The Study Of Inflow Performance Relationship In Multi-layer Commingling Development

Coalbed methane reservoirs are usually developed in multi-layers commingling.The coalseam are pressure sensitive, makes a gas well easy to collapse near the bottom of the well inthe production process, and gas wells can not achieve long-term high-yield production.Therefore, the study of IPR in multi-layers commingling wells as well as the variation ofdownhole pressure and gas production, in order to effectively control the downhole pressurefluctuations and production rate, avoid seam destruction, is critical important to maintain ahigh-yield gas CBM wells important, long-term and stable production.In this paper, through a large number of literature investigation, the current domesticCBM research situation was presented, including the coalbed methane accumulation andrecovery mechanisms. Based on the analysis of influencing factors on commingled productionof multiple coal seams, and different percolation mechanisms between coal seam andconventional gas reservoirs, characteristics of bottom hole inflow performance curve ofcommingled production well were summarized. At the same time, using the research methodsof inflow performance of multilayer reservoirs at home and abroad for reference, andconsidering the matrix shrinkage effect and the effective stress’s influence on permeability,three concept models of single, dual and triple coal bed methane reservoirs were builtutilizing Eclipse, and the production and bottom-hole flowing pressure data were obtained,thus commingled production well’s inflow performance curve were plotted, and thecharacteristics of IPR curves were analyzed. In order to make the model and dynamic datamore representative, the ranges of fracture permeability, porosity, Langmuir pressure, theLangmuir volume, CBM parsing time are based on the actual data of Hancheng blocks andother domestic CBM fields. In additon, the influence of fracture’s permeability and porosityon commingled production well’s IPR curve were analyzed.