Research and Practice of Deep Profile Control in a High Temperature, High Salinity, and Large Well Spacing Reservoir

Controlling the deep profile of oil reservoirs with high temperature, high salinity, and large well spacing has always been challenging. In response to the technical requirements faced by deep profile control in such reservoirs, research has been conducted, including the development of temperature-resistant and salt-tolerant agents, optimization of target well groups, and optimization of injection process parameters. Based on the physical intercalation blending theory, a pre-crosslinked gel particle was synthesized with acrylamide (AM) monomer, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) monomer and montmorillonite as the main materials. The particle exhibits high temperature resistance (120 ℃) and high salt tolerance (200,000 mg/L). With an adjustable particle size (μm-cm) and density (1.05–1.18 g/cm3), the gel particles has good adaptability. The screening principles for the target well group of profile control in large well spacing reservoirs (average 700 m) were established to guide the optimization of the target well group. Methods for optimizing the injection process were proposed, such as increasing the radius of the profile control treatment, adjusting the particle size and concentration of the profile control agent in real-time during the injection process, and adopting alternating positive and negative injection for horizontal wells to avoid blockage in the horizontal section. The injection of 7 well groups in Reservoir D was completed in two stages, with technical success rate of 85.7%. It achieved a cumulative increase of 72,800 tons of oil during the evaluation period, and a longest validity period lasted for 36 months. The profile control trials in a sandstone reservoir provides a good case for improving the water injection sweep efficiency of similar reservoirs.