Method for flaking fine rock debris under PDC (polycrystalline diamond compact) drill bit

Abstract

The invention provides a flaking method for fine rock debris under a PDC drill bit, and relates to the field of oil field exploration and development. The flaking method comprises the following steps: (1) sieving fine rock debris to obtain small-particle-size rock debris; (2) mixing the small-particle-size rock debris with an epoxy resin mixture, and curing to obtain an aggregate bonded by fine rock debris particles; (3) cutting and preparing rock slices according to a rock slice preparation method in the industrial standard SY / T5913-2021, so as to obtain the rock slices; the epoxy resin mixture is a mixture of epoxy resin-crystal glue A and epoxy resin-crystal glue B in a weight ratio of (2-4): 1. According to the flaking method, the problems that under PDC drill bit construction, rock debris particles are small, flaking cannot be conducted, and flaking identification data do not exist are solved. Meanwhile, the number of sheets which cannot be ground in the early stage can be increased, and data support is provided for exploration and development.

Description

Technical Field

[0001] The present invention belongs to the field of oilfield exploration and development, and particularly relates to a method for preparing thin sections of fine rock debris under a PDC bit. Background Art

[0002] Rock thin section preparation is a method of grinding core or cuttings obtained during drilling into various types of thin sections. At present, the standard method for rock thin section preparation is SY / T 5913-2021 "Rock Thin Section Preparation Method". The standard method requires that the minimum size of the selected rock sample for core thin section preparation is 25mm×25mm×5mm, and more than three samples are selected for cuttings sample thin section preparation. Even for senior technicians in thin section preparation in this field, due to the influence of detection methods and detection conditions, etc., the smallest particle that can be successfully prepared into a thin section and smoothly detected is currently 5mm×5mm.

[0003] With the development of deep earth exploration engineering and the improvement of drilling technology, PDC (Polycrystalline Diamond Compact) bits are widely used in drilling operations. However, 95% of the cuttings generated by this drilling technology are less than 5mm×5mm. Although the rock mineral composition and mineral element composition can be obtained using rock X-ray technology and mineral element analysis, the rock fabric data such as mineral structure, texture, cement, and matrix cannot be analyzed. Therefore, to conduct more accurate, in-depth, and extensive research on the properties of rocks, thin section detection is still required. However, the extremely small rock debris particles cannot be successfully prepared into thin sections, and the detection and confirmation of identification data cannot be carried out on them.

[0004] At present, although there are technical patents or literatures on preparing thin sections of fine cuttings. For example, Chinese invention patent CN111122263B discloses a manual method for preparing rock cast thin sections of fine cuttings. From the initial selection of on-site samples to a series of thin section preparation processes such as sample cover glass, all use simple manual production, mainly including steps: cementing the flat surface of the sample (surface infiltration and cementing with blue casting resin), sticking the flat surface of the sample with rosin, grinding the rough surface of the sample into a flat surface, casting on one side of the flat surface, sticking the casting on one side with "502" glue, removing the film on the side of heating rosin, grinding the flat surface of the sample, and finally covering the sample with a cover glass; by simple manual production, the requirements for experimental equipment are simplified, the experimental cycle is shortened, and the rate can reach 0.5-1 h / sample, enabling the preparation of rock cast thin sections to be widely applied in drilling sites or field investigation sites, providing a guiding basis for on-site operations, and having great on-site application significance. However, the thin section preparation process in this patent is complex, and treatments such as sticking the sample with rosin and sticking the casting on one side of the sample surface with 502 glue are also required, greatly prolonging the thin section preparation time.

[0005] Chinese invention patent CN101424600B discloses a method for preparing a thin section of smectite-rich sandstone cast. First, select an oil-free sample of smectite-rich sandstone; drill an oil-free sample in the shape of a cylinder or cube from the determined oil-free rock sample using saturated brine, and cut a rock sample of 25mm×25mm×5mm; wash the rock sample with toluene to remove oil at room temperature and air dry it; in a vacuum oven, at room temperature, continuously maintain a negative pressure of -0.08MPa and dry it under vacuum for 48 hours to pump out toluene and water molecules in the rock by negative pressure. Then, press the rock sample at room temperature using a rock pore cast instrument, and inject the casting liquid according to the mass ratio of 100 parts of epoxy resin: 35 parts of 593 curing agent: 1 part of pigment. The casting time is 1 hour, the pressure is 30MPa, and the vacuum degree value ≥ 8×10 -2 ; After casting, grind the cast body into a thin section without boiling the glue; it can truly reflect the pore structure parameters in the formation and plays an important role in correctly judging the quality of the reservoir properties.

[0006] However, the above technology still fails to overcome the technical problem of being unable to prepare thin sections for extremely small (less than 5mm×5mm×5mm) rock particles. In view of this, it is of great significance to provide a method for preparing thin sections for extremely small rock particles, and the prepared thin sections can reflect the performance of real cuttings, thus solving the problem of lack of thin section identification data in geological logging. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for preparing a thin section of fine rock debris under a PDC bit. Mix and cure a mixture of extremely small rock debris and epoxy resin to obtain a corresponding aggregate composed of fine rock debris particles, and then prepare it into a rock thin section according to SY / T5913-2021 "Rock Thin Section Preparation Method"; the thin section preparation method of the present invention solves the problems of extremely small rock debris particles during PDC bit construction, inability to prepare thin sections, and lack of thin section identification data. At the same time, through the above thin section preparation method, the number of thin sections that could not be ground before can be increased, providing data support for exploration and development.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] On the one hand, the present invention provides a method for preparing a thin section of fine rock debris under a PDC bit, including the steps:

[0010] (1) Sieve the fine rock debris to obtain small-sized rock debris;

[0011] (2) Mix the small-sized rock debris with an epoxy resin mixture, and after curing, obtain an aggregate bonded by fine rock debris particles;

[0012] (3) Cut and prepare thin rock slices according to the rock slicing method described in industry standard SY / T5913-2021 to obtain thin rock slices.

[0013] Preferably, in step (1), the sieving is to sieve through sieves with particle sizes of 5 mm, 2 mm, and 0.5 mm respectively to screen out particles of different particle sizes.

[0014] Preferably, step (2) can be carried out in mold boxes of different shapes and specifications; the present invention has no specific requirements for the shape and specifications of the mold box, and it can be any small paper box or test tube, etc.

[0015] Preferably, in step (2), the epoxy resin mixture is a mixture of epoxy resin - crystal drop glue A and epoxy resin - crystal drop glue B.

[0016] Further preferably, the weight ratio of the epoxy resin - crystal drop glue A to the epoxy resin - crystal drop glue B is 2 - 4:1.

[0017] Even more preferably, the weight ratio of the epoxy resin - crystal drop glue A to the epoxy resin - crystal drop glue B is 3:1.

[0018] In the present invention, the epoxy resin is used as an adhesive to bond the rock debris together.

[0019] Preferably, step (2) is specifically: put the rock debris with small particle size into the mold box, then add the epoxy resin mixture, and the addition amount of the epoxy resin mixture is such that the height covers the rock debris with small particle size. The bonded rock debris with small particle size naturally settles to the bottom by its own gravity before consolidation, and is placed at room temperature for 20 - 36 h. After the epoxy resin cures, remove the mold to obtain an aggregate bonded by fine rock debris particles.

[0020] Further preferably, the preparation method of the epoxy resin mixture is to mix the epoxy resin - crystal drop glue A and the epoxy resin - crystal drop glue B according to a certain weight ratio and stir evenly.

[0021] Preferably, in step (3), for the cutting, use a cutting machine to cut the aggregate into modules of 25×25×5 mm, and then make the modules into various required thin rock slices according to the rock slicing method described in SY / T5913-2021.

[0022] After successfully preparing the thin rock slices in the present invention, perform performance detection on them, and it is possible to clearly distinguish the size and content of intraclasts on the rock debris, and the identification work can be carried out without hindrance; the rock performance data obtained by identification is consistent with the real data.

[0023] On the other hand, the present invention provides the application of an epoxy resin mixture as an adhesive in the preparation of thin sections of fine rock debris.

[0024] Preferably, in the above application, the epoxy resin mixture is specifically a mixture of epoxy resin - crystal drop glue A and epoxy resin - crystal drop glue B.

[0025] More preferably, the weight ratio of the epoxy resin - crystal drop glue A to the epoxy resin - crystal drop glue B is 2 - 4:1.

[0026] Even more preferably, the weight ratio of the epoxy resin - crystal drop glue A to the epoxy resin - crystal drop glue B is 3:1.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The thin - section preparation method of the present invention solves the problem that under the construction of PDC bits, the rock debris particles are too fine to prepare thin sections and there is no thin - section identification data.

[0029] 2. The thin - section preparation method of the present invention avoids the operation of replacing drill tools to obtain important formation rock data, thus saving construction time.

[0030] 3. The thin - section preparation method of the present invention is not only applicable to the preparation of thin sections of rock debris with particles smaller than 5 mm, but also applicable to broken rocks with smaller particle sizes such as 0.5 - 2 mm; and the success rate of thin - section preparation can still reach nearly 100%.

[0031] 4. The thin - section preparation method of the present invention can reach hundreds of particles for one - time sample preparation, providing sufficient statistical samples for detection.

[0032] 5. The thin - section preparation method of the present invention is a supplement to SY / T5913 - 2021 "Rock Thin - Section Preparation Method". The thin - section preparation method of the present invention can not only improve the integrity of geological logging data, but also reflect scientific information in aspects such as sedimentation, diagenesis, and rock structure and texture through thin - section identification research, which plays a very important role in the exploration and development of the petroleum industry; through the method of the present invention, the number of thin sections that could not be ground previously can be increased, providing data support for exploration and development. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is an example diagram of the aggregate prepared in step (2) of the present invention.

[0034] Figure 2 is an example diagram of the rock thin section made in step (3) of the present invention.

[0035] Figure 3 is an optical microscope observation diagram of the conventional thin - section identification of the rock thin section of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] The following non-limiting examples can enable those of ordinary skill in the art to more comprehensively understand the present invention, but do not limit the present invention in any way. The following content is merely an exemplary illustration of the scope claimed by the present invention. Those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and such changes and modifications should also fall within the scope claimed by the present invention. When an example gives a numerical range, it should be understood that unless otherwise specified in the present invention, any value between the two endpoints of each numerical range and either endpoint can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0037] The present invention will be further described below by way of specific examples. All various chemical reagents used in the embodiments of the present invention are obtained through conventional commercial channels unless otherwise specified.

[0038] In the following examples, the epoxy resin mixture is an adhesive, purchased from Shenzhen Juhengchuang Electronic Materials Co., Ltd., Indigo brand. Epoxy resin - crystal glue A and Epoxy resin - crystal glue B are configured to obtain the epoxy resin mixture according to a weight ratio of 2 - 4:1.

[0039] For the above components, products from different manufacturers do not have a significant impact on the effect.

[0040] In the following examples, the rock section preparation method described in SY / T5913 - 2021 "Rock Section Preparation Method" includes the steps:

[0041] S1. Sampling, the core is 25mm×25mm×5mm, and there are more than three cuttings.

[0042] S2. Fixing the glue, select according to the rock properties, and use the drop - glue fixing method, boiling - glue fixing method or embedding machine fixing method to fix the glue.

[0043] S3. Grinding the plane, use different emery papers to grind one side smooth.

[0044] S4. Mounting the slice, use the strong - glue mounting method or fir - glue mounting method to stick the rock ground in the previous step on the glass slide.

[0045] S5. Slicing, use the manual method or machine slicing method to cut off the excess part until the thickness of the rock slice is 0.8 - 12.mm.

[0046] S6. Polishing the slice, use the emery - paper polishing method, gradually polish the rock slice on the polishing machine to 0.04 - 0.05mm, and finally polish it on the glass plate to about 0.03mm.

[0047] Example 1

[0048] (1) Sieve the fine rock debris and collect the rock debris with a small particle size between 2 - 5 mm;

[0049] (2) Put the rock debris with a small particle size into a mold box, and then add an epoxy resin mixture. The addition amount of the epoxy resin mixture is such that the height covers the rock debris with a small particle size. The bonded rock debris with a small particle size naturally settles to the bottom by its own gravity before consolidation. Leave it at room temperature for 24 h. After the epoxy resin cures, remove the mold to obtain an aggregate bonded by fine rock debris particles; The example diagram of the aggregate prepared in this example can be seen in Figure 1 .

[0050] The epoxy resin mixture is a mixture obtained by mixing epoxy resin - crystal drop glue A and epoxy resin - crystal drop glue B in a weight ratio of 3:1 and stirring evenly;

[0051] (3) Use a cutting machine to cut the aggregate obtained in step (2) into modules with dimensions of 25 mm × 25 mm × 5 mm, and then make the modules into rock thin sections according to the rock section preparation method described in SY / T5913 - 2021 "Rock Section Preparation Method", using the drop - glue solidification method, with a thickness of 0.03 mm. The example diagram of the rock thin section prepared in this example can be seen in Figure 2 .

[0052] In the experiment where the section preparation method of this example was repeated 50 times, the success rate of section preparation was 100%.

[0053] Observe the prepared rock thin section with an optical microscope. The observation image can be seen in Figure 3 , and the scale shown is 500 μm. From Figure 3 it can be seen that the present invention can not only successfully prepare rock thin sections, but also the prepared rock thin sections can clearly distinguish the size and content of intraclasts on the cuttings, and the identification work can be carried out without hindrance; the rock property data obtained by identification is consistent with the real data.

[0054] Example 2

[0055] (1) Sieve the fine rock debris and collect the rock debris with a small particle size between 0.5 - 2 mm;

[0056] (2) Put the rock debris with a small particle size into a mold box, and then add an epoxy resin mixture. The addition amount of the epoxy resin mixture is such that the height covers the rock debris with a small particle size. The bonded rock debris with a small particle size naturally settles to the bottom by its own gravity before consolidation. Leave it at room temperature for 24 h. After the epoxy resin cures, remove the mold to obtain an aggregate bonded by fine rock debris particles;

[0057] The epoxy resin mixture is a mixture obtained by mixing epoxy resin - crystal drop glue A and epoxy resin - crystal drop glue B in a weight ratio of 3:1 and stirring evenly;

[0058] (3) Use a cutting machine to cut the aggregate obtained in step (2) into modules with dimensions of 25*25*5 mm, and then make rock thin sections from the modules according to the rock section preparation method described in SY / T5913 - 2021 "Rock Section Preparation Method", using the boiling glue solidification method, with a thickness of 0.03 mm.

[0059] Generally, cuttings that can reflect the true formation are selected from debris with a particle size of more than 2 mm; while when the particle size of the present invention is less than 2 mm (0.5 - 2 mm), the rock properties of the true formation can still be reflected.

[0060] In the experiment where the section preparation method of this example was repeated 50 times, the section preparation success rate was 98%.

[0061] Example 3

[0062] (1) Sieve the fine rock debris and collect the rock debris with a small particle size between 0.5 - 5 mm;

[0063] (2) Put the small - particle - size rock debris into a mold box, and then add the epoxy resin mixture. The addition amount of the epoxy resin mixture is such that the height covers the small - particle - size rock debris. The small - particle - size rock debris to be bonded naturally settles to the bottom by its own gravity before consolidation. Place it at room temperature for 30 h. After the epoxy resin cures, remove the mold to obtain an aggregate bonded by fine rock debris particles;

[0064] The epoxy resin mixture is a mixture obtained by mixing epoxy resin - crystal drop glue A and epoxy resin - crystal drop glue B in a weight ratio of 4:1 and stirring evenly;

[0065] (3) Use a cutting machine to cut the aggregate obtained in step (2) into modules with dimensions of 25×25×5 mm, and then make rock thin sections from the modules according to the rock section preparation method described in SY / T5913 - 2021 "Rock Section Preparation Method", using the embedding machine solidification method, with a thickness of 0.03 mm.

[0066] In the experiment where the section preparation method of this example was repeated 50 times, the section preparation success rate was 98%.

[0067] Comparative Example 1

[0068] Different from Example 1, directly use the rock section preparation method described in SY / T5913 - 2021 "Rock Section Preparation Method" to prepare sections for the fine rock debris.

[0069] This method cannot successfully prepare thin sections of fine rock debris, that is, the success rate of preparing thin sections is 0%.

[0070] Comparative Example 2

[0071] Different from Example 1, the epoxy resin mixture used as the binder in step (2) is replaced with blue casting resin, which is prepared by mixing 502 glue and oil-soluble blue N in a mass ratio of 100:1, and the blue casting resin is prepared and used immediately. In the method for preparing thin sections of this comparative example, the prepared thin sections are casting thin sections, not ordinary rock thin sections under normal circumstances. The blue binder is used to show micro-pores, which will affect the estimation of the content of rock minerals and matrix during the identification of rocks.

[0072] In the experiment repeated 50 times, the success rate of preparing thin sections is 74%.

[0073] Comparative Example 3

[0074] Different from Example 1, the weight ratio of epoxy resin-crystal drip glue A and epoxy resin-crystal drip glue B in step (2) is different, and the weight ratio of this comparative example is 1:3.

[0075] In the method for preparing thin sections of this comparative example, the prepared thin sections are prone to problems such as cracks and unclear textures, which affect the identification of rock properties.

[0076] In the experiment repeated 50 times, the success rate of preparing thin sections is 78%.

[0077] Comparative Example 4

[0078] Different from Example 1, the epoxy resin mixture used as the binder in step (2) is replaced with a mixture of epoxy resin and 593 curing agent;

[0079] Among them, the epoxy resin is low-viscosity epoxy resin Adicol EP-4080E; the 593 curing agent is purchased from Jinan Rongzheng Chemical Co., Ltd.; the weight ratio of epoxy resin and 593 curing agent is 100:35.

[0080] In the method for preparing thin sections of this method, the prepared thin sections are prone to problems such as cracks, unclear textures, fractures, and powders. At the same time, the blue binder will also affect the estimation of the content of rock minerals and matrix.

[0081] In the experiment repeated 50 times, the success rate of preparing thin sections is only 66%.

[0082] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than a limitation on the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solution of the present invention by those of ordinary skill in the art shall not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing specimens of small rock debris under a PDC bit, characterized in that, Including the steps: (1) Sieving the fine rock debris to obtain rock debris with a small particle size; (2) Mixing the rock debris with a small particle size with an epoxy resin mixture, and after curing, obtaining an aggregate bonded by fine rock debris particles; (3) Cutting and preparing thin rock slices according to the rock slice preparation method described in the industry standard SY / T5913-2021 to obtain thin rock slices.

2. The film production method according to claim 1, characterized in that, In step (1), for the sieving, sieves with particle sizes of 5 mm, 2 mm, and 0.5 mm are used respectively.

3. The film production method according to claim 1, characterized in that, In step (2), the epoxy resin mixture is a mixture of epoxy resin - crystal drop glue A and epoxy resin - crystal drop glue B.

4. The film production method according to claim 3, characterized in that, The weight ratio of the epoxy resin - crystal drop glue A to the epoxy resin - crystal drop glue B is 2 - 4:

1.

5. The film production method according to claim 4, characterized in that, The weight ratio of the epoxy resin - crystal drop glue A to the epoxy resin - crystal drop glue B is 3:

1.

6. The film production method according to claim 3, characterized in that, The preparation method of the epoxy resin mixture is to mix the epoxy resin - crystal drop glue A and the epoxy resin - crystal drop glue B according to a certain weight ratio and stir evenly.

7. The film production method according to claim 1, characterized in that, Step (2) is specifically: putting the rock debris with a small particle size into a mold box, then adding the epoxy resin mixture, and the addition amount of the epoxy resin mixture is such that the height covers the rock debris with a small particle size. The rock debris with a small particle size to be bonded naturally settles to the bottom by its own gravity before consolidation. It is placed at room temperature for 20 - 36 h. After the epoxy resin cures, the mold is removed to obtain an aggregate bonded by fine rock debris particles.

8. The film production method according to claim 1, characterized in that, In step (3), for the cutting, the aggregate is cut into a module of 25×25×5 mm using a cutting machine, and then the module is made into various required thin rock slices according to the rock slice preparation method described in SY / T5913-2021.

9. Application of an epoxy resin mixture as an adhesive in the preparation of thin slices of fine rock debris.

10. The application according to claim 9, wherein The epoxy resin mixture is specifically a mixture of epoxy resin - crystal drop glue A and epoxy resin - crystal drop glue B; preferably, the weight ratio of the epoxy resin - crystal drop glue A to the epoxy resin - crystal drop glue B is 2 - 4:1; more preferably, the weight ratio of the epoxy resin - crystal drop glue A to the epoxy resin - crystal drop glue B is 3:1.

Images