Method and device for predicting sweet spot area of tight oil source rock

Abstract

The invention provides a method and a device for predicting a sweet spot area of tight oil source rock, and relates to the field of sweet spot area prediction. The method for predicting the sweet spot area of the tight oil source rock comprises the following specific prediction methods: step 1, determining a sampling point according to an exploration target, collecting a core sample of a target layer section, and measuring key parameters such as organic carbon content, maturity, porosity and permeability; 2, numbering and cutting the rock core to prepare a powder sample, and keeping the original structural characteristics; and step 3, taking rock core powder, and avoiding exposure in air to prevent light hydrocarbon from volatilizing. By arranging the driving motor, the rotating rod, the crushing cutter and the air pump, the driving motor drives the rotating rod to rotate, and the crushing cutter rotates at a high speed, so that rock cores in the crushing box are crushed, external air is introduced through the air pump after crushing, and through conveying of the air pump, contact with air can be reduced, and circulation in the equipment can be kept.

Description

Technical Field

[0001] The present invention relates to the technical field of sweet spot prediction, and specifically to a method and device for predicting the sweet spot of tight oil source rocks. Background Art

[0002] The sweet spot of tight oil source rocks refers to the core enrichment area in source rocks with high efficient hydrocarbon generation ability, high-quality reservoir space and mobilizability. Its formation needs to meet three key conditions: first, the organic matter abundance of the source rock is high (TOC > 2%) and the maturity is moderate (Ro is 0.7% - 1.3%); second, the reservoir physical properties are excellent (porosity > 8% and microfractures are developed); third, there is an overpressure or natural fracture system, which is conducive to hydrocarbon discharge and exploitation. The prediction of sweet spots needs to comprehensively use geochemical analysis, well logging interpretation and seismic inversion techniques, and achieve accurate positioning through multi-parameter coupling evaluation of TOC-porosity-fracture density. For example, the sweet spot in the Chang 7 section of the Ordos Basin can reach a daily oil production of more than 20 tons per well through the combination mode of "high-TOC shale + quartz brittle mineral enrichment belt + fracture network", and has become the core target area for unconventional oil and gas development.

[0003] In the prior art, the prediction of the sweet spot of tight oil source rocks is carried out by sampling the geology and then detecting and analyzing the data. However, traditional cores are exposed, and the environment will affect the cores. For example, free hydrocarbons and light components in the cores are easily volatilized due to exposure, resulting in distortion of key parameters such as oil saturation and hydrocarbon composition in subsequent experiments (such as thermal desorption analysis); this leads to errors in the results and affects the judgment of sweet spots. Summary of the Invention

[0004] (I) Technical Problems to be Solved Aiming at the deficiencies of the prior art, the present invention provides a method and device for predicting the sweet spot of tight oil source rocks, which solves the problem that traditional cores are exposed and the environment will affect the cores. For example, free hydrocarbons and light components in the cores are easily volatilized due to exposure, resulting in distortion of key parameters such as oil saturation and hydrocarbon composition in subsequent experiments (such as thermal desorption analysis).

[0005] (II) Technical Solutions

[0006] To achieve the above object, the present invention is realized through the following technical solutions: A method for predicting the sweet spot of tight oil source rocks includes the following specific prediction methods: Step 1: Determine sampling points according to exploration targets, collect core samples of the target interval, and measure key parameters such as organic carbon content, maturity, porosity, and permeability; Step 2: Number and cut the cores to prepare powder samples while retaining the original structural characteristics; Step 3: Take core powder and avoid exposure to air to prevent light hydrocarbon volatilization; Step 4: Heat up to 300 °C at a constant rate and keep the temperature constant at this temperature for 10 min to fully desorb the free hydrocarbons; Step 5: Transport the desorbed free hydrocarbons to the FID detector through the carrier gas and record the chromatographic peaks in real time; Step 6: Establish a source rock evaluation model by integrating the chromatographic peaks and laboratory data, and divide the "sweet spot area" in combination with geological parameters such as fracture development degree and mineral distribution to support exploration and development decisions.

[0007] Preferably, the amount of core powder taken in step 3 is: 100 - 130 mg.

[0008] Preferably, the constant rate in step 4 is: 10 °C / min.

[0009] A device for predicting the sweet spot area of tight oil source rocks includes a protective box. At the bottom end inside the protective box, there is a fixed mounting base plate. Above the mounting base plate, a moving plate is arranged on one side. On both sides of the middle above the mounting base plate, there are fixed crushing boxes. At one side of the bottom end of the crushing box, there is a first flow pipe fixedly connected. The end of the first flow pipe away from the crushing box is fixedly connected to a heating box. At the top end inside the heating box, there is a fixed mesh fixedly connected. At one side of the middle of the top end of the heating box, there is an exhaust pipe fixedly connected. The exhaust pipe penetrates through the heating box. On the side of the heating box away from the first flow pipe, there is a second flow pipe fixedly connected. The end of the second flow pipe away from the heating box is fixedly connected to an FID detector; On the other side of the moving plate, there is a fixed plate, and the fixed plate is fixedly connected to the mounting base plate. Between the fixed plate and the moving plate, there is a core, and between the moving plate and the fixed plate, there is a cutting blade.

[0010] Preferably, at one end of the rear side of the mounting base plate, there is a rotatable threaded rod. In the middle of the threaded rod, there is a threaded block threadedly connected. At the rear side of the threaded block, there is a fixed frame fixedly connected. The inside of the fixed frame is open. At one end of the side of the mounting base plate, there is a third motor fixedly connected. The driving end of the third motor is fixedly connected to the threaded rod.

[0011] Preferably, on both sides inside the fixed frame, there are sliding grooves opened. Inside the sliding grooves, there are movable frames slidably engaged. The front side of the movable frame is rotationally engaged with the cutting blade. On the outside of one of the movable frames, there is a second motor fixedly connected. The driving end of the second motor is fixedly connected to the cutting blade.

[0012] Preferably, in the middle of the top end of the fixed frame, there is an electric telescopic rod fixedly connected. The extending end of the electric telescopic rod is fixedly connected to the movable frame. At the bottom end inside the heating box, there is a heating bottom plate fixedly connected.

[0013] Preferably, an air pump is fixedly connected to the other side of the crushing box, a cover plate is hinged to the top end of the crushing box, driving motors are fixedly connected to both sides at the middle part inside the installation base plate, a rotating rod is fixedly connected to the driving end of the driving motor, and a plurality of crushing knives are fixedly connected to both sides of the rotating rod.

[0014] Preferably, a box door is hinged to the front side of the protection box, an adjusting screw rod is threadedly connected to the bottom end of one side of the protection box, the adjusting screw rod is rotationally connected to the moving plate, a chromatographic peak display screen is arranged on the outer side of the FID detector, and air holes are formed in both sides of the top end of the protection box.

[0015] (III) Beneficial effects

[0016] The present invention provides a method and device for predicting sweet spots of tight oil source rocks. It has the following beneficial effects: In the present invention, through the arrangement of: a third motor, a threaded rod, a cutting piece, an electric telescopic rod and a protection box, driven by the third motor, the threaded rod rotates, and after rotation, it is in threaded cooperation with the threaded block, so as to realize threaded movement, and the position of the cutting piece can be adjusted by cutting. After reaching the required cutting position, the electric telescopic rod can be lowered. At this time, driven by the second motor, the cutting piece will rotate at a high speed, so as to cut the core. Through this structure, the core is cut, and through the arrangement of the protection box, contact with air can be prevented to avoid pollution.

[0017] In the present invention, through the arrangement of: a driving motor, a rotating rod, a crushing knife and an air pump, driven by the driving motor, the rotating rod rotates, and the crushing knife rotates at a high speed, so as to perform a crushing operation on the core inside the crushing box. After crushing, external gas is introduced through the air pump. Through the transportation of the air pump, contact with air can be reduced, and the circulation inside the equipment can be maintained.

[0018] In the present invention, through the arrangement of: a crushing box, a heating bottom plate, an FID detector and a chromatographic peak display screen, after the crushed raw materials inside the crushing box flow, the heating bottom plate heats up to ℃, and then the desorbed free hydrocarbons are transported to the FID detector through the carrier gas, the chromatographic peaks are recorded in real time, and are displayed on the chromatographic peak display screen, and the predicted position of the sweet spot can be analyzed through the display of data. Description of the drawings

[0019] Figure 1 It is a three-dimensional sectional view of the protection box of a method and device for predicting sweet spots of tight oil source rocks proposed by the present invention; Figure 2 It is a front sectional view of a method and device for predicting sweet spots of tight oil source rocks proposed by the present invention; Figure 3 It is proposed by the present invention Figure 1 The enlarged view at A in Figure 4 Proposed by the present invention Figure 2 Enlarged view at position B in Figure 5 Top view of a method and device for predicting sweet spots in tight oil source rocks proposed by the present invention; Figure 6 Three-dimensional structure diagram of a method and device for predicting sweet spots in tight oil source rocks proposed by the present invention; Figure 7 Rear three-dimensional structure diagram of the installation base plate of a method and device for predicting sweet spots in tight oil source rocks proposed by the present invention.

[0020] Wherein, 1, protective box; 2, installation base plate; 3, heating box; 4, exhaust pipe; 5, moving plate; 6, FID detector; 7, crushing box; 8, cover plate; 9, driving motor; 10, heating base plate; 11, first flow pipe; 12, second flow pipe; 13, core; 14, adjusting screw; 15, box door; 16, chromatographic peak display screen; 17, air pump; 18, crushing knife; 19, rotating rod; 20, fixing frame; 21, electric telescopic rod; 22, moving frame; 23, sliding groove; 24, second motor; 25, cutting piece; 26, air hole; 27, threaded block; 28, threaded rod; 29, third motor; 30, fixing net. Specific embodiments

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] Embodiment 1:

[0023] The embodiment of the present invention provides a method for predicting sweet spots in tight oil source rocks, which is characterized in that it includes the following specific prediction methods: Step 1: Determine sampling points according to exploration targets, collect core samples of the target interval, and measure key parameters such as organic carbon content, maturity, porosity, and permeability; Step 2: Number and cut the core to prepare powder samples while retaining the original structural characteristics; Step 3: Take 100 mg of core powder and avoid exposure to air to prevent light hydrocarbon volatilization; Step 4: Heat at a constant rate of 10 °C / min to 300 °C and keep it constant at this temperature for 10 min to fully desorb the free hydrocarbons; Step 5: Transport the desorbed free hydrocarbons to the FID detector through the carrier gas and record the chromatographic peaks in real time; Step 6: Integrate chromatographic peaks with laboratory data to establish a hydrocarbon source rock evaluation model, and divide the "sweet spot area" in combination with geological parameters such as fracture development degree and mineral distribution to support exploration and development decisions.

[0024] Example 2:

[0025] As Figures 1-7 shown, the difference between this embodiment and the first embodiment is as follows: A prediction device for the sweet spot area of a tight oil source rock includes a protective box 1. A mounting base plate 2 is fixedly connected to the inner bottom end of the protective box 1. A moving plate 5 is arranged on one side above the mounting base plate 2. On both sides of the middle above the mounting base plate 2, crushing boxes 7 are fixedly connected. The marked cut samples are placed inside the crushing boxes 7. One side of the bottom end of the crushing box 7 is fixedly connected with a first flow pipe 11. The end of the first flow pipe 11 far from the crushing box 7 is fixedly connected with a heating box 3. A fixing net 30 is fixedly connected to the inner top end of the heating box 3. The fixing net 30 can intercept dust. On one side of the middle of the top end of the heating box 3, an exhaust pipe 4 is fixedly connected. Part of the gas and heat generated by the heating box 3 will be discharged through the exhaust pipe 4. The exhaust pipe 4 penetrates through the heating box 3. On the side of the heating box 3 far from the first flow pipe 11, a second flow pipe 12 is fixedly connected. The end of the second flow pipe 12 far from the heating box 3 is fixedly connected with an FID detector 6. The desorbed free hydrocarbons are transported to the FID detector 6 through the carrier gas, and the chromatographic peaks are recorded in real time and displayed on the chromatographic peak display screen 16. The predicted position of the sweet spot area can be analyzed through the display of data. On the other side of the crushing box 7, an air pump 17 is fixedly connected. External gas is introduced through the air pump 17 and blown into the inside of the crushing box 7, and then flows through the first flow pipe 11 into the inside of the heating box 3. The top end of the crushing box 7 is hinged with a cover plate 8. On both sides of the middle inside the mounting base plate 2, driving motors 9 are fixedly connected. Driven by the driving motors 9, the rotating rods 19 rotate, and the crushing knives 18 rotate at high speed, so as to crush the core 13 inside the crushing box 7. The driving ends of the driving motors 9 are fixedly connected with rotating rods 19, and a number of crushing knives 18 are fixedly connected to both sides of the rotating rods 19; On the other side of the moving plate 5, there is a fixing plate, and the fixing plate is fixedly connected to the mounting base plate 2. A core 13 is arranged between the fixing plate and the moving plate 5. Generally, the sampled core 13 is placed between the moving plate 5 and the fixing plate and clamped tightly. A cutting piece 25 is arranged between the moving plate 5 and the fixing plate. The front side of the protective box 1 is hinged with a box door 15. One side of the bottom end of the protective box 1 is threadedly connected with an adjusting screw rod 14. By rotating the adjusting screw rod 14, the core 13 is clamped. The adjusting screw rod 14 is rotationally connected to the moving plate 5. A chromatographic peak display screen 16 is arranged outside the FID detector 6. Air holes 26 are opened on both sides of the top end of the protective box 1.

[0026] One end of the rear side of the mounting base plate 2 is rotatably connected with a threaded rod 28. A threaded block 27 is threadedly connected to the middle of the threaded rod 28. A fixing frame 20 is fixedly connected to the rear side of the threaded block 27. The inside of the fixing frame 20 is open. One end of one side of the mounting base plate 2 is fixedly connected with a third motor 29. Driven by the third motor 29, the threaded rod 28 rotates. After rotation, it is in threaded cooperation with the threaded block 27, and thus threaded movement can be achieved. The driving end of the third motor 29 is fixedly connected to the threaded rod 28. Slide grooves 23 are formed on both sides inside the fixing frame 20. A moving frame 22 is slidably fitted inside the slide grooves 23. The front side of the moving frame 22 is rotatably fitted with a cutting blade 25. A second motor 24 is fixedly connected to the outside of one of the moving frames 22. The driving end of the second motor 24 is fixedly connected to the cutting blade 25. The middle of the top end of the fixing frame 20 is fixedly connected with an electric telescopic rod 21. When the electric telescopic rod 21 descends, at this time, driven by the second motor 24, the high-speed rotation of the cutting blade 25 will be driven, thereby cutting the core 13. The extending end of the electric telescopic rod 21 is fixedly connected to the moving frame 22. A heating bottom plate 10 is fixedly connected to the bottom end inside the heating box 3. When the raw materials pulverized inside the pulverizing box 7 flow through, the heating bottom plate 10 heats them and raises their temperature to 300 °C.

[0027] Working principle: When in use, first place the sampled core 13 between the moving plate 5 and the fixing plate. Subsequently, by rotating the adjusting screw 14, the core 13 is clamped. After clamping, it is driven by the third motor 29 to drive the rotation of the threaded rod 28. After rotation, it is in threaded cooperation with the threaded block 27, and thus threaded movement can be achieved, and the position of the cutting blade 25 can be adjusted for cutting. After reaching the required cutting position, the electric telescopic rod 21 can be lowered. At this time, driven by the second motor 24, the high-speed rotation of the cutting blade 25 will be driven, thereby cutting the core 13. The cut samples will be marked and placed inside the pulverizing box 7. Since there are two pulverizing boxes 7, the cores 13 at different positions or depths can be cut again and placed inside another pulverizing box 7 for testing operations. At this time, the driving motor 9 drives to drive the rotation of the rotating rod 19, and the pulverizing knife 18 rotates at a high speed, thereby pulverizing the core 13 inside the pulverizing box 7. After pulverization, external gas is introduced through the air pump 17 and blown into the inside of the pulverizing box 7. Subsequently, it flows through the first flow pipe 11 into the inside of the heating box 3. Part of the heat generated by the gas and the heating box 3 will be discharged through the exhaust pipe 4. The fixed net 30 can intercept dust. When the raw materials pulverized inside the pulverizing box 7 flow through, the heating bottom plate 10 heats them and raises their temperature to 300 °C. Subsequently, the desorbed free hydrocarbons are transported to the FID detector 6 through the carrier gas, the chromatographic peaks are recorded in real time, and are displayed on the chromatographic peak display screen 16, and the predicted position of the sweet spot area can be analyzed through the display of the data.

[0028] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for predicting sweet spots in tight oil source rocks, characterized in that: It includes the following specific prediction methods: Step 1: Determine sampling points according to exploration targets, collect core samples of the target interval, and measure key parameters such as organic carbon content, maturity, porosity, and permeability; Step 2: Number and cut the core to prepare powder samples while retaining the original structural characteristics; Step 3: Take core powder and avoid exposure to air to prevent light hydrocarbon volatilization; Step 4: Heat up to 300 °C at a constant rate and keep it at this temperature for 10 minutes to fully desorb the free hydrocarbons; Step 5: Transport the desorbed free hydrocarbons to the FID detector through the carrier gas and record the chromatographic peaks in real time; Step 6: Establish a hydrocarbon source rock evaluation model by integrating chromatographic peaks and laboratory data, and divide the "sweet spot" by combining geological parameters such as fracture development degree and mineral distribution to support exploration and development decisions.

2. The prediction method for sweet spots of a tight oil source rock according to claim 1, characterized in that: The amount of core powder taken in Step 3 is: 100 - 130 mg.

3. The prediction method for the sweet spot area of a tight oil source rock according to claim 1, characterized in that: The constant rate in Step 4 is: 10 °C / min.

4. A prediction device for sweet spots of tight oil source rocks, based on the method for predicting sweet spots of tight oil source rocks according to any one of claims 1-3, comprising a protective box (1), characterized in that: The inner bottom end of the protective box (1) is fixedly connected with an installation bottom plate (2). Above the installation bottom plate (2), a moving plate (5) is arranged on one side. On both sides of the middle above the installation bottom plate (2), crushing boxes (7) are fixedly connected. One side of the bottom end of the crushing box (7) is fixedly connected with a first flow pipe (11). The end of the first flow pipe (11) far from the crushing box (7) is fixedly connected with a heating box (3). The inner top end of the heating box (3) is fixedly connected with a fixing net (30). One side of the middle of the top of the heating box (3) is fixedly connected with an exhaust pipe (4). The exhaust pipe (4) penetrates through the heating box (3). The side of the heating box (3) far from the first flow pipe (11) is fixedly connected with a second flow pipe (12). The end of the second flow pipe (12) far from the heating box (3) is fixedly connected with an FID detector (6); On the other side of the moving plate (5), a fixing plate is arranged, and the fixing plate is fixedly connected with the installation bottom plate (2). A core (13) is arranged between the fixing plate and the moving plate (5). A cutting blade (25) is arranged between the moving plate (5) and the fixing plate.

5. The prediction device for the sweet spot area of a tight oil source rock according to claim 4, characterized in that: One end of the rear side of the installation bottom plate (2) is rotatably connected with a threaded rod (28). The middle of the threaded rod (28) is threadedly connected with a threaded block (27). The rear side of the threaded block (27) is fixedly connected with a fixing frame (20). The inside of the fixing frame (20) is open. One end of the side of the installation bottom plate (2) is fixedly connected with a third motor (29). The driving end of the third motor (29) is fixedly connected with the threaded rod (28).

6. The prediction device for the sweet spot area of a tight oil source rock according to claim 5, characterized in that: Chute grooves (23) are opened on both sides inside the fixing frame (20). A moving frame (22) is slidably fitted inside the chute grooves (23). The front side of the moving frame (22) is rotatably fitted with the cutting blade (25). The outside of one side of the moving frame (22) is fixedly connected with a second motor (24). The driving end of the second motor (24) is fixedly connected with the cutting blade (25).

7. The prediction device for the sweet spot area of a tight oil source rock according to claim 5, characterized in that: The middle of the top end of the fixing frame (20) is fixedly connected with an electric telescopic rod (21), the extending end of the electric telescopic rod (21) is fixedly connected with a moving frame (22), and the inner bottom end of the heating box (3) is fixedly connected with a heating bottom plate (10).

8. The prediction device for the sweet spot area of a tight oil source rock according to claim 4, characterized in that: On the other side of the crushing box (7), an air pump (17) is fixedly connected. The top end of the crushing box (7) is hinged with a cover plate (8). On both sides of the middle part inside the mounting bottom plate (2), a driving motor (9) is fixedly connected. The driving end of the driving motor (9) is fixedly connected with a rotating rod (19), and a plurality of crushing knives (18) are fixedly connected to both sides of the rotating rod (19).

9. The prediction device for the sweet spot area of a tight oil source rock according to claim 4, characterized in that: A box door (15) is hinged to the front side of the protection box (1). An adjusting screw rod (14) is threadedly connected to the bottom end of one side of the protection box (1). The adjusting screw rod (14) is rotationally connected with a moving plate (5). A chromatographic peak display screen (16) is arranged on the outer side of the FID detector (6). Air holes (26) are formed in both sides of the top end of the protection box (1).

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