CN102706775A - Method for testing viscoelasticity of oil scavenging system - Google Patents

Abstract

The invention discloses a method for testing viscoelasticity of an oil scavenging system. The method includes the following steps: (1) relevant physical model parameters are obtained according to oil deposit geology parameters, and the physical model parameters are used for determining an oil deposit microcosmic percolation model; (2) digital analogy parameters of the oil scavenging system are calculated according to the oil deposit microcosmic percolation model. The digital analog parameters comprise a deformation amplitude, deformation time and recovery time; (3) a deformation function of the oil scavenging system is obtained according to the digital analogy parameters, the digital analog parameters and the deformation function are converted into a driving program of a rheometer, and the digital analog parameters are input as boundary conditions; and (4) a viscoelasticity test of the oil scavenging system is conducted on the rheometer according to the driving program and the boundary conditions. By means of the method for testing the viscoelasticity of the oil scavenging system, the viscoelasticity during percolation of the oil scavenging system can be obtained under the conditions of different oil deposit environment and different injection parameters.

Description

The viscoelastic method of a kind of test oil displacement system

Technical field

The present invention relates to the viscoelastic method of a kind of test oil displacement system.

Background technology

In field of petroleum exploitation, chemical flooding is a kind of important raising recovery efficiency technique.This technology relates to methods such as polymer flooding, combination flooding, foam flooding, weak gel drive, and injects oil reservoir through high pressure line at water injection well, through injecting the viscosity and the viscoelasticity thereof of fluid, improves oil displacement efficiency.Current research shows that after oil displacement system got into the stratum, its viscoelasticity had crucial effect to the effect of the displacement of reservoir oil.

Although existing rheological technique has solved the problem of testing of materials aspect; But in the petroleum engineering application facet; How to use the existing rheological property of rheological property measuring technique accurate description working fluid under the stratum filtration environmental baseline; It but still is a problem; There are the phenomenon of " two skins " in the rheological property data of indoor acquisition and the rheological property that underground percolation appears; Tracing it to its cause is that the flow field of designing when having the flow graph measurement parameter now is the flow field of designing when being directed against premature polymerization thing processing and forming, although the flow measurement technology has been applied to the petroleum industry field now, existing flow measurement technology and parameter designing thereof can not be described out the rheological property of working fluid under the stratum filtration environmental baseline.

Summary of the invention

The purpose of this invention is to provide the viscoelastic method of a kind of test oil displacement system.

The viscoelastic method of a kind of test oil displacement system provided by the invention comprises the steps:

The physical model parameter of (1) being correlated with according to the reservoir geology parameter acquiring; Confirm oil reservoir microscopic seepage model by said physical model parameter;

(2) according to the digital-to-analogue parameter of the said oil displacement system of said oil reservoir microscopic seepage Model Calculation; Said digital-to-analogue parameter comprises deformation amplitude, deformation time and release time;

Said deformation amplitude calculates according to formula (a), in the formula, and A _MaxAnd A _MinThe maximum overflow section of representing fluid in the said oil reservoir microscopic seepage model respectively is long-pending long-pending with minimum overflow section;

[（A _max/A _min） ^1/2-1]/2×100% （a）

(3) obtain the deformation function of said oil displacement system according to said digital-to-analogue parameter, change said digital-to-analogue parameter and deformation function the driver of flow graph into, and said digital-to-analogue parameter is imported as boundary condition;

(4), said oil displacement system is carried out the viscoelasticity test on flow graph according to said driver and boundary condition.

In the above-mentioned method, the distance that said physical model parameter can be that average grain granularity, hole are shouted size, maximum overflow section is long-pending, minimum overflow section is long-pending, maximum overflow section is long-pending with minimum overflow section between amassing etc.

In the above-mentioned method, the said deformation time can obtain according to the distance of oil displacement system deformation in the flow event ratio with percolation flow velocity, and the distance that can recover according to oil displacement system deformation in the flow event said release time obtains with the ratio of percolation flow velocity.

In the above-mentioned method, said deformation function is suc as formula shown in (b), and in the formula, x is 0 ~ d/2, and d representes average particulate diameter;

$\mathrm{\ϵ}=\frac{d}{2}+\sqrt{\frac{d^2}{4}-x^2}---\left(b\right).$

The viscoelastic method of a kind of test oil displacement system provided by the invention, the viscoelasticity in the time of can obtaining oil displacement system seepage flow under different reservoir medias, the different injection parameter condition.

Description of drawings

Fig. 1 is the microscopic seepage physical model geometric configuration synoptic diagram in the embodiment of the invention.

Fig. 2 applies process synoptic diagram (venturi length is 0) for the deformation-recovery pattern deformation in the embodiment of the invention.

Fig. 3 is that (4.56s) aptitude tests result is recovered in deformation (4.56s, the 200%) back of several kinds of oil displacement systems in the embodiment of the invention.

Embodiment

Employed experimental technique is conventional method like no specified otherwise among the following embodiment.

Used material, reagent etc. like no specified otherwise, all can obtain from commercial sources among the following embodiment.

Implement the hydrophobic associated polymer oil displacement test at the Bohai Bay Oil injection well, the implantation concentration of polymkeric substance is 1750mg/L, diurnal injection 440m ³, on average inject thickness 6.4m, formation porosity 0.289, about 1.5 darcies of permeability, average particulate diameter 0.08mm.

According to document Sridhar R K G A.Viscoelastic effects in non-Newtonian flows through porous media [J] .Rheologica Acta.1985; 24:148-151.; For the reservoir model that even spherical sand grains is formed, the calculating long-pending and that minimum overflow section is long-pending of the maximum overflow section of this oil reservoir microscopic seepage model is following:

A _max=d ²；

$A_{\min }=(\frac{\sqrt{3}}{4}-\frac{\mathrm{\π}}{8})d^2;$

In the formula: A _Max-maximum overflow section is long-pending; A _Min-minimum overflow section is long-pending; D-average particulate diameter.

$\frac{A_{\mathrm{Max}}}{A_{\mathrm{Min}}}=\frac{d^2}{\frac{2\sqrt{3}-\mathrm{\π}}{8}{d}^2}=\frac{8}{2\sqrt{3}-\mathrm{\π}}=24.84,$ Then, radially ratio is: $\sqrt{\frac{A_{\mathrm{Max}}}{A_{\mathrm{Min}}}}=\sqrt{24.84}=4.9837\≈5.$

Can confirm microscopic seepage physical model geometric configuration (according to the long-pending principle design that equates of overflow section) as shown in Figure 1 thus.

The deformation amplitude of calculating this hydrophobic associated polymer according to formula (a) is (5-1)/2 * 100%=200%.

The deformation time of this hydrophobic associated polymer need be considered the position of the oil reservoir displacement of reservoir oil, and the present embodiment hypothesis is the position apart from wellbore centre 50m, and then this moment, linear velocity was calculated according to following formula:

In the formula, Q representes the diurnal injection of injection well, m ³/ d; R representes to study the distance of oil reservoir point apart from wellbore centre, m; H representes reservoir thickness, m; φ representes reservoir pore degree, %.

With above-mentioned parameter substitution following formula, the linear velocity of oil displacement system is 0.76m/d when calculating apart from wellbore centre 50m.

Therefore deformation time and release time are:

$t=\frac{L}{v}=\frac{\frac{d}{2}}{v}=\frac{40\×{10}^{-6}}{0.76/24/3600}=4.56s.$

Therefore the deformation function of releasing this hydrophobic associated polymer is: in

formula, and x=0 ~ d/2.

With above-mentioned deformation function, deformation amplitude, deformation time be written as the driver of flow graph release time; And deformation amplitude, deformation time and release time imported as boundary condition; Use the Austrian anton paar Physica MCR301 of company flow graph; Under cone-plate test macro (75mm/1 °) condition, test, it is as shown in Figure 2 that deformation applies schematic flow sheet, and the viscoelasticity test result is as shown in Figure 3.

Can be known that by Fig. 3 the viscoelasticity of working fluid HNT197-2 is best, reason is that its deformation 200% back recovery rate in 4.56s is the highest; Concentration is that the viscoelasticity of 98% glycerine is the poorest, does not recover basically after the deformation.

Claims (4)

1. the viscoelastic method of test oil displacement system comprises the steps:

The physical model parameter of (1) being correlated with according to the reservoir geology parameter acquiring; Confirm oil reservoir microscopic seepage model by said physical model parameter;

(2) according to the digital-to-analogue parameter of the said oil displacement system of said oil reservoir microscopic seepage Model Calculation; Said digital-to-analogue parameter comprises deformation amplitude, deformation time and release time;

Said deformation amplitude calculates according to formula (a), in the formula, and A _MaxAnd A _MinThe maximum overflow section of representing fluid in the said oil reservoir microscopic seepage model respectively is long-pending long-pending with minimum overflow section;

[（A _max/A _min） ^1/2-1]/2×100% （a）

(3) obtain the deformation function of said oil displacement system according to said digital-to-analogue parameter, change said digital-to-analogue parameter and deformation function the driver of flow graph into, and said digital-to-analogue parameter is imported as boundary condition;

(4), said oil displacement system is carried out the viscoelasticity test on flow graph according to said driver and boundary condition.

2. method according to claim 1 is characterized in that: said physical model parameter is the distance between average grain granularity, hole are shouted that size, maximum overflow section are long-pending, minimum overflow section is long-pending, maximum overflow section is long-pending with minimum overflow section and amassed.

3. method according to claim 1 and 2; It is characterized in that: the said deformation time obtains according to the distance of oil displacement system deformation in the flow event ratio with percolation flow velocity, and the distance of recovering according to oil displacement system deformation in the flow event said release time obtains with the ratio of percolation flow velocity.

4. according to arbitrary described method among the claim 1-3, it is characterized in that: said deformation function is suc as formula shown in (b), and in the formula, x is 0 ~ d/2, and d representes average particulate diameter;

$\mathrm{\ϵ}=\frac{d}{2}+\sqrt{\frac{d^2}{4}-x^2}---\left(b\right).$

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