Case studies of tight-gas carbonate reservoir stimulation: Acid fracturing vs. propped fracturing

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Conference Proceeding

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This paper presents a detailed case history of hydraulic fracture treatments in tight gas wells in a remote onshore location of China. The target formation consists of heterogeneous dolomite deposits and occurs at various depth ranging from 3,100 to 3,700 meters, with an average net pay of a few meters, porosity of about 4%, and effective permeability of <0.1 mD. All the wells in the region were fracture stimulated in an attempt to achieve commercial production and to improve productivity. Because high Young's modulus and high net pressure were observed, placing proppant inside fractures was always a problem and acid fracturing was the choice of stimulation in the past. With acid fracturing treatments, mixed stimulation results were achieved with various acid types and design strategies. Over the last few years, propped fracturing treatments in the region were "re-introduced" with improved technologies, and 46 propped treamtnets were successfully conducted. The propped treatment size increased from 9 tons of proppant with an average proppant concentration of 120 kg/m3 in the early trials to a record size consiting of 56 ton of proppant with an average proppant concentration of 460 kg/m3. This paper provides a brief summary of reservoir background and past development history, but focuses on acid and propped fracture evaluation. A comprehensive data set of logs and post-fracture production results were compiled and employed to understand fracture performance in this complex reservoir environment. Copyright 2006, Society of Petroleum Engineers.

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Proceedings - SPE Annual Technical Conference and Exhibition

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