Fracturing control method for deep volcanic rock gas reservoirs in Daqing exploration area

Abstract

Pores, cavities and fractures are well-developed in deep volcanic reservoirs. The simultaneous break and extension of multi-fractures in treatment caused early stage sand-block, low fracturing success ratios, small treatment scales, and bad stimulation results. Based on the geologic characteristics of the deep volcanic rocks, this paper establishes a fracturing break and extension model of volcanic rocks, introducing with time-relevant leaking factor, peak factor and modulus factor. The model is used to better describe the process of initiation and extension of major fractures and micro-fractures. On this basis, the evaluating method for the “three highs” of pump off pressure gradient, near well friction resistance and leakoff coefficient is studied, and through field practices, integrated processing measures are formed: use rubber plugging to deal with near-well high friction resistances, use silts to seal natural fractures, adjust prepad fluid ratios, and inject multi-section silt slugs. The success ratio of volcanic rock gas reservoir fracturing is raised to 90.0% from the past 36.0%. Key words: volcanic rock reservoir, fractures, massive fracturing, control method