CN103604916B - A kind of continuous and compact sandstone gas hides measuring method and the system of gas range - Google Patents

Abstract

The invention discloses measuring method and system that a kind of continuous and compact sandstone gas hides gas range, wherein, described method comprises: obtain hydrocarbon source rock for air capacity; Set up the corresponding relation formula that tolerance, gas-water interface place diffusion tolerance, continuous and compact sandstone gas Tibetan trap tolerance, trap spilling tolerance and gas range are overflowed in cap rock place respectively; According to hydrocarbon source rock for air capacity with tolerance is overflowed at cap rock place, gas-water interface place spreads tolerance, continuous and compact sandstone gas hides trap tolerance and the relation of tolerance is overflowed in trap, utilize the accounting equation of corresponding relation formula foundation calculating gas range; Gas range is obtained according to accounting equation iterative computation.

Description

Method and system for measuring gas-containing range of continuous tight sandstone gas reservoir

Technical Field

The invention relates to a technical method in the field of unconventional oil and gas resource evaluation, in particular to a method and a system for measuring the gas-containing range of a continuous tight sandstone gas reservoir, which are established by utilizing the relationship between the hydrocarbon supply amount of a hydrocarbon source rock in a tight reservoir and the natural gas loss amount of the tight reservoir.

Background

The compact sandstone gas has porosity less than 10% and in-situ permeability less than 0.1 × 10^-3μm²Or air permeability < 1.0 × 10^-3μm²The natural gas stored in the sandstone with pore throat radius less than 1 mu m and gas saturation less than 60 percent generally has no natural industrial yield, but the industrial natural gas yield can be obtained after certain economic conditions and technical measures are adopted.

The tight sandstone gas reservoir can be divided into two types according to the characteristics of a reservoir layer, the reserve size and the structure position of the region in which the tight sandstone gas reservoir is located: continuous tight sandstone gas reservoir and trap tight sandstone gas reservoir. The continuous compact sandstone gas reservoir is usually positioned at a low part of a structure, the trap boundary is fuzzy, the reservoir is wide in spread and distribution, the gas-water distribution is inverted or a unified gas-water interface does not exist, the reserve is large, the reserve abundance is relatively low, and the reservoir is integrated or close to the source.

Experts at home and abroad research continuous tight sandstone gas reservoirs, but the methods related to quantitative prediction of the gas-containing range of the continuous tight sandstone gas reservoir are few, and mainly comprise a statistical method, a resource space distribution prediction method and a basin simulation method. In addition, from the reservoir formation mechanism of the continuous tight sandstone gas reservoir, the maximum possible reservoir formation range of the continuous tight sandstone gas reservoir is predicted based on the dynamic balance principle in the reservoir formation process.

Disclosure of Invention

The methods all have certain disadvantages, and regarding the statistical method, a large amount of continuous compact sandstone gas reservoir actual geological data are needed, and the method can only be applied to a mature exploration area; in the basin simulation method, a plurality of required calculation parameters need to be acquired by means of simulation experiments or artificial calibration, so that errors are increased, and the reliability is reduced; regarding the method for predicting based on the dynamic balance principle in the continuous tight sandstone gas reservoir formation process, the maximum range of formation can be predicted, which is the maximum distribution possibility, and the actual gas containing range of the continuous tight sandstone gas reservoir cannot be determined.

The invention establishes a method for measuring the gas-containing range of a continuous tight sandstone gas reservoir based on the substance balance principle by utilizing the size relationship between the hydrocarbon supply amount of a hydrocarbon source rock in a tight reservoir and the natural gas loss amount of the tight reservoir.

In order to achieve the aim, the invention provides a method for measuring the gas content range of a continuous tight sandstone gas reservoir, which is characterized by comprising the following steps: acquiring the gas supply and discharge amount of the hydrocarbon source rock; respectively establishing corresponding relational expressions of the gas overflow amount at the cover layer, the diffusion gas amount at the gas-water interface, the trap gas amount of the continuous compact sandstone gas reservoir, the trap gas overflow amount and the gas containing range; establishing a calculation equation for calculating the gas content range by using the corresponding relational expression according to the relationship between the gas supply and exhaust amount of the hydrocarbon source rock and the gas overflow amount at the cover layer, the diffusion amount at the gas-water interface, the trap gas amount of the continuous tight sandstone gas reservoir and the trap gas overflow amount; and carrying out iterative calculation according to the calculation equation to obtain the gas containing range.

In order to achieve the aim, the invention also provides a system for measuring the gas-containing range of the continuous tight sandstone gas reservoir, which comprises a gas-containing measuring device, a gas-containing measuring device and a gas-containing measuring device, wherein the gas-containing measuring device is connected with the gas-containing measuring device; the hydrocarbon source rock gas supply and exhaust amount acquisition module is used for acquiring the gas supply and exhaust amount of the hydrocarbon source rock; the gas content and gas content range corresponding relation establishing module is used for respectively establishing corresponding relation formulas of the overflow gas content at the cover layer, the diffusion gas content at the gas-water interface, the trap gas content of the continuous type tight sandstone gas reservoir, the trap overflow gas content and the gas content range; the gas-containing range calculation equation establishing module is used for establishing a calculation equation for calculating the gas-containing range by utilizing the corresponding relational expression according to the relationship between the gas supply and exhaust amount of the hydrocarbon source rock and the gas overflow amount at the cover layer, the diffusion amount at the gas-water interface, the trap gas amount of the continuous tight sandstone gas reservoir and the trap gas overflow amount; and the gas range calculation module is used for obtaining the gas range through iterative calculation according to the calculation equation.

According to the method and the system for measuring the gas-containing range of the continuous tight sandstone gas reservoir, disclosed by the invention, the evaluation of the gas-containing range is carried out by utilizing the substance balance principle, the problem that the actual distribution range of the continuous tight sandstone gas reservoir in the oil-gas-containing basin is difficult to predict is solved, a feasible technical method is provided for unconventional oil-gas resource evaluation, the risk of oil-gas exploration is reduced, the success rate of oil-gas drilling is improved, and the method and the system have wide applicability.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

fig. 1 is a conceptual model diagram of a continuous tight sandstone gas reservoir.

Fig. 2 is a flow chart illustrating a gas range measurement according to an embodiment of the present invention.

Fig. 3 is a diagram of a gas range measurement system according to an embodiment of the invention.

Fig. 4 is a schematic view of a gas content range of a continuous tight sandstone gas reservoir in a current library depression east region according to an embodiment of the present invention.

Detailed Description

The technical means adopted by the invention to achieve the predetermined object of the invention are further described below with reference to the drawings and the preferred embodiments of the invention.

Fig. 1 is a conceptual model diagram of a continuous tight sandstone gas reservoir. As shown in fig. 1, the invention provides a method and a system for measuring the gas content range of a continuous tight sandstone gas reservoir based on the principle of material balance. As shown in fig. 1: the natural gas discharged from the hydrocarbon source rock into the continuous tight sandstone air trap has a part of natural gas escaping outwards along the air-water interface and the cover layer in the process of discharging and driving pore water in the tight reservoir.

If the amount of the natural gas supplied and exhausted from the hydrocarbon source rock to the tight reservoir is less than the amount of the natural gas escaped, the continuous tight sandstone gas reservoir cannot be formed, or the gas content range of the formed continuous tight sandstone gas reservoir gradually shrinks until the gas content range disappears, so that the continuous tight sandstone gas reservoir is damaged.

When the amount of natural gas supplied and exhausted from the hydrocarbon source rock to the tight reservoir is larger than the amount of natural gas exhausted, the natural gas in the reservoir continuously drives and exhausts pore water in the reservoir, so that the continuous tight sandstone gas reservoir is formed or the gas containing range of the continuous tight sandstone gas reservoir is continuously expanded, but the maximum boundary of the continuous tight sandstone gas reservoir is not beyond the boundary capable of forming the trap of the continuous tight sandstone gas reservoir.

Based on the principle, a conceptual model for determining the gas containing range of the continuous tight sandstone gas reservoir is established (as shown in figure 1). Wherein, the hydrocarbon source rock supplies and discharges the gas flow Q_eA part of the gas diffuses upward from the cover layer (the gas amount overflows from the cover layer)) And part of the gas and water upwards diffuses from the gas and water contact surface (the diffusion gas quantity at the gas and water interface)) The rest part exists in the form of a continuous compact sandstone gas reservoir (the trap gas volume Q of the continuous compact sandstone gas reservoir)_r) If the natural gas supplied and exhausted by the hydrocarbon source rock is dissipated in addition to the diffusion phaseThe trap of the whole continuous compact sandstone gas reservoir is filled, and the redundant natural gas quantity is dissipated as a free phase at the trap overflow point (the trap overflow gas quantity)) And gather in a conventional trap to form a depot. Therefore, the relational expression of the data is:

$Q_e=Q_{\mathrm{ed}}^c+Q_{\mathrm{ed}}^r+Q_r+Q_l^s.$

fig. 2 is a flow chart illustrating a gas range measurement according to an embodiment of the present invention. As shown in fig. 2, the process includes:

step S101, acquiring the gas supply and exhaust quantity Q of the hydrocarbon source rock_e；

Step S102, respectively establishing overflow gas quantity at the cover layerDiffusion gas quantity at gas-water interfaceContinuous tight sandstone gas reservoir trap gas volume Q_rAnd trap the overflow gas volumeA corresponding relation with the gas containing range s;

step S103, supplying and exhausting gas Q according to the hydrocarbon source rock_eThe gas amount overflowing from the cover layerDiffusion gas quantity at gas-water interfaceContinuous tight sandstone gas reservoir trap gas volume Q_rAnd trap the overflow gas volumeEstablishing a calculation equation for calculating the gas containing range s by using the corresponding relational expression;

and step S104, calculating according to a calculation equation to obtain a gas containing range.

In step S101 of this embodiment, the supplied and exhausted gas quantity Q of the source rock is obtained_eThe formula utilized is:

$Q_e={\&Integral;}_{{\mathrm{Ro}}_1}^{{\mathrm{Ro}}_2}{\&Integral;}_0^{S_n}(-5.46+1.26\&times;{10}^{-2}\&times;\mathrm{KTI}+1.764\&times;\mathrm{TOC}+4.8\&times;\mathrm{Ro})\&times;H_n\&times;\frac{{\mathrm{dS}}_n}{\cos a^{\&prime;}}\&times;\mathrm{dRo};---\left(1\right)$

wherein Q is_eSupply of gas, m, to source rock³；

S_nIs the distribution area of the source rock, m²；

KTI is cheese and type index;

TOC is the percentage of organic carbon content of the source rock,%;

Ro、Ro₁、Ro₂is the vitrinite reflectivity, the first vitrinite reflectivity and the second vitrinite reflectivity,%;

H_nis the thickness of the source rock, m;

a' is the dip angle, degree, of the source rock reservoir;

the parameter data can be obtained from the existing data, namely the supply and exhaust gas quantity Q of the hydrocarbon source rock can be obtained through calculation_e(ii) a Or the existing hydrocarbon potential method can be used, and the supply and exhaust gas quantity Q of the hydrocarbon source rock can be directly calculated_e。

In step S102 of this embodiment, the amount of the overflow gas at the cap layerThe corresponding relation with the gas containing range s is as follows:

$Q_{\mathrm{ed}}^c={\&Integral;}_0^{t_1}{\&Integral;}_0^{s}D\&times;\frac{\mathrm{dhc}}{\mathrm{dz}}\&times;{\mathrm{\&phi;}}_1\&times;\frac{\mathrm{ds}}{\cos \mathrm{\&alpha;}}\&times;\mathrm{dt};---\left(2\right)$

wherein,for the gas amount overflowing from the cover layer, m³；

t₁The time until the formation of the continuous type compact sandstone gas reservoir is s;

s is the gas content range, m²；

D is natural gas diffusion coefficient;

is a natural gas concentration gradient, m³/m³/m；

φ₁Porosity,%, of the overburden on the tight sandstone reservoir;

α is the dip angle, degree, of the reservoir;

t is the time of the field history, s.

In step S102, the amount of diffusion gas at the gas-water interfaceThe corresponding relation with the gas containing range s is as follows:

$Q_{\mathrm{ed}}^r=\frac{H\&times;C\&times;{\mathrm{\&phi;}}_2}{\cos \mathrm{\&alpha;}}{\&Integral;}_0^{t_1}D\&times;\frac{\mathrm{dhc}}{\mathrm{dz}}\&times;\mathrm{dt};---\left(3\right)$

when the gas containing range is approximately circular, the circumference C of the gas containing range is obtained by the following formula:

$C=2\sqrt{\mathrm{\&pi;s}};---\left(4\right)$

wherein,the diffusion gas volume m at the gas-water interface³；

H is reservoir thickness, m;

c is the perimeter of the gas containing range, m;

φ₂porosity of the reservoir,%;

α is the dip angle, degree, of the reservoir;

t₁for the formation of continuous compact sandstone gas reservoirTime of (d), s;

d is natural gas diffusion coefficient;

is a natural gas concentration gradient, m³/m³/m；

t is the time of the field history, s;

_sin the gas containing range, m²。

The diffusion gas quantity at the gas-water interface can be obtained by combining the formula (3) with the formula (4)Relation concerning the gas range s.

In step S102 of this embodiment, the gas trap amount Q of the continuous tight sandstone gas reservoir_rThe corresponding relation with the gas containing range is as follows:

$Q_r=\frac{s}{\cos \mathrm{\&alpha;}}\&times;H\&times;{\mathrm{\&phi;}}_2;---\left(5\right)$

wherein Q is_rThe gas trapping volume m is a continuous compact sandstone gas reservoir trap³；

s is the gas content range, m²；

α is the dip angle, degree, of the reservoir;

h is reservoir thickness, m;

φ₂is the porosity of the reservoir,%.

In step S103 of this embodiment, the gas supply amount Q is determined according to the source rock_eThe gas amount overflowing from the cover layerDiffusion gas quantity at gas-water interfaceContinuous tight sandstone gas reservoir trap gas volume Q_rAnd trap the overflow gas volumeIn combination with the above-mentioned corresponding relation equations (1) to (5), a calculation equation of the gas range s is established:

$Q_e=Q_{\mathrm{ed}}^c+Q_{\mathrm{ed}}^r+Q_r+Q_l^s;---\left(6\right)$

wherein Q is_eSupply of gas, m, to source rock³；

For the gas amount overflowing from the cover layer, m³；

The diffusion gas volume m at the gas-water interface³；

Q_rThe gas trapping volume m is a continuous compact sandstone gas reservoir trap³；

To trap the overflow volume, m³。

When the trap of the continuous tight sandstone gas reservoir is not filled, the trap gas overflow amount is 0.

In the present embodiment, according to step S104, when the gas range S is calculated by using the formulas (1) to (6), the gas range S and the amount of the overflow gas at the cap layerDiffusion gas quantity at gas-water interfaceContinuous tight sandstone gas reservoir trap gas volume Q_rTrapped air volume of air overflowFor unknown quantities, including supply or discharge of gas Q from the source rock_eOther parameters may be obtained by known techniques or means.

Referring to fig. 1 and 2, first, assuming that the trap of the continuous tight sandstone reservoir is not filled, i.e. the natural gas in the reservoir is not lost from the trap overflow point, the trap overflow amountIs 0; by using the formulas (1) to (6), a calculation equation about the gas-containing range s can be obtained, and the gas-containing range s can be obtained by an iterative method;

if the gas-containing range S determined on the basis of this assumption is smaller than the gas reservoir trapping range S '(the gas reservoir trapping range S' can be obtained by conventional means, fromReservoir physical boundaries are determined and porosity is generally taken to be less than 10%, which is also the maximum range of continuous tight sandstone gas reservoirs. ) That is, if the assumption is true, the trap gas overflow amount is 0, and the actual gas containing range is s; then, the gas overflow amount of the cover layer can be obtained according to the gas range s by using the formulas (1) to (5)Diffusion gas quantity at gas-water interfaceContinuous tight sandstone gas reservoir trap gas volume Q_r。

If the gas-containing range S determined on the basis of this assumption is greater than the gas reservoir trapping range S', i.e. if the assumption is not true, then the gas reservoir traps an amount of spill gas (traps the amount of spill gas)Greater than 0); the actual gas reservoir is full of the gas reservoir trapping range, and the actual gas containing range is the gas reservoir trapping range S'; then, the gas overflow amount of the cover layer can be obtained according to the gas reservoir trapping range S' by using the formulas (1) to (5)Diffusion gas quantity at gas-water interfaceContinuous tight sandstone gas reservoir trap gas volume Q_r(ii) a Then the trap overflow quantity can be obtained by combining the formula (6)

Fig. 3 is a diagram of a gas range measurement system according to an embodiment of the invention. As shown in fig. 3, the system includes:

a source rock gas supply and discharge amount obtaining module 31 for obtaining the source rock gas supply and discharge amount Q_e(ii) a Wherein a source rock is obtainedAir supply and exhaust quantity Q_eThe formula (1) is as described in the above fig. 2, which is not repeated.

A corresponding relationship establishing module 32 for the gas content and the gas containing range, which is used for respectively establishing the gas content overflowing at the cover layerDiffusion gas quantity at gas-water interfaceContinuous tight sandstone gas reservoir trap gas volume Q_rAnd trap the overflow gas volumeA corresponding relation with the gas containing range s; the corresponding relations are as shown in the formulas (2) to (5) in fig. 2, which is not repeated herein.

A gas range calculation equation establishing module 33 for establishing gas supply and exhaust quantity Q according to the source rock_eThe gas amount overflowing from the cover layerDiffusion gas quantity at gas-water interfaceContinuous tight sandstone gas reservoir trap gas volume Q_rAnd trap the overflow gas volumeEstablishing a calculation equation for calculating the gas containing range s by using the corresponding relational expression; wherein the calculation equation is as shown in the formula (6) in fig. 2, which is not repeated herein.

And the gas range calculation module 34 is used for obtaining the gas range through iterative calculation according to a calculation equation.

According to the method and the system for measuring the gas-containing range of the continuous tight sandstone gas reservoir, disclosed by the invention, the evaluation of the gas-containing range is carried out by utilizing the substance balance principle, the problem that the actual distribution range of the continuous tight sandstone gas reservoir in the oil-gas-containing basin is difficult to predict is solved, a feasible technical method is provided for unconventional oil-gas resource evaluation, the risk of oil-gas exploration is reduced, the success rate of oil-gas drilling is improved, and the method and the system have wide applicability.

Fig. 4 is a schematic view of a gas content range of a continuous tight sandstone gas reservoir in a current library depression east region according to an embodiment of the present invention. The following describes the measurement process of the gas range of the continuous tight sandstone gas reservoir according to the present invention in an embodiment with reference to fig. 4.

The application example area is a eastern region with depression in a Tarim basin library in the west of China, which is a new pre-generation land basin in the Tarim basin and developed on the basis of depression in an ancient passive land edge and a middle passive land, and the oil and gas resources are very rich and are key areas for oil and gas exploration of the Tarim basin. The three-folding series Tarixick coal series hydrocarbon source rock in the region is a main air supply source rock of a Jurassic system target layer in the eastern region depressed by a garage. Meanwhile, the dwarfism develops a compact sandstone reservoir distributed in a large area, which is beneficial to the formation and development of a continuous compact sandstone gas reservoir. As a result of drilling, a continuous tight sandstone gas reservoir exists in an east region depressed by the garage truck, and the continuous tight sandstone gas reservoir has typical geological characteristics of the continuous tight sandstone gas reservoir, but the specific gas containing range of the continuous tight sandstone gas reservoir is not known at present. Therefore, if the gas containing range of the continuous compact sandstone gas reservoir in the region can be determined, the method has important significance for improving the well exploration success rate of the region and reducing the exploration risk.

The determination of the gas containing range of the continuous compact sandstone gas is based on four parameters: supply and exhaust gas quantity Q of hydrocarbon source rock_eThe amount of air dissipated at the cover layerGas quantity at gas-water interfaceAnd continuous tight sandstone gas reservoir trap gas volume Q_r。

In the step S401, the process is executed,supply and exhaust gas quantity Q of hydrocarbon source rock_eAnd (4) determining.

On the basis of recovering hydrocarbon expulsion history and reservoir densification history of the hydrocarbon source rocks, analyzing the matching relationship between the hydrocarbon expulsion history of the hydrocarbon source rocks and the reservoir densification history, forming continuous tight sandstone gas traps after the reservoir is densified, and enabling natural gas exhausted from the hydrocarbon source rocks to be the gas supply and exhaust amount from the hydrocarbon source rocks to the continuous tight sandstone gas traps.

Through the statistical analysis of logging porosity data and relevant geological data of various sandstones in different granularities, different rigid particle contents and different burying modes in the eastern region of the garage vehicle, a porosity prediction mathematical model can be established, and the formula is as follows:

in the formula,to predict model porosity,%; a is the age of the reservoir, Ma; f is the sorting coefficient of the reservoir, and is dimensionless; d' is the average diameter of particles of the reservoir, mm; g is the earth temperature gradient, DEG C/100 m; h' is the logarithm of the reservoir burial depth, m; q is the quartz particle content,%.

On the basis, the influence of other hole increasing and decreasing factors such as cementation, erosion, structural lateral extrusion and fracture is comprehensively considered, the porosity evolution history of the Jurassic reservoir is predicted, and the evolution curve of the porosity of the Jurassic reservoir in the region can be obtained. The medium and low Jurassic system reservoirs are densified, namely the porosity is equal to 10%, the corresponding geological time is about 9-10 Ma, and the reservoir is in the early deposition stage of the Cormura group.

Determination of hydrocarbon discharge history of the Jurassic hydrocarbon source rock in the region: the hydrocarbon discharge history of the Turkish coal series hydrocarbon source rock in the area is researched by using a hydrocarbon generation potential method, and the result shows that the hydrocarbon source rock starts to discharge hydrocarbon at the end of the ancient period (23 Ma), but the exhaust gas quantity is very highSmall, Guidic group end of deposition (12 Ma), cumulative purge 1.28 × 10¹²m³At the final stage of deposition (5 Ma) in the Cormura group, the cumulative gas displacement was 4.26 × 10¹²m³The accumulated displacement of 9.89 × 10 from the end of the deposition of the garage until the present (2-0 Ma)¹²m³。

Then, after the reservoir is densified, namely, the gas displacement Q of the hydrocarbon source rock is 9-10 Ma_eComprises the following steps:

9.89×10¹²m³-1.28×10¹²m³=8.61×10¹²m³。

therefore, the determined gas supply and exhaust amount of the hydrocarbon source rock to the continuous tight sandstone air trap is 8.61 × 10¹²m³。

Step S402, the amount of natural gas escaping from the coverAnd (4) determining.

In this embodiment, the amount of natural gas escaping from the cap layer is obtained by the formula (2)Corresponding relation with the gas range s. Wherein,

the amount of natural gas is dissipated from cover layerThe values of the parameters are as follows:

the natural gas diffusion coefficient D is actually measured data of a mudstone cover and is 7.25 × 10^-7cm²/s；

Porosity phi of overburden layer on tight sandstone reservoir₁2% (porosity of mudstone);

time t from formation of continuous tight sandstone gas reservoir to present₁9-10 Ma, and taking a value of 9.5 Ma;

natural gas concentration gradientAccording to the relation between the water-soluble gas quantity and the temperature and the pressure, the natural gas concentration gradient can be calculated by using the temperature and pressure data of the formation water in the region, wherein the natural gas concentration gradient is mainly the solubility 8.53m of methane in the formation water³At 20 ℃ and 0.1 kPa, the solubility of methane in water is 0.03m³T, the buried depth of the compact reservoir in the research area is about 4800m, and the natural gas concentration gradient is 0.00177083m³/m³/m；

The inclination angle alpha of the reservoir is 45 degrees;

the geographical history time t is 9.5 Ma;

thus, the amount of natural gas escaped from the cover layer of the Jurassic system in the region can be obtainedCalculated as 0.76926 × sm³(ii) a And s is the gas containing range of the continuous compact sandstone gas reservoir.

Step S403, the amount of natural gas escaping from the gas-water interfaceAnd (4) determining.

In this embodiment, the amount of natural gas lost at the gas-water interface is obtained by using the formulas (3) and (4)Corresponding relation with the gas range s. Wherein,

the amount of natural gas is dissipated from gas-water interfaceThe values of the parameters are as follows:

natural gas expanderDispersion coefficient D, time t from formation of continuous tight sandstone gas reservoir to present₁Natural gas concentration gradientThe dip angle α of the reservoir is the same as the value in step S402.

The reservoir thickness H is 500 m;

porosity phi of reservoir₂Is 6 percent;

the geographical history time t is 9.5 Ma;

thus, the amount of natural gas lost at the gas-water interface can be obtainedComprises the following steps:and s is the gas containing range of the continuous compact sandstone gas reservoir.

And step S404, determining the gas range S.

Firstly, assuming that a continuous type tight sandstone gas reservoir trap is not filled with gas, and the amount of natural gas lost as a free phase from a trap overflow point is 0; combining the formulas (5) and (6), the iterative formula of the gas containing range of the continuous tight sandstone gas reservoir is as follows:

$s=\frac{\cos \mathrm{\&alpha;}}{H\&times;{\mathrm{\&phi;}}_2}\&times;(Q_e-Q_{\mathrm{ed}}^c-Q_{\mathrm{ed}}^r);$

wherein the thickness H of the reservoir is 500 m;

porosity phi of reservoir₂Is 6 percent;

the inclination angle alpha of the reservoir is 45 degrees;

Q_ethe natural gas quantity m supplied and discharged from the hydrocarbon source rock to the tight reservoir from the time of the formation of the continuous tight sandstone gas reservoir trap to the present day³；

The amount of natural gas, m, escaping from the cover³；

Is the amount of natural gas, m, lost from the gas-water interface³；

Substituting the calculation results of the steps S401, S402 and S403 into the iterative formula to obtain the iterative formula of the gas containing range S of the Jurassic tight sandstone gas reservoir in the region:

$s=\frac{\sqrt{2}/2}{500m\&times;6\%}\&times;(8.61\&times;{10}^{12}{m}^3-0.76926\&times;s{m}^3-4.085\&times;{10}^3\&times;\sqrt{s}{m}^3);$

in the calculation, the unit of s is m²In the expression of the cover layer dispersion amount and the gas-water interface dispersion amount, the total unit is m³At the moment, the unit problem of s is not considered, and the unit problem is only taken as a number, namely 0.76926 × sm³Is in the total unit of m³If s is considered with the unit m²If so, the amount of the gas dissipated by the covering layer is 0.76926 sm;total unit is m³If s is considered with the unit m²Then the amount of air dissipated from the cover layer is $4.085\&times;{10}^3\&times;\sqrt{s}{m}^2;$

According to the result calculated by the iterative formula, the gas content range s of the Jurassic continuous tight sandstone gas reservoir in the region is 19.94 × 10⁴km²The encirclement system continuous compact sandstone gas reservoir trapping range S' in the region is 6972.44km²It is clear that the original assumption that the continuous tight sandstone gas reservoir traps are not filled is not true. Namely the gas containing range S of the continuous compact sandstone gas reservoir is the range S' of the trap, namely 6972.44km². The following table 1 can be obtained by combining the above calculation methods. Table 1 is a prediction result table of gas content ranges of dwarass continuous tight sandstone gas reservoirs of the depressed east part of the present depot vehicle.

TABLE 1

With reference to table 1, the gas content range of the gas reservoir in the region, the amount of the diffuser in the layer, the amount of the diffusion gas at the gas-water interface, the accumulated gas amount of the continuous tight sandstone gas reservoir and the trap overflow gas amount are obtained by measuring the gas content range of the continuous tight sandstone gas reservoir. In practical application, a feasible technical method is provided for unconventional oil and gas resource evaluation by quantitatively calculating the gas content range of the continuous compact sandstone gas reservoir, and the method has very important practical significance.

According to the method and the system for measuring the gas-containing range of the continuous tight sandstone gas reservoir, disclosed by the invention, the evaluation of the gas-containing range is carried out by utilizing the substance balance principle, the problem that the actual distribution range of the continuous tight sandstone gas reservoir in the oil-gas-containing basin is difficult to predict is solved, a feasible technical method is provided for unconventional oil-gas resource evaluation, the risk of oil-gas exploration is reduced, the success rate of oil-gas drilling is improved, and the method and the system have wide applicability.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (2)

1. A method for measuring the gas containing range of a continuous tight sandstone gas reservoir is characterized by comprising the following steps:

step 1, acquiring the gas supply and discharge amount of a hydrocarbon source rock, wherein the formula is as follows:

$Q_e={\&Integral;}_{{\mathrm{Ro}}_1}^{{\mathrm{Ro}}_2}{\&Integral;}_0^{S_n}(-5.46+1.26\&times;{10}^{-2}\&times;KTI+1.764\&times;TOC+4.8\&times;Ro)\&times;H_n\&times;\frac{{\mathrm{dS}}_n}{{\mathrm{cosa}}^{\&prime;}}\&times;dRo;---\left(1\right)$

wherein Q is_eSupplying gas volume m to the source rock³；

S_nIs the distribution area of the source rock, m²；

KTI is cheese and type index;

TOC is the percentage of organic carbon content of the source rock,%;

Ro、Ro₁、Ro₂is the vitrinite reflectivity, the first vitrinite reflectivity and the second vitrinite reflectivity,%;

H_nis the thickness of the source rock, m;

a' is the dip angle, degree, of the source rock reservoir;

step 2, respectively establishing corresponding relational expressions of the gas overflow amount at the cover layer, the diffusion gas amount at the gas-water interface, the trap gas amount of the continuous type compact sandstone gas reservoir, the trap gas overflow amount and the gas containing range; wherein,

the corresponding relation between the overflow amount of the cover layer and the gas containing range is as follows:

$Q_{ed}^c={\&Integral;}_0^{t_1}{\&Integral;}_0^{s}D\&times;\frac{dhc}{dz}\&times;{\mathrm{\&phi;}}_1\&times;\frac{ds}{cos\mathrm{\&alpha;}}\&times;dt;---\left(2\right)$

wherein,for the amount of gas overflowing at the cover layer, m³；

t₁The time until the formation of the continuous type compact sandstone gas reservoir is s;

s is the gas content range, m²；

D is natural gas diffusion coefficient;

is a natural gas concentration gradient, m³/m³/m；

φ₁Porosity,%, of the overburden on the tight sandstone reservoir;

α is the dip angle, degree, of the reservoir;

t is the time of the field history, s;

the corresponding relation between the diffusion gas amount at the gas-water interface and the gas-containing range is as follows:

$Q_{ed}^r=\frac{H\&times;C\&times;{\mathrm{\&phi;}}_2}{cos\mathrm{\&alpha;}}{\&Integral;}_0^{t_1}D\&times;\frac{dhc}{dz}\&times;dt;---\left(3\right)$

when the gas containing range is approximately circular, the circumference of the gas containing range is obtained by the following formula:

$C=2\sqrt{\mathrm{\&pi;}s};---\left(4\right)$

wherein,the gas diffusion quantity m at the gas-water interface³；

H is reservoir thickness, m;

c is the circumference of the gas containing range, m;

φ₂porosity of the reservoir,%;

α is the dip angle, degree, of the reservoir;

t₁the time until the formation of the continuous type compact sandstone gas reservoir is s;

d is natural gas diffusion coefficient;

is a natural gas concentration gradient, m³/m³/m；

t is the time of the field history, s;

s is the gas content range, m²

The corresponding relation between the gas trapping amount of the continuous tight sandstone gas reservoir and the gas containing range is as follows:

$Q_r=\frac{S}{\cos \mathrm{\&alpha;}}\&times;H\&times;{\mathrm{\&phi;}}_2;---\left(5\right)$

wherein Q is_rFor the closed gas volume, m, of the continuous tight sandstone gas reservoir³；

s is the gas content range, m²；

α is the dip angle, degree, of the reservoir;

h is reservoir thickness, m;

φ₂porosity of the reservoir,%;

step 3, establishing a calculation equation for calculating the gas containing range by using the corresponding relational expression according to the relationship between the gas supply and exhaust amount of the hydrocarbon source rock and the gas overflow amount at the cover layer, the diffusion amount at the gas-water interface, the trapped gas amount of the continuous tight sandstone gas reservoir and the trapped gas overflow amount, wherein the calculation equation is as follows:

$Q_e=Q_{ed}^c+Q_{ed}^r+Q_r+Q_l^s;---\left(6\right)$

wherein Q is_eSupplying gas volume m to the source rock³；

For the amount of gas overflowing at the cover layer, m³；

The gas diffusion quantity m at the gas-water interface³；

Q_rFor the closed gas volume, m, of the continuous tight sandstone gas reservoir³；

For the trapped air volume, m³；

When the trap of the continuous tight sandstone gas reservoir is not filled, the trap overflow gas volume is 0;

step 4, obtaining the gas containing range through iterative calculation according to the calculation equation;

and 5, calculating to obtain the overflow gas quantity at the cover layer, the diffusion gas quantity at the gas-water interface, the trap gas quantity of the continuous compact sandstone gas reservoir and the trap overflow gas quantity according to the gas content range.

2. A measurement system for the gas-containing range of a continuous tight sandstone gas reservoir is characterized by comprising;

the device comprises a hydrocarbon source rock gas supply and discharge quantity acquisition module, a gas supply and discharge quantity acquisition module and a gas discharge quantity acquisition module, wherein the hydrocarbon source rock gas supply and discharge quantity acquisition module is used for acquiring the hydrocarbon source rock gas supply and discharge quantity, and the formula is as follows:

$Q_e={\&Integral;}_{{\mathrm{Ro}}_1}^{{\mathrm{Ro}}_2}{\&Integral;}_0^{S_n}(-5.46+1.26\&times;{10}^{-2}\&times;KTI+1.764\&times;TOC+4.8\&times;Ro)\&times;H_n\&times;\frac{{\mathrm{dS}}_n}{{\mathrm{cosa}}^{\&prime;}}\&times;dRo;---\left(1\right)$

wherein Q is_eSupplying gas volume m to the source rock³；

S_nIs the distribution area of the source rock, m²；

KTI is cheese and type index;

TOC is the percentage of organic carbon content of the source rock,%;

Ro、Ro₁、Ro₂is the vitrinite reflectivity, the first vitrinite reflectivity and the second vitrinite reflectivity,%;

H_nis the thickness of the source rock, m;

a' is the dip angle, degree, of the source rock reservoir;

the gas content and gas content range corresponding relation establishing module is used for respectively establishing corresponding relation formulas of the overflow gas content at the cover layer, the diffusion gas content at the gas-water interface, the trap gas content of the continuous type tight sandstone gas reservoir, the trap overflow gas content and the gas content range; wherein,

the corresponding relation between the overflow amount of the cover layer and the gas containing range is as follows:

$Q_{ed}^c={\&Integral;}_0^{t_1}{\&Integral;}_0^{s}D\&times;\frac{dhc}{dz}\&times;{\mathrm{\&phi;}}_1\&times;\frac{ds}{cos\mathrm{\&alpha;}}\&times;dt;---\left(2\right)$

wherein,for the amount of gas overflowing at the cover layer, m³；

t₁The time until the formation of the continuous type compact sandstone gas reservoir is s;

s is the gas content range, m²；

D is natural gas diffusion coefficient;

is a natural gas concentration gradient, m³/m³/m；

φ₁Porosity,%, of the overburden on the tight sandstone reservoir;

α is the dip angle, degree, of the reservoir;

t is the time of the field history, s;

the corresponding relation between the diffusion gas amount at the gas-water interface and the gas-containing range is as follows:

$Q_{ed}^r=\frac{H\&times;C\&times;{\mathrm{\&phi;}}_2}{cos\mathrm{\&alpha;}}{\&Integral;}_0^{t_1}D\&times;\frac{dhc}{dz}\&times;dt;---\left(3\right)$

when the gas containing range is approximately circular, the circumference of the gas containing range is obtained by the following formula:

$C=2\sqrt{\mathrm{\&pi;}s};---\left(4\right)$

wherein,the gas diffusion quantity m at the gas-water interface³；

H is reservoir thickness, m;

c is the circumference of the gas containing range, m;

φ₂porosity of the reservoir,%;

α is the dip angle, degree, of the reservoir;

t₁is continuously densifiedThe time until formation of a sandstone gas reservoir, s;

d is natural gas diffusion coefficient;

is a natural gas concentration gradient, m³/m³/m；

t is the time of the field history, s;

s is the gas content range, m²

The corresponding relation between the gas trapping amount of the continuous tight sandstone gas reservoir and the gas containing range is as follows:

$Q_r=\frac{s}{\cos \mathrm{\&alpha;}}\&times;H\&times;{\mathrm{\&phi;}}_2;---\left(5\right)$

wherein Q is_rFor the closed gas volume, m, of the continuous tight sandstone gas reservoir³；

s is the gas content range, m²；

α is the dip angle, degree, of the reservoir;

h is reservoir thickness, m;

φ₂porosity of the reservoir,%;

the gas-containing range calculation equation establishing module is used for establishing a calculation equation for calculating the gas-containing range by utilizing the corresponding relational expression according to the relationship between the gas supply and discharge amount of the hydrocarbon source rock and the gas overflow amount at the cover layer, the diffusion amount at the gas-water interface, the trapped gas amount of the continuous tight sandstone gas reservoir and the trapped gas overflow amount, and the calculation equation is as follows:

$Q_e=Q_{ed}^c+Q_{ed}^r+Q_r+Q_l^s;---\left(6\right)$

wherein Q is_eSupplying gas volume m to the source rock³；

For the amount of gas overflowing at the cover layer, m³；

The gas diffusion quantity m at the gas-water interface³；

Q_rFor the closed gas volume, m, of the continuous tight sandstone gas reservoir³；

For the trapped air volume, m³；

When the trap of the continuous tight sandstone gas reservoir is not filled, the trap overflow gas volume is 0;

the gas range calculation module is used for obtaining the gas range through iterative calculation according to the calculation equation;

and the system calculates and obtains the gas overflow amount at the cover layer, the diffusion gas amount at the gas-water interface, the trap gas amount of the continuous compact sandstone gas reservoir and the trap gas overflow amount according to the gas content range.