Discrete element method simulation of the growth and efficiency of multiple hydraulic fractures simultaneously-induced f

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ORIGINAL ARTICLE

Discrete element method simulation of the growth and efficiency of multiple hydraulic fractures simultaneously-induced from two horizontal wells Kang Duan . Yingchun Li . Wendong Yang

Received: 18 August 2020 / Accepted: 22 October 2020 Ó Springer Nature Switzerland AG 2020

Abstract Multiple hydraulic fracturing treatment from horizontal wells has been widely used to enhance the productivity of unconventional hydrocarbons. Interaction among the fractures can cause the reorientation of fractures and lower the stimulation efficiency. We perform discrete element method (DEM) simulations to assess the influence of completion scheme on the trajectory and efficiency of fractures simultaneously-induced from two horizontal wells. Simulation of a single hydraulic fracture yields reasonable agreement with the theoretical solution regarding the fracture pattern and stress alteration and thus confirms the validity of the model. Stress shadowing effect caused by the opening of early fractures alters the state of local stress and thus leads to the appearance of dominant fractures and the reorientation of other fractures located in the altered stress field. Influences of the fracturing scheme including the K. Duan School of Civil Engineering, Shandong University, Jinan 250061, China Y. Li State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China W. Yang (&) College of Pipeline and Civil Engineering, China University of Petroleum, Qingdao 266580, Shandong, China e-mail: [email protected]

distance between wells, the spacing between injection points, and arrangement of injection points are examined. The distribution uniformity index reveals that the effect of distance between wells on improving the efficiency of treatment is conditionally dependent on the spacing between injection points. Under the conditions considered in this study, the distance between wells enhance the efficiency only when the spacing reaches 40 m. Similarly, enlarging the spacing between injection points does not affect the distribution uniformity index when the distance between wells is 40 m, but effectively mitigate the stress shadowing effect and promotes the fracturing efficiency when the distance exceeds 60 m. Arrangement of injection point plays a negligible role on the fracturing efficiency compared with the spacing among them. Keywords Hydraulic fracturing  Discrete element method  Fracturing efficiency  Injection scheme  Distribution uniformity index

1 Article Highlights 1. Growth of multiple hydraulic fractures induced from two horizontal wells is simulated with fully coupled DEM model.

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Geomech. Geophys. Geo-energ. Geo-resour. (2021)7:3

2. Influences of operational parameters on the distribution uniformity index of fractures are assessed. 3. Potential of mitigating the stress shadowing effect by changing injection scheme is discussed.

2 Introduction Successful exploitation of unconventional hydrocarbon resources relies largely on two key techniqu