Method and system for rapidly measuring oil content and gas content of rock debris in drilling site

Abstract

The invention discloses a method and a system for quickly measuring oil content and gas content of rock debris in a drilling site, and the method comprises the following steps: pretreating a rock debris sample through an automatic rock debris screening machine, thereby screening the rock debris sample under a PDC (Polycrystalline Diamond Compact) drill bit according to a unified standard; measuring a hydrogen-containing fluid signal in the rock debris sample by using a portable nuclear magnetic resonance spectrometer, and vacuumizing and saturating the rock debris sample for nuclear magnetic measurement of a saturated water sample; putting the rock debris sample into a small portable centrifugal machine, and eliminating the influence of liquid attached to the surface of the rock debris sample; crushing the rock debris sample into powder, putting the powdery rock debris sample into a manganese chloride saturated solution, and carrying out mass determination and manganese-saturated sample nuclear magnetic measurement to obtain a water volume, an oil volume and a gas volume; and based on the water volume, the oil volume and the gas-containing volume, calculating the porosity and the oil-containing gas volume of the rock debris. According to the invention, the two important reservoir evaluation parameters of the rock debris porosity and the oil and gas content can be rapidly and continuously measured on a drilling site.

Description

Technical Field

[0001] The present invention relates to a technology for measuring physical property parameters of rock cuttings and reservoir evaluation at a petroleum drilling and logging site, and in particular to a method and system for quickly measuring the oil and gas content of rock cuttings at a drilling site. Background Art

[0002] In the oil and gas exploration and development process, petrophysical parameters are crucial for reservoir evaluation and resource assessment. While many petroleum colleges, research institutes, and oilfield operations are actively exploring accurate laboratory petrophysical property measurements, they are also placing greater emphasis on rapid on-site analysis of petrophysical properties and hydrocarbon content. Similar to specialized logging techniques such as elemental and gamma ray logging, nuclear magnetic resonance (NMR) technology is a mature technique long-established for laboratory sample analysis. However, in many cases, laboratory techniques or products are not necessarily suitable for field environments. For example, laboratory products are generally large in size, require long analysis cycles, and lack timely sample delivery (due to oil and gas loss), all of which are drawbacks of NMR technology. Therefore, one of the most important goals of this project is to rapidly analyze shale oil petrophysical properties and hydrocarbon content on-site, providing clients with first-hand analytical data, rather than waiting until the cores are transported to the laboratory.

[0003] The traditional laboratory porosity test method has the following problems: (1) It cannot immediately feedback porosity during drilling; 2) The process is complicated and expensive; (3) It can only be tested by coring, and is not suitable for cuttings (PDC drill bits). (4) The mainstream laboratory method uses one-dimensional T2 distribution to measure the porosity of cuttings. The size of the cuttings directly affects the porosity measurement results, mainly because the proportion of surface fluid has a large impact; at the same time, the volume measurement of the cuttings sample is also a difficulty. (5) The traditional method of processing surface fluids is to use the cutoff value method to deduct the surface fluid signal. For shales with very short relaxation times or carbonate rocks with obvious T2 spectrum characteristics, this method is relatively applicable, but there are large errors and the porosity results are also large. (6) Traditional methods are mainly based on oil wells, measuring oil saturation, but cannot accurately measure gas content.

[0004] In view of this, this application is hereby filed. Summary of the Invention

[0005] The present invention aims to provide a method and system for rapidly measuring the oil and gas content of drilling cuttings at the site. By miniaturizing the equipment and improving the cuttings pre-processing and measurement procedures, the system enables rapid nuclear magnetic resonance (NMR) physical and oil and gas analysis of drilling cuttings at the site. It also enables rapid and continuous measurement of cuttings porosity and oil and gas content, two key reservoir evaluation parameters, at the site. The principle design of the present invention aims to address the problems of traditional methods, such as complex pre-sample processing, laboratory-based measurement, large measurement errors for smaller cuttings samples, and the inability to accurately and timely analyze cuttings on site.

[0006] The present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a method for quickly measuring the oil and gas content of rock cuttings at a drilling site, the method comprising:

[0008] The cuttings samples are pre-processed by an automatic cuttings screening machine, so that the cuttings samples under the PDC drill bit can be screened according to a unified standard;

[0009] A portable nuclear magnetic resonance (NMR) instrument was used to measure the hydrogen-containing fluid signal in the cuttings samples, and the cuttings samples were vacuum-saturated with water for NMR measurement of the saturated samples.

[0010] Then put the cuttings sample into a small portable centrifuge to eliminate the influence of liquid attached to the surface of the cuttings sample;

[0011] The rock cuttings were crushed into powder and placed in a saturated manganese chloride solution for mass measurement and nuclear magnetic resonance measurement of the saturated manganese sample to obtain the water volume, oil volume, and gas volume.

[0012] The porosity and hydrocarbon content of the cuttings are calculated based on the water volume, oil volume, and gas volume.

[0013] The method of the present invention can quickly and continuously measure the porosity and oil and gas content of rock cuttings, two important reservoir evaluation parameters, at the drilling site, solving the problems of traditional methods such as complex operation during early sample processing, limited measurement in the laboratory, and only able to measure core samples, resulting in large errors in the measurement results of smaller rock cuttings samples.

[0014] Furthermore, the automatic rock chip screening machine is a two-layer rock chip screening platform, comprising a first screen on the upper layer, a second screen on the lower layer, a fixed shaft, a rotating blade, and a receiving structure; the rotating blade is arranged on the second screen via the fixed shaft; the second screen is connected to the receiving structure; the receiving structure comprises a first receiving vessel and a second receiving vessel;

[0015] The rock cuttings sample passes through the first screen and enters the second screen at the bottom, and is then stirred by the cross-shaped rotating blades. The screened rock cuttings are sent to the first receiving vessel and discharged through the second receiving vessel.

[0016] Furthermore, the first sieve is 5 mesh and the second sieve is 10 mesh;

[0017] The rock chip samples are pre-processed by an automatic rock chip sieving machine, including: screening the rock chip samples by the automatic rock chip sieving machine to obtain rock chip sizes between 5 meshes and 10 meshes.

[0018] Furthermore, the rock cuttings samples were vacuumed and saturated with water for nuclear magnetic resonance measurement, including:

[0019] The vacuum degree is -0.09 MPa, and the vacuuming time is 3 hours. The rock cuttings samples are saturated in water for 4 hours and then the saturated sample nuclear magnetic resonance measurement is performed.

[0020] Furthermore, the cuttings samples were placed in a small portable centrifuge to eliminate the influence of liquid attached to the surface of the cuttings samples, including:

[0021] A small dewatering centrifuge inner test tube is used to add rock cuttings and fluoride liquid into the test tube to remove the liquid on the surface of the rock cuttings; the test tube is then placed in a portable nuclear magnetic resonance instrument to measure the exact volume of the rock cuttings.

[0022] Furthermore, the rock cuttings sample is crushed into powder, and the powdered rock cuttings sample is placed in a saturated manganese chloride solution, and mass measurement and saturated manganese sample nuclear magnetic resonance measurement are performed to obtain the water volume, oil volume and gas volume, including:

[0023] Put the rock cuttings sample into liquid nitrogen and freeze it for about 1 minute, then take it out and crush it into powder;

[0024] Place the powdered rock cuttings sample in a sample bottle to measure its mass, then place it in a saturated manganese chloride solution, stir it thoroughly, and let it sit for at least 2 hours before performing mass measurement and NMR measurement of the saturated manganese sample.

[0025] By measuring the signal of hydrogen-containing fluid, the water volume, oil volume and gas volume can be obtained.

[0026] Furthermore, the porosity and oil and gas content of the cuttings are calculated as follows:

[0027] Porosity (%) = (water volume + oil volume) / rock cutting sample volume * 100;

[0028] Gas saturation (%) = gas volume / (gas volume + water volume)*100;

[0029] Oil saturation (%) = oil volume * oil density ρ / original sample mass * 100.

[0030] In a second aspect, the present invention further provides a measurement system for implementing the above-mentioned method for rapidly measuring the oil and gas content of rock cuttings at a drilling site, the measurement system comprising:

[0031] Automatic rock cuttings screening machine is used to pre-process rock cuttings samples, so as to screen rock cuttings samples under PDC drill bits according to unified standards;

[0032] A portable nuclear magnetic resonance instrument is used to measure the hydrogen-containing fluid signal in rock cuttings samples and vacuum the rock cuttings to saturate them with water for nuclear magnetic resonance measurement of the saturated samples;

[0033] Small portable centrifuge, used to remove liquid attached to the surface of rock cuttings samples and eliminate the influence of surface effects on porosity measurement;

[0034] A crushing device, used for crushing rock cuttings samples into powder;

[0035] Sample bottle, used to place powdered rock cuttings samples into saturated manganese chloride solution for mass determination and NMR measurement of saturated manganese samples to obtain water volume, oil volume and gas volume;

[0036] The calculation and analysis unit is used to calculate the porosity and oil and gas content of the rock cuttings based on the water volume, oil volume and gas volume.

[0037] Furthermore, the automatic rock chip screening machine is a two-layer rock chip screening platform, comprising a first screen on the upper layer, a second screen on the lower layer, a fixed shaft, a rotating blade, and a receiving structure; the rotating blade is arranged on the second screen via the fixed shaft; the second screen is connected to the receiving structure; the receiving structure comprises a first receiving vessel and a second receiving vessel;

[0038] The rock cuttings pass through the first screen and enter the second screen at the bottom. The rock cuttings are then stirred by the cross-shaped rotating blades and sent to the first receiving vessel and discharged through the second receiving vessel.

[0039] Among them, the first sieve is 5 mesh and the second sieve is 10 mesh; rock chips with a size between 5 mesh and 10 mesh are obtained by screening with an automatic rock chip screening machine.

[0040] Furthermore, the vacuum degree was -0.09 MPa, and the vacuuming time was 3 hours; the rock cuttings samples were saturated in water for 4 hours before nuclear magnetic resonance measurement of the saturated samples.

[0041] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0042] The present invention provides a method and system for rapidly measuring the oil and gas content of drilling cuttings at the drilling site. By miniaturizing the equipment and improving the cuttings pre-processing and measurement procedures, the system enables rapid nuclear magnetic resonance (NMR) physical and oil and gas analysis of drilling cuttings at the drilling site. It also enables rapid and continuous measurement of cuttings porosity and oil and gas content, two key reservoir evaluation parameters, at the drilling site. The principle design of this invention aims to address the problems of traditional methods, such as complex pre-sample processing, laboratory-based measurement, large measurement errors for smaller cuttings samples, and the inability to accurately and timely analyze cuttings on site. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0044] Figure 1 This is a flow chart of a method for quickly measuring the oil and gas content of rock cuttings at a drilling site according to the present invention;

[0045] Figure 2 This is a schematic diagram of the structure of the automatic rock chip screen prototype of the present invention;

[0046] Figure 3 This is a schematic diagram of the principle of removing rock debris from the centrifuge surface of the present invention;

[0047] Figure 4 This is a comparative experimental diagram of nuclear magnetic porosity of cuttings of different sizes in the present invention;

[0048] Figure 5 This is a comparison chart of the nuclear magnetic resonance oil and gas content of a certain well in the present invention and the laboratory oil and gas content.

[0049] Reference numerals and corresponding component names:

[0050] 1-first sieve, 2-second sieve, 3-fixed shaft, 4-rotating blade, 5-first receiving vessel, 6-second receiving vessel, 7-test tube, 8-fluorinated liquid, 9-liquid, 10-rock cuttings. DETAILED DESCRIPTION

[0051] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0052] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that these specific details are not necessarily required to practice the present invention. In other instances, well-known structures, circuits, materials, or methods are not described in detail to avoid obscuring the present invention.

[0053] Throughout this specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Therefore, appearances of the phrases "one embodiment," "an embodiment," "an example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combinations and / or subcombinations. Furthermore, it will be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes only and are not necessarily drawn to scale. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0054] In the description of the present invention, it should be understood that the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present invention.

[0055] The porosity test methods in traditional laboratories have the following problems: (1) they cannot provide immediate feedback on porosity during drilling; 2) the process is complex and expensive; (3) they can only be tested on cores, and are not suitable for cuttings (PDC drill bits). (4) The mainstream laboratory method uses one-dimensional T2 distribution to measure the porosity of cuttings. The size of the cuttings directly affects the porosity measurement results, mainly because the proportion of surface fluid has a large impact; at the same time, the volume measurement of cuttings samples is also a difficult point. (5) The traditional method of processing surface fluids is to use the cutoff value method to deduct the surface fluid signal. This method is relatively applicable to shales with very short relaxation times or carbonate rocks with obvious T2 spectrum characteristics, but there are large errors and the porosity results are also biased. (6) Traditional methods are mainly based on oil wells, measuring oil saturation, but cannot accurately measure oil and gas content.

[0056] Therefore, the present invention improves and perfects the cuttings pretreatment and measurement methods and steps by miniaturizing the equipment, so that it can perform rapid nuclear magnetic resonance physical property and oil and gas content analysis on the drilling cuttings at the drilling site, thereby obtaining comprehensive parameters such as the nuclear magnetic resonance T2 spectrum, nuclear magnetic resonance porosity, gas saturation, original water saturation, oil saturation, lost fluid saturation, SDR permeability and pore size distribution of the core in the shortest time, providing timely data for subsequent geological analysis.

[0057] Example 1

[0058] like Figure 1 As shown, the present invention provides a method for quickly measuring the oil and gas content of rock cuttings at a drilling site, the method comprising:

[0059] Step S1: pre-processing the rock cuttings sample by an automatic rock cuttings screening machine, thereby screening the rock cuttings sample under the PDC drill bit according to a unified standard;

[0060] Specifically, the automatic rock chip screening machine is a two-layer rock chip screening platform, including a first screen 1 on the upper layer, a second screen 2 on the lower layer, a fixed shaft 3, a rotating blade 4 and a receiving structure; the rotating blade 4 is set on the second screen 2 through the fixed shaft 3; the second screen 2 is connected to the receiving structure; the receiving structure includes a first receiving container 5 and a second receiving container 6;

[0061] The rock cuttings sample passes through the first sieve 1 and enters the second sieve 2 at the bottom, and is then stirred by the cross-shaped rotating blades 4. The screened rock cuttings are then sent to the first receiving vessel 5 and discharged through the second receiving vessel 6.

[0062] In this embodiment, the rock cuttings sampling method and standard are unified in step S1. The screening and washing of rock cuttings is particularly important. If the particle size is too small, it is inconvenient to measure the volume. If the rock cuttings are too large, they may be fragments dropped from the well wall during drilling. Therefore, it is particularly important to unify the particle size. Figure 2 The two-layer rock cuttings screening table shown has a first screen 1 of 5 mesh and a second screen 2 of 10 mesh. Rock cuttings with a size between 5 mesh and 10 mesh are finally obtained through screening by an automatic rock cuttings screening machine.

[0063] Step S2: Using a portable nuclear magnetic resonance instrument to measure the hydrogen-containing fluid signal in the rock cuttings sample, and vacuuming the rock cuttings sample to saturate it with water for nuclear magnetic resonance measurement of the saturated sample;

[0064] Specifically, the rock cuttings samples were vacuumed and saturated with water for nuclear magnetic resonance measurement, including:

[0065] The vacuum degree is -0.09 MPa, and the vacuuming time is 3 hours. The rock cuttings samples are saturated in water for 4 hours and then the saturated sample nuclear magnetic resonance measurement is performed.

[0066] In this embodiment, water calibration is first performed, and four gradient water standards (0.05 g, 0.6 g, 1 g, and 2 g) are taken for signal quantity testing. Secondly, manganese calibration is performed, a saturated manganese chloride solution is prepared, and 4-5 gradient manganese standards are taken for signal quantity testing. The sample is vacuum-saturated with water for 4 hours, and then a saturated water sample nuclear magnetic resonance test is performed. After the nuclear magnetic resonance test, the sample needs to be tested for mass, volume, and density.

[0067] Step S3: Place the rock cuttings sample into a small portable centrifuge to remove liquid attached to the surface of the rock cuttings sample and eliminate the influence of surface effects on porosity measurement;

[0068] In this embodiment, the mainstream of conventional laboratories uses one-dimensional T2 distribution to measure the porosity of rock chips. The size of rock chip particle size directly affects the porosity measurement result, mainly because the proportion of surface fluid has a greater impact; at the same time, the volume measurement of rock chip samples is also a difficult point. Figure 3 As shown, the present invention first uses a test tube 7 in a small dewatering centrifuge, adds rock cuttings 10 and fluoride liquid 8 into the test tube 7, thereby removing liquid 9 on the surface of the rock cuttings 10; then puts the test tube 7 into a portable nuclear magnetic resonance instrument to measure the exact volume of the rock cuttings.

[0069] Step S4: crushing the rock cuttings sample into powder, placing the powdered rock cuttings sample into a saturated manganese chloride solution, performing mass measurement and nuclear magnetic resonance measurement of the saturated manganese sample to obtain the water volume, oil volume, and gas volume;

[0070] In this embodiment, step S4 specifically includes:

[0071] Put the rock cuttings sample into liquid nitrogen and freeze it for about 1 minute, then take it out and crush it into powder;

[0072] Place the powdered rock cuttings sample in a sample bottle to measure its mass, then place it in a saturated manganese chloride solution, stir it thoroughly, and let it sit for at least 2 hours before performing mass measurement and NMR measurement of the saturated manganese sample.

[0073] The instrument is calibrated using oil and water standard samples to obtain the calibrated water scale slope kw; water scale intercept bw (default 0); oil scale slope ko; oil scale intercept bo (default 0); manganese scale slope km; manganese scale intercept bm (default 0); oil density ρ (default 0.88);

[0074] Then calculate the water volume, oil volume and gas volume.

[0075] Corrected saturated manganese signal amount = (mass before saturated manganese - mass after saturated manganese correction) * manganese line slope km + manganese line intercept bm

[0076] Water volume = (water saturation signal - corrected manganese saturation signal - bw) / kw

[0077] Oil volume = (corrected saturated manganese signal - bo) / ko

[0078] Gas volume = (water-saturated signal - original signal) / water-saturated signal

[0079] Step S5: Calculate the porosity and oil and gas content of the rock cuttings based on the water volume, oil volume, and gas volume.

[0080] In this embodiment, the porosity and oil and gas content of the cuttings are calculated using the following formula:

[0081] Porosity (%) = (water volume + oil volume) / rock cutting sample volume * 100;

[0082] Gas saturation (%) = gas volume / (gas volume + water volume)*100;

[0083] Oil saturation (%) = oil volume * oil density ρ / original sample mass * 100.

[0084] like Figure 4 As shown, according to the present invention, in steps S1 to S5, six samples of varying porosity were collected in the laboratory. For each sample, core and cutting samples of varying sizes were tested, with their diameters represented by Φ. The results show that NMR porosity measurements with diameters greater than 2.5 mm have good consistency, while smaller cuttings exhibit greater measurement errors. Field cuttings typically range in diameter from 2 to 12 mm, making this method suitable for analyzing small, fragmented cuttings.

[0085] like Figure 5 As shown in the figure, the results of 60-meter continuous rock cuttings measurement data of a certain well show that the porosity and oil and gas content values ​​​​measured by nuclear magnetic resonance are consistent with the values ​​measured by conventional methods and the well depth curve. The inventive method has a good effect when used for field testing.

[0086] Example 2

[0087] The difference between this embodiment and embodiment 1 is that this embodiment provides a measurement system for implementing the method for quickly measuring the oil and gas content of drilling site cuttings in embodiment 1. The measurement system includes:

[0088] Automatic rock cuttings screening machine is used to pre-process rock cuttings samples, so as to screen rock cuttings samples under PDC drill bits according to unified standards;

[0089] A portable nuclear magnetic resonance instrument is used to measure the hydrogen-containing fluid signal in rock cuttings samples and vacuum the rock cuttings to saturate them with water for nuclear magnetic resonance measurement of the saturated samples;

[0090] Small portable centrifuge, used to remove liquid attached to the surface of rock cuttings samples and eliminate the influence of surface effects on porosity measurement;

[0091] A crushing device, used for crushing rock cuttings samples into powder;

[0092] Sample bottle, used to place powdered rock cuttings samples into saturated manganese chloride solution for mass determination and NMR measurement of saturated manganese samples to obtain water volume, oil volume and gas volume;

[0093] The calculation and analysis unit is used to calculate the porosity and oil and gas content of the rock cuttings based on the water volume, oil volume and gas volume.

[0094] As a further implementation, the automatic rock chip screening machine is a two-layer rock chip screening station, comprising a first screen 1 on the upper layer, a second screen 2 on the lower layer, a fixed shaft 3, a rotating blade 4 and a receiving structure; the rotating blade 4 is arranged on the second screen 2 through the fixed shaft 3; the second screen 2 is connected to the receiving structure; the receiving structure includes a first receiving vessel 5 and a second receiving vessel 6;

[0095] The rock cuttings pass through the first screen 1 and enter the second screen 2 at the bottom. The rock cuttings are then stirred by the cross-shaped rotating blades 4 and sent to the first receiving vessel 5 and discharged through the second receiving vessel 6.

[0096] Among them, the first sieve 1 is 5 mesh, and the second sieve 2 is 10 mesh; the rock chips with a size between 5 mesh and 10 mesh are screened by the automatic rock chip screening machine.

[0097] As a further implementation, the vacuum degree was -0.09 MPa and the vacuuming time was 3 hours; the rock cuttings samples were saturated in water for 4 hours and then nuclear magnetic resonance measurements of the saturated samples were performed.

[0098] The execution process of each unit can be performed according to the process steps of a method for quickly measuring the oil and gas content of rock cuttings at a drilling site in Example 1, and will not be described in detail in this embodiment.

[0099] This invention, through miniaturized equipment and improved cuttings pre-processing and measurement procedures, enables rapid nuclear magnetic resonance (NMR) physical and hydrocarbon analysis of drilling cuttings at the drilling site. It also enables rapid and continuous measurement of cuttings porosity and hydrocarbon content, two key reservoir evaluation parameters, at the drilling site. This design principle addresses the challenges of traditional methods, including complex pre-sample processing, laboratory-based measurement, large measurement errors for smaller cuttings, and the inability to accurately and timely analyze cuttings on-site.

[0100] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for quickly measuring the oil and gas content of rock cuttings at a drilling site, characterized in that: The method includes: The cuttings samples are pre-processed by an automatic cuttings screening machine, so that the cuttings samples under the PDC drill bit can be screened according to a unified standard; Using a portable nuclear magnetic resonance instrument to measure the hydrogen-containing fluid signal in the rock cuttings sample, and vacuuming the rock cuttings sample to saturate it with water to perform nuclear magnetic resonance measurement of the saturated sample; Then, the rock cuttings sample is placed in a small portable centrifuge to eliminate the influence of liquid attached to the surface of the rock cuttings sample; The rock cuttings sample is crushed into powder, and the powdered rock cuttings sample is placed in a saturated manganese chloride solution, and mass measurement and nuclear magnetic resonance measurement of the saturated manganese sample are performed to obtain water volume, oil volume and gas volume; Based on the water volume, oil volume and gas volume, the porosity and oil and gas content of the cuttings are calculated.

2. The method for quickly measuring the oil and gas content of rock cuttings at a drilling site according to claim 1, characterized in that: The automatic rock chip screening machine is a two-layer rock chip screening platform, comprising a first screen (1) on the upper layer, a second screen (2) on the lower layer, a fixed shaft (3), a rotating blade (4) and a receiving structure; the rotating blade (4) is arranged on the second screen (2) through the fixed shaft (3); the second screen (2) is connected to the receiving structure; the receiving structure comprises a first receiving vessel (5) and a second receiving vessel (6); The rock cuttings sample passes through the first sieve (1) and enters the second sieve (2) at the bottom, and is then stirred by the cross-shaped rotating blades (4). The screened rock cuttings are then sent to the first receiving vessel (5) and discharged through the second receiving vessel (6).

3. The method for quickly measuring the oil and gas content of drilling site cuttings according to claim 2, characterized in that: The first sieve (1) has a 5-mesh size, and the second sieve (2) has a 10-mesh size; The rock chip samples are pre-processed by an automatic rock chip sieving machine, including: screening the rock chip samples by the automatic rock chip sieving machine to obtain rock chip sizes between 5 meshes and 10 meshes.

4. The method for quickly measuring the oil and gas content of rock cuttings at a drilling site according to claim 1, characterized in that: The rock cuttings sample is vacuumed and saturated with water to perform nuclear magnetic resonance measurement of the saturated sample, including: The vacuum degree is -0.09 MPa, and the vacuuming time is 3 hours. The rock cuttings sample is saturated in water for 4 hours and then subjected to nuclear magnetic resonance measurement of the saturated sample.

5. The method for quickly measuring the oil and gas content of rock cuttings at a drilling site according to claim 1, characterized in that: The rock cuttings sample is then placed in a small portable centrifuge to remove the influence of liquid attached to the surface of the rock cuttings sample, including: A test tube (7) is used in a small dewatering centrifuge, rock cuttings (10) and fluorinated liquid (8) are added into the test tube (7), thereby removing liquid (9) on the surface of the rock cuttings (10); and the test tube (7) is then placed in a portable nuclear magnetic resonance instrument to measure the volume of the rock cuttings.

6. The method for quickly measuring the oil and gas content of rock cuttings at a drilling site according to claim 1, characterized in that: The rock chip sample is crushed into powder, and the powdered rock chip sample is placed in a saturated manganese chloride solution to perform mass determination and saturated manganese sample nuclear magnetic resonance measurement, including: The rock cuttings sample was placed in liquid nitrogen for freezing for 1 minute, taken out and crushed into powder; Place the powdered rock cuttings sample in a sample bottle to measure its mass, then place it in a saturated manganese chloride solution, stir it thoroughly, and let it sit for at least 2 hours before performing mass measurement and NMR measurement of the saturated manganese sample. By measuring the signal of hydrogen-containing fluid, the water volume, oil volume and gas volume can be obtained.

7. The method for quickly measuring the oil and gas content of rock cuttings at a drilling site according to claim 1, characterized in that: The porosity and oil and gas content of rock cuttings are calculated as follows: Porosity (%) = (water volume + oil volume) / rock cutting sample volume * 100; Gas saturation (%) = gas volume / (gas volume + water volume)*100; Oil saturation (%) = oil volume * oil density ρ / original sample mass * 100.

8. A measurement system for implementing the method for quickly measuring the oil and gas content of drilling site cuttings as claimed in any one of claims 1 to 7, characterized in that: The measurement system includes: Automatic rock cuttings screening machine is used to pre-process rock cuttings samples, so as to screen rock cuttings samples under PDC drill bits according to unified standards; A portable nuclear magnetic resonance instrument is used to measure the hydrogen-containing fluid signal in the rock cuttings sample, and vacuum the rock cuttings sample to saturate it with water for nuclear magnetic resonance measurement of the saturated sample; A small portable centrifuge, used to eliminate the influence of liquid attached to the surface of the rock cuttings sample; A crushing device, used for crushing the rock cuttings sample into powder; Sample bottle, used to place powdered rock cuttings samples into saturated manganese chloride solution for mass determination and NMR measurement of saturated manganese samples to obtain water volume, oil volume and gas volume; The calculation and analysis unit is used to calculate the porosity and oil and gas content of the rock cuttings based on the water volume, oil volume and gas volume.

9. The measurement system according to claim 8, characterized in that The automatic rock chip screening machine is a two-layer rock chip screening platform, comprising a first screen (1) on the upper layer, a second screen (2) on the lower layer, a fixed shaft (3), a rotating blade (4) and a receiving structure; the rotating blade (4) is arranged on the second screen (2) through the fixed shaft (3); the second screen (2) is connected to the receiving structure; the receiving structure comprises a first receiving vessel (5) and a second receiving vessel (6); The rock cuttings sample passes through the first sieve (1) and enters the second sieve (2) at the bottom, and is then stirred by the cross-shaped rotating blades (4). The screened rock cuttings are then sent to the first receiving vessel (5) and discharged through the second receiving vessel (6); The first sieve (1) has a 5-mesh size, and the second sieve (2) has a 10-mesh size. Rock chips with a size between 5 and 10 meshes are obtained by screening with an automatic rock chip screening machine.

10. The speed measurement system according to claim 8, characterized in that: The vacuum degree is -0.09 MPa, and the vacuuming time is 3 hours. The rock cuttings sample is saturated in water for 4 hours and then subjected to nuclear magnetic resonance measurement of the saturated sample.

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