CN103226089B - Shale gas permeability determination method - Google Patents

Abstract

The invention relates to a shale gas permeability tester, which comprises a gas cylinder, a pressure regulating valve, a pneumatic valve I, a pressure sensor I, a pneumatic valve II, a pressure sensor II and an emptying valve which are sequentially connected through a sealing pipeline, and further comprises a manual valve, a model cup, a temperature sensor, a sample cup and a constant temperature device; the method comprises the steps of drilling a rock core into particles with a certain shape, placing the particles in a constant-temperature closed container, adding a certain pressure, recording the change of the pressure along with time in real time, and calculating the permeability of a shale matrix. The test of the shale permeability is not influenced by the crack permeability any more, and the matrix permeability of the shale can be accurately measured.

Description

A kind of shale gas permeability determination method

Technical field

The present invention relates to experimental facilities and the method field of the conventional physical parameter of oil-gas field development measuring, be specifically related to a kind of shale gas permeability determination method and shale gas permeability detector.

Background technology

Along with the demand of commercial production to the energy, new take over the energy to obtain, the exploitation about Unconventional forage becomes worldwide one large focus.Think the reservoir with impermeability in the past, also can try every possible means now to be exploited.Past, for the permeability method of testing of common reservoir, if conventionally testing when running into the extremely low reservoir of permeability now, can become because flow is little and being difficult to metering,

The method can lose efficacy when running into low permeability reservoir.Prior one side, due to the mechanical properties of rock that shale is special, easily crack is produced under the surface conditions of shale core after from underground to release, by original conventional permeability method of testing or existing pressure pulse damped method, all cannot eliminate the impact on permeability that crack is brought, measuring the penetration value come will be bigger than normal, thus cannot test out shale matrix permeability accurately, and the seepage flow situation of logarithm value simulated formation produces very large interference and error.

Summary of the invention

In order to solve above technical matters, the invention provides a kind of shale gas permeability determination method and shale gas permeability detector, making the test of shale permeability not by the impact of fracture permeability, accurately can record the matrix permeability of shale.

The present invention is achieved through the following technical solutions:

A kind of shale gas permeability detector, comprise successively by sealing gas cylinder, pressure-regulating valve, pneumatic valve I, pneumatic valve II and atmospheric valve that pipeline connects, also comprise and be connected to pressure transducer I, hand valve and model cup between pneumatic valve I and pneumatic valve II by sealing pipeline, the connection of hand valve Controlling model cup, between pneumatic valve II and atmospheric valve, be provided with pressure transducer II, temperature sensor and sample cup that sealing pipeline connects, pneumatic valve II, pressure transducer II, atmospheric valve, temperature sensor and sample cup are placed in thermostat.

A using method for shale gas permeability detector, comprises the steps:

Be T in temperature ₀constant temperature under to be equipped with shale particle sample cup apply be greater than atmospheric pulse p ₀, by pressure transducer II and temperature sensor record pressure, temperature and time, until pressure stabilizes to p gradually in sample cup _eand remain unchanged;

The measured curve of zero dimension pressure-non dimensional time relation is made after the pressure recorded by pressure transducer II, time zero dimension;

Make zero dimension pressure-non dimensional time relational theory curve according to theoretical non dimensional time and theoretical zero dimension pressure, measured curve and theoretical curve are contrasted, the permeability of the good measured curve of matching is exactly the permeability of this sample.

In technique scheme, described measured curve makes by the following method:

By pseudopressure formula calculate pseudopressure, wherein μ is the viscosity of gas, and unit is mPas, Z is deviation factor for gas, the actual measurement gaseous tension of unit to be 1, p be pressure transducer II, and p0 is the initial pressure that pressure transducer II records;

Pass through formula the pseudopressure zero dimension obtained is turned to zero dimension pressure;

Pass through formula the time t zero dimension recorded by pressure transducer II turns to non dimensional time, in formula p is the mean value of the pressure that pressure transducer II records, with in above formula, represent the zero dimension force value in t sample cup, represent the force value in 0 moment sample cup, refer to the force value before not adding pulse in sample cup, t _dbe non dimensional time, K is matrix permeability, the factor of porosity of unit to be mD, φ be surveyed shale particle, and the viscosity of unit to be 1, μ be gas in sample cup, unit is mPas, C _gfor gas volume compressibility coefficient in sample cup, unit is MPa ^-1, L is the mean grain size of shale particle, and unit is cm, and footmark D represents nondimensional number;

According to zero dimension pressure with non dimensional time t _ddraw measured curve.

In technique scheme, described theoretical curve makes by the following method:

Pass through $\mathrm{\μ}\left(t_D\right)=-\frac{12}{R^3}\left[\underset{k=1}{\overset{\∞}{\mathrm{\Σ}}}\frac{{\mathrm{\α}}_k\sin {\mathrm{\α}}_k(\sin {\mathrm{\α}}_k-{\mathrm{\α}}_k\cos {\mathrm{\α}}_k)}{2{\mathrm{\α}}_k-\sin \left(2{\mathrm{\α}}_k\right)}\right]{\∫}_0^{t_D}\mathrm{\μ}\left(\mathrm{\τ}\right)e^{-\frac{{{\mathrm{\α}}_k}^2}{R^2}(t_D-\mathrm{\τ})}\mathrm{d\τ}$ Calculate the zero dimension pressure μ (t of shale granule boundary _d), α in formula _k=tan α _k, k=1,2,3 ... ∞, can try to achieve α by dichotomy _kvalue, turn to discrete for above-mentioned equation

${\mathrm{\μ}}_j=-\frac{12}{R^3}\underset{k=1}{\overset{\∞}{\mathrm{\Σ}}}\frac{{\mathrm{\α}}_k\sin {\mathrm{\α}}_k(\sin {\mathrm{\α}}_k-{\mathrm{\α}}_k\cos {\mathrm{\α}}_k)}{2{\mathrm{\α}}_k-\sin \left(2{\mathrm{\α}}_k\right)}\frac{T}{N}\underset{i=1}{\overset{j}{\mathrm{\Σ}}}{\mathrm{\μ}}_i{e}^{-\frac{{{\mathrm{\α}}_k}^2}{R^2}(t_j-t_i)},$ J=1,2,3 ... N, i=1,2 ... j, realizes the step (compiling see Li Qingyang, Wang Nengchao, the easily cardinal principles of righteousness, publishing house of the Central China University of Science and Technology, numerical analysis (the 4th edition) 79-80 page) of numerical integration, in formula, R is zero dimension grain diameter, and during calculating, R gets 1, α and meets α _k=tan α _kthe different value of k, k arrives in calculating formula value level off to till zero, T refers to and substitutes into formula by from applying the time of pulse to pressure complete equipilibrium in t value after the time value that obtains, N needs the number of T decile according to computational accuracy, obtains the system of linear equations be made up of N number of N unit linear function group, tries to achieve μ by existing algorithm _j(specific algorithm is compiled see Li Qingyang, Wang Nengchao, the easily cardinal principles of righteousness, publishing house of the Central China University of Science and Technology, numerical analysis (the 4th edition) 163-169 page);

Pass through formula ask the theoretical zero dimension pressure μ in sample cup _dt (), will discretize obtains realize the step (compiling see Li Qingyang, Wang Nengchao, the easily cardinal principles of righteousness, publishing house of the Central China University of Science and Technology, numerical analysis (the 4th edition) 79-80 page) of numerical integration, substitute into the described μ tried to achieve by existing algorithm _jvalue to the μ of discretize formula _iin, i=0 in formula, 1,2 ... j, j=1,2,3 ... N, m is the gross mass of particle, and ρ is the density value of rock particles, and unit is g/cm ³, v ₂refer to that sample cup volume adds the volume of the pipeline being placed in thermostat;

According to theoretical zero dimension pressure μ _djwith theoretical non dimensional time draw theoretical curve, wherein j=1,2,3 ... N.

In technique scheme, described sample cup volume adds the volume v of the pipeline being placed in thermostat ₂measuring process as follows:

1. open pneumatic valve I, close pneumatic valve II, by pressure-regulating valve, pressure is adjusted to p ₁, opening hand valve connection known volume is V _modelmodel cup, pressure transducer I record now pressure p ' ₁, calculate the volume of part pipeline between pneumatic valve I, hand valve and pneumatic valve II wherein p _afor the atmospheric pressure under room temperature;

2. closing presure variable valve, opens pneumatic valve I, pneumatic valve II, atmospheric valve and hand valve, by gas emptying;

3. close atmospheric valve, hand valve, by pressure-regulating valve, pressure is adjusted to p ₂and record, open hand valve and be communicated with model cup, pressure transducer I record pressure p now ' ₂, calculate the cumulative volume of pipeline between pneumatic valve I, atmospheric valve and sample cup _v1+ _v2, wherein substitute into step 1. middle V ₁value calculates V ₂.

In technique scheme, described shale even particle size.

In technique scheme, described shale particle is spheroid.

Analyzer of the present invention and assay method can the matrix permeabilities of Accurate Determining shale, solve the problem that the matrix permeability measurement of crack to shale impacts.

Accompanying drawing explanation

The shale gas permeability detector schematic diagram that Fig. 1 provides for the embodiment of the present invention;

The sample cup schematic diagram that Fig. 2 provides for the embodiment of the present invention.

The measured curve that Fig. 3 provides for the embodiment of the present invention and theoretical curve matching comparison diagram.

Embodiment

Below in conjunction with drawings and Examples, technical scheme of the present invention is described in detail.

See Fig. 1, for a kind of shale gas permeability detector that the embodiment of the present invention provides, comprise successively by the gas cylinder 1 of sealing pipeline connection, pressure-regulating valve 2, pneumatic valve I 3, pneumatic valve II 5 and atmospheric valve 7, also comprise and be connected to pressure transducer I 4 between pneumatic valve I 3 and pneumatic valve II 5 by sealing pipeline, hand valve 8 and model cup 9, the connection of hand valve 8 Controlling model cup 9, the pressure transducer II 6 that sealing pipeline connects is provided with between pneumatic valve II 5 and atmospheric valve 7, temperature sensor 10 and sample cup 11, pneumatic valve II 5, pressure transducer II 6, atmospheric valve 7, temperature sensor 10 and sample cup 11 are placed in thermostat 12.

The method of this shale gas permeability detector is used to comprise the steps:

Be apply to be greater than atmospheric pulse p to the sample cup 11 that shale particle is housed under the constant temperature of 10-30 DEG C in temperature ₀, by pressure transducer and temperature sensor record pressure, temperature and time, until pressure stabilizes to p gradually in sample cup _eand remain unchanged;

According to the pressure of pressure transducer record, time intercropping pressure vs time measured curve;

Described measured curve makes by the following method:

By pseudopressure formula calculating pressure, wherein μ is the viscosity of gas, and Z is deviation factor for gas, and p is the actual measurement gaseous tension of pressure transducer II 6, p ₀for the initial pressure that pressure transducer II 6 records; During calculating, Z value gets 1;

Pass through formula the pressure zero dimension obtained is turned to zero dimension pressure;

Pass through formula the time t zero dimension that pressure transducer II 6 records is turned to non dimensional time, in formula p is the mean value of the pressure that pressure transducer II 6 records, with in above formula, represent the zero dimension force value in t sample cup, represent the force value in 0 moment sample cup 11, refer to the force value in sample cup 11 before not adding pulse, t _dbe non dimensional time, K is matrix permeability, the factor of porosity of unit to be mD, φ be surveyed shale particle, and the viscosity of unit to be 1, μ be gas in sample cup 11, unit is mPas, C _gfor gas volume compressibility coefficient in sample cup 11, unit is MPa ^-1, L is the mean grain size of shale particle, and unit is cm, and footmark D represents nondimensional number;

K value gets 2.01 × 10 in concrete example ^-05, 2.01 × 10 ^-06, 2.01 × 10 ^-07, 2.01 × 10 ^-08with 2.01 × 10 ^-09, φ value is 0.036, and the viscosity, mu of gas is 0.01824mPas.

According to zero dimension pressure with non dimensional time t _ddraw measured curve, measured curve is see Fig. 3.The data of drafting required for measured curve are see table 1.

Table 1

Described theoretical curve makes by the following method:

Pass through $\mathrm{\μ}\left(t_D\right)=-\frac{12}{R^3}\left[\underset{k=1}{\overset{\∞}{\mathrm{\Σ}}}\frac{{\mathrm{\α}}_k\sin {\mathrm{\α}}_k(\sin {\mathrm{\α}}_k-{\mathrm{\α}}_k\cos {\mathrm{\α}}_k)}{2{\mathrm{\α}}_k-\sin \left(2{\mathrm{\α}}_k\right)}\right]{\∫}_0^{t_D}\mathrm{\μ}\left(\mathrm{\τ}\right)e^{-\frac{{{\mathrm{\α}}_k}^2}{R^2}(t_D-\mathrm{\τ})}\mathrm{d\τ}$ Calculate the zero dimension pressure μ (t of shale granule boundary _d), α in formula _k=tan α _k, k=1,2,3 ... ∞, turns to discrete for above-mentioned equation

${\mathrm{\μ}}_j=-\frac{12}{R^3}\underset{k=1}{\overset{\∞}{\mathrm{\Σ}}}\frac{{\mathrm{\α}}_k\sin {\mathrm{\α}}_k(\sin {\mathrm{\α}}_k-{\mathrm{\α}}_k\cos {\mathrm{\α}}_k)}{2{\mathrm{\α}}_k-\sin \left(2{\mathrm{\α}}_k\right)}\frac{T}{N}\underset{i=1}{\overset{j}{\mathrm{\Σ}}}{\mathrm{\μ}}_i{e}^{-\frac{{{\mathrm{\α}}_k}^2}{R^2}(t_j-t_i)},$ J=1,2,3 ... N, i=1,2 ... j, the step realizing numerical integration is compiled see Li Qingyang, Wang Nengchao, the easily cardinal principles of righteousness, and publishing house of the Central China University of Science and Technology, numerical analysis (the 4th edition) 79-80 page, in formula, R is zero dimension grain diameter, and during calculating, R gets 1, α _kmeet α _k=tan α _kthe different positive of k, in the present embodiment, k gets 20 when calculating from 1, now zero, the T that leveled off to refers to and substitutes into formula by from applying the time of pulse to pressure complete equipilibrium in t value after the time value that obtains, T value is 100, N after calculating in the present embodiment is need the number of T decile according to computational accuracy, obtains the system of linear equations be made up of N number of N unit linear function group, tries to achieve μ by existing algorithm _jvalue;

Pass through formula ask the theoretical zero dimension pressure μ in sample cup _dt (), will discretize obtains the step realizing numerical integration is compiled see Li Qingyang, Wang Nengchao, the easily cardinal principles of righteousness, and publishing house of the Central China University of Science and Technology, numerical analysis (the 4th edition) 79-80 page, substitutes into the described μ tried to achieve by existing algorithm _jvalue to the μ of discretize formula _iin, i=0 in formula, 1,2 ... j, j=1,2,3 ... N, m is the gross mass of particle, and ρ is the density value of rock particles, and unit is g/cm ³, v ₂refer to that sample cup 11 volume adds the volume of the pipeline being placed in thermostat 12; In the present embodiment, β value is 0.01173 after calculating.

According to theoretical zero dimension pressure μ _djwith theoretical non dimensional time draw theoretical curve, wherein j=1,2,3 ... N, the theoretical curve of drafting is see Fig. 3.

The data of drafting required for theoretical curve are in table 2.

Table 2

Measured curve and theoretical curve are contrasted, the permeability of the good measured curve of matching is exactly the permeability of this sample.

The curve of the Diamond spot on Fig. 3 is exactly theoretical curve, and the curve of the point of other shapes is exactly the measured curve that we are obtained by measured data zero dimension, we can see foursquare expression curve and theoretical value more consistent, Here it is so-called " matching must be got well ", just can find out that the permeability value of institute's test sample product is exactly permeability value corresponding to the Curves of foursquare expression, be 2.01 × 10- ⁰⁷mD.

The present invention be directed to the measuring method that shale particle is formulated, grain diameter is little not easily produces crack, so this method avoids the impact of measuring matrix permeability in crack, constant temperature oven keeps the constant temperature of measuring instrument to decrease the impact of temperature variation on pressure accuracy, therefore the present invention can Measurement accuracy matrix permeability, and permeability also provides effective data supporting to numerical simulation for oil-gas reservoir, waterfrac treatment accurately.

It should be noted last that, above embodiment is only in order to illustrate implementer's case of this material and unrestricted, although with reference to preferred embodiment to invention has been detailed description, those of ordinary skill in the art is to be understood that, can modify to technical scheme of the present invention or equivalent replacement, and not departing from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of right of the present invention.

Claims (6)

1. the shale gas permeability determination method of a shale gas permeability detector, wherein, described shale gas permeability detector comprises successively by the gas cylinder (1) of sealing pipeline connection, pressure-regulating valve (2), pneumatic valve I (3), pneumatic valve II (5) and atmospheric valve (7), also comprise and be connected to pressure transducer I (4) between pneumatic valve I (3) and pneumatic valve II (5) by sealing pipeline, hand valve (8) and model cup (9), the connection of hand valve (8) Controlling model cup (9), the pressure transducer II (6) that sealing pipeline connects is provided with between pneumatic valve II (5) and atmospheric valve (7), temperature sensor (10) and sample cup (11), pneumatic valve II (5), pressure transducer II (6), atmospheric valve (7), temperature sensor (10) and sample cup (11) are placed in thermostat (12),

It is characterized in that, the using method of described shale gas permeability detector, comprises the steps:

Be T in temperature ₀constant temperature under to be equipped with shale particle sample cup (11) apply be greater than atmospheric pulse p ₀, by pressure transducer II (6) and temperature sensor (10) record pressure, temperature and time, until pressure stabilizes to p gradually in sample cup _eand remain unchanged;

The measured curve of zero dimension pressure-non dimensional time relation is made after the pressure recorded by pressure transducer II (6), time zero dimension;

Make zero dimension pressure-non dimensional time relational theory curve according to theoretical non dimensional time and theoretical zero dimension pressure, measured curve and theoretical curve are contrasted, the permeability of the good measured curve of matching is exactly the permeability of this shale samples.

2. shale gas permeability determination method as claimed in claim 1, is characterized in that: described measured curve makes by the following method:

By pseudopressure formula calculate pseudopressure, wherein μ is the viscosity of gas, and unit is mPas, Z is deviation factor for gas, the actual measurement gaseous tension of unit to be 1, p be pressure transducer II (6), p _iIfor the initial pressure that pressure transducer II (6) records;

Pass through formula the pseudopressure zero dimension obtained is turned to zero dimension pressure;

Pass through formula the time t zero dimension recorded by pressure transducer II (6) turns to non dimensional time, in formula p ₁for the mean value of the pressure that pressure transducer II (6) records, Z is deviation factor for gas, with in above formula, represent the zero dimension force value in t sample cup, represent the force value in 0 moment sample cup, refer to the force value in sample cup (11) before not adding pulse, t _dbe non dimensional time, K is matrix permeability, the factor of porosity of unit to be mD, φ be surveyed shale particle, and the viscosity of unit to be 1, μ be gas in sample cup (11), unit is mPas, C _gfor gas volume compressibility coefficient in sample cup (11), unit is MPa ^-1, L is the mean grain size of shale particle, and unit is cm, and footmark D represents nondimensional number;

According to zero dimension pressure with non dimensional time t _ddraw measured curve.

3. shale gas permeability determination method as claimed in claim 1, is characterized in that: described theoretical curve makes by the following method:

Pass through $\mathrm{\μ}\left(t_D\right)=-\frac{12}{R^3}\left[\underset{k=1}{\overset{\∞}{\mathrm{\Σ}}}\frac{{\mathrm{\α}}_k\sin {\mathrm{\α}}_k(\sin {\mathrm{\α}}_k-{\mathrm{\α}}_k\cos {\mathrm{\α}}_k)}{{2\mathrm{\α}}_k-\sin \left({2\mathrm{\α}}_k\right)}\right]{\∫}_0^{t_D}\mathrm{\μ}\left(\mathrm{\τ}\right)e^{-\frac{{{\mathrm{\α}}_k}^2}{R^2}(t_D-\mathrm{\τ})}\mathrm{d\τ}$ Calculate the zero dimension pressure μ (t of shale granule boundary _d), α in formula _k=tan α _k, k=1,2,3 ... ∞, turns to discrete for above-mentioned equation

${\mathrm{\μ}}_j=-\frac{12}{R^3}\underset{k=1}{\overset{\∞}{\mathrm{\Σ}}}\frac{{\mathrm{\α}}_k\sin {\mathrm{\α}}_k(\sin {\mathrm{\α}}_k-{\mathrm{\α}}_k\cos {\mathrm{\α}}_k)}{{2\mathrm{\α}}_k-\sin \left({2\mathrm{\α}}_k\right)}\frac{T}{N}\underset{i=1}{\overset{j}{\mathrm{\Σ}}}{\mathrm{\μ}}_i{e}^{-\frac{{{\mathrm{\α}}_k}^2}{R^2}({\mathrm{\τ}}_j-{\mathrm{\τ}}_i)},$ J=1,2,3 ... N, i=1,2 ... j, in formula, R is zero dimension grain diameter, and α meets α _k=tan α _kthe different value of k, k value arrives level off to till zero, T refers to and substitutes into formula by from applying the time of pulse to pressure complete equipilibrium in t value after the time value that obtains, t _dbe non dimensional time, K is matrix permeability, and the viscosity of gas in unit to be mD, μ be sample cup (11), unit is mPas, C _gfor gas volume compressibility coefficient in sample cup (11), unit is MPa ^-1, L is the mean grain size of shale particle, and unit is cm, N is need the number of T decile according to computational accuracy, and obtain the system of linear equations be made up of N number of N unit linear function group, solving equations tries to achieve μ _j;

Pass through formula ask the theoretical zero dimension pressure μ in sample cup _dt (), will discretize obtains substitute into described μ _jvalue to the μ of discretize formula _iin, i=0 in formula, 1,2 ... j, j=1,2,3 ... N, m is the gross mass of particle, and φ is the factor of porosity of surveyed shale particle, and the density value of unit to be 1, ρ be rock particles, unit is g/cm ³, v ₂refer to that sample cup (11) volume adds the volume of the pipeline being placed in thermostat (12);

According to theoretical zero dimension pressure μ _djwith theoretical non dimensional time draw theoretical curve, wherein j=1,2,3 ... N.

4. shale gas permeability determination method as claimed in claim 3, is characterized in that: described sample cup volume adds the volume v of the pipeline being placed in thermostat ₂measuring process as follows:

1. open pneumatic valve I (3), close pneumatic valve II (5), by pressure-regulating valve (2), pressure is adjusted to p ₁, opening hand valve (8) connection known volume is V _modelmodel cup, now pressure p recorded by pressure transducer I (4) ₁', calculate pneumatic valve I (3), the volume of part pipeline between hand valve (8) and pneumatic valve II (5) wherein p _afor the atmospheric pressure under room temperature;

2. closing presure variable valve (2), opens pneumatic valve I (3), pneumatic valve II (5), atmospheric valve (7) and hand valve (8), by gas emptying;

3. close atmospheric valve (7), hand valve (8), by pressure-regulating valve (2), pressure is adjusted to p ₂and record, open hand valve (8) and be communicated with model cup, pressure p now recorded by pressure transducer I (4) ₂', calculate the cumulative volume V of pipeline between pneumatic valve I (3), atmospheric valve (7) and sample cup (11) ₁+ V ₂, wherein substitute into step 1. middle V ₁value calculates V ₂.

5., as the shale gas permeability determination method as described in arbitrary in claim 1-4, it is characterized in that: described shale even particle size.

6. shale gas permeability determination method as claimed in claim 5, is characterized in that: described shale particle is spheroid.