致密油储层可动流体饱和度计算方法——以合水地区长7致密油储层为例

A method of determining movable fluid saturation of tight oil reservoirs: A case study of tight oil reservoirs in seventh member of Yanchang Formation in Heshui area

喻建 杨孝 李斌 刘小静 田建锋

Yu Jian Yang Xiao Li Bin Liu Xiaojing Tian Jianfeng

中国石油 长庆油田分公司 油藏评价处, 西安 710021 2. 西安石油大学 地球科学与工程学院, 西安 710065

Reservoir Evaluation Office, PetroChina Changqing Oilfield Company, Xi'an, Shaanxi 710021, China 2. School of Earth Sciences and Engineering, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China

致密油储层可动流体饱和度是评价致密油潜力的关键因素之一。核磁共振技术可以获得准确的可动流体饱和度,但因其成本较高、周期较长,应用的普遍性受到限制。核磁共振、恒速压汞和高压压汞的实验原理表明,T2谱、恒速压汞曲线和高压压汞曲线均是岩石孔隙结构的反映,他们之间具有内在的一致性。相同样品的核磁共振和恒速压汞测试结果表明,致密油储层可动流体饱和度与恒速压汞总进汞饱和度相关性极强,可通过恒速压汞总进汞饱和度参数计算致密油储层的可动流体饱和度,而高压压汞7.0 MPa时的进汞饱和度与恒速压汞总进汞饱和度相同,从而提出了利用高压压汞资料计算致密油可动流体饱和度的方法。计算结果表明,合水地区致密油储层可动流体饱和度较高,以Ⅲ类和Ⅳ类储层为主,其次为Ⅱ类储层。

The movable fluid saturation is one of the key factors in tight oil evaluation, and can be tested accurately by nuclear magnetic resonance (NMR) technology. The high cost and long cycle prohibited the widespread use of NMR technology to determine movable fluid saturation. The testing principles of NMR, constant-speed mercury injection and high-pressure mercury injection indicated that the relaxation time distributions, constant-speed mercury injection curves and high-pressure mercury injection curves are the reflections of pore structures and have the ingenerate consistency. The movable fluid saturations and total mercury saturations of the same samples were tested by NMR and constant-speed mercury injection respectively. Correlation between the movable fluid saturation and the total mercury saturation was closely strong. The movable fluid saturation can be calculated from total mercury saturation. Considering the similarity between total mercury saturation of constant-speed mercury injection and mercury saturation at 7.0 MPa of high-pressure mercury injection, a method to determine movable fluid saturation of tight oil reservoirs was proposed based on high-pressure mercury injection data. The calculation results indicated that the tight oil reservoirs, with high movable fluid saturation, are mainly type-Ⅲ and type-Ⅳ reservoirs, followed by type-Ⅱreservoir.

国家自然科学基金项目(41202105) 资助。

https://doi.org/10.11781/sysydz201406767