致密储层样品体积测量对孔隙度误差的影响

Influence of bulk volume measurement on porosity error in tight reservoir core plug analysis

陈思宇 田华 柳少波 李才喜 郝加庆 郑永平

Chen Siyu Tian Hua Liu Shaobo Li Caixi Hao Jiaqing Zheng Yongping

中国农业大学, 北京 100083 2. 中国石油天然气集团公司 盆地构造与油气成藏重点实验室, 北京 100083 3. 中国石油勘探开发研究院, 北京 100083 4. 北京信桥恒达环保股份有限公司, 北京 100080

China Agricultural University, Beijing 100083, China 2. Key Laboratory of Basin Structure and Hydrocarbon Accumulation, CNPC, Beijing 100083, China 3. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China 4. Beijing Bridge Information Ltd, Beijing 100080, China

非常规油气致密储层孔隙度较低，一般小于10%，页岩储层甚至小于5%，常规方法对这类岩石样品孔隙度测定误差近来受到关注。针对常用的孔隙度测量方法（氦气注入法），对致密储层和常规储层样品建立了孔隙度测量误差计算数学模型，统计样品体积测量的误差来源和误差限，结合数学模型和统计结果，确定孔隙度误差限。研究得出以下结论：①采用游标卡尺测量的致密储层孔隙度绝对偏差为0.59%~2.47%，高精度三维扫描方法孔隙度测量绝对偏差可以减小到0.38%~1.04%，与常规储层不同，致密储层需提高孔隙度测试精度并进行误差分析；②不同精度的测量方法均很难达到行业标准规定（孔隙度绝对偏差小于0.5%），建议将孔隙度误差质量控制标准降低，即孔隙度绝对偏差放宽到小于1%，并给出了相应的体积测量误差要求；③孔隙度测量误差与样品长度成反比，为了提高测量精度，样品长度应尽量大于3 cm。

Unconventional tight reservoir has a low porosity, which is usually less than 10%, while that of shale reservoir is even less than 5%. The porosity test error of helium injection method has been considered. A mathema-tical model is established for the error of porosity determination and the statistical data of source and error limit was obtained for volume measurement. (1) The error limit of porosity determination of tight reservoir using vernier caliper is 0.59%-2.47%, while that can be reduced to 0.38%-1.04% by using a high-precision 3D laser scanner. Different from conventional reservoirs, the porosity measurement accuracy of tight reservoir should be improved and analyzed. (2) The accuracy of all porosity determination methods cannot reach the industry standard (<0.5%), so a new standard is suggested that reducing the error limit standard (i.e. <1%). The demand of volume measurement was made based on the new standard. (3) An inverse proportion is found between porosity error and core plug length, so sample length should be longer than 3 cm to reduce porosity error.

中国石油天然气股份有限公司科技攻关项目（2014A-0214，2014E-3209）和国家重大科学仪器设备开发专项（2013YQ17046305）资助。

https://doi.org/10.11781/sysydz201606850