Applying Horizontal Wells to Develop Oilfields with Complex Low Relief Structure in High Water Cut Stage in Tarapoa

Abstract The feasibility of horizontal well technology is analyzed for the M1 reservoir of the Tarapoa Block. Applying advanced location deployment technologies of horizontal well, and optimizing key parameters are aimed to expand the application scale of horizontal wells in the Tarapoa Block. The approach is based on the research of genetic model of lithologic reservoirs, reservoir distribution characteristics and remaining oil distribution. The successful application of using combined drilling and completion technologies is already confirmed, and methods are described which focus on key parameters for optimizing horizontal well drilling and completion technology. From 2006 to 2014, nearly 67 wells have been successfully put on production on Tarapoa Block. According to petrogenesis, remaining oil of micro-structural type and well pattern imperfect type in M1 sandstone are major potential areas of applying horizontal technology. Because most wells are in a high water cut phase with thin net pays and bottom water drive, the optimal horizontal segment position, horizontal section length and well flow regime, need to be studied in order to ensure its economic benefit. Studies suggest that the relative height of the horizontal section to avoid bottom water should be more than 70%. Due to the small size of the remaining microstructures for the M1 reservoir, the longer the horizontal section, the greater the difficulty for controlling the trajectory. Considering that the produced water needs to be treated, the initial fluid volume of the horizontal wells should be controlled. Horizontal well technology in the Tarapoa Block has been successfully applied. Horizontal wells have accounted for 44% of the production of all new wells during the period and production from horizontal wells is 2.75 times that of the directional wells. They play a key role in stabilizing oil production, slowing declines and maintaining water control.