常规定向井表皮系数的分解方法及其应用

Application of Decomposition Method of Skin Factor for Conventional Directional Wells

表皮系数是评价油气井近井地带污染程度及储层伤害的一个重要技术指标,通常由不稳定试井方法得到,但不稳定试井方法得到的表皮系数是与射孔打开程度不完善、井斜及地层污染等多种因素有关的总表皮系数,若仅以总表皮大小制定增产措施方案,则往往会导致酸化解堵后效果不佳的问题。本文通过对W油田B04井两次测试的总表皮系数进行分解,确定酸化后油井的污染表皮系数由18.8降低到5.3,表明酸化有效改善了井筒的完善程度,目前的表皮系数主要为产气量增大所致,理清了产生地层污染的原因,避免了因对试井解释总表皮系数的片面认识而进行的盲目作业,为以后的增产措施设计提供了参考,从而提高了油田措施的成功率。表皮系数分解方法在W油田应用后,找出了油井多次酸化效果不佳的原因,为后续同类油井或类似油田酸化作业提供了依据,明确了表皮系数的具体构成因素,对类似油田或油井增产措施评价具有明显的指导意义。

Skin factor is an important technical index for evaluating pollution levels near wellbore area of oil and gas wells and reservoir damage.It usually known by the unstable well test method is the total one related to insufficient perforating open degree,hole deviation and formation pollution and other factors.If the stimulation is made only by the total skin factor,it often leads to the poor effect after acidizing for plugging removal.In this paper,the total skin factor of Well B04 in Oilfield W was decomposed for two tests,and it was determined that the pollution skin factor of oil wells after acidification decreased from 18.8 to 5.3,indicating that the acidification effectively improved the degree of wellbore completion.The current skin factor mainly results in the increase of gas production,and the cause of formation pollution is clarified.It avoids the blind operation due to the one-sided understanding of the total skin factor of well test interpretation,and provides a reference for the design of stimulation in the future,thus improves the success rate of oilfield measures.After the decomposition method of skin factories applied in Oilfield W,the reason for the poor acidification effect of oil wells was found out,and it provides foundation for subsequent acidification in similar oil wells or oilfields.The specific components of skin factor are clarified,which has obvious guiding significance for the evaluation on the stimulation in similar oilfields or oil wells.