simulate the state of water loss and wall building.

[0071] In this embodiment, the downhole drilling fluid density measuring device can simulate the high temperature and high pressure environment downhole and the "water loss and wall formation" process of the drilling fluid. The downhole drilling fluid density measuring device has a liquid cylinder 4, in which the drilling fluid to be measured is loaded, and there is a displacement piston 3 in the liquid cylinder 4 that can make linear motion. The motor at one end of the liquid cylinder 4 rotates and drives the motor output shaft 2, thereby causing the piston to produce linear motion and squeeze the drilling fluid to be measured. The other end of the liquid cylinder 4 is a filter disc 5, and the water in the drilling fluid is squeezed out through the filter disc 5. Since the drilling fluid to be measured has the ability to seal, after the water is (partially) squeezed out, the filter disc 5 will be blocked. At this time, the displacement piston 3 continues to squeeze the drilling fluid, and the drilling fluid is in a high-pressure closed environment. A high-temperature environment is generated by a built-in heating rod in the liquid cylinder 4 or an external heating sleeve.

[0072] The density of the drilling fluid being tested is explained below: after the filling cylinder 4 is filled with drilling fluid, the volume and mass of the drilling fluid are determined, and then a temperature and pressure value are set. During the heating and pressurizing process, the pressure and temperature are collected. After the temperature and pressure reach the set value, the volume of the squeezed water and the volume of the drilling fluid in the cylinder can be calculated by collecting (or calculating) the displacement of the displacement piston 3. The density of water at a certain pressure and temperature can be known by looking up the table. According to the law of conservation of mass, the density of the drilling fluid in the cylinder can be further calculated.

[0073] In this embodiment, the downhole drilling fluid density measuring device includes a driving motor 1, a motor output shaft 2, a displacement piston 3, a liquid cylinder 4, and a filter plate 5. The driving motor 1 is connected to the first end of the motor output shaft 2, and the displacement piston 3 is connected to the second end of the motor output shaft 2. The driving motor 1 and the motor output shaft 2 cooperate to control the displacement piston 3 to move to compress the liquid chamber and convert the rotational motion into linear motion. Secondly, there are many ways to obtain the displacement x of the piston, which will also be different depending on the different structural forms of the motor-driven piston.

[0074] A simulated cavity is provided inside the liquid-filling cylinder 4, and the simulated cavity is used to place the drilling fluid to be tested. A displacement opening is provided at the first end of the simulated cavity. The displacement piston 3 is located at the displacement opening of the liquid-filling cylinder 4, and the displacement piston 3 is adapted to the displacement opening. A simulated opening is provided on the side of the simulated cavity, and a filter disc 5 is provided at the simulated opening. Among them, the filter disc 5 is provided with neatly arranged simulated gaps and simulated holes. The filter disc 5, the simulated gaps and the simulated holes are used to simulate the state of loss of water wall formation, and the initial volume and initial weight of the drilling fluid to be tested in the liquid-filling cylinder 4 are determined before the test. In the state of loss of water wall formation, water is discharged from the filter disc 5 to the outside, and the current residual volume is determined by the displacement piston 3. The density of the discharged water in the current state of loss of water wall formation is determined by looking up a table, and the mass of the discharged water is determined. The current residual mass of the drilling fluid in the liquid-filling cylinder 4 is calculated by the mass of the discharged water, and finally the density in the current state of loss of water wall formation is calculated by the residual mass and residual volume of the drilling fluid.

[0075] In this embodiment, the filter disc 5 is detachably installed at the simulated opening, and the filter disc 5 can be sealed to become a sealed pipe state, thereby increasing the types of simulated underground environments.

[0076] The specific structure and material of the filter disc 5 are not limited, as long as it can achieve the effect of "allowing only the liquid in the solid-liquid mixture to pass through".

[0077] The beneficial effects are as follows:

[0078] 1. It can simulate the process of "water loss and wall formation" of drilling fluid under high temperature and high pressure environment, and calculate the density of drilling fluid under this situation.

[0079] 2. The motor drives the displacement piston 3 to squeeze the liquid to generate pressure, which is safer and more compact than using gas or liquid to pressurize. The pressure regulation response speed is faster and the pressure control is more precise.

[0080] 3. Automatically increase and control pressure to ensure test accuracy.

[0081] Secondly, the drilling fluid to be tested can also be input or discharged from the simulated opening.

[0082] Optionally, the downhole drilling fluid density measuring device further includes an end cover 6;

[0083] The second end of the liquid filling cylinder 4 is provided with an input port for the drilling fluid to be tested;

[0084] The end cover 6 is installed on the input port.

[0085] In this embodiment, in addition to inputting or discharging the tested drilling fluid from the simulated opening, an input port for the tested drilling fluid is provided at the second end of the liquid-containing cylinder 4, and the tested drilling fluid can also be inputted or discharged from the input port.

[0086] Specifically, the filter disc 5 is provided with neatly arranged simulated gaps and simulated holes, and the filter disc 5, the simulated gaps and the simulated holes are used to simulate the water loss wall forming state.

[0087] Optionally, the downhole drilling fluid density measuring device further includes a pressure sensor 7 and a temperature sensor 8;

[0088] The pressure sensor 7 and the temperature sensor 8 are arranged on the end cover 6 .

[0089] In order to better detect the pressure, in this embodiment, a pressure sensor 7 and a temperature sensor 8 are provided on the end cover 6. The parameters given by the pressure sensor 7 and the temperature sensor 8 are used to look up a table to obtain the density parameters of the discharged water.

[0090] Optionally, the motor output shaft 2 is an electric cylinder output shaft, a linear motor output shaft, a ball screw or a worm gear.

[0091] In this embodiment, the motor output shaft 2 can be any one of an electric cylinder output shaft, a linear motor output shaft, a ball screw or a worm gear.

[0092] Optionally, the liquid-filling cylinder 4 is provided with a pipeline thermal simulation module 9;

[0093] The pipeline thermal simulation module 9 is a non-contact heating cylinder or a built-in heating rod.

[0094] In this embodiment, the pressure inside the liquid-filling cylinder 4 mainly comes from the movement of the displacement piston 3 , and the temperature change mainly comes from the pipeline thermal simulation module 9 .

[0095] Optionally, the downhole drilling fluid density measuring device further includes a displacement sensor 10;

[0096] The displacement sensor 10 is installed at the connection between the motor output shaft 2 and the displacement piston 3 .

[0097] In order to better obtain the volume change data of the liquid-filling cylinder 4 , the displacement sensor 10 is installed at the connection between the motor output shaft 2 and the displacement piston 3 , which can effectively detect the operation of the displacement piston 3 .

[0098] Optionally, the downhole drilling fluid density measuring device further includes a sand bed tube 11 and a measuring medium;

[0099] The sand bed cylinder 11 is detachably connected to the filter disc 5;

[0100] The sand bed tube 11 is provided with a formation simulation groove 12, and the measuring medium is placed inside the formation simulation groove 12;

[0101] The sand bed cylinder 11 is provided with a transparent window, and the material of the transparent window is sapphire or sapphire glass;

[0102] The sand bed cylinder 11 is fixed by a support seat.

[0103] In this embodiment, in order to better simulate the downhole environment, a sand bed tube 11 and a measuring medium are provided, and the measuring medium is placed in the formation simulation slot of the sand bed tube 11. Specifically, the measuring medium is the soil component in the corresponding test environment. In the case of water loss wall building, water will penetrate into the sand bed tube 11, and the displacement of the drilling fluid under test during water loss wall building is determined by the degree of invasion of the measuring medium. Specifically, the invasion depth can be observed and measured through a transparent window on the sand bed tube 11. The displacement can be converted according to the invasion depth, providing another method for calculating the displacement.

[0104] The measuring medium can be one or more mixtures of stratum soil, crushed stone, ceramsite, quartz sand, etc.

[0105] Optionally, a pressurizing cylinder 13 and a vibration propulsion cylinder 14 are provided inside the sand bed cylinder 11;

[0106] The shape of the pressure cylinder 13 is adapted to the inner wall of the sand bed cylinder 11;

[0107] The first end of the vibration propulsion cylinder 14 is fixed to one end of the sand bed cylinder 11 , and the second end of the cylinder is fixed to the bottom of the pressure cylinder 13 .

[0108] Optionally, the pressurizing cylinder 13 is further provided with a pressurizing air hole 15;

[0109] The pressurized air holes 15 are evenly arranged on the bottom surface and the inner side surface of the pressurized cylinder 13;

[0110] The pressurized air hole 15 is connected to an external air pump.

[0111] In this embodiment, in order to simulate the formation, in addition to the corresponding samples, when the formation reaches a certain depth, there is a certain pressure and temperature. The temperature is simulated by the sand bed cylinder 11, and the formation pressure is formed by the pressure cylinder 13, the vibration propulsion cylinder 14 and the pressurized air hole 15.

[0112] The pressure cylinder 13 includes a side surface and a bottom surface, and is open at one end. In this embodiment, the interior of the sand bed tube 11 is a cylinder, and the pressure cylinder 13 is adapted to the internal shape of the sand bed tube 11. After the sand bed tube 11 is loaded with the measuring medium, the pressure cylinder 13 is put in from one end, with the open side facing the crack simulation module, and the other end of the pressure cylinder 13 is connected to the vibration propulsion cylinder 14, and the vibration propulsion cylinder 14 is fixed to the other side of the sand bed tube 11. There is a very small gap between the pressure cylinder 13 and the sand bed tube 11 to prevent the measuring medium from entering the pressure cylinder 13 and the sand bed tube 11. Secondly, the working space of the vibration propulsion cylinder 14 is separated from the sand bed tube 11 and the outside world to prevent the penetration of internal and external gases, liquids and solids. The pressure air hole 15 is a one-way air hole to prevent the entry of gas, liquid and solids, thereby improving safety.

[0113] The vibration propulsion cylinder 14 is used to control the vibration of the pressure cylinder 13, and can also propel the inside of the sand bed cylinder 11, and can autonomously control the porosity c of the measuring medium to a certain extent. The porosity c can be determined by the travel position of the pressure cylinder 13 and the particle volume of the measuring medium. The formation of the pressure cylinder 13 can also control the density of the measuring medium, and can compress the formation sample to reach the preset formation density, which is used to simulate the formation density, and then the pressure hole 15 is filled with the corresponding gas to pressurize the formation sample through an external air pump. The gas includes nitrogen, methane and other gases existing in the formation to simulate the gas state and pressure in the formation.

[0114] This design can fully restore the state of the formation, allowing the device to obtain more accurate evaluation results.

[0115] Optionally, the downhole drilling fluid density measuring device further includes a measuring tube 16;

[0116] The measuring cylinder 16 is detachably connected to the filter disc 5 .

[0117] When there is no need to measure the plugging effect of the drilling fluid on the formation, a measuring cylinder 16 can be installed on the filter disc 5, and the measuring cylinder 16 can directly determine the drainage volume under the current temperature and pressure.

[0118] An example is given below to illustrate that in this embodiment, a water loss wall building environment can be simulated, and a general normal pipeline environment can also be simulated.

[0119] Example 1 (not considering "water loss wall building", measuring liquid density under high temperature and high pressure):

[0120] After the drilling fluid to be measured is filled into the liquid cylinder 4 of the device through the threaded hole on the end cover 6, the temperature sensor 8 and the pressure sensor 7 are installed on the threaded hole on the end cover 6. The volume and mass of the liquid are determined as V0 and M0 respectively, and the inner radius of the liquid cylinder 4 is r. Set a temperature and pressure value. During the heating and pressurizing process, a closed-loop control is formed by collecting the values ​​of the pressure and temperature sensors 8. After the temperature and pressure reach the set value, the piston displacement x (along the piston axis, the direction toward the liquid is positive) collected by the displacement sensor 10 installed on the piston can be used to calculate the volume change of the liquid in the cylinder V1 = x*π*r 2 , the volume of the liquid in the cylinder is V2=V0-V1, and the density of the liquid in the cylinder is P=M0 / V2.

[0121] Embodiment 2 (considering "water loss wall building", measuring the density of drilling fluid under high temperature and high pressure; the displacement x of the piston is collected by the displacement sensor 10 installed on the piston):

[0122] First, assemble the filter plate 5 and the liquid cylinder 4. Fill the liquid cylinder 4 of the device with the drilling fluid to be tested through the threaded hole on the end cover 6. Then install the temperature sensor 8 and the pressure sensor 7 on the threaded hole on the end cover 6. The volume and mass of the liquid are determined as V0 and M0 respectively. The inner radius of the liquid cylinder 4 is r. Set a temperature and pressure value. During the heating and pressurizing process, a closed-loop control is formed by collecting the values ​​of the pressure and temperature sensors 8. After the temperature and pressure reach the set value, the piston displacement x (along the piston axis, the direction toward the liquid is positive) collected by the displacement sensor 10 installed on the piston can be used to calculate the volume of the squeezed water V1 = x*π*r 2, the volume of the drilling fluid in the cylinder is V2=V0-V1, and the density of water at this pressure and temperature is determined by looking up the table P1. The mass of the squeezed water is M1=P1*V1, the mass of the drilling fluid in the cylinder is M2=M0-M1, and the density of the drilling fluid in the cylinder is P2=M2 / V2.

[0123] Example 3 (Considering "water loss wall building", measuring the density of drilling fluid under high temperature and high pressure; the motion mechanism driving the piston is a ball screw, and the piston displacement x is calculated according to the rotation angle of the motor shaft driving the ball screw):

[0124] First, assemble the filter plate 5 and the liquid cylinder 4. Fill the liquid cylinder 4 of the device with the liquid to be measured through the threaded hole on the end cover 6, and then install the temperature sensor 8 and the pressure sensor 7 on the threaded hole on the end cover 6. The volume and mass of the liquid are determined as V0 and M0 respectively, and the inner radius of the liquid cylinder 4 is r. Set a temperature and pressure value. During the heating and pressurizing process, a closed-loop control is formed by collecting the values ​​of the pressure and temperature sensors 8. After the temperature and pressure reach the set value, the encoder installed on the motor collects the motor shaft rotation angle θ (the direction in which the piston is pushed toward the liquid is positive, and the unit is radian), and the volume of the squeezed water V1 = S*(θ / 2 / π)*π*r can be calculated. 2 , where S is the lead of the ball screw, the volume of the drilling fluid in the cylinder is V2=V0-V1, and the density of water at this pressure and temperature is determined by looking up the table. The mass of the squeezed water is M1=P1*V1, the mass of the drilling fluid in the cylinder is M2=M0-M1, and the density of the drilling fluid in the cylinder is P2=M2 / V2.

[0125] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0126] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0127] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0128] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0129] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, read-only memory), random access memory (RAM, random access memory), disk or optical disk and other media that can store program code.

Claims

1. A downhole drilling fluid density measuring device, characterized in that: include: Driving motor, motor output shaft, displacement piston, liquid cylinder, filter disc; The driving motor is connected to the first end of the motor output shaft; The displacement piston is connected to the second end of the motor output shaft; The liquid-containing cylinder is provided with a simulated cavity inside, and the simulated cavity is used to place the drilling fluid to be tested; The first end of the simulation cavity is provided with a displacement opening; The displacement piston is located at the displacement opening of the liquid-containing cylinder, and the displacement piston is adapted to the displacement opening in size; The side of the simulated cavity is provided with a simulated opening; The filter disc is disposed at the simulated opening; The filter disc is used to simulate the water loss wall building state.

2. The downhole drilling fluid density measuring device according to claim 1, characterized in that: The downhole drilling fluid density measuring device also includes an end cover; The second end of the liquid-filling cylinder is provided with an input port for the drilling fluid to be tested; The end cover is mounted on the input port.

3. The downhole drilling fluid density measuring device according to claim 2, characterized in that: The downhole drilling fluid density measuring device also includes a pressure sensor and a temperature sensor; The pressure sensor and the temperature sensor are arranged on the end cover.

4. The downhole drilling fluid density measuring device according to claim 1, characterized in that: The motor output shaft is an electric cylinder output shaft, a linear motor output shaft, a ball screw or a worm gear.

5. The downhole drilling fluid density measuring device according to claim 1, characterized in that: The liquid-containing cylinder is provided with a pipeline thermal simulation module; The pipeline thermal simulation module is a non-contact heating cylinder or a built-in heating rod.

6. The downhole drilling fluid density measuring device according to claim 1, characterized in that: The downhole drilling fluid density measuring device also includes a displacement sensor; The displacement sensor is installed at the connection between the motor output shaft and the displacement piston.

7. The downhole drilling fluid density measuring device according to any one of claims 1 to 6, characterized in that: The downhole drilling fluid density measuring device also includes a sand bed tube and a measuring medium; The sand bed cylinder is detachably connected to the filter disc; The sand bed cylinder is provided with a formation simulation groove, and the measuring medium is placed inside the formation simulation groove; The sand bed cylinder is provided with a transparent window, and the material of the transparent window is sapphire or sapphire glass; The sand bed cylinder is fixed by a supporting seat.

8. The downhole drilling fluid density measuring device according to claim 7, characterized in that: The sand bed cylinder is provided with a pressurizing cylinder and a vibration propulsion cylinder inside; The shape of the pressure cylinder is adapted to the inner wall of the sand bed cylinder; The first end of the vibration propulsion cylinder is fixed to one end of the sand bed cylinder, and the second end of the cylinder is fixed to the bottom of the pressure cylinder.

9. The downhole drilling fluid density measuring device according to claim 8, characterized in that: The pressurizing cylinder is also provided with a pressurizing air hole; The pressurized air holes are evenly arranged on the bottom surface and the inner side surface of the pressurized cylinder; The pressurized air hole is connected to an external air pump.

10. The downhole drilling fluid density measuring device according to any one of claims 1 to 6, characterized in that: The downhole drilling fluid density measuring device also includes a measuring cylinder; The measuring cylinder is detachably connected to the filter disc.

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