Method for determining gathering efficiency of substrate source helium in natural gas reservoir

Abstract

The invention provides a method for determining the gathering efficiency of substrate source helium in a natural gas reservoir. The method comprises the following steps: determining the total helium release amount of the base rock based on the helium release efficiency and the total helium generation amount of the base rock; obtaining the contribution duration of the hydrocarbon source rock to helium in the natural gas reservoir, wherein the contribution duration of the hydrocarbon source rock to helium in the natural gas reservoir is the duration from the beginning of hydrocarbon gas generation of the hydrocarbon source rock to now; based on the density, the porosity, the total volume and the helium release efficiency of the hydrocarbon source rocks, determining the contribution amount of the hydrocarbon source rocks to the helium in the natural gas reservoir by combining the contribution duration of the hydrocarbon source rocks to the helium in the natural gas reservoir; determining the contribution of the base rock to the helium in the natural gas reservoir based on the total amount of the helium in the natural gas reservoir and the contribution of the hydrocarbon source rock to the helium in the natural gas reservoir; and determining the gathering efficiency of helium generated by the basement rock in the natural gas reservoir based on the contribution amount of the basement rock to helium in the natural gas reservoir in combination with the total helium release amount of the basement rock, namely the gathering efficiency of the basement source helium in the natural gas reservoir.

Description

Technical Field

[0001] The present invention specifically relates to a method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir. Background Art

[0002] Helium is an important resource with significant scarcity and irreplaceability. Conducting helium resource exploration and research is an important task to solve the shortage of helium resources. At present, the only way to produce helium industrially is to extract helium from helium-rich natural gas reservoirs. The study of the source of helium in helium-rich natural gas reservoirs provides a theoretical basis and important support for the evaluation of helium resources in the future. In addition, it can provide key evidence and understanding for the prediction of key helium resource blocks. At present, the helium in most of the reported helium-rich natural gas reservoirs comes from the decay of radioactive elements in crustal rocks, and the ancient basin basement rocks are the key conditions for the formation of helium-rich gas reservoirs. Therefore, it is an urgent problem to determine the contribution of various helium source rocks to helium-rich gas reservoirs and further determine the accumulation efficiency of basement-derived helium in natural gas reservoirs. Summary of the invention

[0003] The object of the present invention is to provide a technical solution capable of determining the accumulation efficiency of helium released from the basement rocks of a basin in a natural gas reservoir.

[0004] In order to achieve the above object, the present invention provides a method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, wherein the method comprises:

[0005] Based on the helium release efficiency and total helium generation of the basement rocks in the target natural gas reservoir area, determine the total helium release of the basement rocks in the target natural gas reservoir area;

[0006] Obtain the duration of the contribution of the source rock to the helium in the natural gas reservoir in the target natural gas reservoir area; wherein, the duration of the contribution of the source rock to the helium in the natural gas reservoir is the duration from the beginning of hydrocarbon gas generation in the source rock to the present;

[0007] Based on the density, porosity, total volume and helium release efficiency of the source rocks in the target natural gas reservoir area, combined with the contribution time of the source rocks in the target natural gas reservoir area to the helium in the natural gas reservoir, the contribution of the source rocks in the target natural gas reservoir area to the helium in the natural gas reservoir is determined;

[0008] Based on the total amount of helium in the target natural gas reservoir area and the contribution of the source rock in the helium source rock in the target natural gas reservoir area to the helium in the natural gas reservoir, the contribution of the basement rock in the helium source rock in the target natural gas reservoir area to the helium in the natural gas reservoir is determined;

[0009] Based on the contribution of basement rocks in the target natural gas reservoir area to helium in the natural gas reservoir and the total amount of helium released from basement rocks in the target natural gas reservoir area, the accumulation efficiency of helium generated from basement rocks in the target natural gas reservoir area is determined as the accumulation efficiency of basement-derived helium in the natural gas reservoir.

[0010] According to a preferred embodiment of the method for determining the accumulation efficiency of basement-derived helium in a natural gas reservoir, the total amount of helium released from basement rocks in the helium source rock of the target natural gas reservoir area is determined by the following formula:

[0011] E 基 =D 基 ×C 基

[0012] Where D 基 is the total helium generation of basement rocks, in cm 3 ; C 基 is the helium release efficiency of basement rock, unit: %; E 基 is the total amount of helium released from the basement rock, in cm 3 .

[0013] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises a helium release efficiency determination step, which comprises:

[0014] Based on the residual helium amount and helium generation amount per unit mass of basement rock in the helium source rock of the target natural gas reservoir area, the helium release efficiency of the basement rock in the helium source rock of the target natural gas reservoir area is determined; Based on the residual helium amount and helium generation amount per unit mass of source rock in the helium source rock of the target natural gas reservoir area, the helium release efficiency of the source rock in the helium source rock of the target natural gas reservoir area is determined;

[0015] Furthermore, the helium release efficiency is determined by the following formula:

[0016] C i =[1-(A i ÷B i )]×100%

[0017] In the formula, C i is the helium release efficiency of type i rock, unit: %; A i is the residual helium content per unit mass of rock type i, in cm 3 / g rock; B i is the helium generation per unit mass of rock type i, in cm 3 / g rock; i type rock is basement rock and source rock.

[0018] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises a step of obtaining the amount of residual helium, which comprises:

[0019] Obtain the residual helium amount per unit mass of basement rock and the residual helium amount per unit mass of source rock in the helium source rock of the target natural gas reservoir area;

[0020] The residual helium amount per unit mass of basement rock in the helium source rock of the target natural gas reservoir area is preferably determined by the following method: obtaining a basement rock sample in the helium source rock of the target natural gas reservoir area, crushing the basement rock sample, placing the crushed basement rock sample in a ball mill to perform a helium source rock release experiment, and using the ball mill in conjunction with a quadrupole mass spectrometer to determine the helium release amount per unit mass of the basement rock sample, which is the residual helium amount per unit mass of basement rock in the helium source rock of the target natural gas reservoir area;

[0021] Among them, the residual helium amount per unit mass of source rock in the helium source rock of the target natural gas reservoir area is preferably determined by the following method: obtaining a source rock sample in the helium source rock of the target natural gas reservoir area, crushing the source rock sample, placing the crushed source rock sample in a ball mill for a helium source rock release experiment, and using the ball mill in conjunction with a quadrupole mass spectrometer to determine the helium release amount per unit mass of the source rock sample, which is the residual helium amount per unit mass of source rock in the helium source rock of the target natural gas reservoir area.

[0022] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises a step of determining the amount of helium generated per unit mass of rock, which step comprises:

[0023] Based on the formation age of the basement rocks in the target natural gas reservoir area and the unit mass of the basement rocks 4 The annual production of He is used to determine the helium production per unit mass of basement rock in the target natural gas reservoir area; based on the formation age of the source rock in the target natural gas reservoir area and the helium production per unit mass of the source rock, the 4 He annual production, to determine the helium production per unit mass of source rock in the target natural gas reservoir area;

[0024] Furthermore, the helium generation per unit mass of basement rock and the helium generation per unit mass of source rock are determined by the following formulas:

[0025] B i =t i ×α i

[0026] In the formula, B iis the helium generation per unit mass of rock type i, in cm 3 / g rock; t i is the formation age of type i rock, in years; α i is the unit mass of type i rock 4 He annual output, unit: cm 3 / g rock / year.

[0027] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises a formation age acquisition step, which comprises:

[0028] Obtain the formation age of basement rocks in the helium source rocks and the formation age of hydrocarbon source rocks in the helium source rocks in the target natural gas reservoir area;

[0029] The formation age of the basement rocks in the helium source rocks of the target natural gas reservoir area is preferably determined by: obtaining the stratigraphic information of the basement rocks based on well logging data, and then determining the formation age and the corresponding geological time;

[0030] The formation age of the source rock in the helium source rock of the target natural gas reservoir is preferably determined by the following method: based on the well logging data, the stratigraphic information of the source rock is obtained, and then the formation age and the corresponding geological time are determined.

[0031] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises: 4 The annual output determination step includes:

[0032] Based on the uranium and thorium content per unit mass of basement rock in the target natural gas reservoir area, the helium source rock per unit mass of basement rock in the target natural gas reservoir area is determined. 4 He annual production; based on the uranium and thorium content per unit mass of source rock in the target natural gas reservoir area, determine the helium source rock per unit mass of source rock in the target natural gas reservoir area. 4 Annual production;

[0033] Furthermore, the unit mass of basement rock 4 Annual production and unit mass of source rock 4 The annual output is determined by the following formula:

[0034] α i =0.2355×10 -12 ×U i ×[1+0.123×(Th i ÷U i -4)]

[0035] In the formula, α i is the unit mass of type i rock 4 He annual output, unit: cm 3 / g rock / year; U i is the uranium content of type i rock per unit mass, in cm 3 / g rock; Th i is the thorium content per unit mass of rock type i, in cm 3 / g rock.

[0036] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises a step of obtaining uranium content and thorium content, which comprises:

[0037] Obtain the uranium content and thorium content per unit mass of basement rock and the uranium content and thorium content per unit mass of hydrocarbon source rock in the target natural gas reservoir area;

[0038] The uranium content and thorium content per unit mass of the basement rock in the target natural gas reservoir area are preferably determined by detecting the uranium content and thorium content per unit mass of the basement rock in the target natural gas reservoir area by inductively coupled plasma mass spectrometry (ICP-MS).

[0039] Among them, the uranium content and thorium content per unit mass of hydrocarbon source rock in the target natural gas reservoir area is preferably determined by detecting the uranium content and thorium content per unit mass of hydrocarbon source rock in the target natural gas reservoir area by inductively coupled plasma mass spectrometry (ICP-MS).

[0040] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises a total helium production amount determination step, which comprises:

[0041] Based on the formation age, density, porosity, total volume and unit mass of basement rocks in the helium source rocks of the target natural gas reservoir area, the 4 He annual production, to determine the total helium production in the basement rocks in the target natural gas reservoir area;

[0042] Furthermore, the total helium generation of basement rocks is determined by the following formula:

[0043]

[0044] Where D 基 is the total helium generation of basement rocks, in cm 3 ; α 基 Unit mass of basement rock 4 He annual output, unit: cm 3 / g rock / year; ρ 基 is the density of the basement rock, in g / cm 3 ; V is the porosity of the basement rock, unit is dimensionless; 基 is the total volume of basement rock, in cm 3 ;t 基 is the formation age of the basement rock, in years.

[0045] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises a density acquisition step, which comprises:

[0046] Obtain the density of basement rocks and source rocks in the helium source rocks of the target natural gas reservoir area;

[0047] Wherein, the density of the basement rock in the helium source rock of the target natural gas reservoir area is preferably determined by using a rock density tester to test the density of the basement rock sample;

[0048] The density of the source rock in the helium source rock of the target natural gas reservoir is preferably determined by testing the density of the source rock sample using a rock density tester.

[0049] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises a porosity acquisition step, which comprises:

[0050] Obtain the porosity of basement rocks and source rocks in the helium source rocks of the target natural gas reservoir area;

[0051] The porosity of the basement rock in the helium source rock of the target natural gas reservoir is preferably determined by testing the porosity of the basement rock sample using a rock porosity tester;

[0052] The porosity of the source rock in the helium source rock of the target natural gas reservoir is preferably determined by testing the porosity of the source rock sample using a rock porosity tester.

[0053] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises a total volume acquisition step, which comprises:

[0054] Obtain the total volume of basement rocks and the total volume of hydrocarbon source rocks in the helium source rocks of the target natural gas reservoir area;

[0055] Wherein, the total volume of the basement rock in the helium source rock of the target natural gas reservoir area is preferably equal to the product of the trap area of ​​the target natural gas reservoir area and the thickness of the basement rock in the helium source rock of the target natural gas reservoir area;

[0056] The total volume of the hydrocarbon source rock in the helium source rock of the target natural gas reservoir is preferably equal to the product of the trap area of ​​the target natural gas reservoir and the thickness of the hydrocarbon source rock in the helium source rock of the target natural gas reservoir.

[0057] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises the step of determining the total amount of helium in the target natural gas reservoir area, the step comprising:

[0058] Obtain the concentration of helium in natural gas and the reserves of natural gas in the target natural gas reservoir area;

[0059] Determine the total amount of helium in the target natural gas reservoir based on the concentration of helium in the natural gas and the reserves of the natural gas in the target natural gas reservoir;

[0060] The total amount of helium in the target natural gas reservoir is preferably equal to the product of the concentration of helium in the natural gas in the target natural gas reservoir and the reserves of the natural gas.

[0061] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises a contribution rate determination step, which comprises:

[0062] Based on the total amount of helium in the target natural gas reservoir area, the contribution of source rocks in the helium source rocks in the target natural gas reservoir area to the helium in the natural gas reservoir, and the contribution of basement rocks in the helium source rocks in the target natural gas reservoir area to the helium in the natural gas reservoir, the contribution rate of source rocks in the helium source rocks in the target natural gas reservoir area to the helium in the natural gas reservoir and the contribution rate of basement rocks to the helium in the natural gas reservoir are determined respectively;

[0063] Furthermore, the contribution rate of the source rock in the helium source rock of the target natural gas reservoir area to the helium in the natural gas reservoir and the contribution rate of the basement rock to the helium in the natural gas reservoir are respectively determined by the following formulas:

[0064] G i =F i ÷F 藏×100%

[0065] In the formula, F i is the contribution of type i rock to the helium in the natural gas reservoir, in cm 3 ; F 藏 is the total amount of helium in the natural gas reservoir, in cm 3 ; G i is the contribution rate of type i rock to helium in natural gas reservoirs, unit: %.

[0066] According to a preferred embodiment of the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, the method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further includes a hydrocarbon generation time acquisition step, which includes:

[0067] Obtain the time when the source rock in the helium source rock of the target natural gas reservoir begins to generate hydrocarbon gas;

[0068] Furthermore, a basin simulation method is used to determine the time when the source rock begins to generate hydrocarbon gas. First, the stratigraphic stratification data and the heat flow data of the target natural gas reservoir area are input into the basin simulation software, and then the stratigraphic burial history and thermal evolution history of the target natural gas reservoir area are obtained. The stratigraphic burial history and the thermal history are superimposed to obtain the time when the source rock in the helium source rock of the target natural gas reservoir area begins to generate hydrocarbon gas.

[0069] According to a preferred embodiment of the method for determining the accumulation efficiency of basement-derived helium in a natural gas reservoir, the contribution of the source rock in the helium source rock of the target natural gas reservoir area to the helium in the natural gas reservoir is determined by the following formula:

[0070]

[0071] In the formula, F 烃 is the contribution of source rocks to helium in natural gas reservoirs, in cm 3 ; α 烃 Unit mass of source rock 4 He annual output, unit: cm 3 / g rock / year; ρ 烃 is the density of hydrocarbon, in g / cm 3 ; V is the porosity of hydrocarbons, unit is dimensionless; 烃 is the total volume of hydrocarbons, in cm 3 ; C 烃 is the helium release efficiency of source rocks, unit: %; T 烃 It is the duration of source rock contribution to helium in natural gas reservoirs, in years.

[0072] According to a preferred embodiment of the method for determining the accumulation efficiency of basement-derived helium in a natural gas reservoir, the contribution of basement rocks in the helium source rock of the target natural gas reservoir area to the helium in the natural gas reservoir is determined by the following formula:

[0073] F 基 =F 藏 -F 烃

[0074] In the formula, F 烃 is the contribution of source rocks to helium in natural gas reservoirs, in cm 3 ; F 基 is the contribution of basement rock to helium in natural gas reservoirs, in cm 3 ; F 藏 is the total amount of helium in the natural gas reservoir, in cm 3 .

[0075] According to a preferred embodiment of the method for determining the accumulation efficiency of basement-derived helium in a natural gas reservoir, the accumulation efficiency of helium generated from basement rocks in the target natural gas reservoir area in the natural gas reservoir is determined by the following formula:

[0076] H 基 =F 基 ÷E 基 ×100%

[0077] In the formula, E 基 is the total amount of helium released from the basement rock, in cm 3 ; F 基 is the contribution of basement rock to helium in natural gas reservoirs, in cm 3 ;H 基 It is the accumulation efficiency of helium generated from basement rocks in natural gas reservoirs, in %.

[0078] The technical solution provided by the present invention can clarify the helium contribution of basement-type helium source rocks and sedimentary-type helium source rocks (hydrocarbon source rocks) to natural gas reservoirs, and determine the aggregation efficiency of helium released from basin basement rocks in natural gas reservoirs. It not only helps to identify the source of helium in natural gas reservoirs, but also provides basic theoretical support for the study of helium source rocks. DETAILED DESCRIPTION

[0079] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0080] Example 1

[0081] This example is used to determine the aggregation efficiency of basement-derived helium in a natural gas reservoir A.

[0082] This is specifically achieved through the following method for determining the accumulation efficiency of basement-derived helium in a natural gas reservoir:

[0083] 1. Obtain the residual helium content per unit mass of basement rock and the residual helium content per unit mass of source rock in the helium source rock of the target natural gas reservoir area (i.e., natural gas reservoir area A). Specifically:

[0084] Collect basement rock samples and hydrocarbon source rock samples of the target natural gas reservoir area, and take 5 samples of each type; the helium source rock in the target natural gas reservoir area is mainly composed of granite gneiss basement rock and coal-measure hydrocarbon source rock;

[0085] The basement rock samples and source rock samples were crushed and passed through a 20-mesh sieve. 5 g of each crushed basement rock sample was weighed and put into a ball mill for helium source rock release experiment. The ball mill was connected with a quadrupole mass spectrometer to determine the helium release amount per unit mass of basement rock, that is, the residual helium amount per unit mass of basement rock. 基 Indicated in cm 3 / g; 5g of each crushed source rock sample was weighed and put into a ball mill for helium source rock release experiment. The ball mill was connected with a quadrupole mass spectrometer to determine the helium release amount per unit mass of source rock, that is, the residual helium amount per unit mass of source rock. 烃 Indicated in cm 3 / g.

[0086] In this embodiment, the residual helium amount per unit mass of basement rock in the helium source rock of the target natural gas reservoir is A 基 is 4.81×10 -6 cm 3 / g, residual helium content per unit mass of source rock A 烃 0.23×10 -6 cm 3 / g.

[0087] 2. Obtain the uranium content and thorium content per unit mass of basement rock and the uranium content and thorium content per unit mass of hydrocarbon source rock in the target natural gas reservoir area. Specifically:

[0088] Five basement rock samples of helium source rocks in the target natural gas reservoir area were taken, and the uranium content and thorium content in 1g of basement rock samples were determined by inductively coupled plasma mass spectrometry (ICP-MS). The average value of the uranium content determination results was taken as the uranium content per unit mass of basement rock in the target natural gas reservoir area. 基 The average value of the thorium content determination results is taken as the thorium content per unit mass of the basement rock in the target natural gas reservoir area. 基 ;

[0089] Five source rock samples of helium source rocks in the target natural gas reservoir area were taken, and the uranium content and thorium content in 1g of source rock samples were determined by inductively coupled plasma mass spectrometry (ICP-MS). The average value of the uranium content determination results was taken as the uranium content per unit mass of source rock in the target natural gas reservoir area. 烃 The average value of the thorium content determination results is taken as the thorium content per unit mass of the source rock in the target natural gas reservoir area. 烃 .

[0090] In this embodiment, the uranium content per unit mass of basement rock in the target natural gas reservoir area is U 基 =2.35×10 -6 , the thorium content per unit mass of basement rock in the target natural gas reservoir area is Th 储 =9.99×10 -6 ; Uranium content per unit mass of source rock in the target natural gas reservoir area 烃 =5.12×10 -6 , the thorium content per unit mass of source rock in the target natural gas reservoir area is Th 烃 =13.55×10 -6 .

[0091] 3. Based on the uranium and thorium content per unit mass of basement rock in the target natural gas reservoir area, determine the unit mass of basement rock in the target natural gas reservoir area. 4 He annual production; based on the uranium and thorium content per unit mass of source rock in the target natural gas reservoir area, determine the helium source rock per unit mass of source rock in the target natural gas reservoir area. 4 And annual output.

[0092] Among them, the unit mass of basement rock 4 Annual production and unit mass of source rock 4 The annual output is determined by the following formula:

[0093] α i =0.2355×10 -12 ×U i ×[1+0.123×(Th i ÷U i -4)]

[0094] In the formula, α i is the unit mass of type i rock 4 He annual output, unit: cm 3 / g rock / year; U i is the uranium content of type i rock per unit mass, in cm 3 / g rock; Th i is the thorium content per unit mass of rock type i, in cm 3 / g rock.

[0095] In this embodiment, the unit mass of basement rock in the helium source rock of the target natural gas reservoir area is 4 He annual output α 基 =0.2355×10 -12 ×U 基 ×[1+0.123×(Th 基 ÷U 基 -4)]=0.2355×10 -12 ×2.35×10 -6 ×[1+0.123×(9.99×10 -6 ÷(2.35×10 -6 )-4)]=7.42×10 -14 cm 3 / g rock / year. The unit mass of source rock in the target natural gas reservoir area is 4 He annual output α 烃 =0.2355×10 -12 ×U 烃 ×[1+0.123×(Th 烃 ÷U 烃 -4)]=0.2355×10 -12 ×5.12×10 -6 ×[1+0.123×(13.55×10 -6 ÷(5.12×10 -6 )-4)]=2.01×10 -13 cm 3 / g rock / year.

[0096] 4. Obtain the formation age of the basement rocks in the helium source rocks and the formation age of the source rocks in the helium source rocks in the target natural gas reservoir area, including:

[0097] Obtain the logging data of the target natural gas reservoir area, determine the basement rock layer information and source rock layer information based on the logging data of the target natural gas reservoir area, and then determine the basement rock formation age and the corresponding geological time and the source rock formation age and the corresponding geological time, and finally determine the basement rock formation age t 基 and source rock formation age t 烃 .

[0098] In this example, the formation age of the basement rocks in the helium source rocks in the target natural gas reservoir area is t 基 =1600Ma=1600×10 8 The formation age of source rocks in helium source rocks is t 烃 =300Ma=300×10 6 Year.

[0099] 5. Based on the formation age of the basement rocks in the helium source rocks of the target natural gas reservoir area and the unit mass of the basement rocks 4 He annual production, determine the helium production per unit mass of basement rock in the target natural gas reservoir area 基 ; Based on the formation age of source rocks in the target natural gas reservoir area and the unit mass of source rocks 4 He annual production, determine the helium production per unit mass of source rock in the target natural gas reservoir area 烃 ;

[0100] The helium generation per unit mass of basement rock and the helium generation per unit mass of source rock are determined by the following formulas:

[0101] B i =t i ×α i

[0102] In the formula, B i is the helium generation per unit mass of rock type i, in cm 3 / g rock; t i is the formation age of type i rock, in years; α i is the unit mass of type i rock 4 He annual output, unit: cm 3 / g rock / year.

[0103] In this embodiment, the helium generation amount per unit mass of basement rock in the helium source rock of the target natural gas reservoir is B 基 =T 基 ×α 基 =1600×10 6 ×7.42×10 -14 =1.19×10 -4 cm 3 / g, the helium generation per unit mass of source rock in the target natural gas reservoir area B 烃 =T 烃 ×α 烃 =300×10 6 ×2.01×10 -13 =6.03×10 -5 cm 3 / g.

[0104] 6. Based on the residual helium content and helium generation per unit mass of basement rock in the target natural gas reservoir area, determine the helium release efficiency C of the basement rock in the target natural gas reservoir area. 基 Based on the residual helium content and helium generation per unit mass of source rock in the target natural gas reservoir, the helium release efficiency C of the source rock in the target natural gas reservoir is determined. 烃 ;

[0105] Among them, the helium release efficiency is determined by the following formula:

[0106] C i =[1-(A i ÷B i )]×100%

[0107] In the formula, C i is the helium release efficiency of type i rock, unit: %; A i is the residual helium content per unit mass of rock type i, in cm 3 / g rock; B i is the helium generation per unit mass of rock type i, in cm 3 / g rock; i type rock is basement rock and source rock.

[0108] In this embodiment, the helium release efficiency C of the basement rock in the helium source rock of the target natural gas reservoir area is 基 =[1-(A 基 ÷B 基 )]×100%=[1-4.81×10 -6 ÷(1.19×10 -4 )]×100%=95.95%, the helium release efficiency of the source rock in the target natural gas reservoir area C 烃 =[1-(A 烃 ÷B 烃 )]×100%=[1-0.23×10 -6 ÷(6.03×10 -5 )]×100%=99.62%.

[0109] 7. Obtain the density ρ of the basement rock in the helium source rock of the target natural gas reservoir area 基 and the density of the source rock ρ烃 , specifically including:

[0110] The density of the basement rock samples was tested using a rock density tester (MH-600Z electronic density meter) to obtain the density of the basement rock in the helium source rock of the target natural gas reservoir area. 基 ;

[0111] The density of the source rock samples was tested using a rock density tester (MH-600Z electronic density meter) to obtain the density of the source rock in the target natural gas reservoir area. 烃 .

[0112] In this embodiment, 基 =2.6g / cm 3 and ρ 烃 =2.0g / cm 3 .

[0113] 8. Obtain the porosity of the basement rock in the helium source rock of the target natural gas reservoir area and the porosity of the source rock Specifically include:

[0114] The porosity of the basement rock samples was tested using a rock porosity tester to obtain the porosity of the basement rock in the helium source rock of the target natural gas reservoir area.

[0115] The porosity of the source rock samples was tested using a rock porosity tester to obtain the porosity of the source rock in the target natural gas reservoir area.

[0116] In this embodiment,

[0117] 9. Obtain the total volume V of the basement rock in the helium source rock of the target natural gas reservoir area 基 and the total volume of source rock V 烃 , specifically including:

[0118] The total volume of basement rocks in the target natural gas reservoir area is V 基 It is equal to the product of the trap area of ​​the target natural gas reservoir and the thickness of the basement rock in the helium source rock of the target natural gas reservoir;

[0119] Among them, the total volume of hydrocarbon source rocks in the target natural gas reservoir area is V 烃 It is equal to the product of the trap area of ​​the target natural gas reservoir and the thickness of the source rock in the helium source rock of the target natural gas reservoir;

[0120] The enclosed area of ​​the target natural gas reservoir in this example is 572 km 2 , that is 572×10 10 cm 2The thickness of the basement rock in the helium source rock of the target natural gas reservoir is 4000m, the thickness of the hydrocarbon source rock in the helium source rock of the target natural gas reservoir is 50m, and the total volume of the basement rock in the helium source rock of the target natural gas reservoir is V 基 =572×10 10 ×400000=2.29×10 18 cm 3 , the total volume of hydrocarbon source rocks in the target natural gas reservoir area is V 烃 =572×10 10 ×5000=2.86×10 16 cm 3 .

[0121] 10. Based on the formation age, density, porosity, total volume and unit mass of the basement rocks in the helium source rocks of the target natural gas reservoir area, 4 Annual output 基 , determine the total helium generation of basement rocks in the target natural gas reservoir area; based on the formation age, density, porosity, total volume and unit mass of source rocks in the target natural gas reservoir area 4 He annual production, determine the total helium production of source rocks in the target natural gas reservoir area 烃 ;

[0122] In this embodiment, the unit mass of basement rock 4 Annual output Total helium generation in the source rocks of the target natural gas reservoir

[0123] 11. Based on the helium release efficiency and total helium generation of the basement rocks in the target natural gas reservoir area, determine the total helium release amount E of the basement rocks in the target natural gas reservoir area. 基 Based on the helium release efficiency and total helium generation of the source rocks in the target natural gas reservoir area, determine the total helium release amount E of the source rocks in the target natural gas reservoir area. 烃 ;

[0124] In this embodiment, the total amount of helium released from the basement rocks in the helium source rocks in the target natural gas reservoir area is E 基 =C 基 ×D 基 =95.95%×6.99×10 14 =6.71×10 14 cm 3 , the total amount of helium released from the source rocks in the target natural gas reservoir area is E 烃 =C 烃 ×D 烃=99.62%×3.33×10 12 =3.32×10 12 cm 3 .

[0125] 12. Obtain the duration T of the contribution of source rocks in the target natural gas reservoir to the helium in the natural gas reservoir 烃 ; Among them, the contribution time of source rocks to helium in natural gas reservoirs is the time from the beginning of hydrocarbon gas generation in source rocks to the present, which specifically includes:

[0126] The basin simulation method is used to determine the time when the source rock starts to generate hydrocarbon gas. First, the stratigraphic stratification data and the heat flow data of the target natural gas reservoir area are input into the basin simulation software, and then the stratigraphic burial history and thermal evolution history of the target natural gas reservoir area are obtained. The stratigraphic burial history and thermal history are superimposed to obtain the time when the source rock in the helium source rock of the target natural gas reservoir area starts to generate hydrocarbon gas; based on the time when the source rock in the helium source rock of the target natural gas reservoir area starts to generate hydrocarbon gas, the time from the start of hydrocarbon gas generation in the source rock to the present is determined as the contribution time T of the source rock in the helium source rock of the target natural gas reservoir area to the helium in the natural gas reservoir. 烃 .

[0127] In this embodiment, the contribution time T of the source rock in the target natural gas reservoir to the helium in the natural gas reservoir is 烃 =140Ma=140×10 6 Year.

[0128] 13. Based on the density, porosity, total volume and total helium release of the source rock in the target natural gas reservoir area, combined with the contribution time of the source rock in the target natural gas reservoir area to the helium in the natural gas reservoir, determine the contribution of the source rock in the target natural gas reservoir area to the helium in the natural gas reservoir F 烃 ;

[0129] In this embodiment,

[0130] 14. Obtain the concentration of helium in the natural gas and the reserves of natural gas in the target natural gas reservoir area; the product of the concentration of helium in the natural gas in the target natural gas reservoir area and the reserves of natural gas is the total amount of helium in the target natural gas reservoir area F 藏 .

[0131] In this embodiment, the concentration of helium in the natural gas in the target natural gas reservoir is 0.118% (molar fraction), and the total amount of helium in the target natural gas reservoir is F 藏 =2.44×10 14 cm 3 .

[0132] 15. Based on the total amount of helium in the target natural gas reservoir area and the contribution of the source rock in the helium source rock in the target natural gas reservoir area to the helium in the natural gas reservoir, determine the contribution of the basement rock in the helium source rock in the target natural gas reservoir area to the helium in the natural gas reservoir F 基 ;

[0133] In this embodiment, the contribution of the basement rock in the helium source rock of the target natural gas reservoir to the helium in the natural gas reservoir is F 基 =F 藏 -F 烃 =2.44×10 14 -1.55×10 12 =2.4245×10 14 cm 3 .

[0134] 16. Based on the total amount of helium in the target natural gas reservoir area, the contribution of the source rock in the helium source rock in the target natural gas reservoir area to the helium in the natural gas reservoir, and the contribution of the basement rock in the helium source rock in the target natural gas reservoir area to the helium in the natural gas reservoir, the contribution rate G of the source rock in the helium source rock in the target natural gas reservoir area to the helium in the natural gas reservoir is determined respectively. 基 and the contribution rate of basement rock to helium in natural gas reservoirs G 烃 ;

[0135] In this embodiment, G 基 =F 基 ÷F 藏 ×100%=2.4245×10 14 ÷(2.44×10 14 )×100%≈99.37%,G 烃 =F 烃 ÷F 藏 ×100%=1.55×10 12 ÷(2.44×10 14 )×100%≈0.63%.

[0136] 17. Based on the contribution of the basement rocks in the target natural gas reservoir area to the helium in the natural gas reservoir, combined with the total amount of helium released from the basement rocks in the target natural gas reservoir area, the accumulation efficiency of the helium generated by the basement rocks in the target natural gas reservoir area is determined as the accumulation efficiency of the basement-derived helium in the natural gas reservoir, H. 基 .

[0137] In this embodiment, the accumulation efficiency of the basement-derived helium in the natural gas reservoir is H 基 =F 基 ÷E 基 ×100%=2.4245×10 14 ÷(6.71×10 14 )×100%≈36.13%.

[0138] It is clear that the helium in gas reservoir A mainly comes from basement rocks (the helium contribution rate of basement rocks is 99.37%), and the accumulation efficiency of helium from the basement in the gas reservoir is about 36.13%.

[0139] The preferred embodiments of the present invention are described above. Many features and advantages of these embodiments are clear from this detailed description, and therefore the claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. In addition, since many modifications and changes are readily apparent to those skilled in the art, it is not intended to limit the embodiments of the present invention to the precise structure and operation illustrated and described, but all suitable modifications and equivalents that fall within its scope may be included.

Claims

1. A method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir, wherein: The method includes: Based on the helium release efficiency and total helium generation of the basement rocks in the target natural gas reservoir area, determine the total helium release of the basement rocks in the target natural gas reservoir area; Obtain the duration of the contribution of the source rock to the helium in the natural gas reservoir in the target natural gas reservoir area; wherein, the duration of the contribution of the source rock to the helium in the natural gas reservoir is the duration from the beginning of hydrocarbon gas generation in the source rock to the present; Based on the density, porosity, total volume and helium release efficiency of the source rocks in the target natural gas reservoir area, combined with the contribution time of the source rocks in the target natural gas reservoir area to the helium in the natural gas reservoir, the contribution of the source rocks in the target natural gas reservoir area to the helium in the natural gas reservoir is determined; Based on the total amount of helium in the target natural gas reservoir area and the contribution of the source rock in the helium source rock in the target natural gas reservoir area to the helium in the natural gas reservoir, the contribution of the basement rock in the helium source rock in the target natural gas reservoir area to the helium in the natural gas reservoir is determined; Based on the contribution of basement rocks in the target natural gas reservoir area to helium in the natural gas reservoir and the total amount of helium released from basement rocks in the target natural gas reservoir area, the accumulation efficiency of helium generated from basement rocks in the target natural gas reservoir area is determined as the accumulation efficiency of basement-derived helium in the natural gas reservoir.

2. The method according to claim 1, wherein: The method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further includes a helium release efficiency determination step, which includes: Based on the residual helium amount and helium generation amount per unit mass of basement rock in the helium source rock of the target natural gas reservoir area, the helium release efficiency of the basement rock in the helium source rock of the target natural gas reservoir area is determined; Based on the residual helium amount and helium generation amount per unit mass of source rock in the helium source rock of the target natural gas reservoir area, the helium release efficiency of the source rock in the helium source rock of the target natural gas reservoir area is determined; Preferably, the helium release efficiency is determined by the following formula: C i =[1-(A i ÷B i )]×100% In the formula, C i is the helium release efficiency of type i rock, in %; A i is the residual helium per unit mass of rock type i, in cm 3 / g rock; B i is the helium generation per unit mass of rock type i, in cm 3 / g rock; i type rock is basement rock and source rock.

3. The method according to claim 2, wherein: The method for determining the accumulation efficiency of basement-derived helium in a natural gas reservoir further includes a step of determining the amount of helium generated per unit mass of rock, which step includes: Based on the formation age of the basement rocks in the target natural gas reservoir area and the unit mass of the basement rocks 4 The annual production of He is used to determine the helium production per unit mass of basement rock in the target natural gas reservoir area; based on the formation age of the source rock in the target natural gas reservoir area and the helium production per unit mass of the source rock, the 4 He annual production, to determine the helium production per unit mass of source rock in the target natural gas reservoir area; Preferably, the helium generation amount per unit mass of basement rock and the helium generation amount per unit mass of source rock are respectively determined by the following formulas: B i =t i ×α i In the formula, B i is the helium generation per unit mass of rock type i, in cm 3 / g rock; t i is the formation age of type i rock, in years; α i is the unit mass of type i rock 4 He annual output, unit: cm 3 / g rock / year.

4. The method according to claim 3, wherein: The method for determining the accumulation efficiency of basement-derived helium in a natural gas reservoir also includes: 4 The annual output determination step includes: Based on the uranium and thorium content per unit mass of basement rock in the target natural gas reservoir area, the helium source rock per unit mass of basement rock in the target natural gas reservoir area is determined. 4 He annual production; based on the uranium and thorium content per unit mass of source rock in the target natural gas reservoir area, determine the helium source rock per unit mass of source rock in the target natural gas reservoir area. 4 Annual production; Preferably, the unit mass of basement rock 4 Annual production and unit mass of source rock 4 The annual output is determined by the following formula: a i =0.2355×10 -12 ×U i ×[1+0.123×(Th i ÷U i -4)] In the formula, α i is the unit mass of type i rock 4 He annual output, unit: cm 3 / g rock / year; U i is the uranium content of type i rock per unit mass, in cm 3 / g rock; Th i is the thorium content per unit mass of rock type i, in cm 3 / g rock.

5. The method according to claim 1, wherein: The method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further comprises a step of determining the total amount of helium generated, which comprises: Based on the formation age, density, porosity, total volume and unit mass of basement rocks in the helium source rocks of the target natural gas reservoir area, the 4 He annual production, to determine the total helium production in the basement rocks in the target natural gas reservoir area; Preferably, the total helium generation of the basement rock is determined by the following formula: Where D 基 is the total helium generation of basement rocks, in cm 3 ; α 基 Unit mass of basement rock 4 He annual output, unit: cm 3 / g rock / year; ρ 基 is the density of the basement rock, in g / cm 3 ; V is the porosity of the basement rock, unit is dimensionless; 基 is the total volume of the basement rock, in cm 3 ;t 基 is the formation age of the basement rock, in years.

6. The method according to claim 1 or 5, wherein: The method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further includes a total volume acquisition step, which includes: Obtaining the total volume of basement rocks and / or the total volume of hydrocarbon source rocks in the helium source rocks of the target natural gas reservoir area; The total volume of the basement rock in the helium source rock of the target natural gas reservoir area is equal to the product of the trap area of ​​the target natural gas reservoir area and the thickness of the basement rock in the helium source rock of the target natural gas reservoir area; The total volume of the source rock in the helium source rock of the target natural gas reservoir area is equal to the product of the trap area of ​​the target natural gas reservoir area and the thickness of the source rock in the helium source rock of the target natural gas reservoir area.

7. The method according to claim 1, wherein: The method for determining the accumulation efficiency of substrate-derived helium in a natural gas reservoir further includes a contribution rate determination step, which includes: Based on the total amount of helium in the target natural gas reservoir area, the contribution of source rocks in the helium source rocks in the target natural gas reservoir area to the helium in the natural gas reservoir, and the contribution of basement rocks in the helium source rocks in the target natural gas reservoir area to the helium in the natural gas reservoir, the contribution rate of source rocks in the helium source rocks in the target natural gas reservoir area to the helium in the natural gas reservoir and the contribution rate of basement rocks to the helium in the natural gas reservoir are determined respectively; Preferably, the contribution rate of the source rock in the helium source rock of the target natural gas reservoir area to the helium in the natural gas reservoir and the contribution rate of the basement rock to the helium in the natural gas reservoir are respectively determined by the following formulas: G i =F i ÷F 藏 ×100% In the formula, F i is the contribution of type i rock to the helium in the natural gas reservoir, in cm 3 ; F 藏 is the total amount of helium in the natural gas reservoir, in cm 3 ; G i is the contribution rate of type i rock to helium in natural gas reservoirs, unit: %.

8. The method according to claim 1 or 7, wherein: The contribution of source rocks in the target natural gas reservoir area to the helium in the natural gas reservoir is determined by the following formula: In the formula, F 烃 is the contribution of source rocks to helium in natural gas reservoirs, in cm 3 ; α 烃 Unit mass of source rock 4 He annual output, unit: cm 3 / g rock / year; ρ 烃 is the density of hydrocarbon, in g / cm 3 ; V is the porosity of hydrocarbons, unit is dimensionless; 烃 is the total volume of hydrocarbons, in cm 3 ; C 烃 is the helium release efficiency of source rocks, unit: %; T 烃 It is the duration of source rock contribution to helium in natural gas reservoirs, in years.

9. The method according to claim 1, wherein: The contribution of basement rocks in the helium source rock of the target natural gas reservoir area to the helium in the natural gas reservoir is determined by the following formula: F 基 =F 藏 -F 烃 In the formula, F 烃 is the contribution of source rocks to helium in natural gas reservoirs, in cm 3 ; F 基 is the contribution of basement rock to helium in natural gas reservoirs, in cm 3 ; F 藏 is the total amount of helium in the natural gas reservoir, in cm 3 .

10. The method according to claim 1, wherein: The accumulation efficiency of helium generated from basement rocks in the target natural gas reservoir area is determined by the following formula: H 基 =F 基 ÷E 基 ×100% In the formula, E 基 is the total amount of helium released from the basement rock, in cm 3 ; F 基 is the contribution of basement rock to helium in natural gas reservoirs, in cm 3 ; H 基 It is the accumulation efficiency of helium generated from basement rocks in natural gas reservoirs, in %.

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