Method for measuring porosity of drilling cuttings
By screening, cleaning, and drying drill cuttings samples and optimizing them, and combining this with nuclear magnetic resonance technology, the problem of measuring the porosity of drill cuttings after drilling with PDC drill bits was solved, and the accurate calculation of the porosity of fine drill cuttings was achieved.
Patent Information
- Application Number
- CN202410601740.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-15
- Publication Date
- 2025-11-18
AI Technical Summary
Existing technologies struggle to accurately measure the porosity of fine drilling cuttings generated after drilling with PDC drill bits, especially given the small size of the cuttings, the difficulty in removing surface water, and the challenge in determining their size.
By screening drilling cuttings of different particle sizes, and optimizing the cleaning, drying, and appearance volume measurement, the porosity was calculated by using nuclear magnetic resonance technology and measuring the transverse relaxation time T2 spectrum of the samples using standard sample calibration.
It enables accurate measurement of the porosity of fine drilling cuttings, solves the problems of small cutting particles and difficulty in removing surface water, and provides technical support for oil exploration.
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Figure CN120971293A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of oil exploration and well drilling, and particularly relates to a drilling rock debris porosity measurement method. BACKGROUND
[0002] In the petrophysical experimental research in the field of oil exploration and well drilling, a regular-shaped core is the basis for experimental research, and the core is usually required to be in the shape of a regular cylinder. The most commonly used rock porosity measurement method in the laboratory is the helium method. When the rock cannot be processed into a core in the shape of a cylinder, the helium method cannot be used to measure the porosity of the core.
[0003] The nuclear magnetic resonance technology is based on the response of hydrogen nuclei, and identifies the content of fluid in the rock pores through the measurement of the nuclear magnetic resonance signal of hydrogen nuclei, and then calculates the porosity of the rock and other information. It can be found from the principle of the nuclear magnetic resonance technology that the technology does not have strict requirements on the appearance shape of the rock experimental sample, and only needs the fluid in the rock pores to contain a certain amount of hydrogen nuclei. Therefore, the nuclear magnetic resonance technology is an effective measurement method for the porosity of irregular cores.
[0004] After the underground rock is crushed by the drill bit of the drilling equipment, the rock fragments are called drilling rock debris as the mud is brought to the ground. During the conventional mechanical drilling operation, although the drilling rock debris is of different sizes, large pieces of rock debris can be selected, and the porosity of the drilling rock debris is measured by using the nuclear magnetic resonance technology. Since 2000, with the deepening understanding of the rock breaking mechanism of the polycrystalline diamond compact (PDC) drill bit and the continuous progress of the science of superhard materials and its production process, the PDC drill bit has gradually been popularized in the application of oil and gas drilling engineering. While the PDC drill bit improves the drilling speed and reduces the drilling cost, due to its special rock breaking mechanism, the drilling rock debris produced is particularly small, with a diameter of millimeter level, and is also mixed with muddy particles and other false rock debris. In the face of the small drilling rock debris produced by the PDC drill bit operation, the nuclear magnetic resonance technology faces great challenges in measuring the porosity thereof.
[0005] Specifically, the drilling rock debris after the drilling by the PDC drill bit usually has the problems of small rock debris particles, difficulty in completely wiping off the water on the surface of the small rock debris, and difficulty in accurately determining the appearance volume of the rock debris. Therefore, it is necessary to propose a porosity measurement method for the drilling rock debris obtained by the drilling by the PDC drill bit in view of the above problems. SUMMARY
[0006] In order to overcome the defects of the prior art, the present application provides a porosity measurement method for drilling cuttings obtained by drilling with a PDC bit, representative drilling cuttings are selected according to particle size to prepare a sample for measuring porosity, and the cleaning, drying and appearance volume measurement processes of the test sample are optimized and designed, solving the technical problems of small particle size of the drilling cuttings after drilling with the PDC bit, difficult to clean the surface water, and difficult to accurately determine the appearance volume of the drilling cuttings.
[0007] In order to achieve the above object, the present application provides the following technical scheme:
[0008] A drilling cuttings porosity measurement method, comprising:
[0009] Selecting drilling cuttings particles of different particle sizes at a target horizon as a measurement sample;
[0010] Cleaning the measurement sample;
[0011] Removing surface water of the cleaned measurement sample;
[0012] Determining the appearance volume of the measurement sample after removing the surface water;
[0013] Performing a nuclear magnetic resonance experiment on the measurement sample to obtain a transverse relaxation time T2 spectrum of the measurement sample;
[0014] Calibrating the transverse relaxation time T2 spectrum of the measurement sample based on the transverse relaxation time T2 spectrum of the standard sample, and cumulatively summing the envelope area of the calibrated transverse relaxation time T2 spectrum of the measurement sample to obtain the porosity of the measurement sample.
[0015] Further, the drilling cuttings particles include drilling cuttings particles obtained by drilling with a PDC bit.
[0016] Further, selecting drilling cuttings particles of different particle sizes at a target horizon as a measurement sample comprises:
[0017] Screening the drilling cuttings particles using different mesh size sieves to obtain drilling cuttings of different particle sizes;
[0018] Selecting drilling cuttings of multiple particle sizes to mix to obtain the measurement sample.
[0019] Further, cleaning the measurement sample comprises:
[0020] Immersing the measurement sample in water and stirring, and periodically replacing the clean water until the water immersed in the measurement sample remains clear.
[0021] Further, removing the surface water of the cleaned measurement sample comprises:
[0022] The measurement sample is dried at 39-41 DEG C for 9-11 minutes.
[0023] Further, the apparent volume of the measurement sample after the surface water is removed is determined, comprising:
[0024] The measurement sample is immersed in a container containing a fluorination liquid, and the apparent volume of the measurement sample is calculated according to the liquid level difference of the fluorination liquid.
[0025] Further, the measurement sample is subjected to a nuclear magnetic resonance experiment to obtain a transverse relaxation time T2 spectrum of the measurement sample, comprising:
[0026] The nuclear magnetic resonance signal of the water in the pores of the measurement sample is measured by using a spin echo pulse sequence of a nuclear magnetic resonance instrument to obtain a transverse relaxation time T2 spectrum of the measurement sample.
[0027] Further, the standard sample is a rock sample with a known porosity.
[0028] Further, the longitudinal axis of the transverse relaxation time T2 spectrum of the measurement sample and the standard sample is the size of the nuclear magnetic signal amplitude.
[0029] Further, the transverse relaxation time T2 spectrum of the measurement sample is calibrated based on the transverse relaxation time T2 spectrum of the standard sample, comprising:
[0030] Based on the size of the nuclear magnetic signal amplitude of the transverse relaxation time T2 spectrum of the standard sample, the longitudinal axis of the transverse relaxation time T2 spectrum of the measurement sample is converted into a porosity component.
[0031] The technical effects and advantages of the present application:
[0032] The present application selects representative drilling cuttings with particle sizes for preparing a sample for measuring porosity, and optimizes the cleaning, drying and apparent volume measurement process of the detection sample, solves the technical problems of small particle size of the rock cuttings after drilling by a PDC drill bit, difficulty in wiping off the surface water completely, and difficulty in accurately determining the apparent volume of the rock cuttings, provides a new idea for measuring the porosity of small drilling cuttings, and provides technical support for oil exploration.
[0033] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and obtained by the structure indicated in the specification, claims and drawings. BRIEF DESCRIPTION OF DRAWINGS
[0034] Figure 1 A flowchart of a drilling cuttings porosity measurement method of the present application;
[0035] Figure 2A schematic diagram of a nuclear magnetic resonance transverse relaxation time T2 spectrum of a sample measured in the present application, wherein the longitudinal axis represents the amplitude of the nuclear magnetic signal;
[0036] Figure 3 A schematic diagram of a nuclear magnetic resonance transverse relaxation time T2 spectrum of a sample measured in the present application, wherein the longitudinal axis represents the porosity component. DETAILED DESCRIPTION
[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.
[0038] It should be noted that the drilling cuttings particles of the present application are the drilling cuttings particles obtained by drilling with a PDC drill bit. During conventional mechanical drilling operations, although the drilling cuttings are of different sizes, large pieces of cuttings with relatively large volumes can be selected to facilitate the measurement of the porosity of the drilling cuttings using nuclear magnetic resonance technology. However, after drilling with a PDC drill bit, the drilling cuttings usually have the following problems: the drilling cuttings particles are small, the surface water of the small drilling cuttings is difficult to wipe clean, and the apparent volume of the drilling cuttings is difficult to accurately determine,
[0039] In order to overcome the above problems, as shown in the present application, a drilling cuttings porosity measurement method is provided, comprising: Figure 1
[0040] Selecting drilling cuttings particles of different particle sizes at a target layer as a measurement sample;
[0041] Cleaning the measurement sample;
[0042] Removing the surface water of the cleaned measurement sample;
[0043] Determining the apparent volume of the measurement sample after removing the surface water;
[0044] Performing a nuclear magnetic resonance experiment on the measurement sample to obtain a transverse relaxation time T2 spectrum of the measurement sample;
[0045] Calibrating the transverse relaxation time T2 spectrum of the measurement sample based on the transverse relaxation time T2 spectrum of the standard sample, and cumulatively summing the envelope area of the calibrated transverse relaxation time T2 spectrum of the measurement sample to obtain the porosity of the measurement sample.
[0046] In some embodiments of the present application, selecting drilling cuttings particles of different particle sizes at a target layer as a measurement sample comprises: screening the drilling cuttings particles using filtering screens of different mesh sizes to obtain drilling cuttings of different particle sizes; and selecting drilling cuttings of multiple particle sizes to mix to obtain the measurement sample.
[0047] Specifically, the filter screens are stacked from top to bottom in order of mesh size from large to small, the collected drilling cuttings are poured into the uppermost filter screen with the largest mesh size, the drilling cuttings are leveled in the filter screen, the filter screen is gently shaken, the drilling cuttings with a particle size larger than the mesh size of the current filter screen are retained in the current filter screen, and the drilling cuttings with a particle size smaller than the mesh size of the current filter screen fall into the next level of filter screen, and the operation is sequentially performed, so that the collected drilling cuttings are screened into drilling cuttings with different particle sizes by using filter screens with different mesh sizes. Since the PDC drill bit breaks the underground rock into small particles of different sizes, it is difficult to fully reflect the characteristics of the underground rock by using only one particle size grade of drilling cuttings. Therefore, according to the screening result, a plurality of (for example, three, four or five) drilling cuttings with different particle sizes are selected from the screened drilling cuttings and mixed together as a measurement sample representing the rock at the layer where the drilling cuttings are located.
[0048] In some embodiments of the present application, the measurement sample is cleaned, including: immersing the measurement sample in water and stirring, and periodically replacing the clean water until the water immersed in the measurement sample remains clear.
[0049] Specifically, the measurement sample is placed in a container filled with water, continuously stirred with a glass rod, and the water in the container is periodically replaced, so that the clay attached to the surface of the drilling cuttings is washed away, until the water immersed in the measurement sample in the last container remains clear, indicating that the clay particles adsorbed on the surface of the measurement sample are completely cleaned.
[0050] In some embodiments of the present application, the surface water of the cleaned measurement sample is removed, including:
[0051] The measurement sample is dried at 39-41℃ for 9-11 minutes, preferably dried at 40℃ for 10 minutes, so that the surface water adsorbed by the measurement sample can be effectively removed, and the measurement sample is not completely dried to affect the subsequent nuclear magnetic resonance experiment.
[0052] In some embodiments of the present application, the apparent volume of the measurement sample after the surface water is removed is determined, including: immersing the measurement sample in a container filled with fluorinated liquid, and calculating the apparent volume of the measurement sample according to the liquid level difference of the fluorinated liquid.
[0053] It should be noted that the fluorinated liquid is a fluid without hydrogen nucleus, and the nuclear magnetic resonance technology is a technical means for collecting the response of hydrogen nucleus in the fluid. Therefore, the fluorinated liquid has no response information in the nuclear magnetic resonance instrument, and does not affect the collection of the nuclear magnetic signal of the drilling cuttings by the nuclear magnetic resonance instrument.
[0054] In some embodiments of the present application, a nuclear magnetic resonance experiment is performed on a measurement sample to obtain a transverse relaxation time T2 spectrum of the measurement sample, and a transverse relaxation time T2 spectrum of a standard sample is compared with the transverse relaxation time T2 spectrum of the measurement sample to obtain a porosity of the measurement sample, including: using a spin echo pulse sequence of a nuclear magnetic resonance instrument to measure a nuclear magnetic resonance signal of water in a pore of the measurement sample to obtain a transverse relaxation time T2 spectrum of the measurement sample as shown in Figure 2 . The vertical axis of the transverse relaxation time T2 spectrum of the measurement sample and the standard sample is the size of the nuclear magnetic signal amplitude. Based on the size of the nuclear magnetic signal amplitude of the transverse relaxation time T2 spectrum of the standard sample, the vertical axis of the transverse relaxation time T2 spectrum of the measurement sample is converted into a porosity component as shown in Figure 3 . The envelope area of the transverse relaxation time T2 spectrum of the measurement sample after conversion and the horizontal axis is the porosity of the drilling debris. The standard sample is a sample with a known porosity, for example, different types of fluids are configured in a certain volume, and the number of hydrogen nuclei of the fluid is accurately controlled to accurately obtain the porosity, thereby establishing a standard.
[0055] In summary, the present application selects representative drilling debris with different particle sizes to prepare samples for measuring porosity, and optimizes the cleaning, drying, and appearance volume measurement processes of the detection samples, thereby solving the technical problems of small particle size of drilling debris after drilling by a PDC drill bit, difficulty in wiping off the surface water, and difficulty in accurately determining the appearance volume of the drilling debris, providing a new idea for measuring the porosity of small drilling debris cores, and providing technical support for oil exploration and well drilling.
[0056] Finally, it should be noted that: the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features, as long as they are within the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made within the scope of the present application should be included in the protection scope of the present application.
Claims
1. A method for measuring the porosity of drilling cuttings, characterized in that, include: Drill cuttings of different sizes from the target formation were selected as measurement samples. The measured sample is cleaned; Remove the surface water from the measured sample after cleaning; Determine the apparent volume of the measured sample after removing surface water; Nuclear magnetic resonance experiments were performed on the measured sample to obtain the transverse relaxation time T2 spectrum of the measured sample; The transverse relaxation time T2 spectrum of the measured sample is calibrated based on the transverse relaxation time T2 spectrum of the standard sample. The envelope area of the calibrated transverse relaxation time T2 spectrum of the measured sample is accumulated and summed to obtain the porosity of the measured sample.
2. The method for measuring the porosity of drilling cuttings according to claim 1, characterized in that, The drilling cuttings include cuttings obtained from drilling with a PDC drill bit.
3. The method for measuring the porosity of drilling cuttings according to claim 1, characterized in that, The selection of drilling cuttings of different sizes from the target formation as measurement samples includes: The drilling cuttings particles were screened using filter sieves with different mesh sizes to obtain drilling cuttings of different particle sizes; The measured sample was obtained by mixing drilling cuttings of various particle sizes.
4. The method for measuring the porosity of drilling cuttings according to claim 1, characterized in that, The cleaning of the measured sample includes: Immerse the sample in water and stir, changing the water periodically until the water used to soak the sample remains clear.
5. The method for measuring the porosity of drilling cuttings according to claim 1, characterized in that, The removal of surface water from the measured sample after cleaning includes: The measured sample was dried at 39-41°C for 9-11 minutes.
6. The method for measuring the porosity of drilling cuttings according to claim 1, characterized in that, Determining the apparent volume of the measured sample after removing surface water includes: The measurement sample is immersed in a container containing fluorinated liquid, and the apparent volume of the measurement sample is calculated based on the liquid level difference of the fluorinated liquid.
7. The method for measuring the porosity of drilling cuttings according to claim 1, characterized in that, The method of performing nuclear magnetic resonance experiments on the measured sample to obtain the transverse relaxation time T2 spectrum of the measured sample includes: The nuclear magnetic resonance signal of water in the pores of the sample was measured using a spin echo pulse sequence of a nuclear magnetic resonance instrument to obtain the transverse relaxation time T2 spectrum of the sample.
8. The method for measuring the porosity of drilling cuttings according to claim 1, characterized in that, The standard sample is a sample with known porosity.
9. The method for measuring the porosity of drilling cuttings according to claim 1, characterized in that, The vertical axis of the transverse relaxation time T2 spectrum of the measured sample and the standard sample represents the magnitude of the NMR signal.
10. A method for measuring the porosity of drilling cuttings according to claim 9, characterized in that, The calibration of the transverse relaxation time T2 spectrum of the measured sample based on the standard sample's transverse relaxation time T2 spectrum includes: Based on the magnitude of the NMR signal amplitude of the transverse relaxation time T2 spectrum of the standard sample, the vertical axis of the transverse relaxation time T2 spectrum of the measured sample is converted into a porosity component.