Guo Zhi
Research Institute of Petroleum Exploration and Development, China
Title: Horizontal Well Geological Optimization in Tight Sand Gasfiled of Braided-river Facies
Biography
Biography: Guo Zhi
Abstract
Sulige gasfield is a typical tight sandstone gasfield of braided-river facies in China with features of poor reservoir property and strong reservoir heterogeneity. Horizontal well technology is an effective means to improve gasfield development effect. The control of braided-river system zones’ distribution on effective sand bodies was analyzed quantitatively, and the horizontal well geological target selection standards were formed respectively in superimposed zone and transitional zone of braided river system. Considering the poor applicability of conventional modeling method, a new modeling method is put forward called “multi-stage constraints, hierarchical facies and multi-step models”. The modelling method strengthens the prior knowledge control, reduces data interpretation uncertainty, and improves the model’s reliability. Based on the geological model, with 3D visualization technology, horizontal well were designed and well trajectories were optimized.It is pointed out that in superimposed zone, channel bars are developed with relatively high ratio and larger scale, similarly, effective sand bodies are enriched with massive and thick type. Thus, the horizontal wells there may be deployed uniformly with large-scale corresponding to straight or high angle trajectory. While in transitional zone, channel filling microfacies are more developed, and sand bodies are scattered and scarce, so horizontal wells there should be deployed cautiously with dessert type, and the well trajectory is mainly ladder type. This geological optimization process of horizontal wells, combining multidisciplinary data such as logging and seismic data, is more intuitive in image display, more convenient in data transmission and update, and improves the effective reservoir drilling rate up to over 70% from previous 60%. This research can play a more reliable geo-steering function for horizontal wells while drilling and can enhance horizontal well exploitation effect. Furthermore, it may provide rapid and accurate reference for gasfield development.