Research and application of distribution characteristics of depositional sand bodies in delta-front facies under the condition of large area dense well pattern

Abstract

Geological reserves in sedimentary unit of small channel sand developed in Gaotaizi reservoir cover 38% of their proved reserves, about 50% of penetration wells are perforated, most of the oil is not recovered, it seriously affects the development effect, in order to produce remaining oil, increase reservoir producing degree, and realize Gaotaizi reservoir fine potential tapping. This paper researches distributing feature of sedimentary sand bodies of in Gaotaizi reservoir and water control and the method for potential tapping by sue of core data and abundant well logging curves, based on analysis of sedimentary facies and logging facies, boundaries of sedimentary units of Gao I reservoir group 1-9 are unified through stratigraphic correlation. The microfacies of the studied area are divided into such three types: subaqueous distributary channel microfacies, sheet sand and subaqueous interdistributary channel microfacies. Based on the detailed study of reservoir thickness, logging curve features, lithologic character, sandbodies and depositional genesis, subaqueous distributary channel and delta front sheet sand microfacies are subdivided into 4 relatively homogeneous units, so as to further reveals the channel sand and sheet internal heterogeneity. Six plane maps sedimentary microfacies of the studied area are drew. It reveals connecting relation of sandbody and describes the sandstone distribution, which can establish geological foundation for identification of high water channel, analysis of injection - production problem and development adjustment scheme design. These methods are used to guide for water control and potential tapping, and the obvious effect of stabilizing oil production by controlling water-cut is shown.