Abstract

X basin was located in the eastern China with diverse types and complex structures, is dominated by algal dolomite. The formation charactristers are summarized as following: high temperature from 180 °C to 230°C(quick acid reaction) and ultra-low porosity and permeability(less than 10% and 0.1md), high in-situ stress(>90MPa), high leak-off and because of natural fracture networks which making fracture encounted many problems. This paper presents a new type of synthetic anionic terpolymer gelatinizer and the related influencing factors were studied including a new polymer and a new crosslinking. During the development process of synthetic polymers, the monomer selection, synthesis processes and other conditions directly affect temperature resistance capability of the polymer fracturing fluid. Furthermore, the optimal reaction conditions of polymer thickener with high temperature resistance capability are acquired through "single-factor method", obtaining high temperature polymer thickener with certain temperature resistance capability. Moreover, the temperature resistance, shear resistance and gel breaking performance of cross-linked fracturing fluid were also investigated which shear viscosity was retained more than 150 mPa.s at 220 °C sheared at 170s-1 for 120min. The pilot and production of polymer gelatinizes was carried out and the results showed that new polymeric fracturing fliud system overcomes the thermal limitations of traditional guar. The post-fracturing rate is encourge with 80m3/d oil and 10×104m3/d gas, respectivity. The new fracturing fluid provides a new way to improve production in HTHP reservoirs.

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