摘要
对于致密气藏而言,常规的Arps分析方法受到应用条件的限制,不适用于该类气藏。为此,考虑生产过程中气体PVT随压力变化和变流压生产的情况,提出了一种基于产量和压力相耦合的动态分析新方法。其步骤为:(1)根据产量和压力历史数据计算出拟压力标准化产量;(2)基于产量历史计算出物质平衡时间;(3)根据拟压力标准化产量和物质平衡时间得出标准化递减率;(4)由拟压力标准化递减率进一步计算出标准化递减指数。通过理论分析发现:(1)拟压力标准化的递减率与物质平衡时间呈幂指数关系;(2)由标准化递减指数的变化规律可以得出致密气藏气井的流动存在井筒储集及裂缝线性流(n=1左右)、线性流到拟径向流的过渡流(1<n<2)、拟径向流向边界控制流的过渡流(0.5<n<2.0)、边界控制流(n<0.5)等4个阶段。实例应用结果表明,分析结果与理论结果符合程度高,能够提高递减规律预测的准确性,表明新方法适用于致密气藏的动态分析,可为致密气藏开发提供可靠的分析手段。
The conventional Arps analysis method is not applicable to tight gas reservoirs due to its application condition restriction. In view of this, a new dynamic analysis method based on pressure and production coupling was proposed by taking into consideration the variable flowing pressure production and the variation of gas PVT with pressure during production. This method consists of four steps. First, calculate the pseudo-pressure normalized production rate based on historical production rate and pressure data. Second, ca!culate material balance time based on production history. Third, calculate the normalized decline rate by using the pseudo-pressure normalized production rate and the material balance time. And fourth, calculate the normalized decline index based on the pseudo-pressure normal- ized decline rate. Theoretical analysis indicates that there is a power exponent relation between the pseudo-pressure normalized decline rate and the material balance time. Besides, based on the variation rules of normalized decline index, the flow in tight gas wells is divided into four phases, i.e., wellbore storage and fracture linear flow （n=l or so）, transition flow from linear flow to pseudo-radial flow （l〈n 〈2）, transition flow from pseudo-radial flow to boundary-dominated flow （0.5〈n〈2.0）, and boundary-dominated flow （n〈0.5）. Practical application of this method shows that the actual results are highly accordant with the theoretical results and the accuracy of decline rule prediction is improved. It is indicated that this method is applicable to dynamic analysis of tight gas reservoirs, thus providing a reliable analysis means for the develolament of tight eas reservoirs.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2016年第8期88-93,共6页
Natural Gas Industry
基金
中国石油天然气股份有限公司科学研究与技术开发项目"长庆气田稳产及提高采收率技术研究"(编号:2011E-1306)
国家自然科学基金项目"缝洞性碳酸盐岩多段酸压水平井压力动态研究"(编号:51304164)
霍英东教育基金会高等院校青年教师基金项目"深层裂缝性致密油气藏复杂非线性渗流模型及非稳定态渗流特征研究"(编号:151050)
关键词
致密气藏
动态分析
耦合
拟压力标准化产量
物质平衡时间
递减率
新方法
Tight gas reservoir
Dynamic analysis
Coupling
Pseudo-pressure normalized production rate
Material balance time
Declinerate
New method
