摘要
四川盆地碳酸盐岩储层大多埋藏较深,溶洞和裂缝发育。裂缝开度低且溶蚀孔洞之间多为细小喉道沟通。在衰竭式开采过程中,伴随着储层流体压力减小,净应力增大,岩石孔洞缝连通空间受上覆压力影响逐渐被压缩,流体流动能力降低。裂缝作为主要的渗流通道,其闭合将更大地影响流体的渗流能力。该类气藏储层地层压力和温度较高,进行储层流体渗流机理室内实验较为困难。为此,国内有些学者尝试用非地层温度和压力条件下的渗流实验结果进行相似性推导得到地层条件下的实验结果,并以此来提出指导实际生产的建议。然而除了受净应力影响以外,地层中流体所处的压力、温度、密度、黏度等都会对渗流产生不同程度的影响,因此必须开展地层条件下的实验才能真实反映气相的渗流情况。通过开展川中LY碳酸盐岩缝洞型气藏地层条件下应力敏感实验,并对比分析不同应力敏感系数下产能变化的情况发现,采用真实地层条件下得到的应力敏感系数与常规实验的结果差异明显,如果按常规应力敏感实验的结果指导生产,可能会误导生产措施的制定,带来不可挽回的后果,因此有必要开展缝洞性碳酸盐岩储层应力敏感实验研究,才能为渗流特征和生产动态研究提供更为准确的参考依据。
In Sichuan Basin, majority of carbonate reservoirs developed with dissolved pore and fracture are of great burial depth. In these reservoirs, the fracture opening is low and the dissolved pore is mainly connected through fine throat. During their depletion development, with a decrease of reservoir-fluid pressure and an increase of net stress, the pore-fracture connecting space among rock may be gradually compressed under overburden pressure, and the fluid-flow capacity may be reduced. Moreover, for fracture as the main flow channel, its closure has a greater effect on this capacity. Its’ difficult to carry out its mechanism experiment since these reservoirs are of high formation pressure and temperature. So, domestic scholars carried out similarity deduction on flow experiments under non-formation temperature and pressure to achieve results under formation condition, and accordingly made some suggestions to guide production. In addition to net stress, however, the formation-fluid pressure, temperature, density, and viscosity may affect the flow more or less. Therefore, it’s necessary to implement other experiments under formation condition to truly reflect gas seepage. In this paper, several experiments on stress sensitivity under formation condition were carried out for LY fractured-vuggy carbonate gas reservoirs, central Sichuan Basin. And productivity changes under different stress-sensitivity coefficients were compared and analyzed. Results show that these obtained coefficients under real formation condition are quite different from others from conventional experiments. And if these experimental results of conventional stress sensitivity used to guide production and formulate production measures may be mislead, furthermore irreversible consequences may happen. Therefore, it’s essential to carry out stress-sensitivity experiments on fractured-vuggy carbonate reservoirs in order to provide more accurate reference to make clear flow characteristics and production performance.
作者
鄢友军
刘义成
徐伟
邓惠
罗文军
Yan Youjun;Liu Yicheng;Xu Wei;Deng Hui;Luo Wenjun(National Energy R&D Center of High-Sulfur Gas Exploitation,Chengdu,Sichuan 610041,China)
出处
《天然气勘探与开发》
2020年第1期52-57,共6页
Natural Gas Exploration and Development
基金
中国石油重大科技专项“西南油气田天然气上产300亿立方米关键技术研究与应用”(编号:2016E-0606)。
关键词
缝洞型
碳酸盐岩
地层条件
应力敏感实验
渗流能力
Fractured-vuggy
Carbonate rock
Formation condition
Stress-sensitivity experiment
Flow capacity
