Model of Effective Width and Fracture Conductivity for Hydraulic Fractures in Tight Reservoirs
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RESEARCH ARTICLE-PETROLEUM ENGINEERING
Model of Effective Width and Fracture Conductivity for Hydraulic Fractures in Tight Reservoirs Shan Jiang1,2 · Peng Chen2 · Min Yan3 · Botao Liu4 · Hong Liu5 · Hao Wang6 Received: 16 December 2019 / Accepted: 30 April 2020 © King Fahd University of Petroleum & Minerals 2020
Abstract Hydraulic fracturing technology is widely used in the development of tight reservoirs. Hydraulic fracture closure highly impacts oil and gas production in tight reservoirs, and a quantitative description of the effective width and fracture conductivity has a guiding significance for fracturing design and productivity prediction. In this paper, based on the mechanical characteristics of proppants in hydraulic fracturing, a fracture width model is first established for sandstone and shale reservoirs, and the effect of the closing pressure on the rock mechanics parameters of proppants is considered. Then, by the changes in fracture width and proppant permeability, a fracture conductivity model is built. Finally, the models are verified with existing experimental data, and are applied to analyze the influence of relevant parameters on the effective width and fracture conductivity of hydraulic fractures. Fracture closure is primarily affected by proppant deformation and embedment. An increase in the proppant elastic modulus can reduce proppant deformation and avoid fracture closure. A fracture containing large proppant more readily closes during the production process, and the closing pressure has a considerable effect on the proppant rock mechanical parameters, which can prevent the fracture from closing to maintain its conductivity. In this study, fracture closure and its conductivity are predicted, which is conducive to the production of tight reservoirs. Keywords Hydraulic fracturing · Fracture closure · Fracture conductivity · Proppant deformation · Closing pressure List of Symbols a Coefficient b Coefficient cp Compression coefficient (1/MPa) C Physical quantity (unitless) E Elasticity modulus (MPa)
F Conductivity coefficient (μm2 cm) h Depth (mm) k Permeability (mD) K Coefficient (unitless) p Pressure (MPa) P Force (N) w Fracture width (cm) R Radius (mm)
* Peng Chen [email protected]
Greek Symbols α′ Variable (mm) ν Poisson’s ratio (unitless) β Deformation value (mm) ξ Coefficient (unitless) χ Coefficient (unitless) γ Coefficient (unitless) λ Coefficient (unitless)
1
State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China
2
College of Earth Science, Yangtze University, Wuhan 430100, China
3
Exploration and Development Research Institute, PetroChina, Huabei Oilfield Company, Changzhou 062552, Hebei, China
4
College of Computer Science, Yangtze University, Jingzhou 434023, China
5
East China University of Technology, Nanchang 330013, China
6
Geology Exploration and Development Research Institute, CNPC Chuanqing Drilling Engineering Co., Ltd., Chengdu 610051, China
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