裂缝型碳酸盐岩应力敏感性评价室内实验方法研究

A STUDY OF LABORATORY METHODS OF EVALUATING THE STRESS SENSITIVITY OF FRACTURED CARBONATE ROCKS

裂缝是致密碳酸盐岩储集层中油气的主要渗流通道。在裂缝型岩石中 ,应力变化的影响主要体现在裂缝的形变上 ,一旦发生裂缝闭合 ,将会严重影响油气产量。因此 ,在实验室进行裂缝型岩石应力敏感性的研究 ,对保护储层 ,制定合理的生产方案是非常有意义的。本文利用裂缝型碳酸盐岩样进行了应力敏感性评价实验方法的初步研究 ,并且给出了应力敏感性的概念 ,提出了几种实验方法 ,并在进行理论分析和实验结果比较的基础上 ,确定了应力敏感性评价的实验方法。文中给出了实验设备、流程、实验步骤及实验结果分析 ,并得到一些初步结论 :应力与渗透率呈反比关系 ;裂缝渗透率急剧降低的临界压力约在 2 .5～ 3.0MPa左右。

The fractures are the main percolating channels of oil and gas in dense carbonate reservoirs.In fractured rocks,the change of stress is mainly reflected by the deformation of fractures.Once the fractures close,the oil and gas production will be seriously influenced.Therefore the study of the stress sensitivity of fractured rocks in laboratory is of great importance to protecting reservoirs and to drawing up a reasonable production plan.On the basis of entrusting a concept to the stress sensitivity and in light of a primary research on the laboratory methods of evaluating stress sensitivity by use of fractured carbonate rock samples,several laboratory methods are proposed and through a theoretic analysis and comparing the experimental results,the laboratory method of evaluating stress sensitivity is determined in the paper.The experimental facilities,flowsheet,procedure and results are given out and it is primarily concluded that the stress is inversely proportional to the permeability and the critical pressures of causing the fracture permeability to be rapidly reduced are about 2.5～3.0 MPa.Finally the methods of protecting reservoirs are proposed in the paper also.