3D Full-Field and Pad Geomechanics Models Aid Shale Gas Field Development in China

Abstract

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper IPTC 18984, “Three-Dimensional Full-Field and Pad Geomechanics Modeling Assists Effective Shale Gas Field Development, Sichuan Basin, China,” by Liang Xing, PetroChina; Xian Chenggang, SPE, Schlumberger; Shu Honglin, PetroChina; Chen Xin, Schlumberger; Zhang Jiehui, PetroChina; Wen Heng, Schlumberger; Wang Gaocheng, PetroChina; and Wang Lizhi, Guo Haixiao, Zhao Chunduan, Luo Fang, and Qiu Kaibin, SPE, Schlumberger, prepared for the 2016 International Petroleum Technology Conference, Bangkok, Thailand, 14–16 November. The paper has not been peer reviewed. Copyright 2016 International Petroleum Technology Conference. Reproduced by permission. The oilfield-development plan (ODP) for a shale gas field at the southern edge of the Sichuan Basin in China started in early 2014. The first wells drilled in the field and its adjacent blocks experienced significant challenges, such as severe mud losses, stuck tools, losses in the hole, high treating pressure, and unexpected screenout. Because an accurate understanding of geomechanics and its roles at various scales is vital, 3D full-field and pad geomechanics models were developed for achieving efficiency and effectiveness in implementing the ODP. Introduction The Ordovician-Silurian Wufeng-Longmaxi hot shale is an emerging shale gas play in China. Currently, the major exploration and development activities of the play are in the Sichuan Basin and its adjacent areas. For shale gas development in the Sichuan Basin and its adjacent areas, using the megascale, high-density, and continuous and regular pad drilling as is used in North America is difficult because surface and subsurface conditions are significantly different from those of the well-known North American shale plays. The strong environmental and social constraints that typify the Sichuan Basin and surrounding area are shown in Fig. 1. Drilling pads for shale gas developments are commonly located in narrow valleys that are often home to farmland and residential villages with dense populations. Differences of elevation among neighboring pads can be from several hundred meters to more than 1000 m. To speed up development of marine shale gas in the Sichuan Basin and its adjacent areas with a minimized learning curve, a geoscience-to-production integration of research, engineering, and operation with its associated research and development, methodologies, and work flows must be applied. This geoscience-to-production integration aims to optimize both efficiency and effectiveness dynamically at single-well, pad, and field scales with systematic and continuous optimization of technologies and solutions and the accumulation of knowledge and experience to enhance well productivity. One shale gas field, which is the study area of this paper, is in the mountainous area at the southern edge of the Sichuan Basin. The first wells drilled in this field and its adjacent blocks experienced significant geomechanics-associated challenges, such as severe mud losses, tools or drillingpipe sticking, losses in the hole, high treating pressure while hydraulic fracturing, and unexpected screen out of fracturing stages. Having reliable yet evolving understanding of geomechanics and its role at various scales during the progress of the ODP is vital. This paper describes the development of 3D full-field geomechanics models and high-resolution 3D pad geo-mechanics models and their engineering applications.