Distribution of Flow Characteristics and Productivity Evaluation of Herringbone Wells in Bottom-Water Reservoirs

Abstract

With the characteristics of large drainage area and low drilling cost, the herringbone wells are becoming a significant way to boost the well production, improve the dynamic flow profile, delay the coning of bottom water, and enhance the development effect. Due to the complex flow characteristics of herringbone wells, result in a disparity between expected and actual production, therefore, it is crucial to investigate the productivity and flow characteristics of herringbone wells. In this paper, taking into account the interference between branch wellbores and perforations, the herringbone wells productivity model in bottom-water reservoirs is derived, the flow characteristics and the productivity sensitivity factors are analyzed. The results indicate that the transient flow time in reservoir is brief and that pressure changes increase with proximity to the wellbore, the productivity declines as the production time increases and subsequently tends to a certain value, reaching a quasi-steady-state. The per unit length radial inflow of wellbore decreases as the branch length, branch angle, and the number of branches increase, however, the rate of decrease slows down when exceeding three branches. The phase angle has a larger effect on production in high anisotropy reservoirs, and the production is the highest at 180 deg phase angle. When the perforation density rises above 16 shots/m, the production increasing trend slows down. This study provides significant guidance for practical application in the oil fields, including optimizing the shape of herringbone wells, allocating production in a rational manner, defining appropriate work systems, and improving oil recovery in bottom-water reservoirs.