CN103046924B - Based on acquisition methods and the system of the gas condensate reservoir absolute open flow (AOF) of exponential form - Google Patents

Abstract

The present invention relates to acquisition methods and the system of gas condensate reservoir absolute open flow (AOF) under Different Strata pressure, the method based on the change of gas composition in gas condensate reservoir under Different Strata pressure and the change of gas phase permeability to the acquisition of absolute open flow (AOF); Comprise: exponential deliverability equation under determining Different Strata pressure; According to described exponential deliverability equation, by the first strata pressure and the second strata pressure and corresponding the first Natural Gas Viscosity, the first deviation factor and the first gas phase permeability of the first strata pressure, and corresponding the second Natural Gas Viscosity, the second deviation factor and the second gas phase permeability of the second strata pressure obtains the relation between the first coefficient of exponential deliverability equation and the second coefficient; Gas condensate reservoir absolute open flow (AOF) under Different Strata pressure is obtained according to relation, the first known gas condensate reservoir absolute open flow (AOF) and the first strata pressure between the first coefficient of exponential deliverability equation and the second coefficient and the second strata pressure.

Description

Based on acquisition methods and the system of the gas condensate reservoir absolute open flow (AOF) of exponential form

Technical field

The present invention relates to absolute open flow (AOF) and obtain field, particularly based on acquisition methods and the system of gas condensate reservoir absolute open flow (AOF) under the Different Strata pressure of exponential deliverability equation.

Background technology

Document 1: Chen Yuanqian, oil-gas reservoir engineering practice [M]. Beijing: petroleum industry publishing house, is considered the impact of condensate on gas well deliverability in the method that 2005,142-146 proposes, is expressed as by formula:

$P_e^2-P_{\mathrm{wf}}^2={\mathrm{aq}}_{\mathrm{sc}}+{\mathrm{bq}}_{\mathrm{sc}}^2$

Wherein: $a=\frac{\mathrm{TZ}{\mathrm{\μp}}_{\mathrm{sc}}}{\mathrm{\πkh}{T}_{\mathrm{sc}}{Z}_{\mathrm{sc}}}(\ln \frac{r_e}{r_w}+S_c+S_b);$ $b=\frac{\mathrm{\β}{\mathrm{\ρ}}_{\mathrm{sc}}}{2{\mathrm{\π}}^2{h}^2}\frac{p_{\mathrm{sc}}\mathrm{TZ}}{Z_{\mathrm{sc}}{T}_{\mathrm{sc}}}\frac{1}{r_w{e}^{-s}}{S}_b=(\frac{1}{k_{\mathrm{rgc}}}-1)\ln \frac{r_b}{r_w};$ P _efor strata pressure, MPa, ρ are natural gas relative density; P _wffor flowing bottomhole pressure (FBHP), MPa, μ are Natural Gas Viscosity, mpas; Z is gas deviation factor, T _scfor ground standard temperature, K; T is formation temperature, K; H is effective thickness, m; r _efor gas well Control Radius, m, r _wfor Wellbore of Gas Wells radius, m; K is permeability, 10 ^-3μm ², S _cfor completion skin factor; A and b is binomial coefficient, S _bfor condensate blocks skin factor; r _bfor condensate blocks radius, m; β is non-Darcy seepage coefficient; K _rgcfor gas phase relative permeability under critical condensate saturation ratio.

Document 2: Liao Huawei, Tanghai, Li Ning etc. determine the method [J] of gas well deliverability under Different Strata pressure. natural gas technology, 2008, consider the impact of stratum pressure drop on gas well deliverability in 16 (4): the 30-32 methods proposed, be expressed as by formula:

Exponential form: $\begin{array}{ccc}{q_{\mathrm{AOF}}}_2=\frac{c_2}{c_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1\frac{Z_1{\mathrm{\μ}}_1}{Z_2{\mathrm{\μ}}_2}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1\end{array}$

Binomial: $q_{\mathrm{AOF}2}=\frac{p_{e2}}{p_{e1}}\sqrt{\frac{Z_1}{Z_2}}\·q_{\mathrm{AOF}1}$

In formula: a ₁, b ₁and a ₂, b ₂be respectively the coefficient of binomial potential curve and equation, and the Natural Gas Viscosity of correspondence, deviation factor and gas phase permeability are respectively μ ₁, Z ₁, K ₁and μ ₂, Z ₂, K ₂; P _e1and P _e2be respectively the strata pressure of different mining phase.

Document 3: Zheng Likun, considers the Absolute Open Flow of Gas Wells Study on Forecasting Method [J] of permeability stress sensitive. petroleum geology and engineering .2010,24 (2).

This article considers strata pressure and to decline the reservoir permeability stress sensitive effect caused, and releases Absolute Open Flow of Gas Wells computational methods under Different Strata pressure condition by binomial potential curve and equation.

$\frac{k}{k_0}={\mathrm{be}}^{\mathrm{ap}}$

$P_R^2-P_{\mathrm{wf}}^2={\mathrm{Aq}}_g+{\mathrm{Bq}}_g^2$

$q_{\mathrm{AOF}2}\frac{P_{R2}}{P_{R1}}\sqrt{\frac{Z_1{\mathrm{\μ}}_{g1}{k}_2}{Z_2{\mathrm{\μ}}_{g2}{k}_1}}{q}_{\mathrm{AOF}1}=\frac{P_{R2}}{P_{R1}}\sqrt{\frac{Z_1{\mathrm{\μ}}_{g1}}{Z_2{\mathrm{\μ}}_{g2}}{\mathrm{be}}^{\mathrm{ap}}}{q}_{\mathrm{AOF}1}$

The deficiency of the method is that it is only applicable to common dry gas reservoir, can not be applied to gas condensate reservoir, because the calculating changing permeability in section article is the stress sensitive effect based on rock, and not condensate precipitation has an impact to reservoir gas phase permeability.Although all consider the impact of permeability on result of calculation, under both of these case, the computational methods of permeability are the differences having essence.

From above documents and materials, according to the situation of change of pneumatic jack strata pressure, there is the absolute open flow (AOF) of two kinds of equation determination gas wells at present.The first, if pressure change is little, then thinks that the coefficient of Gas Well Productivity is constant on stream, can directly utilize early stage Gas Well Productivity; Second, consider the impact of strata pressure change on the aspect such as gas viscosity, deviation factor, the gas well absolute open flow (AOF) under Different Strata pressure is derived by Gas Well Productivity, but current derivation is based on the constant precondition of reservoir permeability, and in the viscosity calculating gas and deviation factor process, think that the composition of gas is constant, namely molecular weight does not change.This hypothesis is set up for general dry gas reservoir, but then there will be larger error of calculation for gas condensate reservoir.

Summary of the invention

The object of the invention is for the problems referred to above, propose a kind of acquisition methods and system of the gas condensate reservoir absolute open flow (AOF) based on exponential form, the effect that the acquisition precision realizing gas condensate reservoir gas recovery well absolute open flow (AOF) improves.

For achieving the above object, the invention provides the acquisition methods of gas condensate reservoir absolute open flow (AOF) under Different Strata pressure, the method based on the change of gas composition in gas condensate reservoir under Different Strata pressure and the change of gas phase permeability to the acquisition of absolute open flow (AOF); Comprise:

Exponential deliverability equation under determining Different Strata pressure;

According to described exponential deliverability equation, by the first strata pressure and the second strata pressure and corresponding the first Natural Gas Viscosity, the first deviation factor and the first gas phase permeability of the first strata pressure, and corresponding the second Natural Gas Viscosity, the second deviation factor and the second gas phase permeability of the second strata pressure obtains the relation between the first coefficient of exponential deliverability equation and the second coefficient;

Gas condensate reservoir absolute open flow (AOF) under Different Strata pressure is obtained according to relation, the first known gas condensate reservoir absolute open flow (AOF) and the first strata pressure between the first coefficient of exponential deliverability equation and the second coefficient and the second strata pressure.

Optionally, in an embodiment of the present invention, the acquisition methods of described gas phase permeability comprises:

According to etc. hold depletion experiments and draw condensate content under Different Strata pressure;

The condensate saturation ratio under Different Strata pressure is obtained according to the condensate content under Different Strata pressure and irreducible water saturation;

Do not change the form of oil gas phase percolation curve according to the precipitation of condensate, utilize the condensate saturation ratio under oil gas phase percolation curve and Different Strata pressure to obtain gas phase relative permeability under different gas saturation;

Gas phase permeability is obtained according to gas phase relative permeability and air absolute permeability.

Optionally, in an embodiment of the present invention, the step of the described condensate saturation ratio obtained under Different Strata pressure according to the condensate content under Different Strata pressure and irreducible water saturation comprises:

The condensate saturation ratio under Different Strata pressure is obtained according to following formula;

S _o(p)＝[V _roCVD(p)](1-S _wi)

Wherein, S _op () is the condensate saturation ratio under Different Strata pressure; S _wifor irreducible water saturation; V _roCVDp () is the condensate content under Different Strata pressure.

Optionally, in an embodiment of the present invention, the described step obtaining gas phase permeability according to gas phase relative permeability and air absolute permeability comprises:

Gas phase permeability is obtained according to following formula;

K _rg=K/K _a

Wherein, K _rgfor gas phase relative permeability; K _afor air absolute permeability, recorded by core experiment; K is gas phase permeability.

Optionally, in an embodiment of the present invention, the relation between the first coefficient of described exponential deliverability equation and the second coefficient is expressed as:

$\frac{c_1}{c_2}=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}$

Wherein, c ₁be the first exponential deliverability equation coefficient, c ₂be the second exponential deliverability equation coefficient, Z ₁be the first deviation factor accordingly under the first strata pressure, Z ₂be the second deviation factor accordingly under the second strata pressure, μ ₁be the first Natural Gas Viscosity accordingly under the first strata pressure, μ ₂be the second Natural Gas Viscosity accordingly under the second strata pressure, K ₁be the first gas phase permeability accordingly under the first strata pressure, K ₂it is the second gas phase permeability accordingly under the second strata pressure.

Optionally, in an embodiment of the present invention, under described Different Strata pressure, gas condensate reservoir absolute open flow (AOF) design formulas is:

$\begin{array}{ccc}{q_{\mathrm{AOF}}}_2=\frac{c_2}{c_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1\end{array}$

Wherein, for gas condensate reservoir absolute open flow (AOF) under Different Strata pressure, c ₁be the first exponential deliverability equation coefficient, c ₂be the second exponential deliverability equation coefficient, P _e1be the first strata pressure, P _e2be the second strata pressure, for known gas condensate reservoir absolute open flow (AOF), μ ₁be the first Natural Gas Viscosity accordingly under the first strata pressure, μ ₂it is the second Natural Gas Viscosity accordingly under the second strata pressure; K ₁be the first gas phase permeability accordingly under the first strata pressure, K ₂it is the second gas phase permeability accordingly under the second strata pressure; N is deliverability curve index, and the span of n is 0.5-1, wherein, during n=1, represents complete Darcy seepage flow; As n=0.5, represent complete non-Darcy seepage.

For achieving the above object, the present invention also proposes the acquisition system of gas condensate reservoir absolute open flow (AOF) under Different Strata pressure, this system based on the change of gas composition in gas condensate reservoir under Different Strata pressure and the change of gas phase permeability to the acquisition of absolute open flow (AOF); Comprise:

Exponential form deliverability equation determining unit, for exponential deliverability equation under determining Different Strata pressure;

Exponential form Relationship of Coefficients determining unit, for according to described exponential deliverability equation, by the first strata pressure and the second strata pressure and corresponding the first Natural Gas Viscosity, the first deviation factor and the first gas phase permeability of the first strata pressure, and corresponding the second Natural Gas Viscosity, the second deviation factor and the second gas phase permeability of the second strata pressure obtains the relation between the first coefficient of exponential deliverability equation and the second coefficient;

Absolute open flow (AOF) acquiring unit, for obtaining gas condensate reservoir absolute open flow (AOF) under Different Strata pressure according to relation, the first known gas condensate reservoir absolute open flow (AOF) and the first strata pressure between the first coefficient of exponential deliverability equation and the second coefficient and the second strata pressure.

Optionally, in an embodiment of the present invention, described exponential Relationship of Coefficients determining unit comprises:

Deng appearance exhaustion module, for according to waiting appearance depletion experiments to draw condensate content under Different Strata pressure;

Condensate saturation ratio acquisition module, for obtaining the condensate saturation ratio under Different Strata pressure according to the condensate content under Different Strata pressure and irreducible water saturation;

Relative permeability value acquisition module, for not changing the form of oil gas phase percolation curve according to the precipitation of condensate, utilizes the condensate saturation ratio under oil gas phase percolation curve and Different Strata pressure to obtain gas phase relative permeability under different gas saturation;

Gas phase permeability acquisition module, for obtaining gas phase permeability according to gas phase relative permeability and air absolute permeability.

Optionally, in an embodiment of the present invention, described condensate saturation ratio acquisition module obtains the condensate saturation ratio under Different Strata pressure according to following formula;

S _o(p)＝[V _roCVD(p)](1-S _wi)

Wherein, S _op () is the condensate saturation ratio under Different Strata pressure; S _wifor irreducible water saturation; V _roCVDp () is the condensate content under Different Strata pressure.

Optionally, in an embodiment of the present invention, described gas phase permeability acquisition module obtains gas phase permeability according to following formula;

K _rg=K/K _a

Wherein, K _rgfor gas phase relative permeability; K _afor air absolute permeability, recorded by core experiment; K is gas phase permeability.

Optionally, in an embodiment of the present invention, the relation between the first coefficient of exponential deliverability equation of obtaining of described exponential Relationship of Coefficients determining unit and the second coefficient is expressed as:

$\frac{c_1}{c_2}=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}$

Wherein, c ₁be the first exponential deliverability equation coefficient, c ₂be the second exponential deliverability equation coefficient, Z ₁be the first deviation factor accordingly under the first strata pressure, Z ₂be the second deviation factor accordingly under the second strata pressure, μ ₁be the first Natural Gas Viscosity accordingly under the first strata pressure, μ ₂be the second Natural Gas Viscosity accordingly under the second strata pressure, K ₁be the first gas phase permeability accordingly under the first strata pressure, K ₂it is the second gas phase permeability accordingly under the second strata pressure.

Optionally, in an embodiment of the present invention, under the Different Strata pressure that obtains of described absolute open flow (AOF) acquiring unit, gas condensate reservoir absolute open flow (AOF) design formulas is:

$\begin{array}{ccc}{q_{\mathrm{AOF}}}_2=\frac{c_2}{c_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1\end{array}$

Wherein, for gas condensate reservoir absolute open flow (AOF) under Different Strata pressure, c ₁be the first exponential deliverability equation coefficient, c ₂be the second exponential deliverability equation coefficient, P _e1be the first strata pressure, P _e2be the second strata pressure, for known gas condensate reservoir absolute open flow (AOF), μ ₁be the first Natural Gas Viscosity accordingly under the first strata pressure, μ ₂it is the second Natural Gas Viscosity accordingly under the second strata pressure; K ₁be the first gas phase permeability accordingly under the first strata pressure, K ₂it is the second gas phase permeability accordingly under the second strata pressure; N is deliverability curve index, and the span of n is 0.5-1, wherein, during n=1, represents complete Darcy seepage flow; As n=0.5, represent complete non-Darcy seepage.

Technique scheme has following beneficial effect: the technical scheme proposed due to the application considers the change of condensate on the impact of gas phase permeability and condensate gas component, more accurate to the acquisition of absolute open flow (AOF), to instruct the reasonable effective exploitation of gas condensate reservoir.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is the acquisition methods flow chart based on gas condensate reservoir absolute open flow (AOF) under exponential deliverability equation Different Strata pressure that the present invention proposes;

Fig. 2 is the acquisition system construction drawing based on gas condensate reservoir absolute open flow (AOF) under exponential deliverability equation Different Strata pressure that the present invention proposes;

Fig. 3 is the acquisition system middle finger numerical expression Relationship of Coefficients determining unit structure chart based on gas condensate reservoir absolute open flow (AOF) under exponential deliverability equation Different Strata pressure that the present invention proposes;

Fig. 4 is the change curve of mixture molecular weight with pressure;

Fig. 5 is the change curve of gas phase permeability with pressure;

Fig. 6 is the change curve of exponential gas condensate reservoir absolute open flow (AOF) with strata pressure;

Fig. 7 is the acquisition methods flow chart of the gas phase permeability that the present invention proposes.

Detailed description of the invention

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described.Obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.

Gas condensate reservoir is a kind of special, complicated gas reservoir.On stream, condensate gas well presents different flow regions with the decline of strata pressure, and different flow regions is just with different percolation equationk.Oil gas branch and corresponding oil gas phase percolation curve are very difficult accurately to obtain zones of different, the application is on labor and continuous basis of attempting, adopt approximate gas phase permeability computational methods, achieve good effect, reduce error of calculation, meet the requirement of engineering calculation precision.

As shown in Figure 1, be the acquisition methods flow chart based on gas condensate reservoir absolute open flow (AOF) under exponential deliverability equation Different Strata pressure of the present invention's proposition.The method based on the change of gas composition in gas condensate reservoir under Different Strata pressure and the change of gas phase permeability to the acquisition of absolute open flow (AOF); Comprise:

Step 301: exponential deliverability equation under determining Different Strata pressure;

Step 302: according to described exponential deliverability equation, by strata pressure P _e1with strata pressure P _e2and strata pressure P _e1corresponding Natural Gas Viscosity μ ₁, deviation factor Z ₁with gas phase permeability K ₁, and strata pressure P _e2corresponding Natural Gas Viscosity μ ₂, deviation factor Z ₂and and gas phase permeability K ₂obtain exponential deliverability equation coefficient c ₁and c ₂between relation;

Step 303: according to exponential deliverability equation coefficient c ₁and c ₂between relation, known gas condensate reservoir absolute open flow (AOF) and strata pressure P _e1with strata pressure P _e2obtain gas condensate reservoir absolute open flow (AOF) under Different Strata pressure

Optionally, in an embodiment of the present invention, described exponential deliverability equation coefficient c ₁and c ₂between relation be expressed as:

$\frac{c_1}{c_2}=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}.$

Optionally, in an embodiment of the present invention, described gas condensate reservoir absolute open flow (AOF) design formulas is:

$\begin{array}{ccc}{q_{\mathrm{AOF}}}_2=\frac{c_2}{c_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_1{\mathrm{\μ}}_2{K}_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1\end{array}.$

As shown in Figure 7, be the acquisition methods flow chart of the gas phase permeability of the present invention's proposition.Comprise:

Step a: according to etc. hold depletion experiments and draw condensate content under Different Strata pressure;

Step b: obtain the condensate saturation ratio under Different Strata pressure according to the condensate content under Different Strata pressure and irreducible water saturation;

Step c: the form not changing oil gas phase percolation curve according to the precipitation of condensate, utilizes the condensate saturation ratio under oil gas phase percolation curve and Different Strata pressure to obtain gas phase relative permeability under different gas saturation;

Steps d: obtain gas phase permeability according to gas phase relative permeability and air absolute permeability.

Optionally, in an embodiment of the present invention, the step of the described condensate saturation ratio obtained under Different Strata pressure according to the condensate content under Different Strata pressure and irreducible water saturation comprises:

The condensate saturation ratio under Different Strata pressure is obtained according to following formula;

S _o(p)＝[V _roCVD(p)](1-S _wi)

Wherein, S _op () is the condensate saturation ratio under Different Strata pressure; S _wifor irreducible water saturation; V _roCVDp () is the condensate content under Different Strata pressure.

Optionally, in an embodiment of the present invention, the described step obtaining gas phase permeability according to gas phase relative permeability and air absolute permeability comprises:

Gas phase permeability is obtained according to following formula;

K _rg=K/K _a

Wherein, K _rgfor gas phase relative permeability; K _afor air absolute permeability, recorded by core experiment; K is gas phase permeability.

As shown in Figure 2, be the acquisition system construction drawing based on gas condensate reservoir absolute open flow (AOF) under exponential deliverability equation Different Strata pressure of the present invention's proposition.This system based on the change of gas composition in gas condensate reservoir under Different Strata pressure and the change of gas phase permeability to the acquisition of absolute open flow (AOF); Comprise:

Exponential form deliverability equation determining unit 401, for exponential deliverability equation under determining Different Strata pressure;

Exponential form Relationship of Coefficients determining unit 402, for according to described exponential deliverability equation, by strata pressure P _e1with strata pressure P _e2and strata pressure P _e1corresponding Natural Gas Viscosity μ ₁, deviation factor Z ₁with gas phase permeability K ₁, and strata pressure P _e2corresponding Natural Gas Viscosity μ ₂, deviation factor Z ₂and and gas phase permeability K ₂obtain exponential deliverability equation coefficient c ₁and c ₂between relation;

Absolute open flow (AOF) acquiring unit 403, for according to exponential deliverability equation coefficient c ₁and c ₂between relation, known gas condensate reservoir absolute open flow (AOF) and strata pressure P _e1with strata pressure P _e2obtain gas condensate reservoir absolute open flow (AOF) under Different Strata pressure

As shown in Figure 3, be the acquisition system middle finger numerical expression Relationship of Coefficients determining unit structure chart based on gas condensate reservoir absolute open flow (AOF) under exponential deliverability equation Different Strata pressure of the present invention's proposition.Described exponential Relationship of Coefficients determining unit 402 comprises:

Deng appearance exhaustion module 4021, for according to waiting appearance depletion experiments to draw condensate content under Different Strata pressure;

Condensate saturation ratio acquisition module 4022, for obtaining the condensate saturation ratio under Different Strata pressure according to the condensate content under Different Strata pressure and irreducible water saturation;

Relative permeability value acquisition module 4023, for not changing the form of oil gas phase percolation curve according to the precipitation of condensate, utilizes the condensate saturation ratio under oil gas phase percolation curve and Different Strata pressure to obtain gas phase relative permeability under different gas saturation;

Gas phase permeability acquisition module 4024, for obtaining gas phase permeability according to gas phase relative permeability and air absolute permeability.

Optionally, in an embodiment of the present invention, described condensate saturation ratio acquisition module 4022 obtains the condensate saturation ratio under Different Strata pressure according to following formula;

S _o(p)＝[V _roCVD(p)](1-S _wi)

Wherein, S _op () is the condensate saturation ratio under Different Strata pressure; S _wifor irreducible water saturation; V _roCVDp () is the condensate content under Different Strata pressure.

Optionally, in an embodiment of the present invention, described gas phase permeability acquisition module 4024 obtains gas phase permeability according to following formula;

K _rg=K/K _a

Wherein, K _rgfor gas phase relative permeability; K _afor air absolute permeability, recorded by core experiment; K is gas phase permeability.

Optionally, in an embodiment of the present invention, the described exponential deliverability equation coefficient c of described exponential Relationship of Coefficients determining unit 402 acquisition ₁and c ₂between relation be expressed as:

$\frac{c_1}{c_2}=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}.$

Optionally, in an embodiment of the present invention, the gas condensate reservoir absolute open flow (AOF) of described absolute open flow (AOF) acquiring unit 403 acquisition design formulas is:

$\begin{array}{ccc}{q_{\mathrm{AOF}}}_2=\frac{c_2}{c_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1\end{array}.$

The device that the present invention proposes is for utilizing general processor, digital signal processor, special IC (ASIC), field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, computer installation, or circuit load distribution in the automation equipment of power distribution network that realizes of the design of above-mentioned any combination, do not need the communication device of main station and substation and complexity.

Those skilled in the art can also recognize in device of the present invention that various illustrative components, blocks (illustrativelogicalblock), unit and the step listed can pass through electronic hardware, computer software, or both combinations realize.For the replaceability (interchangeability) of clear displaying hardware and software, above-mentioned various illustrative components (illustrativecomponents), unit and step have universally described their function.Such function is the designing requirement realizing depending on specific application and whole device by hardware or software.Those skilled in the art for often kind of specifically application, can use the function described in the realization of various method, but this realization can should not be understood to the scope exceeding embodiment of the present invention protection.

Various illustrative logical block described in device of the present invention, or unit can pass through general processor, digital signal processor, special IC (ASIC), field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or the design of above-mentioned any combination realizes or operates described function.General processor can be microprocessor, and alternatively, this general processor also can be any traditional processor, controller, microcontroller or state machine.Processor also can be realized by the combination of calculation element, such as digital signal processor and microprocessor, multi-microprocessor, and a Digital Signal Processor Core combined by one or more microprocessor, or other similar configuration any realizes.

The software module that method described in device of the present invention or the step of algorithm directly can embed hardware, processor performs or the combination of both.Software module can be stored in the storage medium of other arbitrary form in RAM memory, flash memory, ROM memory, eprom memory, eeprom memory, register, hard disk, moveable magnetic disc, CD-ROM or this area.Exemplarily, storage medium can be connected with processor, with make processor can from storage medium reading information, and write information can be deposited to storage medium.Alternatively, storage medium can also be integrated in processor.Processor and storage medium can be arranged in ASIC, and ASIC can be arranged in user terminal.Alternatively, processor and storage medium also can be arranged in the different parts in user terminal.

In one or more exemplary design, the above-mentioned functions described in device of the present invention can realize in any combination of hardware, software, firmware or this three.If realized in software, these functions can store on the medium with computer-readable, or are transmitted on the medium of computer-readable with one or more instruction or code form.Computer readable medium comprises computer storage medium and is convenient to make to allow computer program transfer to the telecommunication media in other place from a place.Storage medium can be that any general or special computer can the useable medium of access.Such as, such computer readable media can include but not limited to RAM, ROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage device, or other anyly may be used for carrying or store the medium that can be read the program code of form with instruction or data structure and other by general or special computer or general or special processor.In addition, any connection can be properly termed computer readable medium, such as, if software is by a coaxial cable, fiber optic cables, twisted-pair feeder, Digital Subscriber Line (DSL) or being also comprised in defined computer readable medium with wireless equation transmission such as such as infrared, wireless and microwaves from a web-site, server or other remote resource.Described video disc (disk) and disk (disc) comprise Zip disk, radium-shine dish, CD, DVD, floppy disk and Blu-ray Disc, and disk is usually with magnetic duplication data, and video disc carries out optical reproduction data with laser usually.Above-mentioned combination also can be included in computer readable medium.

For gas condensate reservoir, when strata pressure drops to after below dew-point pressure, the heavy component in condensate gas can in stratum, cause the composition of condensate gas to change by retrograde condensation gradually, retrograde condensation condensate out can adsorb rock surface simultaneously, affects Reservoir Seepage kinetic force.The technical scheme that gas condensate reservoir absolute open flow (AOF) obtains under Different Strata pressure has been inquired in the embodiment of the present invention, by the impact that the decline of research strata pressure forms gas phase permeability and condensate gas, utilization index formula deliverability equation, the Gas Well Productivity of gas condensate reservoir under Different Strata pressure can be derived, to instruct the reasonable effective exploitation of gas condensate reservoir.

Essential difference for gas condensate reservoir and dry gas reservoir is following two aspects: the first, the change of gas composition.As shown in Figure 4, for mixture molecular weight is with the change curve of pressure; The second, the change of gas phase permeability.As shown in Figure 5, for gas phase permeability is with the change curve of pressure.Wherein, gas composition change is mainly manifested in the change of admixture of gas molecular weight the impact of production capacity.According to existing gas testing data, utilize mathematical method just can draw the molecular weight of Different Strata gas under pressure.When condensate is separated out from gas, the permeability of gas phase can change, and the phase percolation curve experimentally drawn just can draw the gas phase permeability under different gas saturation.

In this application, the acquisition methods of gas phase permeability under Different Strata pressure:

The change of gas phase permeability K is that this is the special properties decision of gas condensate reservoir, but not the permeability that stress sensitive causes changes because the precipitation of condensate has an impact to vapor phase stream is dynamic.

The condensate content under Different Strata pressure can be drawn according to CVD experiment, at this moment there will be oil, gas, water three-phase in blowhole, irreducible water saturation S _wican be obtained by measured data, by formula S _o(p)=[V _roCVD(p)] (1-S _wi) can obtain under Different Strata pressure condensate saturation ratio.Suppose that the precipitation of condensate does not change the form of oil gas phase percolation curve, according to the condensate saturation ratio under oil gas phase percolation curve and Different Strata pressure, the relative permeability value of oil phase and gas phase under different gas saturation can be obtained.

In the method for existing numerous acquisition gas phase permeability, for gas condensate reservoir, there is following features:

A): be difficult to obtain oil gas phase percolation curve under actual formation state;

B): according to the rock core information of reality, oil gas phase percolation curve can be obtained in laboratory;

C): this phase percolation curve reflects oil gas two phase fluid flow feature, then tested the condensate content drawn under Different Strata pressure by CVD, just approximate calculation can go out gas phase permeability under Different Strata pressure.In a word, the method can utilize limited condition to obtain being similar to the flow effect of oil gas two-phase under layer state truly, significantly reduces the error of calculation of gas condensate reservoir Absolute Open Flow of Gas Wells.

Embodiment:

According to exponential deliverability equation, when flowing bottomhole pressure (FBHP) is atmospheric pressure, have:

$q_{\mathrm{AOF}}={\mathrm{cP}}_e^{2n}$

In like manner suppose that strata pressure is respectively P at two different mining phases _e1and P _e2, corresponding deliverability equation coefficient is respectively c ₁and c ₂, can obtain:

$\begin{array}{ccc}{q_{\mathrm{AOF}}}_2=\frac{c_2}{c_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}& {q_{\mathrm{AOF}}}_1\end{array}$

Under normal circumstances, the change of gas well flow index n is negligible, but after gas well carried out the measure such as acidifying or pressure break, the flow index n of equation can have a greater change, and at this moment must set up deliverability equation by well testing again.

As shown in Figure 6, for exponential gas condensate reservoir absolute open flow (AOF) is with the change curve of strata pressure.A curve in Fig. 6 does not consider the impact of condensate on reservoir permeability and molecular weight gas, and B curve considers the impact of stratum pressure drop on molecular weight gas and reservoir permeability simultaneously.As can be seen from the figure, when strata pressure drops to below dew-point pressure, consider the change of condensate on the impact of gas phase permeability and condensate gas component, result of calculation is more accurate.

End value is calculated from following table 1, according to the actual gas testing data in certain oil field and the detection analysis report of this well, adopt common dry gas reservoir computational methods and calculate the absolute open flow (AOF) of gas well respectively based on gas condensate reservoir computational methods under the Different Strata pressure of exponential form.Its result of calculation shows, all can there is larger error in the gas well output adopting the computational methods of dry gas reservoir to calculate gas condensate reservoir, exceed the required precision (0-10%) of engineering calculation, then error of calculation is greatly reduced based on gas condensate reservoir computational methods under the Different Strata pressure of exponential form, meet the required precision of engineering calculation, therefore the method can well instruct the production in oil field.

The result of calculation of table 12007 year Q1 well exponential form and error

Above-described specific embodiment party journey; object of the present invention, technical scheme and beneficial effect are further described; be understood that; the foregoing is only specific embodiment of the invention equation; the protection domain be not intended to limit the present invention; within the spirit and principles in the present invention all, any amendment made, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (10)

1. the acquisition methods of gas condensate reservoir absolute open flow (AOF) under Different Strata pressure, is characterized in that, the method based on the change of gas composition in gas condensate reservoir under Different Strata pressure and the change of gas phase permeability to the acquisition of absolute open flow (AOF); Comprise:

Exponential deliverability equation under determining Different Strata pressure;

According to described exponential deliverability equation, by the first strata pressure and the second strata pressure and corresponding the first Natural Gas Viscosity, the first deviation factor and the first gas phase permeability of the first strata pressure, and corresponding the second Natural Gas Viscosity, the second deviation factor and the second gas phase permeability of the second strata pressure obtains the relation between the first coefficient of exponential deliverability equation and the second coefficient;

Gas condensate reservoir absolute open flow (AOF) under Different Strata pressure is obtained according to relation, the first known gas condensate reservoir absolute open flow (AOF) and the first strata pressure between the first coefficient of exponential deliverability equation and the second coefficient and the second strata pressure;

Wherein, the acquisition methods of described gas phase permeability comprises:

According to etc. hold depletion experiments and draw condensate content under Different Strata pressure;

The condensate saturation ratio under Different Strata pressure is obtained according to the condensate content under Different Strata pressure and irreducible water saturation;

Do not change the form of oil gas phase percolation curve according to the precipitation of condensate, utilize the condensate saturation ratio under oil gas phase percolation curve and Different Strata pressure to obtain gas phase relative permeability under different gas saturation;

Gas phase permeability is obtained according to gas phase relative permeability and air absolute permeability.

2. method according to claim 1, is characterized in that, the step of the described condensate saturation ratio obtained under Different Strata pressure according to the condensate content under Different Strata pressure and irreducible water saturation comprises:

The condensate saturation ratio under Different Strata pressure is obtained according to following formula;

S _o(p)＝[V _roCVD(p)](1-S _wi)

Wherein, S _op () is the condensate saturation ratio under Different Strata pressure; S _wifor irreducible water saturation; V _roCVDp () is the condensate content under Different Strata pressure.

3. method according to claim 1, is characterized in that, the described step obtaining gas phase permeability according to gas phase relative permeability and air absolute permeability comprises:

Gas phase permeability is obtained according to following formula;

K _rg＝K/K _a

Wherein, K _rgfor gas phase relative permeability; K _afor air absolute permeability, recorded by core experiment; K is gas phase permeability.

4. the method according to the arbitrary claim of claims 1 to 3, is characterized in that, the relation between the first coefficient of described exponential deliverability equation and the second coefficient is expressed as:

$\frac{c_1}{c_2}=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}$

Wherein, c ₁be the first exponential deliverability equation coefficient, c ₂be the second exponential deliverability equation coefficient, Z ₁be the first deviation factor corresponding under the first strata pressure, Z ₂be the second deviation factor corresponding under the second strata pressure, μ ₁be the first Natural Gas Viscosity corresponding under the first strata pressure, μ ₂be the second Natural Gas Viscosity corresponding under the second strata pressure, K ₁be the first gas phase permeability corresponding under the first strata pressure, K ₂it is the second gas phase permeability corresponding under the second strata pressure.

5. the method according to the arbitrary claim of claims 1 to 3, is characterized in that, under described Different Strata pressure, gas condensate reservoir absolute open flow (AOF) design formulas is:

$q_{{\mathrm{AOF}}_2}=\frac{c_2}{c_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n},q_{{\mathrm{AOF}}_1}=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}{q}_{{\mathrm{AOF}}_1}$

Wherein, for gas condensate reservoir absolute open flow (AOF) under Different Strata pressure, c ₁be the first exponential deliverability equation coefficient, c ₂be the second exponential deliverability equation coefficient, Ρ _e1be the first strata pressure, Ρ _e2be the second strata pressure, for known gas condensate reservoir absolute open flow (AOF), μ ₁be the first Natural Gas Viscosity corresponding under the first strata pressure, μ ₂it is the second Natural Gas Viscosity corresponding under the second strata pressure; K ₁be the first gas phase permeability corresponding under the first strata pressure, K ₂it is the second gas phase permeability corresponding under the second strata pressure; N is deliverability curve index, and the span of n is 0.5-1.

6. the acquisition system of gas condensate reservoir absolute open flow (AOF) under Different Strata pressure, is characterized in that, this system based on the change of gas composition in gas condensate reservoir under Different Strata pressure and the change of gas phase permeability to the acquisition of absolute open flow (AOF); Comprise:

Exponential form deliverability equation determining unit, for exponential deliverability equation under determining Different Strata pressure;

Exponential form Relationship of Coefficients determining unit, for according to described exponential deliverability equation, by the first strata pressure and the second strata pressure and corresponding the first Natural Gas Viscosity, the first deviation factor and the first gas phase permeability of the first strata pressure, and corresponding the second Natural Gas Viscosity, the second deviation factor and the second gas phase permeability of the second strata pressure obtains the relation between the first coefficient of exponential deliverability equation and the second coefficient;

Absolute open flow (AOF) acquiring unit, for obtaining gas condensate reservoir absolute open flow (AOF) under Different Strata pressure according to relation, the first known gas condensate reservoir absolute open flow (AOF) and the first strata pressure between the first coefficient of exponential deliverability equation and the second coefficient and the second strata pressure;

Wherein, described exponential Relationship of Coefficients determining unit comprises:

Deng appearance exhaustion module, for according to waiting appearance depletion experiments to draw condensate content under Different Strata pressure;

Condensate saturation ratio acquisition module, for obtaining the condensate saturation ratio under Different Strata pressure according to the condensate content under Different Strata pressure and irreducible water saturation;

Relative permeability value acquisition module, for not changing the form of oil gas phase percolation curve according to the precipitation of condensate, utilizes the condensate saturation ratio under oil gas phase percolation curve and Different Strata pressure to obtain gas phase relative permeability under different gas saturation;

Gas phase permeability acquisition module, for obtaining gas phase permeability according to gas phase relative permeability and air absolute permeability.

7. system according to claim 6, is characterized in that, described condensate saturation ratio acquisition module obtains the condensate saturation ratio under Different Strata pressure according to following formula;

S _o(p)＝[V _roCVD(p)](1-S _wi)

Wherein, S _op () is the condensate saturation ratio under Different Strata pressure; S _wifor irreducible water saturation; V _roCVDp () is the condensate content under Different Strata pressure.

8. system according to claim 6, is characterized in that, described gas phase permeability acquisition module obtains gas phase permeability according to following formula;

K _rg＝K/K _a

Wherein, K _rgfor gas phase relative permeability; K _afor air absolute permeability, recorded by core experiment; K is gas phase permeability.

9. the system according to the arbitrary claim of claim 6 ~ 8, is characterized in that, the relation between the first coefficient of the exponential deliverability equation that described exponential Relationship of Coefficients determining unit obtains and the second coefficient is expressed as:

$\frac{c_1}{c_2}=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}$

Wherein, c ₁be the first exponential deliverability equation coefficient, c ₂be the second exponential deliverability equation coefficient, Z ₁be the first deviation factor corresponding under the first strata pressure, Z ₂be the second deviation factor corresponding under the second strata pressure, μ ₁be the first Natural Gas Viscosity corresponding under the first strata pressure, μ ₂be the second Natural Gas Viscosity corresponding under the second strata pressure, K ₁be the first gas phase permeability corresponding under the first strata pressure, K ₂it is the second gas phase permeability corresponding under the second strata pressure.

10. the system according to the arbitrary claim of claim 6 ~ 8, is characterized in that, under the Different Strata pressure that described absolute open flow (AOF) acquiring unit obtains, gas condensate reservoir absolute open flow (AOF) design formulas is:

$q_{{\mathrm{AOF}}_2}=\frac{c_2}{c_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n},q_{{\mathrm{AOF}}_1}=\frac{Z_1{\mathrm{\μ}}_1{K}_2}{Z_2{\mathrm{\μ}}_2{K}_1}{\left(\frac{p_{e2}}{p_{e1}}\right)}^{2n}{q}_{{\mathrm{AOF}}_1}$

Wherein, for gas condensate reservoir absolute open flow (AOF) under Different Strata pressure, c ₁be the first exponential deliverability equation coefficient, c ₂be the second exponential deliverability equation coefficient, Ρ _e1be the first strata pressure, Ρ _e2be the second strata pressure, for known gas condensate reservoir absolute open flow (AOF), μ ₁be the first Natural Gas Viscosity corresponding under the first strata pressure, μ ₂it is the second Natural Gas Viscosity corresponding under the second strata pressure; K ₁be the first gas phase permeability corresponding under the first strata pressure, K ₂it is the second gas phase permeability corresponding under the second strata pressure; N is deliverability curve index, and the span of n is 0.5-1.