A Sand Control Downhole Fracturing Technique for Tight Reservoir Development in the Ordos Basin

Reservoir formations in Ordos Basin are tight and exhibit complicated features. Under such circumstances, conventional stimulated reservoir volume (SRV) fracturing could hardly produce desirable fracture networks, without which productivities of individual wells were low. To enhance productivity, innovative down-hole fracturing techniques with sand control were introduced. With the development of fit-for-purpose down-hole sand-mixing tools, full-scale simulation tests were performed on surface to determine optimal fracturing parameters. The innovative fracturing techniques may be deployed to control concentrations of sands at wellbore in real time to generate proppant networks in newly-formed fractures and to enhance complexity of fracture networks. These new techniques have been deployed successfully for fracturing operations in 30 wells in Ordos Basin with maximum sand concentration of 1 800 kg/m3 (20/40 mesh quartz sand with volume density of 1.62 g/cm3 and density of 2.64 g/cm3). Compared with oil producers fractured by using mixed water, producers fractured by using these innovative techniques have average productivity enhanced significant with reduction of hydraulic power and fluid volumes for approximately 1/3. In this way, operation costs were reduced dramatically. On-site application results showed the newly developed fracturing techniques with down-hole sand control could effectively enhance net pressures in fractures of tight reservoirs, promote complexity of fracture networks, improve the properties of tight oil-bearing formations and enhance the productivity of individual wells.