CAJ | 학술논문

水平井经多段压裂后，其表皮系数通常为负值。现有的多段压裂水平井渗流模型均利用 Duhamel 公式考虑表皮系数，然而，Duhamel 公式仅能处理正表皮水平井，计算的负表皮渗流特征曲线振荡，无法反映真实的压力动态特性。针对这一问题，通过引入类似于直井的表皮系数做为渗流模型新变量，重新定义了无因次距离、无因次储层厚度等模型参数，建立了均质无限大油藏负表皮多段压裂水平井不稳定渗流新模型；利用正交变换法进行求解，获得了模型在时空间的压力解析表达式；再将实空间的解转换到 Laplace 空间下考虑井筒储集系数的影响；最后利用 Stehfest 数值反演绘制了多段压裂水平井负表皮压力动态特征曲线，曲线不再振荡，能够真实反映负表皮渗流特性，成功解决了现有理论模型与实际情况不相符的问题。研究的新模型可同时计算负表皮压力动态特征曲线和正表皮压力动态特征曲线，因此，不仅可用于多段压裂水平井渗流特征分析，还可应用于多段压裂水平井实测压力资料的试井解释。
수평정경다단압렬후，기표피계수통상위부치。현유적다단압렬수평정삼류모형균이용 Duhamel 공식고필표피계수，연이，Duhamel 공식부능처리정표피수평정，계산적부표피삼류특정곡선진탕，무법반영진실적압력동태특성。침대저일문제，통과인입유사우직정적표피계수주위삼류모형신변량，중신정의료무인차거리、무인차저층후도등모형삼수，건립료균질무한대유장부표피다단압렬수평정불은정삼류신모형；이용정교변환법진행구해，획득료모형재시공간적압력해석표체식；재장실공간적해전환도 Laplace 공간하고필정통저집계수적영향；최후이용 Stehfest 수치반연회제료다단압렬수평정부표피압력동태특정곡선，곡선불재진탕，능구진실반영부표피삼류특성，성공해결료현유이론모형여실제정황불상부적문제。연구적신모형가동시계산부표피압력동태특정곡선화정표피압력동태특정곡선，인차，불부가용우다단압렬수평정삼류특정분석，환가응용우다단압렬수평정실측압력자료적시정해석。
The skin of a horizontal well after multi-stage fracturing usually has a negative value.All the existing models of multi-ple fractured horizontal wells used the Duhamel formulation to consider skin factor.However,the Duhamel formulation can only deal with positive skin.The negative skin type curves using the Duhamel formulation were oscillating,so that the type curves could not reveal the real pressure dynamic characteristics.To address the problem,we introduced a skin factor that is similar to the vertical well skin as a new variable.The dimensionless model parameters,such as the dimensionless distance and the dimen-sionless formation thickness,were redefined,and then a new model of multiple fractured horizontal wells with negative skin was established for infinite homogenous reservoirs.The model was solved using orthogonal transformation,so the analytical solution expressions in real space were obtained.The solutions in real space were converted to the Laplace space to consider the wellbore storage coefficient.As a result,the pressure dynamic curves of multiple fractured horizontal wells with negative skin were plotted using Stehfest numerical inversion.The curves did not oscillate and could reveal the real flow characteristics of negative skin hori-zontal well.Therefore,the problem that theoretical models did not match the real conditions was solved.Both negative and posi-tive pressure dynamic curves can be calculated using the researched new model,so it not only can be applied to the flow character-istics analysis of multiple fractured horizontal wells,but also can be applied to the well test interpretations of multiple fractured horizontal wells with real testing pressure data.