Fine Characterization of High Productivity Channel Zone of Braided River Sedimentary Reservoir and Its Application

Abstract

The tight sandstone gas reservoir in the H formation of the block in the Sulige gas field in Ordos Basin is braided river delta plain deposit. The reservoir sand body changes rapidly laterally and develops vertically in multiple thin layers, the block is difficult to be economical and effective developed. In order to achieve effective and large-scale development of the gas reservoir, based on the comprehensive study of reservoir sedimentary microfacies, the genetic types of reservoir sand bodies are defined, and the identification criteria of single sand bodies in the H formation of the block in the Sulige gas field is established. Reservoir sand bodies are divided into four structural types which are massive thick layer, multi zone stack, thin bedded alternation and isolated type. According to the comprehensive evaluation of reservoir sand bodies with different structures, the identification criteria of high productivity channel sand bodies in the H formation of the block in the Sulige gas field is established. The massive thick layer and multi zone stack sand bodies have good reservoir quality and high gas productivity. They are both high productivity channel sand bodies in the H formation of the block in the Sulige gas field. The fine comparison of the reservoir sand bodies with different structures is realized by comprehensive contrast method, cross-section shape identification method and sedimentary microfacies identification method, and the sand body occurrence is quantitatively determined by combining three-dimensional seismic data. The width of channel sand body in the H formation of the block in the Sulige gas field is mainly 1.0–5.1 km. On the basis of fine reservoir comparison and quantitative characterization of sand bodies, the dynamic parameters of gas reservoirs are used to continuously modify the shape and boundary of high productivity channel, the three-in-one high productivity channel zone identification technology which includes geological identification, seismic prediction and gas reservoir dynamic correction is formed. Four different deployment modes which includes the horizontal well stereoscopic deployment, large cluster mixed well group deployment, large cluster horizontal well group deployment and the large cluster deployment of vertical and directional well groups are established. It improves the pertinence and applicability of well location deployment. The productivity ratio of horizontal wells is more than 70%, high-efficiency and large-scale production has been realized. The proportion of medium and high production vertical wells has been increased by 10%, and the development effect of gas field has been significantly improved.