CN117607005B - Method for measuring rock starting pressure gradient - Google Patents
Method for measuring rock starting pressure gradient Download PDFInfo
- Publication number
- CN117607005B CN117607005B CN202410090577.XA CN202410090577A CN117607005B CN 117607005 B CN117607005 B CN 117607005B CN 202410090577 A CN202410090577 A CN 202410090577A CN 117607005 B CN117607005 B CN 117607005B
- Authority
- CN
- China
- Prior art keywords
- pressure
- constant
- test fluid
- tested
- core holder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 31
- 239000011435 rock Substances 0.000 title claims abstract description 29
- 238000012360 testing method Methods 0.000 claims abstract description 103
- 239000012530 fluid Substances 0.000 claims abstract description 89
- 238000011049 filling Methods 0.000 claims abstract description 6
- 229920006395 saturated elastomer Polymers 0.000 claims abstract description 6
- 230000000977 initiatory effect Effects 0.000 claims description 18
- 239000011148 porous material Substances 0.000 claims description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000002347 injection Methods 0.000 claims description 6
- 239000007924 injection Substances 0.000 claims description 6
- 238000007664 blowing Methods 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 238000011161 development Methods 0.000 abstract description 2
- 238000004364 calculation method Methods 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000002955 isolation Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001595 flow curve Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000013178 mathematical model Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
- G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L13/00—Devices or apparatus for measuring differences of two or more fluid pressure values
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/0806—Details, e.g. sample holders, mounting samples for testing
Landscapes
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- General Physics & Mathematics (AREA)
- Dispersion Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Fluid Mechanics (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a method for measuring rock start pressure gradient, which relates to the field of oil and gas field development, and comprises the following steps: injecting a first test fluid into the core holder, and enabling a core sample to be tested in the core holder to last for a set time in a constant pressure mode; closing the first end of the core holder and the second end of the second pressure-resistant container, and filling the first test fluid into the first pressure-resistant container through the first constant-pressure constant-speed pump until the pressure of the first constant-pressure constant-speed pump reaches a set pressure value; closing the second end of the first pressure-resistant container, opening the first end of the core holder, collecting the pressure difference between the two ends of the core holder in real time, and recording the pressure difference between the two ends of the core holder as a first starting pressure difference when the pressure difference change value between the two ends of the core holder is smaller than a set threshold value; according to the first starting pressure difference and the length of the core sample to be tested, the starting pressure gradient of the first test fluid when the core sample to be tested is saturated with the first test fluid is determined, and the measuring efficiency is improved.
Description
Technical Field
The invention relates to the technical field of oil and gas field development, in particular to a method for measuring rock start pressure gradient.
Background
The initiation pressure gradient is an important parameter that affects the initiation and flow of fluids in a hydrocarbon reservoir. Currently, methods for determining reservoir initiation pressure gradients mainly include experimental testing methods and theoretical calculations. The experimental test method is to apply a certain pressure difference to two ends of an actual core or an etching model, measure the flow passing through the core or the etching model after stable flow, draw a stable flow curve under different pressure differences, and further determine a starting pressure gradient according to curve forms. The theoretical calculation method is to preset certain simplified hypothesized conditions and mathematical models, and calculate the starting pressure gradient through the deduction of a mathematical formula.
Common drawbacks of both methods are: it is difficult to accurately determine the starting pressure gradient of each phase under different saturation conditions when two-phase fluids coexist by measuring only the starting pressure gradient when a single-phase fluid flows. In addition, the existing experimental method must rely on stable flow data to determine the starting pressure gradient, so that the experimental time is long for low-permeability reservoirs such as shale, coal and rock, and the testing efficiency is low. The reliability of the theoretical calculation method depends on the accuracy of the model, and the reliability of the calculation result is insufficient for reservoirs with complex wettability and pore structures.
Disclosure of Invention
The invention aims to provide a method for measuring the rock start pressure gradient, which improves the measurement efficiency of the rock start pressure gradient.
In order to achieve the above object, the present invention provides the following solutions: the method for measuring the rock start pressure gradient adopts an experimental testing device, wherein the experimental testing device comprises a core holder, a first pressure-resistant container, a second pressure-resistant container, a first piston container and a first constant-pressure constant-speed pump; the first end of the core holder is connected with the first end of the first pressure-resistant container, the second end of the core holder is connected with the second end of the second pressure-resistant container, the second end of the first pressure-resistant container and the second end of the second pressure-resistant container are connected with the first end of the first piston container through a three-way valve, and the second end of the first piston container is connected with the first constant-pressure constant-speed pump; the first piston container is used for containing a first test fluid; the core holder is used for holding a core sample to be measured.
The method for determining the rock initiation pressure gradient comprises the following steps.
And injecting a first test fluid in the first piston container into the first pressure-resistant container, the core holder and the second pressure-resistant container through the first constant-pressure constant-speed pump, and enabling a core sample to be tested in the core holder to continuously set for a time in a constant-pressure mode.
And closing the first end of the core holder and the second end of the second pressure-resistant container, and filling the first test fluid into the first pressure-resistant container through the first constant-pressure constant-speed pump until the pressure of the first constant-pressure constant-speed pump reaches a set pressure value.
And closing the second end of the first pressure-resistant container, opening the first end of the core holder, and collecting the pressure difference at the two ends of the core holder in real time, wherein when the pressure difference change value at the two ends of the core holder is smaller than a set threshold value, the pressure difference at the two ends of the core holder is recorded as a first starting pressure difference.
And determining a starting pressure gradient of the first test fluid when the core sample to be tested is saturated with the first test fluid according to the first starting pressure difference and the length of the core sample to be tested, and recording the starting pressure gradient as a first starting pressure gradient.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects: according to the invention, a core sample to be tested is continuously set for a time in a constant pressure mode after being filled with a first test fluid, then the first test fluid is input into a first pressure-resistant container at one end of the core sample to be tested, the first pressure-resistant container is communicated with the core sample to be tested after the pressure of the first pressure-resistant container is stable, the pressure difference at two ends of the core sample to be tested is recorded, and when the variation value of the pressure difference is smaller than a set threshold value, the starting pressure gradient of the first test fluid is calculated according to the pressure difference.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a method for determining a rock initiation pressure gradient according to an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of an experimental testing apparatus according to an embodiment of the present invention.
Symbol description: the core holder-1, the first pressure-resistant container-2, the second pressure-resistant container-3, the first constant-pressure constant-speed pump-4, the second constant-pressure constant-speed pump-5, the first piston container-6, the second piston container-7, the vacuum pump-8, the differential pressure sensor-9, the pressure sensor-10, the back pressure valve-11, the measuring cylinder-12, the three-way valve-13, the first four-way valve-14, the second four-way valve-15, the first valve-16, the second valve-17, the third valve-18, the fourth valve-19, the fifth valve-20, the sixth valve-21, the seventh valve-22, the eighth valve-23, the ninth valve-24 and the tenth valve-25.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a method for measuring the rock start pressure gradient, which improves the measurement efficiency of the rock start pressure gradient.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
The invention discloses a method for measuring rock start pressure gradient, which adopts an experimental testing device, as shown in figure 2, and comprises a core holder 1, a first pressure-resistant container 2, a second pressure-resistant container 3, a first piston container 6 and a first constant-pressure constant-speed pump 4; the first end of the core holder 1 is connected with the first end of the first pressure-resistant container 2, the second end of the core holder 1 is connected with the second end of the second pressure-resistant container 3, the second end of the first pressure-resistant container 2 and the second end of the second pressure-resistant container 3 are connected with the first end of the first piston container 6 through a three-way valve 13, and the second end of the first piston container 6 is connected with the first constant-pressure constant-speed pump 4; the first piston container 6 is used for containing a first test fluid; the core holder 1 is used for holding a core sample to be measured.
The experimental testing device also comprises a second constant pressure and constant speed pump 5, a second piston container 7 and a measuring cylinder 12; the first end of the second piston container 7 is connected with the first end of the core holder 1, the second end of the second piston container 7 is connected with the second constant pressure constant speed pump 5, and the measuring cylinder 12 is connected with the second end of the second piston container 7 through a back pressure valve 11; the second piston container 7 is for holding a second test fluid.
The transverse line between the first piston container 6 and the second piston container 7 is an isolation plunger, a groove is formed in the side face of the plunger, a rubber ring is arranged at the groove, the rubber ring can play a role in sealing between the plunger and the wall face of the container, and distilled water and test liquid are isolated through the isolation plunger.
The experimental testing device further comprises a vacuum pump 8, wherein the vacuum pump 8 is respectively connected with the first end of the core holder 1, the first end of the first pressure-resistant container 2 and the first end of the piston container through a first four-way valve 14; the vacuum pump 8 is used to evacuate the first pressure-resistant container 2, the second pressure-resistant container 3, the pressure-resistant line between the vacuum pump 8 and the first pressure-resistant container 2, and the pressure-resistant line between the first pressure-resistant container 2 and the second pressure-resistant container 3.
The experimental testing device further comprises a differential pressure sensor 9 and a pressure sensor 10, wherein the differential pressure sensor 9 is used for collecting pressure differences at two ends of the core holder 1.
The first end of the core holder 1 is an inlet, the second end is an outlet, and two ends of the differential pressure sensor 9 are respectively connected with the inlet and the outlet of the core holder 1.
The pressure sensor 10 is respectively connected with the second end of the core holder 1, the second end of the second pressure-resistant container 3 and one end of the back pressure valve 11 through a second four-way valve 15, and the other end of the back pressure valve 11 is connected with the measuring cylinder 12.
The first piston container 6 has a top at a first end and a bottom at a second end. The first end of the second piston container 7 is the top and the second end is the bottom.
The first valve 16 is connected between the vacuum pump 8 and the first end of the first four-way valve 14, the second valve 17 is connected between the first piston container 6 and the second end of the first four-way valve 14, the third valve 18 is connected between the first end of the core holder 1 and the third end of the first four-way valve 14, the fourth valve 19 is connected between the second end of the core holder 1 and the first end of the second four-way valve 15, the fifth valve 20 is connected between the back pressure valve 11 and the second end of the second four-way valve 15, the sixth valve 21 is connected between the first end of the first pressure-resistant container 2 and the fourth end of the first four-way valve 14, the seventh valve 22 is connected between the first end of the second pressure-resistant container 3 and the third end of the second four-way valve 15, the fourth end of the second four-way valve 15 is connected with the pressure sensor 10, the eighth valve 23 is connected between the second end of the first pressure-resistant container 2 and the first end of the three-way valve 13, the ninth valve 24 is connected between the second end of the second pressure-resistant container 3 and the second end of the three-way valve 13, and the tenth valve 25 is connected between the first piston container 6 and the third end of the third pressure-resistant container 13.
Connecting pipelines among all parts in the experimental testing device are pressure-resistant pipelines.
As shown in fig. 1, a method of determining a rock initiation pressure gradient of the present invention includes the following steps.
Step 101: and injecting a first test fluid in the first piston container into the first pressure-resistant container, the core holder and the second pressure-resistant container through the first constant-pressure constant-speed pump, and enabling a core sample to be tested in the core holder to continuously set for a time in a constant-pressure mode.
Before step 101, the method for determining a rock initiation pressure gradient according to the present invention further includes preparation and pretreatment of a core sample to be tested.
The preparation and pretreatment of the core sample to be tested specifically comprise the following steps.
1) And processing the rock sample to be tested into a plunger-shaped sample by adopting a linear cutting or coring drilling machine.
2) And (3) placing the plunger-shaped sample in a vacuum drying box, carrying out vacuumizing and drying treatment on the sample (the plunger-shaped sample), weighing the sample mass once every 1 hour, and naturally cooling the sample to room temperature in a dryer after the sample mass is not changed.
After preparation and pretreatment of the core sample to be tested, the method for measuring the rock initiation pressure gradient further comprises the following steps.
And (3) placing the core sample to be tested (plunger-shaped sample) into a vacuumizing and pressurizing saturation device after the sample is cooled to room temperature, and vacuumizing the core sample to be tested for more than 6 hours.
And filling a first test fluid into the core sample to be tested, pressurizing the pressure of the first test fluid filled into the core sample to be tested to reservoir pressure (denoted as P0) by adopting a constant-pressure constant-speed pump or a advection pump or a hand pump, and maintaining the reservoir pressure for more than one day to enable the first test fluid to fully saturate the core sample to be tested. The reservoir pressure is the reservoir pressure of the core sample to be tested.
The core sample to be tested, which is saturated with the first test fluid, is placed in the core holder 1 in the experimental testing device, the experimental testing device is built according to the actual stress condition of the stratum, and certain confining pressure is applied to the core sample to be tested.
Closing the second valve 17, the third valve 18, the fourth valve 19, the fifth valve 20 and the tenth valve 25, opening the first valve 16, the sixth valve 21, the seventh valve 22, the eighth valve 23 and the ninth valve 24, opening the vacuum pump 8, vacuumizing the device for more than 2 hours, and after vacuumizing is completed, sequentially closing the first valve 16 and the vacuum pump 8.
The step 101 specifically includes: the third valve 18, the fourth valve 19 and the tenth valve 25 are opened, the first constant pressure constant speed pump 4 is set to be in a constant pressure mode, the pressure value is set to be reservoir pressure, the first test fluid in the first piston container 6 is injected into the first pressure-resistant container 2, the second pressure-resistant container 3 and the core sample to be tested, the constant pressure mode is maintained for more than 1 day, and the first test fluid fully enters the core sample to be tested.
Step 102: and closing the first end of the core holder and the second end of the second pressure-resistant container, and filling the first test fluid into the first pressure-resistant container through the first constant-pressure constant-speed pump until the pressure of the first constant-pressure constant-speed pump reaches a set pressure value.
Reservoir pressure with the set pressure value of 1.1 times; the reservoir pressure is the reservoir pressure of the core sample to be tested.
The step 102 specifically includes: the third valve 18 and the ninth valve 24 are closed, the pressure of the first constant pressure constant speed pump 4 is set to 1.1×p0, and the first test fluid is filled into the first pressure-resistant container 2.
Step 103: and closing the second end of the first pressure-resistant container, opening the first end of the core holder, and collecting the pressure difference at the two ends of the core holder in real time, wherein when the pressure difference change value at the two ends of the core holder is smaller than a set threshold value, the pressure difference at the two ends of the core holder is recorded as a first starting pressure difference.
The threshold was set to 0.001MPa.
Step 103 specifically includes: after the pressure of the first constant-pressure constant-speed pump 4 is stable, namely when the pressure of the first constant-pressure constant-speed pump 4 reaches 1.1 multiplied by P0, closing the eighth valve 23, opening the third valve 18, collecting and recording the differential pressure values of two ends of a core sample to be tested at different times in real time by utilizing the differential pressure sensor 9 and a matched data collector thereof, and recording that the differential pressure value at the moment is delta P when the differential pressure change value of two ends of the core is smaller than 0.001MPa within 12 hours f1 。
Step 104: and determining a starting pressure gradient of the first test fluid when the core sample to be tested is saturated with the first test fluid according to the first starting pressure difference and the length of the core sample to be tested, and recording the starting pressure gradient as a first starting pressure gradient.
Step 104 specifically includes: according to formula lambda 1 =△P f1 and/L calculating the first starting pressure gradient.
Wherein lambda is 1 Represents the first starting pressure gradient, ΔP f1 And representing the first starting pressure difference, wherein L represents the length of the core sample to be tested.
Wherein lambda is 1 When the core sample to be tested is saturated with the first test fluid, the first test fluid is startedDynamic pressure gradient.
Steps 101 to 104 are methods for measuring the pressure gradient of the single-phase fluid start-up.
The invention also provides a two-phase fluid initiation pressure gradient test method when two-phase fluids coexist, and therefore, the method for measuring the rock initiation pressure gradient further comprises the following steps.
Step 105: after recording the pressure difference between the two ends of the core holder 1 as a first starting pressure difference, closing the first end of the first piston container 6 and the second end of the first piston container 6, and setting the control pressure of the back pressure valve 11 as reservoir pressure so as to enable the first test fluid to flow into the measuring cylinder 12; the reservoir pressure is the reservoir pressure of the core sample to be tested.
Step 106: injecting the second test fluid in the second piston container 7 into the core sample to be tested by the second constant pressure and constant speed pump 5 when the volume of the first test fluid collected in the measuring cylinder 12 is not changed any more, and recording the volume of the first test fluid collected by the measuring cylinder 12 during the injection of the second test fluid into the core sample to be tested as a first volume; and determining the first saturation of the first test fluid according to the first volume and the total pore volume of the core sample to be tested.
The steps 105 to 106 specifically include: after testing the single-phase fluid starting pressure gradient, the sixth valve 21 and the seventh valve 22 are closed, the control pressure of the back pressure valve 11 is set to be the reservoir pressure, the fifth valve 20 is opened, and the volume of the first test fluid to be collected in the measuring cylinder 12 is not changed any more.
The second valve 17 is opened, the second constant pressure constant speed pump 5 is set to constant flow displacement mode, the second test fluid in the second piston container 7 is injected into the core, and the volume of the first test fluid collected in the measuring cylinder 12 during injection (denoted as V 1 ) According to S 1 =（V-V 1 ) and/V, (wherein V is the total pore volume of the test core), and calculating the saturation of the first test fluid in the core sample to be tested.
Wherein S is 1 Representing the first saturation, V 1 Representing the first volume, V represents the total pore volume.
Step 107: when the first saturation reaches a saturation preset value, the first ends of the second constant-pressure constant-speed pump 5 and the second piston container 7 are closed, the volume of the first test fluid collected in the measuring cylinder 12 is continuously recorded, after the volume of the first test fluid in the measuring cylinder 12 is no longer changed, the volume of the first test fluid collected in the measuring cylinder 12 from the beginning of the injection of the second test fluid to the process that the volume of the first test fluid is no longer changed is obtained, and the volume is recorded as a second volume.
Step 107 specifically includes: waiting for S 1 When the experimental preset value is reached, the second constant pressure and constant speed pump 5 and the second valve 17 are closed, the volume of the first test fluid collected in the measuring cylinder 12 is continuously recorded, after the volume of the first test fluid in the measuring cylinder 12 is no longer changed, the volume of the first test fluid collected in the measuring cylinder 12 after the injection of the second test fluid is started until the volume of the first test fluid in the measuring cylinder 12 is no longer changed (recorded as V 2 ）。
Step 108: and determining the second saturation of the first test fluid according to the first volume, the second volume and the total pore volume of the core sample to be tested.
Step 108 specifically includes: according to formula S 2 =(V-V 1 -V 2 ) Calculating the saturation S of the first test fluid in the core sample to be tested 2 。
Wherein S is 2 Representing the second saturation, V 1 Representing the first volume, V representing the total pore volume, V 2 Representing the second volume.
Step 109: taking out the core sample to be tested in the core holder 1, and blowing out the second test fluid in the experimental testing device by means of nitrogen; returning to step 101 until the second end of the first pressure-resistant container 2 is closed, the first end of the core holder 1 is opened, the pressure difference between the two ends of the core holder 1 is collected in real time, and when the pressure difference change value between the two ends of the core holder 1 is smaller than the step when the threshold value is set, the pressure difference between the two ends of the core holder 1 is recorded as the second starting pressure difference.
And determining a starting pressure gradient when the saturation of the first test fluid is the second saturation according to the second starting pressure difference and the length of the core sample to be tested, and recording the starting pressure gradient as a second starting pressure gradient.
Step 109 specifically includes: and setting the confining pressure applied to the core sample to be tested to be zero, taking out the core sample to be tested in the core holder 1, and blowing out the second fluid in the pipeline containing the second fluid in the mode of introducing nitrogen.
The core sample to be tested is placed in the core holder 1 again, an experimental testing device is built according to a device structure diagram shown in fig. 2, a certain confining pressure is applied to the core according to the actual stress condition of the stratum, the experiment is repeated according to the method described in the steps 104-104, and the differential pressure value when the differential pressure change value of the two ends of the core is smaller than 0.001MPa is recorded as DeltaP f2 。
The calculation formula of the second starting pressure gradient is represented as lambda 2 =△P f2 /L。
Wherein lambda is 2 Represents a second starting pressure gradient, ΔP f2 Representing a second starting pressure differential.
Aiming at the problems that the existing experimental test method cannot accurately determine the starting pressure gradient of each phase under different saturation conditions and the experimental test is long in time consumption, the invention provides a rock starting pressure gradient determination method for rapidly and simply determining the coexistence of multiphase fluid. Firstly, a core sample to be tested is continuously set for a time in a constant pressure mode after being filled with a first test fluid, then the first test fluid is input into a first pressure-resistant container at one end of the core sample to be tested, the first pressure-resistant container is communicated with the core sample to be tested after the pressure of the first pressure-resistant container is stable, the pressure difference at two ends of the core sample to be tested is recorded, and when the variation value of the pressure difference is smaller than a set threshold value, the starting pressure gradient of the first test fluid is calculated according to the pressure difference.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (8)
1. The method for measuring the rock start pressure gradient is characterized by adopting an experimental testing device, wherein the experimental testing device comprises a core holder, a first pressure-resistant container, a second pressure-resistant container, a first piston container and a first constant-pressure constant-speed pump; the first end of the core holder is connected with the first end of the first pressure-resistant container, the second end of the core holder is connected with the first end of the second pressure-resistant container, the second end of the first pressure-resistant container and the second end of the second pressure-resistant container are connected with the first end of the first piston container through a three-way valve, and the second end of the first piston container is connected with the first constant-pressure constant-speed pump; the first piston container is used for containing a first test fluid; the core holder is used for holding a core sample to be measured;
the method for determining the rock initiation pressure gradient comprises the following steps:
injecting a first test fluid in the first piston container into the first pressure-resistant container, the core holder and the second pressure-resistant container through the first constant-pressure constant-speed pump, and enabling a core sample to be tested in the core holder to continuously set time in a constant-pressure mode;
closing the first end of the core holder and the second end of the second pressure-resistant container, and filling the first test fluid into the first pressure-resistant container through the first constant-pressure constant-speed pump until the pressure of the first constant-pressure constant-speed pump reaches a set pressure value;
closing the second end of the first pressure-resistant container, opening the first end of the core holder, and collecting the pressure difference at the two ends of the core holder in real time, wherein when the pressure difference change value at the two ends of the core holder is smaller than a set threshold value, the pressure difference at the two ends of the core holder is recorded as a first starting pressure difference;
determining a starting pressure gradient of the first test fluid when the core sample to be tested is saturated with the first test fluid according to the first starting pressure difference and the length of the core sample to be tested, and marking the starting pressure gradient as a first starting pressure gradient;
the experimental testing device also comprises a second constant pressure and constant speed pump, a second piston container and a measuring cylinder; the first end of the second piston container is connected with the first end of the core holder, the second end of the second piston container is connected with the second constant pressure constant speed pump, and the measuring cylinder is connected with the second end of the core holder through a back pressure valve; the second piston container is used for containing a second test fluid;
the method for determining the rock initiation pressure gradient further comprises:
after the pressure difference at the two ends of the core holder is recorded as a first starting pressure difference, closing the first end of the first piston container and the second end of the first piston container, and setting the control pressure of the back pressure valve as reservoir pressure so as to enable the first test fluid to flow into the measuring cylinder; the reservoir pressure is the reservoir pressure of the core sample to be tested;
injecting the second test fluid in the second piston container into the core sample to be tested through the second constant pressure and constant speed pump when the volume of the first test fluid collected in the measuring cylinder is not changed any more, and recording the volume of the first test fluid collected by the measuring cylinder during the injection of the second test fluid into the core sample to be tested as a first volume; simultaneously determining a first saturation of the first test fluid according to the first volume and the total pore volume of the core sample to be tested;
when the first saturation reaches a saturation preset value, closing the first ends of the second constant-pressure constant-speed pump and the second piston container, continuously recording the volume of the first test fluid collected in the measuring cylinder, and after the volume of the first test fluid in the measuring cylinder is no longer changed, acquiring the volume of the first test fluid collected in the measuring cylinder from the beginning of injection of the second test fluid to the time when the volume of the first test fluid is no longer changed, and recording the volume of the first test fluid as a second volume;
determining a second saturation of the first test fluid according to the first volume, the second volume and the total pore volume of the core sample to be tested;
taking out the core sample to be tested in the core holder, and blowing out the second test fluid in the experimental testing device by means of nitrogen; returning to the step of injecting the first test fluid in the first piston container into the first pressure-resistant container, the core holder and the second pressure-resistant container through the first constant-pressure constant-speed pump, and enabling a core sample to be tested in the core holder to last for a set time in a constant-pressure mode until the second end of the first pressure-resistant container is closed, the first end of the core holder is opened, the pressure difference at the two ends of the core holder is collected in real time, and when the pressure difference change value at the two ends of the core holder is smaller than the step when the pressure difference change value at the two ends of the core holder is smaller than the set threshold value, recording the pressure difference at the two ends of the core holder as a second starting pressure difference;
and determining a starting pressure gradient when the saturation of the first test fluid is the second saturation according to the second starting pressure difference and the length of the core sample to be tested, and recording the starting pressure gradient as a second starting pressure gradient.
2. The method of determining a rock initiation pressure gradient of claim 1, wherein the first initiation pressure gradient is calculated as:
λ 1 =△P f1 /L；
wherein,λ 1 represents the first starting pressure gradient, ΔP f1 Representing the first start-up pressure difference in question,Lindicating the length of the core sample to be measured.
3. The method of determining a rock initiation pressure gradient of claim 1, wherein a first test fluid in the first piston vessel is injected into the first pressure vessel, the core holder, and the second pressure vessel by the first constant pressure and constant velocity pump, and wherein prior to the core sample to be tested in the core holder being in the constant pressure mode for a set time, further comprising:
placing a core sample to be tested in a vacuumizing and pressurizing saturation device, and vacuumizing the core sample to be tested for more than 6 hours;
filling the first test fluid into the core sample to be tested, setting the pressure of the first test fluid filled into the core sample to be tested as reservoir pressure, and maintaining the reservoir pressure for more than one day; the reservoir pressure is the reservoir pressure of the core sample to be tested.
4. The method of determining a rock initiation pressure gradient of claim 1, wherein the set pressure value is 1.1 times reservoir pressure; the reservoir pressure is the reservoir pressure of the core sample to be tested.
5. The method of determining a rock initiation pressure gradient of claim 1, wherein the experimental testing apparatus further comprises a vacuum pump connected to the first end of the core holder, the first end of the first pressure vessel, and the first end of the piston vessel, respectively, through a first four-way valve; the vacuum pump is used for vacuumizing the first pressure-resistant container, the second pressure-resistant container, a pressure-resistant pipeline between the vacuum pump and the first pressure-resistant container and a pressure-resistant pipeline between the first pressure-resistant container and the second pressure-resistant container.
6. The method of determining a rock start pressure gradient of claim 1, wherein the first saturation is calculated as:
S 1 =(V-V 1 )/V；
wherein,S 1 representing the first saturation level in question,V 1 the first volume is represented by a volume of the first volume,Vrepresenting the total pore volume.
7. The method of determining a rock start pressure gradient of claim 1, wherein the second saturation is calculated as:
S 2 =(V-V 1 -V 2 )/V；
wherein,S 2 representing the said second saturation level of the light,V 1 the first volume is represented by a volume of the first volume,Vrepresenting the total pore volume in question,V 2 representing the second volume.
8. The method of determining a rock initiation pressure gradient of claim 1, wherein the experimental testing apparatus further comprises a differential pressure sensor for collecting a pressure differential across the core holder.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410090577.XA CN117607005B (en) | 2024-01-23 | 2024-01-23 | Method for measuring rock starting pressure gradient |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410090577.XA CN117607005B (en) | 2024-01-23 | 2024-01-23 | Method for measuring rock starting pressure gradient |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN117607005A CN117607005A (en) | 2024-02-27 |
| CN117607005B true CN117607005B (en) | 2024-04-12 |
Family
ID=89953851
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410090577.XA Active CN117607005B (en) | 2024-01-23 | 2024-01-23 | Method for measuring rock starting pressure gradient |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117607005B (en) |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104237098A (en) * | 2013-06-21 | 2014-12-24 | 长江大学 | Method for measuring gradient of rock starting pressure |
| CN106248545A (en) * | 2015-06-04 | 2016-12-21 | 中国石油化工股份有限公司 | The determinator of the Test Liquid Permeability of Core of tight rock and method under reservoir conditions |
| CN107167413A (en) * | 2017-06-26 | 2017-09-15 | 中国石油大学(北京) | A kind of compact rock core apparent permeability test device and method of testing |
| CN107356364A (en) * | 2017-06-26 | 2017-11-17 | 中国石油大学(北京) | The measurement apparatus and method of compact rock core free-boundary problem |
| CN108181209A (en) * | 2018-01-08 | 2018-06-19 | 中国海洋石油集团有限公司 | A kind of heavy crude reservoir fluid starting pressure gradient measuring device |
| CN109387467A (en) * | 2017-08-07 | 2019-02-26 | 中国石油化工股份有限公司 | The method for rapidly testing of the comprehensive starting pressure gradient of grease |
| CN109557010A (en) * | 2018-11-07 | 2019-04-02 | 北京科技大学 | A kind of experimental method measuring pressure gradient |
| CN115452681A (en) * | 2022-11-11 | 2022-12-09 | 中国石油大学(华东) | Method for determining relative permeability of reservoir oil gas |
| CN116413157A (en) * | 2021-12-29 | 2023-07-11 | 中国石油天然气股份有限公司 | New method for determining pressure gradient of tight gas reservoir start |
| CN117030471A (en) * | 2023-06-27 | 2023-11-10 | 中海油能源发展股份有限公司 | Intelligent starting pressure gradient test experimental device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10801943B2 (en) * | 2017-06-26 | 2020-10-13 | China University Of Petroleum-Beijing | Apparatus and method for measuring apparent permeability of tight rock core |
-
2024
- 2024-01-23 CN CN202410090577.XA patent/CN117607005B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104237098A (en) * | 2013-06-21 | 2014-12-24 | 长江大学 | Method for measuring gradient of rock starting pressure |
| CN106248545A (en) * | 2015-06-04 | 2016-12-21 | 中国石油化工股份有限公司 | The determinator of the Test Liquid Permeability of Core of tight rock and method under reservoir conditions |
| CN107167413A (en) * | 2017-06-26 | 2017-09-15 | 中国石油大学(北京) | A kind of compact rock core apparent permeability test device and method of testing |
| CN107356364A (en) * | 2017-06-26 | 2017-11-17 | 中国石油大学(北京) | The measurement apparatus and method of compact rock core free-boundary problem |
| CN109387467A (en) * | 2017-08-07 | 2019-02-26 | 中国石油化工股份有限公司 | The method for rapidly testing of the comprehensive starting pressure gradient of grease |
| CN108181209A (en) * | 2018-01-08 | 2018-06-19 | 中国海洋石油集团有限公司 | A kind of heavy crude reservoir fluid starting pressure gradient measuring device |
| CN109557010A (en) * | 2018-11-07 | 2019-04-02 | 北京科技大学 | A kind of experimental method measuring pressure gradient |
| CN116413157A (en) * | 2021-12-29 | 2023-07-11 | 中国石油天然气股份有限公司 | New method for determining pressure gradient of tight gas reservoir start |
| CN115452681A (en) * | 2022-11-11 | 2022-12-09 | 中国石油大学(华东) | Method for determining relative permeability of reservoir oil gas |
| CN117030471A (en) * | 2023-06-27 | 2023-11-10 | 中海油能源发展股份有限公司 | Intelligent starting pressure gradient test experimental device |
Non-Patent Citations (6)
| Title |
|---|
| 一种测试油气藏岩石启动压力梯度的优化方法;朱维耀;田巍;朱华银;宋智勇;孙岩;;石油与天然气地质;20170228(第01期);全文 * |
| 低渗气藏启动压力梯度实验研究及分析;黄亮;石军太;杨柳;臧加利;张玲;于鹏亮;;断块油气田;20160925(第05期);全文 * |
| 低渗致密气藏启动压力梯度测试方法讨论及分析;汪周华;刘雷;黄亮;刘士鑫;王宪文;;科学技术与工程;20160528(第15期);全文 * |
| 煤层气藏流体运移规律及数值模拟研究：;张纪远;中国博士学位论文全文数据库 (工程科技Ⅰ辑;20200715;全文 * |
| 考虑启动压力的层状油藏开发指标计算方法;冯其红;王守磊;韩晓冬;白军伟;;西南石油大学学报(自然科学版);20150430(第02期);全文 * |
| 超低渗透储层饱和/非饱和渗流启动压力梯度试验研究;谢全;何顺利;焦春艳;朱华银;付春艳;雷刚;;岩石力学与工程学报;20110515(第S1期);全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN117607005A (en) | 2024-02-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109443867B (en) | The method that the physical parameter of a kind of pair of tight rock is continuously detected | |
| CN208171813U (en) | A kind of multi-functional permeability test device | |
| CN110907334B (en) | Device and method for measuring radial flow oil-water relative permeability of conglomerate full-diameter core | |
| CN101967970B (en) | Method for measuring dynamic capillary pressure of core under conditions of reservoir temperature and pressure | |
| CN110823767B (en) | Device for measuring diffusion coefficient of condensate gas-dry gas in porous medium | |
| CN109932272B (en) | CO (carbon monoxide) 2 Displacement experiment system and displacement experiment method | |
| CN113062722A (en) | Long core water-gas stable alternation and accurate volume oil displacement experimental method | |
| CN113075109B (en) | Underground gas storage reservoir drying salting-out blocking injury experiment simulation system and method | |
| CN112986097B (en) | Experimental measurement method for determining relative permeability curve of tight reservoir steady state method | |
| CN104237099A (en) | Device and method for determining radial permeability of compact rock core | |
| CN114136861B (en) | Experimental system and evaluation method for drying salting-out effect of near-wellbore zone of gas storage | |
| CN108444890B (en) | Unsteady state titration device and method for testing medium and high permeability core liquid permeability | |
| CN113358683A (en) | Water flooding experimental device and method for researching core end face effect | |
| CN112198093A (en) | Device and method for testing diffusion coefficient of gas in saturated live oil core | |
| CN209821099U (en) | Multifunctional compact gas reservoir dynamic parameter joint measurement device based on nuclear magnetic resonance | |
| CN110411905A (en) | A kind of high temperature and pressure shale unstable state air water mutually seeps test device and method | |
| CN212748663U (en) | Unsteady gas-water phase seepage testing device | |
| CN113075081A (en) | Device and method for measuring solid phase deposition amount in multiple contact processes of injected gas and crude oil | |
| CN117607005B (en) | Method for measuring rock starting pressure gradient | |
| CN111638158A (en) | Compact sandstone gas-water phase permeability testing device and method based on capacitance method | |
| CN111351738B (en) | Natural gas diffusion coefficient analogue test apparatus | |
| CN113137223A (en) | Drilling fluid chemical osmotic pressure difference testing arrangement | |
| CN113433050B (en) | High-temperature high-pressure gas-water-liquid sulfur three-phase permeability testing device and method | |
| CN113109234B (en) | Low-oil-saturation seepage rule correction method for heavy water nuclear magnetism bound water detection | |
| CN111693676B (en) | System and method for measuring bubble point pressure of crude oil in porous medium |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |