Research On Numerical Simulation Of Directional Perforation In Coalbed Methane Horizontal Wells

The Shouyang block is located at the northern of the Qinshui coalfield.The 15~#coal seam is a stable and recoverable high-rank coal reservoir in the region.The thickness of the coal seam is thinner,the modulus of elasticity is low,the Poisson’s ratio is high,and the difference of ground stress is small.In the earlier period,a lot of vertical well fracturing was carried out in this coal seam.According to the data analysis:the heterogeneity of stress and permeability,the development of the crack in the coal seam,resulted in complex fracture patterns and did not form a large-scale reservoir reconstruction effect.For the development of CBM,horizontal well multi-stage fracturing technology has obvious advantages such as higher economic efficiency,improving conductivity,and increasing desorption area compared with conventional vertical well fracturing technology.At the same time,directional perforation technology can reduce perforation pressure,increase the area of oil and gas discharge and improve the effect after fracturing by perforating in the easiest fracturing direction.Therefore,combining the horizontal well multi-stage fracturing technology with the directional perforating technology,optimizing the construction according to the reservoir characteristics and geological conditions,can achieve the purpose of efficient development of CBM in the Shouyang block and a significant increase in production.This paper takes Shouyang area as the research object,putting forward directional perforation technology of horizontal well in CBM.Then,using the comprehensive judgment method to analyze the Kaiser effect rock acoustic emission experimental results,and combining with viscous residual magnetic method(VRM)to determine the size and direction of the in-situ stress at the Shouyang block sampling points.On the basis of that,taking the sampling point as the constraint condition,the in-situ stress field in Shouyang block is retrieved by Abaqus finite element software.Finally,based on the Abaqus/Standard module,an XFEM model of horizontal well perforating was established,and the entire dynamic process of horizontal multi-stage fracturing was numerically simulated to analyze the initiation,propagation,and final morphology of fracturing cracks,study the application of directional perforation technology of in this block.