A new sinking agent used in water-control fracturing for low-permeability/bottom-water reservoirs: Experimental study and field application

Abstract

Abstract Hydraulic fracturing is widely applied in tight reservoirs for hydrocarbon recovery. However, as for bottom-water reservoirs, the created vertical hydraulic fractures can readily penetrate into the bottom-water layer, leading to a drastic increase of water cut when the pay-zones are too thin and the barrier lying between the pay-zone and bottom water are quite weak. In this work, a new sinking agent is used in hydraulic fracturing for water control in the low-permeability/bottom-water reservoirs. The settlement velocity and the plugging ability of this new sinking agent as well as the flow conductivity of the sinking-agent barrier is measured and compared with that of the other six commonly used sinking agents. We finally investigate the placement rule of the new sinking agent by varying the concentration of the carrying fluid and sand ratio in the modeling fracture. Filtration test show that this new sinking agent can form a barrier, which can strongly plug fracturing fluid. When the closure pressure range is in the range of 6.9 MPa–69.0 MPa, conductivity of the barrier formed by this new sinking agent is at a low level of 2.9 μm2 cm to 1.5 μm2 cm. With a given sand ratio and carrying-fluid concentration, the barrier formed in the fracture by the new sinking agent is more uniform than the other sinking agents. Based on the field application in a low-permeability/bottom-water reservoir, the usage of this new sinking agent increases oil recovery but decreases the water cut compared to other sinking agents.