Study On Downhole Oil/Water Separation Technique In Bottom Water Drive Reservoirs

Downhole oil/water separation (DOWS) technique in the bottom water drive reservoirs, which offers both economical and environmental benefits, can greatly reduce the costs of lifting and treating of the produced water, and extend the economic service lives of oil well with high water cut, by directly reinjecting the partly of produced water into the bottom water formations of the identical oil well. This paper adopt theoretical investigation, physical modeling and numerical simulation three approaches to study on the feasibility and availability of partly produced water reinject into the bottom water formations of the reservoir after the DOWS separated. On the base of wide-ranging document retrieval, this paper study on the exploitation characteristic of bottom water drive reservoir, the bottom water coning mechanism, the common computing methods, the major affecting factors and the common approaches about controlling bottom water coning. Then calculate the distribution of pressure near well bore, and combine with laboratory experiment physical modeling and numerical simulation, analysis the pressure distribution near well bore which impacted by reinjected water, to verify the feasibility and availability of partly produced water reinject into the bottom water formations of the reservoir after the DOWS separated. The three methods findings are as follows: the DOWS technique is applicable in bottom water drive homogeneous reservoirs, and the injection interfere with the production zone faintly and no malignant water flooding occur. Since the baffle can reduce the layer water rate when in low-water cut stage and develop the water free oil production, the technique of reinjection and lifting in the same well can reduce the surface water rate and extend the oil production period in the later stage which produce high water cut, in case of combine with inject chemical form artifical baffle, the technique of reinjection and lifting in the same well will be much effective to enhance the recovery ratio in the bottom water drive reservoirs.