Dynamic imbibition with aid of surfactant in tight oil fracture network model

Abstract The technology of Stimulated reservoir volume (SRV) has been the key technology for unconventional reservoir development, it can create fracture network in formation and increase the contact area between fracture surface and matrix, thus realizing the three-dimensional stimulation and enhancing single well productivity and ultimate recovery. In China, the Ordos Basin contains large areas of tight oil reservoir with the porosity of 2~12 % and permeability of 0.01~1 mD. The most used development mode is conventional fracturing and water flooding, which is different from the natural depletion mode in oversea, but the development effect is still unfavorable. The idea of SRV is proposed in nearly two years in Changqing Oilfield. SRV measures are implemented in some old wells in tight oil formation. It is a significant problem that should be solved urgently about how to evaluate the volume fracturing effect. Based on the real cases of old wells with SRV measures, the microseismic monitoring is used to analyze the scale of formation stimulation and the complexity of fracture network after volume fracturing; the numerical well test and production data analysis (PDA) are selected to explain the well test data, to analyze the dynamic data, and to compare the changes of formation parameters, fluid parameters and plane streamlines before and after volume fracturing; then the interpretation results of well test with the dynamic of oil and water wells are combined to evaluate the stimulation results of old wells after SRV. This paper has presented a set of screening criteria and an evaluation method of fracturing effect for old well with SRV in tight oil reservoir. It will be helpful to the selection of candidate well and volume fracturing operation in Ordos Basin tight oil reservoir. It should be noted that the evaluation method mentioned in the paper can be expanded to volume stimulation effect evaluation in other unconventional reservoirs, such as tight gas, shale gas and so on.

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Fracture Network Model and Unsealing Analysis of Tight Sandstone Reservoir in Dongpu Depression Bohaiwan Basin, China

EAGE/SEG Research Workshop on Fractured Reservoirs - Integrating Geosciences for Fractured Reservoirs Description ◽

10.3997/2214-4609.20146719 ◽

2007 ◽

Author(s):

Q. Li ◽

S.W. Shao ◽

T.F. Wang

Keyword(s):

Network Model ◽

Fracture Network ◽

Tight Sandstone ◽

Dongpu Depression ◽

Sandstone Reservoir ◽

Bohaiwan Basin

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ANALYTICAL SOLUTIONS FOR PERMEABILITY OF A THREE-DIMENSIONAL FRACTAL-LIKE TREE NETWORK MODEL WITH FRACTURES HAVING VARIABLE WIDTHS

Fractals ◽

10.1142/s0218348x20500139 ◽

2020 ◽

Vol 28 (01) ◽

pp. 2050013

Author(s):

RICHENG LIU ◽

LIYUAN YU ◽

YANG GAO ◽

MING HE ◽

YUJING JIANG

Keyword(s):

Network Model ◽

Analytical Solutions ◽

Constant Width ◽

Fracture Network ◽

Length Ratio ◽

Width Ratio ◽

Fracture Aperture ◽

Fracture Width ◽

Fracture Length ◽

Aperture Ratio

This study proposed analytical solutions for permeability of a fractal-like tree network model with fractures having variable widths, which has not been reported before, if any. This model is more realistic with natural fracture networks than the traditional constant width fracture network models. The results show that considering fracture width variations decreases the permeability. Taking the fracture width ratio that equals to 0.6 and the total number of branching levels that equals to 30 as an example, the permeability decreases by more than three orders of magnitude with respect to that of a constant width fracture network model. The fracture length ratio plays a more significant role in permeability when it is larger than 0.8 than that is less than 0.8. The permeability is more sensitive to the fracture aperture ratio that is less than 0.8. When the total number of branching levels is large (i.e. 30), the permeability changes significantly (i.e. more than three orders of magnitude); whereas when the total number of branching levels is small (i.e. 5), the permeability varies in a small range (i.e. less than one order of magnitude). When taking into account the relationships among fracture length ratio, fracture aperture ratio and fracture width ratio, the parameters can be easily obtained and analytical solutions for permeability can also be easily derived. The empirical function for predicting critical hydraulic gradient is proposed, which can be used to estimate whether the fluid flow is within the linear flow regime and whether the proposed analytical solutions are applicable in the present study.

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