Optimization of the Target Layer for Three-Dimensional Shale Gas Development in Weiyuan Block

Abstract

In order to explore whether the Weiyuan block can effectively carry out three-dimensional development well network deployment, we should first explore whether there is a target layer to meet the three-dimensional development. Based on three-dimensional geological, fracture and rock mechanics models, this paper finds that the absolute stress difference between Longyi14a minor layer and Longyi14b minor layer in the study area is less than 5 MPa, and there is no obvious stress isolation section, and the longitudinal distance of the upper part of Longyi14a minor layer from the top of Longyi11 layer distributes in the range of 18~28 m, which is able to effectively avoid strong inter-well interference with the horizontal wells of Longyi11 layer. So, according to the distribution characteristics of the remaining reserves and reservoir characteristics of Weiyuan block, Longyi14a minor layer is initially preferred as the target for three-dimensional development. In order to further explore the specific layers, based on the original three wells of H3 platform, four threedimensional development schemes with different target layers were designed, deploying L4 and L5 wells in the Longyi13 layer~Longyi14c minor layer, and the Longyi14a minor layer was confirmed as a three-dimensional development target layer system based on numerical simulation results. Finally, in the lower half branch of H3 platform, an “M” type three-dimensional well network pattern with five wells was adopted (three 4a wells of the lower layer Longyi11 layer L1, L2 and L3, and two wells of the upper Longyi14a minor layer - L4 and L5). The three-dimensional well network can increase production for the platform by 1.76×108 m3 and recovery increased from 14.3% to 29.3%, an overall increase of 15%. The relevant understanding can provide a reference for the three-dimensional development strategy of Weiyuan shale gas block.