Transient Productivity Analysis and Completion Parameter Optimization of Perforating Herringbone Wells.

Herringbone wells are of great significance in tapping the potential of remaining reservoirs, improving recovery efficiency, and reducing development costs and have been widely used in oilfields, especially offshore oilfields. Due to the complex structure of herringbone wells, there is mutual interference between wellbores during seepage, resulting in complex seepage problems, and it is difficult to analyze the productivity and evaluate the perforating effect. In this paper, considering the mutual interference between branches and perforations, a prediction model of transient productivity of perforated herringbone wells was derived based on the theory of transient seepage, and the complex structure with any number of branches, arbitrary configurations, and orientations in three-dimensional space could be considered in this model. The formation pressure in reservoir points at different production times, IPR curves, and the radial inflow of herringbone well were studied by the line-source superposition method, which directly reflected the process of productivity and pressure change, avoiding the one-sidedness caused by using a point source to replace the line source in the stability analysis. Then, through the productivity calculation of different perforation schemes, the influence curves of perforation density, perforation length, perforation phase angle, and perforation radius on unstable productivity were obtained. Orthogonal tests were performed to obtain the degree of impact of each parameter on productivity. Lastly, the selective completion perforation technology was adopted. When the shot density at the end of the wellbore was increased, the productivity of herringbone wells could be improved economically and effectively. According to the above study, a scientific and reasonable construction scheme is recommended for oil well completion construction, which provides a theoretical basis for the improvement and development of perforation completion technology.