Study of a low-damage and efficient-imbibition fracturing fluid for tight oil fracturing-oil displacement integration

Traditional hydraulic fracturing techniques have long been criticized for their deficiencies, including low recovery efficiency, rapid production decline and complex processes. In order to overcome these shortcomings, fracturing-oil displacement integration has been proposed and attracted great attention in the past few years. In this study, a novel hydrophobically associating polymer (HETP) was synthesized and used as an additive to develop a low-damage and high-efficiency imbibition fracturing fluid that meets the fracturing fluid requirements in fracturing-oil displacement integration. A series of experiments were conducted to systematically study and evaluate the properties of the HETP fracturing fluid, including rheology, shear recovery, proppant transport capacity, gel-breaking performance, oil imbibition efficiency, and formation damage rate. The rheology test results showed that the viscosity retention rate of the fracturing fluid was 100.44% at 100℃. The performance tests demonstrated that the HETP fracturing fluid exhibited superior shear recovery and proppant transport capabilities. The evaluations of the broken fluids showed that the HETP fracturing fluids can effectively alter formation wettability, and can promote oil-washing efficiency and emulsifying ability. The spontaneous imbibition test results showed that the broken HETP fracturing fluid exhibited excellent general performance, with a low formation permeability loss of 8.12% and a high imbibition enhanced oil recovery (IEOR) rate of 36.4%, surpassing other molecular fracturing fluids. The oil recovery mechanisms of the HETP factoring fluid are also discussed in details, implying that HETP has enormous potential for future tight oil development.