CN106940279A - A kind of method for evaluating shale reservoir preservation absorption tolerance - Google Patents

Abstract

The invention discloses a method for evaluating the amount of gas absorbed in shale reservoirs, which belongs to the technical field of petroleum exploration and development. This method can evaluate the amount of adsorbed shale gas in shale reservoirs at different temperatures and pressures, and can make up for the expensive problems of on-site core analysis and isothermal adsorption experiments. The steps of the method are as follows: 1) Analyze the coverage area of each component in the pores of different pore sizes in the unit mass shale sample by multi-scale argon ion polishing-scanning electron microscope imaging method; 2) Molecular simulation constructs a series of various 3) Molecular simulation calculation of the thickness and density of adsorbed methane on the inner surface of various mineral single pore models under different temperature and pressure conditions; 4) Combining pores with different pore sizes in shale samples The surface area covered by each component and the thickness and density of adsorbed methane on the inner surface of various mineral single-pore models under different temperatures and pressures are used to calculate the amount of adsorbed gas in shale reservoirs under corresponding temperature and pressure conditions.

Description

A method for evaluating the amount of adsorbed gas in shale reservoirs

technical field

The invention relates to a method for evaluating the amount of absorbed gas stored in mud shale reservoirs, and belongs to the technical field of petroleum exploration and development.

Background technique

Shale gas is the accumulation of natural gas mainly in the formation of mudstone and shale with hydrocarbon generation capacity in the state of adsorption and free. Adsorption is one of the important mechanisms of shale gas occurrence. At present, scholars at home and abroad generally believe that the content of adsorbed gas in mud shale accounts for at least 40% of the total gas content of mud shale, and the contribution of adsorbed gas to shale gas resources plays a decisive role. The amount of shale gas adsorbed in shale directly affects the gas content of shale reservoirs, and is an important evaluation parameter for calculating shale gas resources, optimizing favorable areas, and formulating shale gas well development plans. The experimental method for analyzing the amount of gas adsorbed by mud shale is mainly based on the isothermal adsorption experiment of coalbed methane. The isothermal adsorption test refers to the high-pressure isothermal adsorption test method of GB/T 9560-2004 coal to evaluate the ability of shale to adsorb shale gas. The isothermal adsorption experiment is to place a shale sample with a certain particle size (60-80 mesh) in a sealed container, and measure the volume of the test gas such as methane adsorbed when it reaches adsorption equilibrium under the same temperature and different pressure conditions; then according to Langmuir Based on the monomolecular layer adsorption theory, the Langer volume V _L , the Langer pressure _PL and the isothermal adsorption curve that characterize the adsorption characteristics of shale to methane and other test gases are calculated theoretically. In addition to isothermal adsorption experiments, shale gas exploration research also uses core field analysis experiments and logging interpretation to quantitatively evaluate the amount of adsorbed gas in shale reservoirs. However, the analysis costs of the three methods of isothermal adsorption experiment, core analysis experiment and logging interpretation are relatively expensive. The first two methods require coring during drilling, and logging interpretation evaluates the ability of shale to absorb shale gas. The core technology of the method is monopolized by multinational companies such as Schlumberger.

For this reason, the present invention determines the coverage area of each component in the pores of different pore sizes in a unit mass of mud shale sample through the multi-scale argon ion polishing-scanning electron microscope imaging method, and combines molecular simulation to calculate the various components under different temperature and pressure conditions. The thickness and density of adsorbed methane on the inner surface of the single pore model, and the method for evaluating the amount of adsorbed gas in shale reservoirs under different temperature and pressure conditions. The method is easy to operate and low in cost.

Contents of the invention

The purpose of the present invention is to provide a method for evaluating the gas adsorption capacity of mud shale reservoirs, so as to realize the quantitative evaluation of the gas adsorption capacity of mud shale reservoirs under different temperature and pressure conditions. The disadvantages of the prior art and method, which are complex in operation and high in cost, are overcome.

The technical scheme adopted in the present invention is: a method for evaluating the amount of gas absorbed in shale reservoirs, characterized in that:

Step 1: Analyze organic matter, illite, illite, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, Dolomite and pyrite cover the inner surface area of pores with different pore sizes S _{organic matter i} , S _{illitemite i} , S _{montmorillonite i} , S _{chlorite i} , S _{kaolinite i} , S _{quartz i} , S _{feldspar i} , S _{calcite i} , S _{dolomite i} , S _{pyrite i} , the unit of inner surface area of pores covered by various components of different pore diameters is nm ² /g, i=1, 2, 3,..., n, is the pore diameter The number of , a dimensionless parameter;

Step 2: Using molecular simulation technology, construct pore diameters of D _i and respectively composed of organic matter, illite, illite, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, pyrite A single pore model covering the inner surface of the pore, the unit of the pore diameter is nm, i=1, 2, 3, ..., n, is the number of the pore diameter, a dimensionless parameter;

Step 3: Under the conditions of temperature T _j and pressure P _k , molecular simulation calculations are made of organic matter, illite, illite mixed layer, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite The thickness of adsorbed methane in the single pore model of rock and pyrite covering the inner surface of pores with different pore sizes h _{organic matter ijk} , h _illite ijk , h illite _{mixed layer ijk} , h _{montmorillonite ijk} , h _{chlorite ijk} , h _{kaolinite ijk} , h _{quartz ijk} , h _{feldspar ijk} , h _{calcite ijk} , h _{dolomite ijk} , h _{pyrite ijk} and the density of adsorbed methane ρ _{organic matter ijk} , ρ _illite ijk , ρ illite _{mixed layer ijk} , ρ _{montmorillonite ijk} , ρ _{chlorite ijk} , ρ _{kaolinite ijk} , ρ _{quartz ijk} , ρ _{feldspar ijk} , ρ _{calcite ijk} , ρ _{dolomite ijk} , ρ _{pyrite ijk} , temperature in K, pressure The unit of is MPa, the unit of thickness of adsorbed methane is nm, the unit of density of adsorbed methane is g/nm ³ , i=1, 2, 3,..., n, is the number of pore diameter, dimensionless parameter, j=1 .

Step 4: Using the results of Step 1 and Step 3, calculate the adsorbed gas content of the shale sample under the conditions of temperature T _j and pressure P _k according to the following formula

In the formula, Q _ij is the content of adsorbed gas in shale samples under the conditions of temperature T _j and pressure P _k , the unit is m ³ /t, M is the molecular weight of methane 16.04, dimensionless parameters, S _{organic matter i} , S _{illite i} , S illite _i , S _{montmorillonite i} , S _{chlorite i} , S _{kaolinite i} , S _{quartz i} , S _{feldspar i} , S _{calcite i} , S _{dolomite i} , S _pyrite i _{Mineral i} is organic matter, illite, illite, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, The area covered by pyrite, the unit is nm ² /g, h _{organic matter ijk} , h _illite ijk , h illite _{mixed layer ijk} , h _{montmorillonite ijk} , h _{chlorite ijk} , h _{kaolinite ijk} , h _{quartz ijk} , h _{feldspar ijk} , h _{calcite ijk} , h _{dolomite ijk} , and h _{pyrite ijk} are the organic matter, illite, and illite with pore size number i constructed by molecular simulation under the conditions of temperature T _j and pressure P _k respectively. Thickness of adsorbed methane on the inner surface of smectite, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, pyrite single-pore model, unit is nm, ρ _{organic matter ijk} , ρ _{Illite ijk} , ρ illite _{mixed layer ijk} , ρ _{montmorillonite ijk} , ρ _{chlorite ijk} , ρ _{kaolinite ijk} , ρ _{quartz ijk} , ρ _{feldspar ijk} , ρ _{calcite ijk} , ρ _{dolomite ijk} , ρ _{pyrite ijk} are organic matter, _illite , _illite mixed layer, montmorillonite, chlorite, kaolinite, quartz, feldspar, The density of adsorbed methane on the inner surface of calcite, dolomite, and pyrite single-pore models, the unit is g/nm ³ , i=1, 2, 3, ..., n, is the number of the pore diameter, a dimensionless parameter, j =1, 2, 3, ..., m, is the number of temperature, a dimensionless parameter, k=1, 2, 3, ..., x, is the number of pressure, a dimensionless parameter;

Beneficial effects of the present invention: the present invention evaluates the method for the occurrence and adsorption of gas in shale reservoirs, realizes the quantitative evaluation of the occurrence and adsorption of gas in shale reservoirs under different temperature and pressure conditions, and the evaluation method is easy to operate, The cost is low, and the amount of adsorbed gas in shale reservoirs evaluated under different temperature and pressure conditions is an important parameter necessary for shale gas exploration and development.

Description of drawings

Fig. 1 is a flow chart of the present invention.

detailed description:

Embodiment 1: As shown in Figure 1, a method for evaluating the amount of adsorbed gas stored in a mud shale reservoir comprises the following steps;

Step 1: Analyze organic matter, illite, illite, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, Dolomite and pyrite cover the inner surface area of pores with different pore sizes S _{organic matter i} , S _{illitemite i} , S _{montmorillonite i} , S _{chlorite i} , S _{kaolinite i} , S _{quartz i} , S _{feldspar i} , S _{calcite i} , S _{dolomite i} , S _{pyrite i} , the unit of inner surface area of pores covered by various components of different pore diameters is nm ² /g, i=1, 2, 3,..., n, is the pore diameter The numbering, dimensionless parameter, n=8 in this embodiment, the result of analysis is shown in Table 1.

Table 1

Step 2: Using molecular simulation technology, construct pore diameters of D _i and respectively composed of organic matter, illite, illite, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, pyrite A single pore model covering the inner surface of the pore, the unit of the pore diameter is nm, i=1, 2, 3, ..., n, is the number of the pore diameter, a dimensionless parameter;

Step 3: Under the conditions of temperature of 330K and pressure of 20MPa, molecular simulation calculations are made of organic matter, illite, illite mixed layer, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, The thickness of adsorbed methane in the single pore model of pyrite covering the inner surface of pores with different pore sizes h _{organic matter ijk} , h _illite ijk , h illite _{mixed layer ijk} , h _{montmorillonite ijk} , h _{chlorite ijk} , h _{kaolinite ijk} , _{hquartz ijk} , h _{feldspar ijk} , h _{calcite ijk} , h _{dolomite ijk} , h _{pyrite ijk} and the density of adsorbed methane ρorganic _{matter ijk} , _{ρilite ijk} , _{ρilite mixed layer ijk} , ρ _{Montmorillonite ijk} , _{ρchlorite ijk} , _ρkaolinite ijk, ρquartz _ijk , ρfeldspar _ijk , _{ρcalcite ijk} , _{ρdolomite ijk} , _{ρpyrite ijk} , the unit of temperature is K, and the unit of pressure is MPa, the thickness unit of adsorbed methane is nm, the density unit of adsorbed methane is g/nm ³ , i=1, 2, 3, ..., n, is the serial number of the aperture, a dimensionless parameter, in this embodiment n=8, j=1, is the number of temperature, a dimensionless parameter, k=1, is the number of pressure, a dimensionless parameter, calculated by the single pore model of various components covering the inner surface of pores with different pore diameters calculated by molecular simulation The results of the thickness of the adsorbed methane are shown in Table 2, and the density results of the adsorbed methane in the single-pore model with various components covering the inner surface of pores with different pore sizes calculated by molecular simulation are shown in Table 3.

Table 2

table 3

Step 4: Using the results of Step 1 and Step 3, calculate the adsorbed gas content of the shale sample as 2.41m ³ /t under the conditions of temperature 330K and pressure 20MPa according to the following formula.

In the formula, Q _ij is the content of adsorbed gas in shale samples under the conditions of temperature T _j and pressure P _k , the unit is m ³ /t, M is the molecular weight of methane 16.04, dimensionless parameters, S _{organic matter i} , S _{illite i} , S illite _i , S _{montmorillonite i} , S _{chlorite i} , S _{kaolinite i} , S _{quartz i} , S _{feldspar i} , S _{calcite i} , S _{dolomite i} , S _pyrite i _{Mineral i} is organic matter, illite, illite, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, The area covered by pyrite, the unit is nm ² /g, h _{organic matter ijk} , h _illite ijk , h illite _{mixed layer ijk} , h _{montmorillonite ijk} , h _{chlorite ijk} , h _{kaolinite ijk} , h _{quartz ijk} , h _{feldspar ijk} , h _{calcite ijk} , h _{dolomite ijk} , and h _{pyrite ijk} are the organic matter, illite, and illite with pore size number i constructed by molecular simulation under the conditions of temperature T _j and pressure P _k respectively. Thickness of adsorbed methane on the inner surface of smectite, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, pyrite single-pore model, unit is nm, ρ _{organic matter ijk} , ρ _{Illite ijk} , ρ illite _{mixed layer ijk} , ρ _{montmorillonite ijk} , ρ _{chlorite ijk} , ρ _{kaolinite ijk} , ρ _{quartz ijk} , ρ _{feldspar ijk} , ρ _{calcite ijk} , ρ _{dolomite ijk} , ρ _{pyrite ijk} are organic matter, _illite , _illite mixed layer, montmorillonite, chlorite, kaolinite, quartz, feldspar, The density of adsorbed methane on the inner surface of calcite, dolomite, and pyrite single-pore models, in units of g/nm ³ , in this embodiment, i=1, 2, 3,..., n is the number of the pore diameter, Dimensionless parameter, n=8, j=1, is the number of temperature, dimensionless parameter, k=1, is the number of pressure, and is a dimensionless parameter.

Claims (1)

1. a kind of method for evaluating shale reservoir preservation absorption tolerance, it is characterised in that：

Step 1：By organic in multiple dimensioned argon ion polishing-ESEM imaging method unit of analysis quality mud shale sample Matter, illite, illite/smectite mixed layer, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, pyrite covering are not With the internal pore surface area S in aperture_{Organic matter i}、S_{Illite/smectite mixed layer i}、S_{Montmorillonite i}、S_{Chlorite i}、S_{Kaolinite i}、S_{Quartzy i}、S_{Feldspar i}、S_{Calcite i}、S_{Dolomite i}、 S_{Pyrite i}, the unit of the internal pore surface area of various component covering different pore sizes is nm²/ g, i=1,2,3 ..., n, be aperture Numbering, dimensionless group；

Step 2：Using Molecular Simulation Technique, structure aperture is D_iAnd it is de- by organic matter, illite, illite/smectite mixed layer, illiteracy respectively Stone, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, pyrite cover single pore model of internal pore surface, hole The unit in footpath be nm, i=1,2,3 ..., n, be the numbering in aperture, dimensionless group；

Step 3：It is T in temperature_j, pressure be P_kUnder the conditions of, molecular simulation calculate respectively by organic matter, illite, illite/smectite mixed layer, Montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, pyrite cover the internal pore surface of different pore size The thickness h of single hole gap model preservation ADSORPTION STATE methane_{Organic matter ijk}、h_{Illite ijk}、h_{Illite/smectite mixed layer ijk}、h_{Montmorillonite ijk}、h_{Chlorite ijk}、h_{Kaolinite ijk}、 h_{Quartzy ijk}、h_{Feldspar ijk}、h_{Calcite ijk}、h_{Dolomite ijk}、h_{Pyrite ijk}With the density p of ADSORPTION STATE methane_{Organic matter ijk}、ρ_{Illite ijk}、ρ_{Illite/smectite mixed layer ijk}、 ρ_{Montmorillonite ijk}、ρ_{Chlorite ijk}、ρ_{Kaolinite ijk}、ρ_{Quartzy ijk}、ρ_{Feldspar ijk}、ρ_{Calcite ijk}、ρ_{Dolomite ijk}、ρ_{Pyrite ijk}, the unit of temperature is K, the list of pressure Position is MPa, and the thickness unit of ADSORPTION STATE methane is nm, and the density unit of ADSORPTION STATE methane is g/nm³, i=1,2,3 ..., n, be The numbering in aperture, dimensionless group, j=1,2,3 ..., m, be the numbering of temperature, dimensionless group, k=1,2,3 ..., x, for pressure The numbering of power, dimensionless group；

Step 4：Using step 1 and the result of step 3, it is T to calculate according to the following formula in temperature_j, pressure be P_kUnder the conditions of mud page Rock sample product preservation adsorbed gas content

In formula, Q_ijTo be T in temperature_j, pressure be P_kUnder the conditions of mud shale sample preservation adsorbed gas content, unit is m³/ t, M are The molecular weight 16.04 of methane, dimensionless group, S_{Organic matter i}、S_{Illite i}、S_{Illite/smectite mixed layer i}、S_{Montmorillonite i}、S_{Chlorite i}、S_{Kaolinite i}、S_{Quartzy i}、S_{Feldspar i}、 S_{Calcite i}、S_{Dolomite i}、S_{Pyrite i}Respectively in unit mass mud shale sample aperture numbering be i internal pore surface organic matter, Erie The area that stone, illite/smectite mixed layer, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, pyrite are covered, Unit is nm²/ g, h_{Organic matter ijk}、h_{Illite ijk}、h_{Illite/smectite mixed layer ijk}、h_{Montmorillonite ijk}、h_{Chlorite ijk}、h_{Kaolinite ijk}、h_{Quartzy ijk}、h_{Feldspar ijk}、h_{Calcite ijk}、 h_{Dolomite ijk}、h_{Pyrite ijk}Respectively temperature is T_j, pressure be P_kUnder the conditions of aperture numbering constructed by molecular simulation be i organic matter, Illite, illite/smectite mixed layer, montmorillonite, chlorite, kaolinite, quartz, feldspar, calcite, dolomite, pyrite list pore model The thickness of inner surface preservation ADSORPTION STATE methane, unit is nm, ρ_{Organic matter ijk}、ρ_{Illite ijk}、ρ_{Illite/smectite mixed layer ijk}、ρ_{Montmorillonite ijk}、ρ_{Chlorite ijk}、 ρ_{Kaolinite ijk}、ρ_{Quartzy ijk}、ρ_{Feldspar ijk}、ρ_{Calcite ijk}、ρ_{Dolomite ijk}、ρ_{Pyrite ijk}Respectively temperature is T_j, pressure be P_kUnder the conditions of molecular simulation institute Structure aperture numbering be i organic matter, illite, illite/smectite mixed layer, montmorillonite, chlorite, kaolinite, quartz, feldspar, Fang Xie Stone, dolomite, the density of pyrite single hole gap mold inner surfaces preservation ADSORPTION STATE methane, unit is g/nm³, i=1,2,3 ..., N, is the numbering in aperture, dimensionless group, j=1,2,3 ..., m, be the numbering of temperature, dimensionless group, k=1,2,3 ..., x, For the numbering of pressure, dimensionless group.