Understanding and application of reservoir pattern in braided river delta front:A case study of the Shahejie Formation in the east block of JX Oilfield
Many underwater distributary channels develop generally at the braided river delta front,which also controls the distribution of other microfacies,so it is important for well pattern deployment and oilfield management to determine the distribution and superposition of underwater distributary channels. The braided river delta front develops in the Shahejie Formation in the east of JX Oilfield. The channel sands overlay each other vertically and connect each other laterally because of swinging of underwater distributary channels. If the channel sands are in the same underwater distributary channel,they connect well with each other. If not,they are poorly connected. The pressure of oil well is low in the oilfield at present,but the injection well presents the appearance of overflowing,which seriously affects the development effect and reduces the recovery ratio. The distribution patterns of channel sands in underwater distributary channel that parallel with the provenance are determined through analyzing depositional marks,deposition characteristics and sand description by application of well and seismic combination,and they become thinner and change into mudstone finally. Channel sands in underwater distributary channel that perpendicular to the provenance deposit in parallel or overlay each other. Their thickness is characterized by thick-thin-thick and their lithology is characterized by sand-clay-sand. The results verified by dynamic materials are accurate and reliable. The development measures in the research area are adjusted based on distribution patterns of reservoirs,and finally has gotten much better results.