Dynamics of Water Sighting and Injection Mechanisms in Fishbone Branch Wells in Bottom Water Reservoirs

Abstract

Herringbone wells are effective in improving productivity for bottom water reservoirs; however, the main problem faced in the exploitation of bottom water reservoir is the ridge and cone of bottom water during the process of waterflooding, which leads to the decline of oil production. Therefore, predicting the breakthrough time and location of herringbone wells in bottom water reservoirs and then adjusting the water injection measures are of great significance for improving production and development. In this paper, we establish a three-dimensional coning model of bottom water to study the dynamic performance of bottom water rise, and the sequence of breakthrough position is determined by studying the breakthrough time along the wellbore. Based on the reservoir numerical simulation, we carry out a comprehensive adjustment of the water injection mechanism and develop a water injection scheme under the combination arrangement of vertical wells and herringbone wells. The results show that the bottom water breakthrough position of the branch well is mainly near the heel of the main branch or near the middle subsidence, and the recovery rate is the highest when the branch angle is 45 deg. The longer the shut-in time, the higher the recovery. The study is of great significance to optimize the layout and spatial structure, determine a reasonable working system, delay water channeling, and increase the cumulative production of herringbone wells.