摘要
多层合采是纵向发育多个层系储层的常用开发手段，碳酸盐岩气藏孔￣缝￣洞发育复杂，导致其合采机理不明确、常规手段评价合采效果难度大。因此，采用新方法评价其多层合采机理及潜在干扰因素具有重要的理论与现实意义。文中基于多松弛格子玻尔兹曼方法（MRT￣LBM），通过追踪合采过程的流线分布，量化评价了不同孔￣缝￣洞配置储层的合采效果。研究结果表明：裂缝￣孔洞合采的层间非均质性最大，裂缝层对产量贡献很小，裂缝￣缝洞合采与缝洞￣孔洞合采的层间非均质性相对更小，两层基本可以实现均衡开发；增加生产压差，合采气层的产量比降低，一定程度有助于低渗产层的气体产出，且生产压差对非均质性强的合采组合敏感性更强；当合采层间的压力梯度差值为0.02 MPa/m时，低压层的稳定倒灌量可能达到高压层的1/8；如果层间非均质大且低渗层初始压力更低时，发生倒灌的可能性更大。研究成果可以为不同孔￣缝￣洞发育的碳酸盐岩气藏多层合采提供理论支撑。
Abstract
Multi-layer commingled production is a popular method for the development of multi-layer reservoir. The occurrence of pore-fracture-cave in carbonate gas reservoir is complex, which results in the uncertainties of commingled production mechanisms and difficulties in evaluation of commingled production performances using conventional methods. Therefore, it is of great significance both in theoretically and practically to understand the multi-layer commingled production mechanisms and the potential interferences by using new method. In this work, based on the multi-relaxation lattice Boltzmann method （MRT-LBM）, through tracking the distribution of streamlines, the commingled production performances of reserviors with different pore-fracture-cave configurations are quantified. The results show that the inter-layer heterogeneity of fracture and pore-cave layer is highest compared with the other two cases, which results in small gas production of the fracture layer. The fracture and fracture-cave layer have relatively small inter-layer heterogeneity with fracture-cave and pore-cave layer, and the two layers can be recovered evenly. With the increase of production pressure difference, the gas production ratio of commingled production layer decreases, which facilitates the gas recovery in the production layer with lower permeability. The commingled production configuration with strong heterogeneity is more sensitive to the production pressure difference. If the pressure gradient difference between the two layers is 0.02 MPa/m, the backflow volume in the low pressure layer can be 1/8 of the production in the high-pressure layer. If the inter-layer heterogeneity is strong and the layer with low permeability has lower initial pressure, the possibility of backflow is higher. This work can provide theoretical support for the commingled production of multi?鄄layer carbonate reservoirs with complex occurrence of pore-fracture-cave.
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