Field Case Studies of Completion FluidsTto Enhance Oil and Gas Production in Depleted Unconventional Reservoir

摘要

A study of completion techniques in depleted/low pressure tight permeability gas/oil reservoirs shows great promise through the use of a microemulsion (ME) additive in energized fracture stimulation treatment of new infill wells. This paper presents a comparison of four (4) wells completed according to historical stimulation practices and two (2) wells completed with microemulsion additive. See Table 1 for baseline data. The damage mechanisms from past practices were exacerbated by depleted/ low bottom-hole pressures, high water saturations, and low bubble point crude. The use of the microemulsion additive reduced the liquid load and promoted liquid recovery, enabling the base fluid gases to establish gas saturated pathways and promote the production of the natural solution gas that is the field’s primary economic resource. CO2 is thought to enhance this process by promoting the reduction of the near fracture face oil saturation. The microemulsion potentially enhances this action by reducing the mobility contrast between introduced fluids and reservoir oil, water, and gas phases. Analysis of the production histories shows that the microemulsion additive significantly enhanced the reservoir conductivity and effective fracture length when compared to the historical completions when in sustained production. The two wells treated with microemulsion additive also experienced less damage as a consequence of the long shut-ins prior to sustained production, than did those with historical completions, which had much shorter shut-ins.