• 油气开发 •

渝东南构造复杂区常压页岩气生产特征及开发技术政策

1. 1. 中国石化 华东油气分公司 勘探开发研究院, 江苏南京 210011
2. 中国石化 重庆页岩气有限公司, 重庆 408400
• 收稿日期:2020-06-08 出版日期:2021-02-28 发布日期:2021-02-07
• 作者简介:何希鹏(1970年-), 男, 研究员, 油气地质综合研究及勘探开发评价。E-mail: hexp.hdsj@sinopec.com
• 基金资助:
国家科技重大专项(2016ZX05061);中国石化科技部项目(P19017-3);中国石化科技部项目(P20059-6)

Production characteristics and optimized development technologies for normal-pressure shale gas in the structurally complex areas of southeastern Chongqing

Xipeng He1(), Bi Lu1, Guisong He1, Jianhua Ren1, Wei Wang1, Zuhua Chen1, Yuqiao Gao1, Dazhi Fang2

1. 1. Exploration and Production Research Institute of East China Oil and Gas Branch Company, SINOPEC, Nanjing, Jiangsu 210011, China
2. Chongqing Shale Gas Company Ltd., SINOPEC, Chongqing 408400, China
• Received:2020-06-08 Online:2021-02-28 Published:2021-02-07

Abstract:

The normal-pressure shale gas reservoirs in some structurally complex areas of southeastern Chongqing is characterized by low pressure coefficient, high proportion of adsorbed gas and complex in-situ stress.Difficulties in forming complex fracture networks in these reservoirs are also frequently experienced during frac operations.Based on the analysis of drilling results and production characteristics of more than 60 horizontal shale gas wells in the areas, we summarized the production law, delineated the production stages, clarified the main factors controlling production capacity, and proposed an optimized technology combination for the reservoir development.It shows that the reservoirs produce mainly fracturing fluids with only a small amount of gas during the initial stage after fracturing and start to yield more gas as the flowback rate of frac fluids increases.At the later stage, gas production gradually stabilizes (depletes slowly) but features relatively high gas production per MPa of pressure drop and limited reserve covered by single wells.The whole production process can be divided into four stages: the liquid (flowback fluid only) stage, transition stage, stable production stage and low-pressure gas drainage stage.The formation pressure coefficient plays a critical role in all of the stages.During the liquid stage, higher pressure coefficient helps to shorten the liquid producing time and to initiate gas production when the flowback rate is still low.In the transition stage, it maintains a longer gas-liquid equilibrium time at lower flowback rate.In the stable production stage, it ensures a stronger gas production capacity that yields more gas with each unit of pressure drop and recover more reserves from a single well.Apart from formation pressure coefficient, the productivity of the reservoirs after fracturing operations is also conditioned by the stimulated reservoir volume (SRV) of frac operations.SRV is in turn controlled mainly by optimal hit ratios of target window, length and orientation of laterals and stimulated areas.Higher formation pressure coefficient and optimal target window drilling rate, longer lateral length, and wider stimulated areas generally signify higher single-well production and more commercially recoverable reserves.Given the above-mentioned understandings, we put forward an optimized technology combination and related fracturing parameters for the normal-pressure shale gas development in the complex areas of southeastern Chongqing.