裂缝发育碳酸盐岩气藏气井产能变化影响因素

应力敏感是影响裂缝发育碳酸盐岩储层气井产能的重要因素,目前大多基于岩心实验分析来描述其对产能的影响。针对含天然裂缝岩样取心难度大,以及不同裂缝发育岩心应力敏感实验结果存在差异等局限性,文中提出了利用试井动态模型预测气井产能的方法。首先,基于典型井试井解释成果,分析储层渗透率应力敏感性;其次,在利用实测产能对试井模型验证基础上,开展是否考虑应力敏感的产能试井设计;最后,根据预测结果定量分析产能变化影响因素。结果表明:地层压力下降是引起气井产能降低最主要的因素,但应力敏感的影响仍不可忽略,随气藏开采应力敏感影响逐渐减小。利用该方法可有效预测该类气藏气井产能。

Influence factors of deliverability change for gas wells in carbonate reservoirs with natural fractures

The stress sensitivity is an important factor which affects the deliverability of gas wells in carbonate reservoirs with natural fractures.At present,the influence of the stress sensitivity on deliverability is mostly based on the results of core experiment analysis.Considering the limitation of difficult coring for carbonate sample with natural fractures and the experimental results varying with different fracture development degree,the method of using the well testing dynamic models to forecast the deliverability of gas wells was presented.Firstly,using the well testing data of the typical gas wells,the permeability stress sensitivity was analyzed.Secondly,based on the reliability verification of pressure buildup testing model by the actual deliverability testing data,the deliverability testing design whether considering stress sensitivity or not was carried out.Finally,according to the forecasting results,the influence factors on deliverability change were quantitatively analyzed.The case study has indicated that the dropping of formation pressure is the primary factor which causes deliverability decreasing of gas wells,but the deliverability decline caused by stress sensitivity cannot be ignored.Furthermore,with the increase of producing time,the effect of stress sensitivity on deliverability is gradually reduced.This method can effectively predict the productivity of gas wells in carbonate reservoirs with natural fractures.