Development of Nanofluid Slickwater System for Stimulating Mahu Tight Glutenite Reservoirs

The drag reducer of fracturing fluid in the tight glutenite reservoir of the Mahu Oilfield is a kind of anionic polymer, which is easily precipitated by the reaction with organic or inorganic positive ions in fracturing additives. The precipitations can easily block the pores of tight glutenite, and cause an abnormal pressure increase in the near-wellbore. It will be not conducive to the further extension of the fracture. In order to realize reservoir protection and promote crack propagation, a nanofluid slick water system with in-situ oil displacement ability was developed. Loop test and surface tension test were used to determine the optimal doses of each components in this system. Based on the field data and materials of Mahu oilfield, continuous shearing resistance, salt tolerance, solvency and wash oil ability of the nanofluid system were evaluated. The results show that, under the shearing rate of 1.2×10⁴s^-1, the drag reduction efficiency of the fluid is 78.92%. In addition, the nanofluid system can work well at the different salinity of the formation water of Mahu oilfield. At the same shearing rate, the drag reduction efficiency after 20 min shearing is still above 73%. What's more, the wash oil efficiency of the system is determined to be 93.3% by the Soxhlet extraction system with Mahu oil sand.