Open Hole Multistage Completion Exceeds Production Expectations from South Sulige Gas Field in China

A joint venture project in the South Sulige gas field began in 2011 with the intent of evaluating horizontal drilling and open hole multistage fracture stimulation. The South Sulige gas field has two main producing formations, both with low permeability and porosity. Like many other tight gas sandstone formations in China, fracturing is necessary in order to get economic production in pad-drilling. To date, five wells have been stimulated with openhole multistage fracturing systems in the South Sulige field. Post-frac initial well performances are outstanding and have greatly exceeded expectations. This significant increase in production mirrors what has been accomplished using open hole multistage systems in North American unconventional reservoirs. The use of open hole multistage completions allows the operator to customize the treatment of specific zones by isolating targeted sections with open hole packers while also allowing better production by focusing on natural fractures in the formation. By eliminating the need to run in hole casing, cementing, and perforating, completion time is greatly reduced. It can further improve operational efficiency by enabling a continuous pumping operation, and allowing for flow back immediately after the fracturing treatment to minimize induced formation damage. This paper will discuss the overall enhanced performance achieved with staging methodology and open hole completions. The discussion will mainly focus on pre-installation wellbore preparation and operation of open hole multistage completion systems, clean-up procedures, mitigation of damage of the formation and taking advantage of natural fractures that are abundant in the South Sulige field. Open hole multi stage completions have applications in other tight formations in China where drilling and stimulation equipment availability is limited, to optimize the treatment efficiency and efficiency on the surface while maximizing production.