Study On Determination Approaches Of Water Injection Rate Of Skewed Pattern With A Combination Of Horizontal And Vertical Wells

In recent years, with the improvement of the horizontal well drilling and completing technology, the production costs of horizontal wells have been substantially reduced, which drive the horizontal well injection and production technology developed rapidly. Compared with vertical wells, horizontal wells have significant advantages, and these are shown as follows. The contact range of wellbore and reservoir is increased and the drainable area is expanded, so the oil displacement efficiency and the oil recovery are improved. The reduction of the production costs and the existence of the advantages make horizontal wells widely used in the oilfield. For the secondary development, horizontal wells were arranged in some oilfield, based on the original vertical well net. It is really a problem confronted in water injection reservoirs that how to determine the water injection rate of this skewed pattern scientifically and rationally.In this paper, using the complex potential theory and the superposition principle, the study on the selected well groups which were horizontal well water flooding-vertical wells oil producing and vertical well water flooding-horizontal wells and vertical wells oil producing were made and the determination approaches of water injection in this two typical well groups were given. The study included the following aspects. (1) The distribution function of reservoir pressure field of skewed pattern which was a water-flooding system with a combination of single-tube waterflood in horizontal wells and oil production in vertical wells and the formula of waterflood efficiency were derived, and the determination approach of horizontal wells water injection in this skewed pattern was given. (2) The distribution function of reservoir pressure field of skewed pattern which was a water-flooding system with a combination of double-tube waterflood in horizontal wells and oil production in vertical wells and the formula of waterflood efficiency were derived, and the determination approach of horizontal wells inside tube water injection and outer tube water injection in this skewed pattern was given. (3) The distribution function of reservoir pressure field of skewed pattern which was a water-flooding system with a combination of waterflood in vertical wells and oil production in horizontal and vertical wells and the formula of waterflood efficiency were derived, and the determination approach of vertical wells water injection in this skewed pattern was given. (4) The software for determination of water injection rate in skewed pattern which was developed according to the above-mentioned approaches was applied to Gao246 Block in Liaohe Oilfield. At the same time, the single-tube rational water injection rate of horizontal well Gao2 Lian-H16 in Gao246 Block, the double-tube rational water injection rate of horizontal well Gao2 Lian-H16 in Gao246 Block and the rational water injection rate of vertical well Gao2-3-6 in Gao246 Block were determined.