Reservoir Architecture of Braided River and Remaining Oil Distribution in YSM Oil Field

Abstract

As a case study, YSM oilfield has high water cut and high recovery factor. With various approaches, such as dynamic analysis, reservoir architecture study, simulation and well monitoring, the difference of seepage between planes, interlamination and interior layers can be evaluated, as well as the factors both from geological aspects, such as small structural high, updip sand pinch-out and fault sealing, and engineering aspects such as non-perforation, poor well status which impacted the formation and distribution of remaining oil. The research results suggest that the seepage flow difference is a critical geological factor for the formation and distribution of remaining oil. The vertical seepage to the upper inner differences make the remaining oil mainly distributed in the mid-upper sections of positive rhythm sands. And laterally, sand body splicing zone on plane and the marginal area of main sand body, normally the relatively low permeability area, the local micro tectonic highs and fault sealing affect the distribution of remaining oil in the oil spill area. The vertical distribution of remaining oil is affected by sedimentary rhythm, single sand bottom seriously flooded upper residual oil, residual oil in general oil sand top 1-2 meters. The coupling between geological factors, such as the scale and shape of the sand and the permeability difference between inter layers, and drilling factors such as well pattern design leads to uncompleted or inefficient injection and production pattern, which ends in a variety of remaining oil distribution patterns, such as the planar retention area, undeveloped reservoir and reservoirs with high pressure holding back.