缝洞型油藏注氮气吞吐效果影响因素分析

Analysis on Influential Factors of Nitrogen Huff and Puff Effect in Fracture- vug Type Reservoir

针对塔河缝洞型油藏的地质和渗流特点,利用数值模拟软件分析了油气两相的相态特征,得到注氮气非混相驱的驱油机理。通过地震、试井、测井等资料,建立数值模型,研究了地质和注氮气等参数对吞吐效果的影响。研究表明:地质参数中洞顶剩余油、充填程度、底水能量和井储关系对吞吐效果的影响很大;注氮气参数中,周期注氮气量是影响吞吐效果的主要因素,需要结合洞顶剩余油储量来具体优化;增加注氮气速度会增加气体的横向波及面积,对吞吐效果的影响存在最优值,而闷井时间和周期注水量对未充填溶洞的吞吐效果影响不大。研究结果初步形成了一种选井原则,对缝洞型油藏的增产稳产有一定的参考价值。

In view of the geologic and filtration characteristics of Tahe fracture- vug type reservoir,this paper used the numerical simulation software to have analyzed the phase behavior of oil and gas,and obtained the oil displacement mechanism of nitrogen immiscible flood. Based on seismic,well test and well logging data,this paper built a numerical model and studied the influence of parameters like geology and nitrogen injection on the huff and puff effect. The study results showed that among the geologic parameters,the ceiling remaining oil,filling degree,bottom water energy and wellbore storage relation had a very great influence on the huff and puff effect; among the nitrogen injection parameters,the cyclic nitrogen injection volume was the principal factor affecting the huff and puff effect,and needed to be specifically optimized based on the ceiling remaining oil reserve; the increase of nitrogen injection velocity could increase the lateral swept area of the gas,and had an optimum value affecting the huff and puff effect,whereas the well killing period and the cyclic water injection volume had little influence on the huff and puff effect of unfilled vug.A well selection principle has preliminarily been formed,which has certain reference value to the production increase and maintenance of fracture- vug type reservoirs.