Volumetric Fracturing with Mixed Water in Tight Gas Reservoirsin the Hangjinqi Block

The goal of the study was to develop best practices for hydraulic fracturing in the complicated mixed water conditions in the tight gas reservoirs of the Hangjinqi Block. The study was necessary due to challenges such as poor physical properties, limited fracture length to cover reservoir stimulation volume, and low initial post-frac production in the tight gas reservoirs of Hangjinqi Block in the Ordos Basin. In viewing of those challenges and combining with reservoir geological characteristics of the lower Shihezi Formation within the block, key factors affecting volumetric fracturing with mixed water were analyzed, fracturing fluid system selected, and the optimization on the pumping flow rate and operation scale carried out to establish volumetric fracturing technology suitable for the tight gas reservoirs in Hangjinqi Block. In this technology, different types of fluids such as slick water, linear gel and cross-linker for the alternative fracturing are adopted, and forms high-conductive main fractures and complex branched fractures while opening the natural fractures in the reservoir to realize 3D stimulation. This technology has been applied in 5 wells in the block with average open flow capacity 13.2×10⁴m³/d. The research showed that this technology can help in solving the problems of non-sufficient reservoir stimulation volume from limited single fracture length and low post-fracturing production, and it demonstrates a good potential for further development of standard application practices.