Method and device for judging wettability of shale oil reservoir

Abstract

The embodiment of the invention provides a shale oil reservoir wettability judgment method and device, and belongs to the technical field of oil and gas development. The shale oil reservoir wettability judgment method comprises the following steps: acquiring the suction rate and / or suction fluid saturation when a rock sample spontaneously sucks fluid; according to the suction rate and / or the suction fluid saturation, the average wettability of the shale oil reservoir is judged; according to the signal intensity increment S1 of the rock sample in a saturated water state compared with a dry state under the same pore radius and the signal intensity increment S2 of the rock sample in a saturated oil state compared with the dry state, the hydrophilic and oleophylic capacities of the shale oil reservoir under the pore radius are judged; and judging the wettability of the shale oil reservoir according to the average wettability of the shale oil reservoir and the hydrophilic and oleophylic capabilities of the shale oil reservoir under different pore radiuses. According to the embodiment of the invention, the wettability of the shale oil reservoir is judged by integrating the average wettability and the hydrophilic and oleophylic capabilities of the shale oil reservoir under different pore radiuses, and the oil and water wetting characteristics of the shale oil reservoir can be reflected from multiple dimensions, so that the evaluation is more comprehensive.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas development, and in particular to a method and device for judging the wettability of a shale oil reservoir, and a method, processor and storage medium for optimizing the amount of liquid injected into the ground and the time of well plugging in the shale oil development. Background Art

[0002] In recent years, unconventional oil and gas resources, mainly shale oil and shale gas, have gradually become the main force for increasing oil and gas production at home and abroad. However, compared with conventional oil reservoirs, shale oil has worse reservoir properties, and conventional water injection to supplement energy development is no longer suitable for the exploitation of such oil reservoirs.

[0003] At present, the main development method of shale oil is volume fracturing horizontal well development. In addition to creating fractures, the amount of liquid injected into the ground also has the function of imbibition and energy replenishment. If the amount of liquid injected into the ground is too large, the oil-seeping period of the shale oil horizontal well will be long, the amount of return fluid will be large, and the water content will be high after normal production in the later stage, which will waste water resources and increase the operating cost; if the amount of liquid injected into the ground is too small, the energy replenishment effect may not be obvious. On the other hand, if the well is blocked for too long, it is easy to cause excessive pressure diffusion, affecting the oil production contribution rate of new wells in that year; if the well is blocked for too short a time, the shale oil reservoir will not be fully imbibed and replaced, affecting the effect of energy replenishment and displacement. Therefore, a reasonable amount of liquid injected into the ground and the time of blocking the well are important factors affecting the effect of shale oil development.

[0004] The current difficulty in optimizing the amount of liquid injected into the ground and the time of well plugging in the development of shale oil horizontal wells is mainly due to the inability to accurately characterize the wettability of the shale oil reservoir.

[0005] The existing indoor evaluation methods for shale oil reservoir wettability have three problems:

[0006] First, the wettability evaluation standards at home and abroad are mainly aimed at medium and high permeability shale oil reservoirs, and there is no unified implementation standard for wettability evaluation of tight shale oil reservoirs such as shale oil. At present, there are two industry standard wettability quantitative evaluation methods: self-imbibition method (Amott method) (Amott, 1959) and centrifugal method (USBM method) (Donaldson et al, 1969). The self-imbibition method of shale oil has a small amount of self-imbibition oil and is difficult to measure; on the other hand, it is difficult to displace, and the oil-to-water and water-to-oil processes are time-consuming, and it is difficult to displace to the bound water state required by the standard, resulting in large errors in the test results and the inability to obtain consistent results. Due to the limitation of centrifugal force, the centrifugal method is even less suitable for tight low-permeability shale oil reservoirs.

[0007] Second, due to the complexity of shale oil rock minerals, the rock surface has mixed wettability characteristics, which makes it difficult to use the conventional wettability classification methods of strong oil-wet, oil-wet, weak oil-wet, neutral, weak hydrophilic, hydrophilic, and strong hydrophilic;

[0008] Third, the mechanism of shale oil recovery is generally believed to be that the oil in small pores is displaced to large pores by imbibition, and then flows into the artificial fracture system under the action of displacement pressure difference for recovery. Different pore sizes play different roles in the shale oil recovery process, so it is of great significance to quantitatively evaluate the wettability differences at different pore sizes. Summary of the invention

[0009] The purpose of the embodiment of the present invention is to provide a method and device for judging the wettability of a shale oil reservoir. Through the embodiment of the present invention, the amount of liquid injected into the ground and the time of well blocking in the development of shale oil can be optimized.

[0010] In order to achieve the above object, an embodiment of the present invention provides a method for determining the wettability of a shale oil reservoir, the method comprising:

[0011] Obtaining the absorption rate and / or the absorption fluid saturation when the rock sample spontaneously absorbs the fluid, wherein the absorption rate includes the water absorption rate and the oil absorption rate, and the absorption fluid saturation includes the water absorption saturation and the oil absorption saturation;

[0012] Determine the average wettability of the shale oil reservoir according to the absorption rate and / or the absorption fluid saturation;

[0013] Obtaining a first corresponding relationship between the pore radius and the signal strength when the rock sample is in a dry state, a second corresponding relationship between the pore radius and the signal strength when the rock sample is in a water-saturated state, and a third corresponding relationship between the pore radius and the signal strength when the rock sample is in an oil-saturated state;

[0014] Based on the first corresponding relationship, the second corresponding relationship and the third corresponding relationship, the signal intensity increment S1 of the rock sample in the water-saturated state versus the dry state and the signal intensity increment S2 of the rock sample in the oil-saturated state versus the dry state under the same pore radius are compared to determine the hydrophilicity and oleophilicity of the shale oil reservoir under the pore radius;

[0015] The wettability of the shale oil reservoir is determined based on the average wettability of the shale oil reservoir and the hydrophilicity and oleophilicity of the shale oil reservoir at different pore radii.

[0016] Optionally, obtaining the spontaneous fluid absorption rate and / or fluid saturation of the rock sample, and judging the average wettability of the shale oil reservoir according to the absorption rate and / or fluid saturation, includes:

[0017] Obtaining the weight of the rock sample before self-imbibing water, the weight of the rock sample when saturated with water, and the pore volume of the rock sample after self-imbibing water, as well as the weight of the rock sample before self-imbibing oil, the weight of the rock sample when saturated with oil, and the pore volume of the rock sample after self-imbibing oil;

[0018] Calculate the water saturation of the rock sample in a water-saturated state according to the weight of the rock sample before self-absorption of water, the weight of the rock sample in a water-saturated state, and the pore volume of the rock sample after self-absorption of water;

[0019] Calculate the oil absorption saturation of the rock sample in the oil-saturated state according to the weight of the rock sample before self-absorption of oil, the weight of the rock sample in the oil-saturated state, and the pore volume of the rock sample after self-absorption of oil;

[0020] The average wettability of the shale oil reservoir is determined based on the water saturation and oil saturation of the rock sample.

[0021] Optionally, judging the average wettability of the shale oil reservoir according to the water saturation and oil saturation of the rock sample includes:

[0022] The difference between the water saturation and the oil saturation of the rock sample is used as the oil and water saturation index I1 of the shale oil reservoir;

[0023] When -a<I1≤a, the average wettability of the shale oil reservoir is mixed wettability, where 0.5<a<0;

[0024] When -1<I1≤-a, the average wettability of the shale oil reservoir is oleophilic;

[0025] When a<I1≤1, the average wettability of the shale oil reservoir is hydrophilic.

[0026] Optionally, when -1<I1≤-a, if -1.0<I1≤-0.5, the average wettability of the shale oil reservoir is oil-wet, and if -0.5<I1≤-a, the average wettability of the shale oil reservoir is mixed wettability and partial oil-wet;

[0027] When a<I1≤1, if a<I1≤0.5, the average wettability of the shale oil reservoir is mixed wetting and slightly hydrophilic, and if 0.5<I1≤1.0, the average wettability of the shale oil reservoir is hydrophilic.

[0028] Optionally, obtaining the spontaneous fluid absorption rate and / or fluid saturation of the rock sample, and judging the average wettability of the shale oil reservoir according to the absorption rate and / or fluid saturation, includes:

[0029] Obtaining the weight of the rock sample before self-absorption of water, the weight of the rock sample when it is saturated with water, and the time required for the rock sample to reach the saturated state with water, as well as the weight of the rock sample before self-absorption of oil, the weight of the rock sample when it is saturated with oil, and the time required for the rock sample to reach the saturated state with oil;

[0030] Calculate the water absorption rate of the rock sample according to the weight of the rock sample before self-absorption of water, the weight of the rock sample in a water-saturated state, and the time required for the rock sample to reach the water-saturated state;

[0031] Calculate the oil absorption rate of the rock sample according to the weight of the rock sample before self-absorption of oil, the weight of the rock sample when it is saturated with oil, and the time required for the rock sample to reach the saturated oil state;

[0032] The average wettability of the shale oil reservoir is determined based on the water absorption rate and oil absorption rate of the rock sample.

[0033] Optionally, judging the average wettability of the shale oil reservoir according to the water absorption rate and oil absorption rate of the rock sample includes:

[0034] The ratio of the water absorption rate to the oil absorption rate of the rock sample is used as the oil absorption and water absorption rate index I2 of the shale oil reservoir;

[0035] When 0.75<I2≤1.0, the average wettability of the shale oil reservoir is mixed wettability;

[0036] When I2<0.5, the average wettability of the shale oil reservoir is oil-wet;

[0037] When 0.5<I2≤0.75, the average wettability of the shale oil reservoir is mixed wettability and partial oil-wetting;

[0038] When 1.25<I2, the average wettability of the shale oil reservoir is hydrophilic;

[0039] When 1.0<I2≤1.25, the average wettability of the shale oil reservoir is mixed wettability and partial hydrophilicity.

[0040] Optionally, obtaining the spontaneous fluid absorption rate and / or fluid saturation of the rock sample, and judging the average wettability of the shale oil reservoir according to the absorption rate and / or fluid saturation, includes:

[0041] Obtain the weight of the rock sample before self-imbibing water, the weight of the rock sample when saturated with water, the pore volume of the rock sample after self-imbibing water, and the time required for the rock sample to reach a saturated state with water, as well as the weight of the rock sample before self-imbibing oil, the weight of the rock sample when saturated with oil, the pore volume of the rock sample after self-imbibing oil, and the time required for the rock sample to reach a saturated state with oil;

[0042] Calculate the water saturation and water absorption rate of the rock sample in a saturated water state according to the weight of the rock sample before self-absorption of water, the weight of the rock sample in a saturated water state, the pore volume of the rock sample after self-absorption of water, and the time required for the rock sample to reach a saturated water state;

[0043] Calculate the oil absorption saturation and oil absorption rate of the rock sample in the oil-saturated state according to the weight of the rock sample before self-absorption of oil, the weight of the rock sample in the oil-saturated state, the pore volume of the rock sample after self-absorption of oil, and the time required for the rock sample to reach the oil-saturated state;

[0044] The average wettability of the shale oil reservoir is determined based on the water saturation, oil saturation, water absorption rate and oil absorption rate of the rock sample.

[0045] Optionally, judging the average wettability of the shale oil reservoir according to the water absorption saturation, oil absorption saturation, water absorption rate and oil absorption rate of the rock sample includes:

[0046] The difference between the water absorption saturation and the oil absorption saturation of the rock sample is used as the oil absorption and water absorption saturation index I1 of the shale oil reservoir, and the ratio of the water absorption rate and the oil absorption rate of the rock sample is used as the oil absorption and water absorption rate index I2 of the shale oil reservoir;

[0047] The ratio of the oil and water absorption saturation index I1 to the oil and water absorption rate index I2 of the shale oil reservoir is used as the wetting strength index I of the shale oil reservoir. According to the wetting strength index I, the average wettability of the shale oil reservoir is judged.

[0048] Optionally, judging the average wettability of the shale oil reservoir according to the wettability intensity index I includes:

[0049] When -0.15<I≤0.10, the average wettability of the shale oil reservoir is mixed wettability;

[0050] When I<-1.0, the average wettability of the shale oil reservoir is oil-wet;

[0051] When -1.0<I≤-0.15, the average wettability of the shale oil reservoir is mixed wettability and partial oil-wetting;

[0052] When 0.50<I, the average wettability of the shale oil reservoir is hydrophilic;

[0053] When 0.10<I≤0.50, the average wettability of the shale oil reservoir is mixed wetting and partial hydrophilicity. Optionally, the water saturation of the rock sample in a water-saturated state is calculated by the following formula:

[0054] S wn =((W wn -W1) / ρw) / V p1

[0055] In the formula, S wn W is the water saturation of the rock sample when it is saturated with water; wnis the weight of the rock sample in a water-saturated state; W1 is the weight of the rock sample before self-imbibition of water; ρw is the density of simulated water during the self-imbibition of water; Vp1 is the pore volume of the rock sample after self-imbibition of water;

[0056] The oil absorption saturation of the rock sample in the oil-saturated state is calculated by the following formula:

[0057] S on =((W on -W2) / ρo) / V p2

[0058] In the formula, S on W is the oil absorption saturation of the rock sample when it is saturated with oil; on is the weight of the rock sample when it is saturated with oil; W2 is the weight of the rock sample before self-imbibing oil; ρo is the density of the simulated oil during the self-imbibing process of the rock sample; Vp2 is the pore volume of the rock sample after self-imbibing oil.

[0059] Optionally, the water absorption rate of the rock sample is calculated by the following formula:

[0060] V wn =((W wn -W1) / ρw) / V) / t wi

[0061] Where V wn is the water absorption rate of the rock sample; W wn is the weight of the rock sample when it is saturated with water; W1 is the weight of the rock sample before self-absorption of water; ρw is the density of simulated water during self-absorption of water; V is the total volume of the rock sample; t wi The time required for the rock sample to reach a water-saturated state;

[0062] The oil absorption rate of the rock sample was calculated by the following formula:

[0063] V on =((W on -W2) / ρo) / V) / t oi

[0064] Where V on is the oil absorption rate of the rock sample; W on is the weight of the rock sample when it is saturated with oil; W2 is the weight of the rock sample before self-imbibing oil; ρo is the density of the simulated oil during the self-imbibing process of the rock sample; V is the total volume of the rock sample; t oi The time required for a rock sample to become saturated with oil.

[0065] Optionally, the step of obtaining a first correspondence between the pore radius and the signal strength when the rock sample is in a dry state, a second correspondence between the pore radius and the signal strength when the rock sample is in a water-saturated state, and a third correspondence between the pore radius and the signal strength when the rock sample is in an oil-saturated state includes:

[0066] Obtaining nuclear magnetic resonance T2 spectra of the rock sample in a dry state, a water-saturated state, and an oil-saturated state, respectively; wherein the nuclear magnetic resonance T2 spectrum represents the relationship between the T2 value and the signal intensity;

[0067] According to the relationship between the T2 value and the signal intensity, and the conversion relationship between the T2 value and the pore radius, a first corresponding relationship between the pore radius and the signal intensity when the rock sample is in a dry state, a second corresponding relationship between the pore radius and the signal intensity when the rock sample is in a water-saturated state, and a third corresponding relationship between the pore radius and the signal intensity when the rock sample is in an oil-saturated state are obtained.

[0068] Optionally, the comparison of the signal strength increment S1 of the rock sample in the water-saturated state versus the dry state, and the signal strength increment S2 of the rock sample in the oil-saturated state versus the dry state at the same pore radius to obtain the hydrophilicity and oleophilicity of the shale oil reservoir at the pore radius includes:

[0069] When the signal intensity increment S1 of the rock sample in the water-saturated state compared with the dry state is greater than the signal intensity increment S2 of the rock sample in the oil-saturated state compared with the dry state, the water-wetting ability of the shale oil reservoir at this pore radius is greater than the oil-wetting ability;

[0070] When the signal intensity increment S1 of the rock sample in the water-saturated state compared with the dry state is not greater than the signal intensity increment S2 of the rock sample in the oil-saturated state compared with the dry state, the oil-wetting ability of the shale oil reservoir at this pore radius is greater than its water-wetting ability.

[0071] Optionally, the determination method further includes:

[0072] The pore radius where the hydrophilicity is greater than the lipophilicity and the pore radius where the lipophilicity is greater than the hydrophilicity are divided into a first interval range and a second interval range respectively;

[0073] The left boundary of the first interval range and / or the second interval range is used as the critical pore radius during the current oil-water reversal, and the right boundary is used as the critical pore radius during the next oil-water reversal.

[0074] Accordingly, an embodiment of the present invention further provides a method for adjusting the amount of liquid injected into the ground and the time of well blocking in shale oil development, the adjustment method comprising:

[0075] Based on the shale oil reservoir wettability judgment method, judging the wettability of the shale oil reservoir;

[0076] According to the wettability of the shale oil reservoir, the amount of liquid injected into the ground and the time of well blocking in shale oil development are adjusted.

[0077] Correspondingly, an embodiment of the present invention further provides a shale oil reservoir wettability judgment device, and the shale oil reservoir wettability judgment device is used to execute the shale oil reservoir wettability judgment method.

[0078] Correspondingly, an embodiment of the present invention also provides a device for adjusting the amount of liquid injected into the ground and the time of well plugging in shale oil development. The device for adjusting the amount of liquid injected into the ground and the time of well plugging in shale oil development is used to execute the method for adjusting the amount of liquid injected into the ground and the time of well plugging in shale oil development.

[0079] Correspondingly, an embodiment of the present invention also provides a machine-readable storage medium, on which instructions are stored, and the instructions are used to enable a machine to execute the shale oil reservoir wettability judgment method or the method for adjusting the amount of liquid injected into the ground and the well blocking time in shale oil development.

[0080] Correspondingly, an embodiment of the present invention also provides a processor for running a program, wherein the program, when being run, is used to execute the shale oil reservoir wettability judgment method or the method for adjusting the amount of liquid injected into the ground and the well blocking time in shale oil development.

[0081] The embodiment of the present invention determines the average wettability of the shale oil reservoir by the suction rate and the saturation of the suction fluid, and determines the hydrophilicity and lipophilicity of the shale oil reservoir at different pore radii by the signal intensity increment in the water-saturated state and the oil-saturated state. Among them, the average wettability reflects the wettability of the shale oil reservoir at a macroscopic level, and the hydrophilicity and lipophilicity of the shale oil reservoir at different pore radii reflects the hydrophilicity and lipophilicity of the shale oil reservoir at a microscopic level at different pore radii. The embodiment of the present invention determines the wettability of the shale oil reservoir by combining the average wettability and the hydrophilicity and lipophilicity of the shale oil reservoir at different pore radii, which can reflect the wetting characteristics of oil and water in the shale oil reservoir from multiple dimensions, making the evaluation more comprehensive, and providing a theoretical basis for the optimization of reasonable liquid injection volume and well blocking time in the development of shale oil horizontal wells.

[0082] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0084] Figure 1 It is a flow chart of a method for determining wettability of a shale oil reservoir provided by an embodiment of the present invention;

[0085] Figure 2 Schematic diagram of an experimental device for determining average wettability of a shale oil reservoir provided by an embodiment of the present invention;

[0086] Figure 3 It is a T2 spectrum of nuclear magnetic resonance test of rock samples in dry state and saturated water state provided by an embodiment of the present invention;

[0087] Figure 4 It is a T2 spectrum of nuclear magnetic resonance testing of a rock sample in a dry state and in an oil-saturated state provided by an embodiment of the present invention;

[0088] Figure 5 It is a comparison curve of the nuclear magnetic resonance T2 spectrum of the self-absorption water and self-absorption oil experiments provided in the embodiments of the present invention;

[0089] Figure 6 is a graph of rock sample weight and time data during the self-absorption of water provided by an embodiment of the present invention;

[0090] Figure 7 is a graph of rock sample weight and time data during the self-priming oil process provided by an embodiment of the present invention;

[0091] Figure 8A-8F It is a nuclear magnetic resonance T2 spectrum data diagram of self-absorption water and self-absorption oil experiments provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0092] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0093] Figure 1 It is a flow chart of a method for determining wettability of a shale oil reservoir provided in an embodiment of the present invention.

[0094] like Figure 1 As shown, the method for determining the wettability of a shale oil reservoir comprises:

[0095] S110: Obtaining an absorption rate and / or an absorption fluid saturation when the rock sample spontaneously absorbs fluid, wherein the absorption rate includes a water absorption rate and an oil absorption rate, and the absorption fluid saturation includes a water absorption saturation and an oil absorption saturation;

[0096] S120: Determine the average wettability of the shale oil reservoir according to the suction rate and / or the suction fluid saturation;

[0097] S130: Acquire a first corresponding relationship between the pore radius and the signal strength when the rock sample is in a dry state, a second corresponding relationship between the pore radius and the signal strength when the rock sample is in a water-saturated state, and a third corresponding relationship between the pore radius and the signal strength when the rock sample is in an oil-saturated state;

[0098] S140: Based on the first corresponding relationship, the second corresponding relationship and the third corresponding relationship, the signal strength increment S1 of the rock sample in the water-saturated state versus the dry state and the signal strength increment S2 of the rock sample in the oil-saturated state versus the dry state under the same pore radius are compared to determine the hydrophilicity and oleophilicity of the shale oil reservoir under the pore radius;

[0099] S150: judging the wettability of the shale oil reservoir according to the average wettability of the shale oil reservoir and the hydrophilicity and oleophilicity of the shale oil reservoir at different pore radii.

[0100] In the embodiment of the present invention, the average wettability of the shale oil reservoir can be determined through steps S110 and S120, and the hydrophilicity and lipophilicity of the shale oil reservoir at different pore radii can be determined through steps S130 and S140. Among them, the average wettability reflects the wettability of the shale oil reservoir at a macroscopic level, and the hydrophilicity and lipophilicity of the shale oil reservoir at different pore radii reflects the hydrophilicity and lipophilicity of the shale oil reservoir at a microscopic level at different pore radii. The embodiment of the present invention comprehensively considers the average wettability and the hydrophilicity and lipophilicity of the shale oil reservoir at different pore radii to determine the wettability of the shale oil reservoir, which can reflect the wetting characteristics of oil and water in the shale oil reservoir from multiple dimensions, making the evaluation more comprehensive.

[0101] In steps S110 and S120, any of the following methods may be used to determine the average wettability of the shale oil reservoir:

[0102] 1) Obtaining the water saturation and oil saturation of the rock sample, and judging the average wettability of the shale oil reservoir according to the water saturation and oil saturation;

[0103] For example, the method first obtains the weight of the rock sample before self-absorption of water, the weight of the rock sample when saturated with water, the pore volume of the rock sample after self-absorption of water, and the weight of the rock sample before self-absorption of oil, the weight of the rock sample when saturated with oil, and the pore volume of the rock sample after self-absorption of oil;

[0104] Further, the water saturation of the rock sample in a water-saturated state is calculated according to the weight of the rock sample before self-absorption of water, the weight of the rock sample in a water-saturated state, and the pore volume of the rock sample after self-absorption of water; the oil saturation of the rock sample in an oil-saturated state is calculated according to the weight of the rock sample before self-absorption of oil, the weight of the rock sample in an oil-saturated state, and the pore volume of the rock sample after self-absorption of oil;

[0105] Finally, the average wettability of the shale oil reservoir is determined according to the water saturation and oil saturation of the rock sample;

[0106] Specifically, the difference between the water absorption saturation and the oil absorption saturation of the rock sample is used as the oil absorption and water absorption saturation index I1 of the shale oil reservoir;

[0107] When -a<I1≤a, the average wettability of the shale oil reservoir is mixed wettability, where 0.5<a<0 (such as a is 0.1);

[0108] When -1<I1≤-a, the average wettability of the shale oil reservoir is oleophilic;

[0109] When a<I1≤1, the average wettability of the shale oil reservoir is hydrophilic.

[0110] More preferably, when -1<I1≤-a, if -1.0<I1≤-0.5, the average wettability of the shale oil reservoir is classified as oil-wet, and if -0.5<I1≤-a, the average wettability of the shale oil reservoir is classified as mixed wettability and partial oil-wet;

[0111] When a<I1≤1, if a<I1≤0.5, the average wettability of the shale oil reservoir is classified as mixed wettability and partial hydrophilicity, and if 0.5<I1≤1.0, the average wettability of the shale oil reservoir is classified as hydrophilicity.

[0112] 2) obtaining the water absorption rate and oil absorption rate of the rock sample, and judging the average wettability of the shale oil reservoir according to the water absorption rate and oil absorption rate;

[0113] For example, the method first obtains the weight of the rock sample before self-absorption of water, the weight of the rock sample when it is saturated with water, and the time required for the rock sample to reach the saturated water state, as well as the weight of the rock sample before self-absorption of oil, the weight of the rock sample when it is saturated with oil, and the time required for the rock sample to reach the saturated oil state;

[0114] Further, the water absorption rate of the rock sample is calculated according to the weight of the rock sample before self-absorption of water, the weight of the rock sample when it is saturated with water, and the time required for the rock sample to reach the saturated water state; the oil absorption rate of the rock sample is calculated according to the weight of the rock sample before self-absorption of oil, the weight of the rock sample when it is saturated with oil, and the time required for the rock sample to reach the saturated oil state;

[0115] Finally, the average wettability of the shale oil reservoir is determined according to the water absorption rate and oil absorption rate of the rock sample;

[0116] Specifically, the ratio of the water absorption rate to the oil absorption rate of the rock sample is used as the oil absorption and water absorption rate index I2 of the shale oil reservoir;

[0117] When 0.75<I2≤1.0, the average wettability of the shale oil reservoir is mixed wettability;

[0118] When I2<0.5, the average wettability of the shale oil reservoir is oil-wet;

[0119] When 0.5<I2≤0.75, the average wettability of the shale oil reservoir is mixed wettability and partial oil-wetting;

[0120] When 1.25<I2, the average wettability of the shale oil reservoir is hydrophilic;

[0121] When 1.0<I2≤1.25, the average wettability of the shale oil reservoir is mixed wettability and partial hydrophilicity.

[0122] 3) Obtain the water saturation, oil saturation, water absorption rate and oil absorption rate of the rock sample, and determine the average wettability of the shale oil reservoir based on the water saturation, oil saturation, water absorption rate and oil absorption rate of the rock sample.

[0123] For example, the method first obtains the weight of the rock sample before self-absorption of water, the weight of the rock sample when it is saturated with water, the pore volume of the rock sample after self-absorption of water, and the time required for the rock sample to reach the saturated water state, as well as the weight of the rock sample before self-absorption of oil, the weight of the rock sample when it is saturated with oil, the pore volume of the rock sample after self-absorption of oil, and the time required for the rock sample to reach the saturated oil state;

[0124] Further, the water saturation and water absorption rate of the rock sample in the water-saturated state are calculated based on the weight of the rock sample before self-absorption of water, the weight of the rock sample in the water-saturated state, the pore volume of the rock sample after self-absorption of water, and the time required for the rock sample to reach the water-saturated state; the oil saturation and oil absorption rate of the rock sample in the oil-saturated state are calculated based on the weight of the rock sample before self-absorption of oil, the weight of the rock sample in the oil-saturated state, the pore volume of the rock sample after self-absorption of oil, and the time required for the rock sample to reach the oil-saturated state;

[0125] Finally, the average wettability of the shale oil reservoir is determined according to the water absorption saturation, oil absorption saturation, water absorption rate and oil absorption rate of the rock sample;

[0126] Specifically, the difference between the water absorption saturation and the oil absorption saturation of the rock sample can be used as the oil absorption and water absorption saturation index I1 of the shale oil reservoir, and the ratio of the water absorption rate and the oil absorption rate of the rock sample can be used as the oil absorption and water absorption rate index I2 of the shale oil reservoir; the ratio of the oil absorption and water absorption saturation index I1 of the shale oil reservoir to the oil absorption and water absorption rate index I2 can be used as the wetting strength index I of the shale oil reservoir, and the average wettability of the shale oil reservoir can be judged according to the wetting strength index I;

[0127] When -0.15<I≤0.10, the average wettability of the shale oil reservoir is mixed wettability;

[0128] When I<-1.0, the average wettability of the shale oil reservoir is oil-wet;

[0129] When -1.0<I≤-0.15, the average wettability of the shale oil reservoir is mixed wettability and partial oil-wetting;

[0130] When 0.50<I, the average wettability of the shale oil reservoir is hydrophilic;

[0131] When 0.10<I≤0.50, the average wettability of the shale oil reservoir is mixed wettability and partial hydrophilicity.

[0132] The following is an introduction to the calculation methods of the water absorption saturation, oil absorption saturation, water absorption rate and oil absorption rate in the above three implementation modes.

[0133] The water saturation of the rock sample in a water-saturated state can be calculated by the following formula:

[0134] S wn =((W wn -W1) / ρw) / V p1

[0135] In the formula, S wn W is the water saturation of the rock sample when it is saturated with water; wn is the weight of the rock sample in a water-saturated state; W1 is the weight of the rock sample before self-imbibition of water; ρw is the density of simulated water during the self-imbibition of water; Vp1 is the pore volume of the rock sample after self-imbibition of water;

[0136] The oil absorption saturation of the rock sample in the oil-saturated state can be calculated by the following formula:

[0137] S on =((W on -W2) / ρo) / V p2

[0138] In the formula, S on W is the oil absorption saturation of the rock sample when it is saturated with oil;on is the weight of the rock sample when it is saturated with oil; W2 is the weight of the rock sample before self-imbibing oil; ρo is the density of the simulated oil during the self-imbibing process of the rock sample; Vp2 is the pore volume of the rock sample after self-imbibing oil.

[0139] The water absorption rate of the rock sample can be calculated by the following formula:

[0140] V wn =((W wn -W1) / ρw) / V) / t wi

[0141] Where V wn is the water absorption rate of the rock sample; W wn is the weight of the rock sample when it is saturated with water; W1 is the weight of the rock sample before self-absorption of water; ρw is the density of simulated water during self-absorption of water; V is the total volume of the rock sample; t wi The time required for the rock sample to reach a water-saturated state;

[0142] The oil absorption rate of the rock sample can be calculated by the following formula:

[0143] V on =((W on -W2) / ρo) / V) / t oi

[0144] Where V on is the oil absorption rate of the rock sample; W on is the weight of the rock sample when it is saturated with oil; W2 is the weight of the rock sample before self-imbibing oil; ρo is the density of the simulated oil during the self-imbibing process of the rock sample; V is the total volume of the rock sample; t oi The time required for a rock sample to become saturated with oil.

[0145] In step S130, when obtaining the first corresponding relationship between the pore radius and the signal strength when the rock sample is in a dry state, the second corresponding relationship between the pore radius and the signal strength when the rock sample is in a water-saturated state, and the third corresponding relationship between the pore radius and the signal strength when the rock sample is in an oil-saturated state, the nuclear magnetic resonance T2 spectra of the rock sample in a dry state, a water-saturated state, and an oil-saturated state can be obtained respectively; wherein the nuclear magnetic resonance T2 spectrum represents the relationship between the T2 value and the signal strength; then, according to the relationship between the T2 value and the signal strength, and the conversion relationship between the T2 value and the pore radius, the first corresponding relationship between the pore radius and the signal strength when the rock sample is in a dry state, the second corresponding relationship between the pore radius and the signal strength when the rock sample is in a water-saturated state, and the third corresponding relationship between the pore radius and the signal strength when the rock sample is in an oil-saturated state are obtained.

[0146] In step S140, based on the first corresponding relationship, the second corresponding relationship and the third corresponding relationship, the signal strength increment S1 of the rock sample in the water-saturated state versus the dry state and the signal strength increment S2 of the rock sample in the oil-saturated state versus the dry state under the same pore radius are compared, and when judging the hydrophilicity and oleophilicity of the shale oil reservoir under the pore radius, if the signal strength increment S1 of the rock sample in the water-saturated state versus the dry state is greater than the signal strength increment S2 of the rock sample in the oil-saturated state versus the dry state, it can be judged that the hydrophilicity of the shale oil reservoir under the pore radius is greater than the oleophilicity;

[0147] The signal intensity increment S1 of the rock sample when it is saturated with water compared with the dry state is not greater than the signal intensity increment S2 of the rock sample when it is saturated with oil compared with the dry state, which indicates that the oil-wetting ability of the shale oil reservoir is greater than its water-wetting ability at this pore radius.

[0148] More preferably, the pore radius where the hydrophilicity is greater than the lipophilicity and the pore radius where the lipophilicity is greater than the hydrophilicity can be divided into a first interval range and a second interval range respectively; the left boundary of the first interval range and / or the second interval range is used as the critical pore radius during the current oil-water reversal, and the right boundary is used as the critical pore radius during the next oil-water reversal.

[0149] The inventor of the present application has found that dry rocks can spontaneously absorb fluids (water and oil) under the action of capillary pressure. Due to the different mineral composition of the rock, the organic matter richness in the pores, the different pore throat structures of the rock, and the influence of external conditions, the amount of oil and water spontaneously absorbed, as well as the spontaneous oil and water absorption rates are also different. The embodiment of the present invention provides a method for comprehensively determining the wettability of shale oil reservoirs by using the self-absorbed water and oil amount of the core, as well as the water absorption rate and oil absorption rate under the action of the rock's own capillary force; based on the self-absorbed water amount, self-absorbed oil amount, water absorption rate and oil absorption rate of the rock, the differences in the wettability of different shale oil reservoirs are evaluated; by using nuclear magnetic resonance technology, the distribution state of oil and water of different pore sizes of rock samples is analyzed, and the influence of different pore sizes of rocks on the self-absorbed water and oil is further quantified, providing a theoretical basis for the optimization of reasonable in-ground liquid volume and well blocking time for the development of shale oil horizontal wells.

[0150] The following is a detailed explanation of the method for determining the wettability of shale oil reservoirs with examples.

[0151] In the example, Figure 2 Schematic diagram of an experimental device provided in an embodiment of the present invention.

[0152] First, prepare the experimental samples. Select the core of the target shale oil reservoir and drill a column with a diameter of 2.5 cm and a length of 3.0 cm in the original state without washing the oil. It is required that the rock of the shale oil reservoir of the target well should use fresh cores just taken out from the bottom of the well as much as possible. Such cores have less organic matter loss and can maintain the original state of the shale oil reservoir; if there is no fresh core, the existing core can be pressurized and saturated for aging, and the treated core can be immersed in simulated oil (simulated oil: oil used for experiments, configured in accordance with the People's Republic of China Petroleum and Natural Gas Industry Standard SY-T 5345-2007 Two-Phase Relative Permeability Determination Method in Rocks) for more than 1 week.

[0153] Then, cut the experimental sample (hereinafter referred to as sample) with a length of 0.5-0.7cm and put it into the oven for drying at a low temperature of 50℃ for at least 2 hours. When the drying time is greater than 2 hours, weigh the sample with a balance, and weigh it once every 30 minutes. When the sample weight change is less than 1‰, the drying process is completed. Take out the sample and place it in a dryer for experimental use.

[0154] Further, the sample is taken out from the dryer and weighed on a balance, the weight W1 is recorded, and then the sample is subjected to a first nuclear magnetic resonance test to obtain T2 spectrum data of the sample background of the test sample (the nuclear magnetic resonance test is conducted in accordance with the petroleum and natural gas industry standard SY / T 6490-2007 of the People's Republic of China).

[0155] Furthermore, the sample after the first test was placed in a wide-mouth bottle, and simulated water was added (simulated water: water used for the experiment, prepared in accordance with the Petroleum and Natural Gas Industry Standard SY-T 5345-2007 of the People's Republic of China for the determination of two-phase relative permeability in rocks), and the density of the simulated water was tested. w Then the sample starts to absorb water by itself (self-absorption process: the process of injecting simulated water into the sample through capillary force). During the self-absorption process, the sample is measured once every 10 minutes with a balance and the sample weight W is recorded. wi and time T wi Before each weighing, it is required to wipe off the floating water on the sample surface with wet gauze, and there should be no obvious water droplets on the sample. When the self-absorption process lasts for more than 72 hours and the sample weight change is less than 1‰, the self-absorption process ends. Then a second nuclear magnetic resonance test is performed to obtain the T2 spectrum data of the self-absorption of the test sample (the nuclear magnetic resonance test is carried out in accordance with the petroleum and natural gas industry standard SY / T 6490-2007 of the People's Republic of China). The T2 spectrum data obtained from the first and second nuclear magnetic resonance tests are plotted into the nuclear magnetic resonance test T2 spectrum of the water phase, as shown in FIG. Figure 3 After the water absorption is completed, the pore volume of the sample is tested and recorded.

[0156] Furthermore, the samples that have completed the second NMR test were soaked in water for 2 hours. After the soaking, the samples were dried and placed in an oven for at least 2 hours at a low temperature of 50°C. When the drying time is greater than 2 hours, the samples were weighed with a balance, and weighed once every 30 minutes. When the sample weight change is less than 1‰, the drying process is completed. The samples were taken out and placed in a dryer for experimental use.

[0157] Further, take out the sample from the dryer and weigh it, record the weight W2, put the sample into a wide-mouth bottle, add simulated oil, and test the density of simulated water ρ o , the sample starts to absorb oil (self-absorption process: the process of injecting simulated oil into the sample through capillary force). During the self-absorption process, the sample is measured once every 10 minutes with a balance and the sample weight W is recorded. oi and time T oi Before each weighing, it is required to wipe off the floating oil on the sample surface with wet gauze, and there should be no obvious oil droplets on the sample. When the self-priming oil process lasts for more than 72 hours and the sample weight change is less than 1‰, the self-priming oil process ends. Then the third nuclear magnetic resonance test is carried out to obtain the T2 spectrum data of the self-priming oil of the test sample (the nuclear magnetic resonance test is carried out in accordance with the petroleum and natural gas industry standard SY / T 6490-2007 of the People's Republic of China). The T2 spectrum data obtained from the first and third nuclear magnetic resonance tests are plotted into the nuclear magnetic resonance test T2 spectrum of the oil phase, as shown in FIG. Figure 4 shown.

[0158] Combine the T2 spectrum data obtained from the first, second and third NMR tests to draw a comparison curve of the NMR T2 spectra of the self-absorption water and self-absorption oil experiments (see Figure 5 ). The T2 spectrum data obtained from the first, second and third NMR tests were used to draw the NMR T2 spectrum comparison curves of self-absorption water and self-absorption oil experiments, and the signal intensity increment S1 of the rock sample when the saturated water state was compared with the dry state and the signal intensity increment S2 of the rock sample when the saturated oil state was compared with the dry state were calculated.

[0159] Furthermore, the sample that has completed the third NMR test is placed in an oil washing instrument for oil washing (required to be carried out in accordance with the core analysis method of the People's Republic of China Petroleum and Natural Gas Industry Standard SY-T 5336-2006). Note that the sample should not fall off during the oil washing process. After the oil absorption is completed, the pore volume V of the sample is tested P2 , and record it.

[0160] Furthermore, the water absorption saturation, oil absorption saturation, water absorption rate and oil absorption rate of the sample are calculated.

[0161] (1) Water saturation: simulates the proportion of water in the pore volume.

[0162] S wi =((W wi -W1) / ρw) / V p

[0163] The weight W at the end of the self-absorption process wn According to the above formula, the water saturation S at the end of the self-absorption process is calculated. wn ;

[0164] S wi —Sample at T wi Water saturation at 100°, decimal; W wi —Sample at T wi W1—weight of sample before self-absorption, g; ρw—density of simulated water, g / cm 3 ; Vp—pore volume of the sample, cm 3 ; S wn —Water saturation of the sample at the end of the water absorption process; W wn —The weight of the sample at the end of the water absorption process;

[0165] Among them, the sample weight W in the process of self-absorption of water wi and time T wi Data formation Figure 6 , simulated water density ρ w =1.036g / cm 3 , simulated oil density ρ o =0.792g / cm 3 , W1=6.614g, W2=6.592g, Vp=0.2774cm 3 , sample length 0.67cm, sample diameter 2.497cm, sample total volume V = 4.163cm 3 ;extract Figure 6 The last set of data determines W wn , W wn =6.701g;

[0166] S wn =((W wn -W1) / ρw) / V p =(6.701-6.614) / 1.036 / 0.2774=0.30;

[0167] (2) Oil saturation: simulates the proportion of oil in the pore volume.

[0168] S oi =((W oi -W2) / ρo) / V p

[0169] Weight W at the end of the self-priming processon According to the above formula, the oil absorption saturation S at the end of the self-absorption process is calculated. on ;

[0170] S oi —Sample at T oi Oil absorption saturation at , decimal; W oi —Sample at T oi W2—sample weight before the self-priming process, g; ρo—density of simulated oil, g / cm 3 ; Vp—pore volume of the sample, cm 3 ; Vp—pore volume of the sample, cm 3 ; S on —Oil absorption saturation of the sample at the end of the self-absorption process; W on —The sample weight at the end of the self-priming process.

[0171] Among them, the sample weight W in the process of self-priming oil oi and time T oi Data formation Figure 7 ,extract Figure 7 The last set of data determines W on , W on =6.781g;

[0172] S on =((W oi -W2) / ρo) / V p =(6.781-6.592) / 0.792 / 0.2774=0.86;

[0173] (3) Water absorption rate: the amount of water absorbed by the sample per unit volume and per unit time.

[0174] V wi =((W wi -W1) / ρw) / V) / t wi

[0175] V wi —Sample at T wi Water absorption rate at 1 second, decimal; W wi —Sample at T wi W1—weight of sample before self-absorption, g; ρw—density of simulated water, g / cm 3 ; V—total volume of the sample, cm 3 ;t wi —A certain period of time during the sample's self-absorption of water, min.

[0176] Among them, extraction Figure 6 Time and weight data of sequence number 14, time t wi=4800min,W wi =6.696g;

[0177] V wi =((W wi -W1) / ρw) / V) / t wi

[0178] =(6.696-6.614) / 1.036 / 4.163 / 4800=0.00000396cm3 / m

[0179] (4) Oil absorption rate: the amount of oil absorbed by the sample per unit volume and per unit time.

[0180] V oi =((W oi -W2) / ρo) / V) / t oi

[0181] V oi —Sample at T oi Oil absorption saturation at , decimal; W oi —Sample at T oi W2—sample weight before the self-priming process, g; ρo—density of simulated oil, g / cm 3 ; V—total volume of the sample, cm 3 ;t oi —A certain period of time during the sample's self-absorption of water, min.

[0182] Among them, extraction Figure 7 Time and weight data of sequence number 12, time t oi =4855min,

[0183] W oi =6.776g;

[0184] V oi =((W oi -W2) / ρo) / V) / t oi

[0185] =(6.776-6.592) / 0.792 / 4.163 / 4855=0.0000115cm 3 / min.

[0186] (5) Oil and water absorption saturation index I1:

[0187] I1=S wn -S on

[0188] S wn —Water saturation of the sample at the end of the water absorption process; S on—Oil absorption saturation of the sample at the end of the self-absorption process; I1—Oil and water absorption saturation index.

[0189] The oil absorption and water absorption saturation index I1 was used to identify the wettability of the sample.

[0190] When -1.0<I1≤-0.5, the wettability of the sample is oleophilic; when -0.5<I1≤-0.1, the wettability of the sample is mixed wetting-partially oleophilic; when -0.1<I1≤0.1, the wettability of the sample is mixed wetting; when 0.1<I1≤0.5, the wettability of the sample is mixed wetting-partially hydrophilic; 0.5<I1≤1.0, the wettability of the sample is hydrophilic.

[0191] Where I1 = S wn -S on =0.30-0.86=-0.56, judging that the average wettability of the Y60 sample is lipophilic.

[0192] (6) Oil and water absorption rate index I2:

[0193] I2=V wi / V oi

[0194] V wi —The amount of water absorbed by the sample per unit volume per unit time; V oi —The amount of oil absorbed by the sample per unit volume and per unit time; I2—Oil and water absorption rate index.

[0195] The oil and water absorption rate index I2 was used to identify the wettability of the sample.

[0196] When 1.25<I2, the wettability of the sample is hydrophilic; when 1.0<I2≤1.25, the wettability of the sample is mixed wetting-partially hydrophilic; when 0.75<I2≤1.0, the wettability of the sample is mixed wetting; when 0.5<I2≤0.75, the wettability of the sample is mixed wetting-partially oleophilic; when I2<0.5, the wettability of the sample is oleophilic.

[0197] Where I2 = V wi / V oi =0.00000396 / 0.0000115=0.34, judging that the average wettability of the Y60 sample is oleophilic.

[0198] (7) Wetting strength index I:

[0199] I=I1 / I2

[0200] The wetting intensity index I is used to identify the wettability of rock samples.

[0201] When I≤-1.0, the wettability of the sample is oleophilic; when -1.0<I≤-0.15, the wettability of the sample is mixed wetting-partially oleophilic; when -0.15<I≤0.10, the wettability of the sample is mixed wetting; when 0.10<I≤0.50, the wettability of the sample is mixed wetting-partially hydrophilic; and when 0.50<I, the wettability of the sample is hydrophilic.

[0202] (8) Determine the hydrophilicity and oleophilicity of shale oil reservoirs at different pore radii:

[0203] like Figure 5 As shown in the figure, when S1≥S2, it is considered that the hydrophilicity at this pore radius is greater than the lipophilicity. The left boundary of the pore radius interval is the pore radius value at this oil-water reversal, and the right boundary is the pore radius value at the next oil-water reversal (oil-water reversal: the relative relationship between S1 and S2 changes), and all intervals of pore radius with hydrophilicity greater than lipophilicity are counted together;

[0204] When S1≤S2, it is determined that the lipophilicity in this pore radius interval is greater than the hydrophilicity. The left boundary of the pore radius interval is the pore radius value at the time of this oil-water reversal, and the right boundary is the pore radius value at the next oil-water reversal (oil-water reversal: the relative relationship between S1 and S2 changes), and all intervals of pore radius where the lipophilicity is greater than the hydrophilicity are counted together.

[0205] Among them, the T2 spectrum data of the first to third nuclear magnetic resonance tests are used to form Figure 8. According to the data in Figure 8, it can be obtained that:

[0206] The range of pore radius where hydrophilicity is greater than lipophilicity is:

[0207] [0.0002, 0.0007], [1.0966, 1.6667];

[0208] The range of pore radius where the lipophilicity is greater than the hydrophilicity is:

[0209] [0.0008, 0.9537], [1.9163, 10.2265];

[0210] In summary, the average wettability of Y60 samples is lipophilic, and the intervals of pore radius where hydrophilicity is greater than lipophilicity are: [0.0002, 0.0007], [1.0966, 1.6667]; the intervals of pore radius where lipophilicity is greater than hydrophilicity are: [0.0008, 0.9537], [1.9163, 10.2265].

[0211] The purpose of the present invention is to objectively evaluate the wettability characteristics of core tight shale oil shale oil reservoirs, provide technical support for optimizing the amount of liquid entering the ground and the wellbore time, achieve the dual goals of artificial fracturing and energy replenishment in horizontal wells, reduce investment costs from the source, and increase single well production.

[0212] The embodiment of the present invention adopts an indoor experimental evaluation method, using the property that dry rock can spontaneously absorb fluid (water, oil) under the action of the capillary pressure of the rock. Under the influence of the mineral composition of the rock, the organic matter in the pores, the throat structure of the rock pores, and the external conditions, the amount of oil and water spontaneously absorbed, as well as the spontaneous oil and water absorption rate are different, and the mixed wettability index is quoted to determine the average wettability of the shale oil reservoir.

[0213] At the same time, it further determines the water-wet and oil-wet capabilities of shale oil reservoirs at different pore radii, providing a theoretical basis for optimizing the reasonable amount of liquid injected into the ground and the well-clogging time in the development of shale oil horizontal wells, achieving the goals of increasing single well production, improving recovery rate and reducing investment, and promoting the scale and efficiency development of shale oil;

[0214] The method provided by the present invention is simple and easy to operate, and provides a specific standard for wettability evaluation of tight shale oil reservoirs. Compared with the Amott test and the USBM test, the method is not restricted by the small pore throat and strong capillary force of the shale oil reservoir, and is simpler and easier to operate.

[0215] Furthermore, the sample preparation of this method is simple and fast, and the test process is only self-imbibition without displacement, which takes about 72 hours and is short in time. The rate is used to characterize the wettability, and the measurement is more accurate. At the same time, this method is suitable for shale oil reservoirs with mixed wettability and small pore throats. It can quantitatively characterize the changes in wettability of shale oil reservoirs with different pore sizes during self-imbibition under formation conditions, thereby guiding the optimization of the amount of liquid entering the ground and the time of well blocking;

[0216] Furthermore, this method has simple requirements for testing equipment, clear testing principles, short testing time, and shale oil reservoirs have well-developed micro-nano pores and strong heterogeneity.

[0217] Correspondingly, an embodiment of the present invention further provides a shale oil reservoir wettability judgment device, and the shale oil reservoir wettability judgment device is used to execute the shale oil reservoir wettability judgment method.

[0218] Correspondingly, an embodiment of the present invention also provides a device for adjusting the amount of liquid injected into the ground and the time of well plugging in shale oil development. The device for adjusting the amount of liquid injected into the ground and the time of well plugging in shale oil development is used to execute the method for adjusting the amount of liquid injected into the ground and the time of well plugging in shale oil development.

[0219] Correspondingly, an embodiment of the present invention also provides a machine-readable storage medium, on which instructions are stored, and the instructions are used to enable a machine to execute the shale oil reservoir wettability judgment method or the method for adjusting the amount of liquid injected into the ground and the well blocking time in shale oil development.

[0220] Correspondingly, an embodiment of the present invention also provides a processor for running a program, wherein the program, when being run, is used to execute the shale oil reservoir wettability judgment method or the method for adjusting the amount of liquid injected into the ground and the well blocking time in shale oil development.

[0221] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0222] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0223] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0224] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0225] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0226] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0227] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0228] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0229] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for determining the wettability of a shale oil reservoir, characterized in that: The shale oil reservoir wettability determination method comprises: Obtaining the absorption rate and / or the absorption fluid saturation when the rock sample spontaneously absorbs the fluid, wherein the absorption rate includes the water absorption rate and the oil absorption rate, and the absorption fluid saturation includes the water absorption saturation and the oil absorption saturation; Determining the average wettability of the shale oil reservoir according to the absorption rate and / or the absorption fluid saturation; Obtaining a first corresponding relationship between the pore radius and the signal strength when the rock sample is in a dry state, a second corresponding relationship between the pore radius and the signal strength when the rock sample is in a water-saturated state, and a third corresponding relationship between the pore radius and the signal strength when the rock sample is in an oil-saturated state; Based on the first corresponding relationship, the second corresponding relationship and the third corresponding relationship, the signal intensity increment S1 of the rock sample in the water-saturated state versus the dry state and the signal intensity increment S2 of the rock sample in the oil-saturated state versus the dry state under the same pore radius are compared to determine the hydrophilicity and oleophilicity of the shale oil reservoir under the pore radius; The wettability of the shale oil reservoir is determined based on the average wettability of the shale oil reservoir and the hydrophilicity and oleophilicity of the shale oil reservoir at different pore radii.

2. The method for determining wettability of shale oil reservoir according to claim 1, characterized in that: The step of obtaining the spontaneous fluid absorption rate and / or fluid saturation of the rock sample, and judging the average wettability of the shale oil reservoir according to the absorption rate and / or fluid saturation, comprises: Obtaining the weight of the rock sample before self-imbibing water, the weight of the rock sample when saturated with water, and the pore volume of the rock sample after self-imbibing water, as well as the weight of the rock sample before self-imbibing oil, the weight of the rock sample when saturated with oil, and the pore volume of the rock sample after self-imbibing oil; Calculate the water saturation of the rock sample in a water-saturated state according to the weight of the rock sample before self-absorption of water, the weight of the rock sample in a water-saturated state, and the pore volume of the rock sample after self-absorption of water; Calculate the oil absorption saturation of the rock sample in the oil-saturated state according to the weight of the rock sample before self-absorption of oil, the weight of the rock sample in the oil-saturated state, and the pore volume of the rock sample after self-absorption of oil; The average wettability of the shale oil reservoir is determined based on the water saturation and oil saturation of the rock sample.

3. The method for determining wettability of shale oil reservoir according to claim 2, characterized in that: The method of judging the average wettability of the shale oil reservoir according to the water saturation and oil saturation of the rock sample includes: The difference between the water saturation and the oil saturation of the rock sample is used as the oil and water saturation index I1 of the shale oil reservoir; When -a<I1≤a, the average wettability of the shale oil reservoir is mixed wettability, where 0.5<a<0; When -1<I1≤-a, the average wettability of the shale oil reservoir is oleophilic; When a<I1≤1, the average wettability of the shale oil reservoir is hydrophilic.

4. The method for determining wettability of shale oil reservoir according to claim 3, characterized in that: When -1<I1≤-a, if -1.0<I1≤-0.5, the average wettability of the shale oil reservoir is oil-wet, and if -0.5<I1≤-a, the average wettability of the shale oil reservoir is mixed wettability and partial oil-wetness; When a<I1≤1, if a<I1≤0.5, the average wettability of the shale oil reservoir is mixed wetting and slightly hydrophilic, and if 0.5<I1≤1.0, the average wettability of the shale oil reservoir is hydrophilic.

5. The method for determining wettability of shale oil reservoir according to claim 1, characterized in that: The step of obtaining the spontaneous fluid absorption rate and / or fluid saturation of the rock sample, and judging the average wettability of the shale oil reservoir according to the absorption rate and / or fluid saturation, comprises: Obtaining the weight of the rock sample before self-absorption of water, the weight of the rock sample when it is saturated with water, and the time required for the rock sample to reach the saturated state with water, as well as the weight of the rock sample before self-absorption of oil, the weight of the rock sample when it is saturated with oil, and the time required for the rock sample to reach the saturated state with oil; Calculate the water absorption rate of the rock sample according to the weight of the rock sample before self-absorption of water, the weight of the rock sample in a water-saturated state, and the time required for the rock sample to reach the water-saturated state; Calculate the oil absorption rate of the rock sample according to the weight of the rock sample before self-absorption of oil, the weight of the rock sample when it is saturated with oil, and the time required for the rock sample to reach the saturated oil state; The average wettability of the shale oil reservoir is determined based on the water absorption rate and oil absorption rate of the rock sample.

6. The method for determining wettability of shale oil reservoir according to claim 5, characterized in that: The method of judging the average wettability of the shale oil reservoir according to the water absorption rate and oil absorption rate of the rock sample includes: The ratio of the water absorption rate to the oil absorption rate of the rock sample is used as the oil absorption and water absorption rate index I2 of the shale oil reservoir; When 0.75<I2≤1.0, the average wettability of the shale oil reservoir is mixed wettability; When I2<0.5, the average wettability of the shale oil reservoir is oil-wet; When 0.5<I2≤0.75, the average wettability of the shale oil reservoir is mixed wettability and partial oil-wetting; When 1.25<I2, the average wettability of the shale oil reservoir is hydrophilic; When 1.0<I2≤1.25, the average wettability of the shale oil reservoir is mixed wettability and partial hydrophilicity.

7. The method for determining wettability of shale oil reservoir according to claim 1, characterized in that: The step of obtaining the spontaneous fluid absorption rate and / or fluid saturation of the rock sample, and judging the average wettability of the shale oil reservoir according to the absorption rate and / or fluid saturation, comprises: Obtain the weight of the rock sample before self-imbibing water, the weight of the rock sample when saturated with water, the pore volume of the rock sample after self-imbibing water, and the time required for the rock sample to reach a saturated state with water, as well as the weight of the rock sample before self-imbibing oil, the weight of the rock sample when saturated with oil, the pore volume of the rock sample after self-imbibing oil, and the time required for the rock sample to reach a saturated state with oil; Calculate the water saturation and water absorption rate of the rock sample in a saturated water state according to the weight of the rock sample before self-absorption of water, the weight of the rock sample in a saturated water state, the pore volume of the rock sample after self-absorption of water, and the time required for the rock sample to reach a saturated water state; Calculate the oil absorption saturation and oil absorption rate of the rock sample in the oil-saturated state according to the weight of the rock sample before self-absorption of oil, the weight of the rock sample in the oil-saturated state, the pore volume of the rock sample after self-absorption of oil, and the time required for the rock sample to reach the oil-saturated state; The average wettability of the shale oil reservoir is determined based on the water saturation, oil saturation, water absorption rate and oil absorption rate of the rock sample.

8. The method for determining wettability of shale oil reservoir according to claim 7, characterized in that: The method of judging the average wettability of the shale oil reservoir according to the water absorption saturation, oil absorption saturation, water absorption rate and oil absorption rate of the rock sample includes: The difference between the water absorption saturation and the oil absorption saturation of the rock sample is used as the oil absorption and water absorption saturation index I1 of the shale oil reservoir, and the ratio of the water absorption rate and the oil absorption rate of the rock sample is used as the oil absorption and water absorption rate index I2 of the shale oil reservoir; The ratio of the oil and water absorption saturation index I1 to the oil and water absorption rate index I2 of the shale oil reservoir is used as the wetting strength index I of the shale oil reservoir. According to the wetting strength index I, the average wettability of the shale oil reservoir is judged.

9. The method for determining wettability of shale oil reservoir according to claim 8, characterized in that: The method of judging the average wettability of the shale oil reservoir according to the wettability intensity index I includes: When -0.15<I≤0.10, the average wettability of the shale oil reservoir is mixed wettability; When I<-1.0, the average wettability of the shale oil reservoir is oil-wet; When -1.0<I≤-0.15, the average wettability of the shale oil reservoir is mixed wettability and partial oil-wetting; When 0.50<I, the average wettability of the shale oil reservoir is hydrophilic; When 0.10<I≤0.50, the average wettability of the shale oil reservoir is mixed wettability and partial hydrophilicity.

10. The method for determining wettability of shale oil reservoir according to any one of claims 2-4 and 7-9, characterized in that: The water saturation of the rock sample in a water-saturated state is calculated by the following formula: S wn =((W wn -W1) / ρw) / V p1 In the formula, S wn W is the water saturation of the rock sample when it is saturated with water; wn is the weight of the rock sample in a water-saturated state; W1 is the weight of the rock sample before self-imbibition of water; ρw is the density of simulated water during self-imbibition of water; Vp1 is the pore volume of the rock sample after self-imbibition of water; The oil absorption saturation of the rock sample in the oil-saturated state is calculated by the following formula: S on =((W on -W2) / ρo) / V p2 In the formula, S on W is the oil absorption saturation of the rock sample when it is saturated with oil; on is the weight of the rock sample when it is saturated with oil; W2 is the weight of the rock sample before self-imbibing oil; ρo is the density of the simulated oil during the self-imbibing process of the rock sample; Vp2 is the pore volume of the rock sample after self-imbibing oil.

11. The method for determining wettability of shale oil reservoir according to any one of claims 5 to 9, characterized in that: The water absorption rate of the rock sample was calculated by the following formula: V wn =((W wn -W1) / ρw) / V) / t wi Where V wn is the water absorption rate of the rock sample; W wn is the weight of the rock sample when it is saturated with water; W1 is the weight of the rock sample before self-absorption of water; ρw is the density of simulated water during self-absorption of water; V is the total volume of the rock sample; t wi The time required for the rock sample to reach a water-saturated state; The oil absorption rate of the rock sample was calculated by the following formula: V on =((W on -W2) / ρo) / V) / t oi Where V on is the oil absorption rate of the rock sample; W on is the weight of the rock sample when it is saturated with oil; W2 is the weight of the rock sample before self-imbibing oil; ρo is the density of the simulated oil during the self-imbibing process of the rock sample; V is the total volume of the rock sample; t oi The time required for a rock sample to become saturated with oil.

12. The method for determining wettability of shale oil reservoir according to claim 1, characterized in that: The method of obtaining a first corresponding relationship between the pore radius and the signal strength when the rock sample is in a dry state, a second corresponding relationship between the pore radius and the signal strength when the rock sample is in a water-saturated state, and a third corresponding relationship between the pore radius and the signal strength when the rock sample is in an oil-saturated state includes: Obtaining nuclear magnetic resonance T2 spectra of the rock sample in a dry state, a water-saturated state, and an oil-saturated state, respectively; wherein the nuclear magnetic resonance T2 spectrum represents the relationship between the T2 value and the signal intensity; According to the relationship between the T2 value and the signal intensity, and the conversion relationship between the T2 value and the pore radius, a first corresponding relationship between the pore radius and the signal intensity when the rock sample is in a dry state, a second corresponding relationship between the pore radius and the signal intensity when the rock sample is in a water-saturated state, and a third corresponding relationship between the pore radius and the signal intensity when the rock sample is in an oil-saturated state are obtained.

13. The method for determining wettability of shale oil reservoir according to claim 1, characterized in that: The comparison of the signal strength increment S1 of the rock sample in the water-saturated state versus the dry state, and the signal strength increment S2 of the rock sample in the oil-saturated state versus the dry state under the same pore radius, to obtain the hydrophilicity and oleophilicity of the shale oil reservoir under the pore radius includes: When the signal intensity increment S1 of the rock sample in the water-saturated state compared with the dry state is greater than the signal intensity increment S2 of the rock sample in the oil-saturated state compared with the dry state, the water-wetting ability of the shale oil reservoir at this pore radius is greater than the oil-wetting ability; When the signal intensity increment S1 of the rock sample in the water-saturated state compared with the dry state is not greater than the signal intensity increment S2 of the rock sample in the oil-saturated state compared with the dry state, the oil-wetting ability of the shale oil reservoir at this pore radius is greater than its water-wetting ability.

14. The method for determining wettability of shale oil reservoir according to claim 13, characterized in that: The determination method further comprises: The pore radius where the hydrophilicity is greater than the lipophilicity and the pore radius where the lipophilicity is greater than the hydrophilicity are divided into a first interval range and a second interval range respectively; The left boundary of the first interval range and / or the second interval range is used as the critical pore radius during the current oil-water reversal, and the right boundary is used as the critical pore radius during the next oil-water reversal.

15. A method for optimizing the amount of liquid injected into the ground and the time of well plugging in shale oil development, characterized in that: The adjustment method comprises: Determine the wettability of a shale oil reservoir based on the method for determining the wettability of a shale oil reservoir according to any one of claims 1 to 14; According to the wettability of the shale oil reservoir, the amount of liquid injected into the ground and the time of well plugging in the well are optimized in the development of shale oil.

16. A device for determining wettability of a shale oil reservoir, characterized in that: The shale oil reservoir wettability judgment device is used to execute the shale oil reservoir wettability judgment method described in any one of claims 1-14.

17. A machine-readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the shale oil reservoir wettability determination method described in any one of claims 1 to 14 of the present application or the method for optimizing the amount of liquid injected into the ground and the wellbore time in shale oil development described in claim 15.

18. A processor, characterized in that: Used to run a program, wherein the program, when run, is used to execute the shale oil reservoir wettability judgment method described in any one of claims 1 to 14 or the method for optimizing the amount of liquid injected into the ground and the well blocking time in shale oil development described in claim 15.

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