摘要
鄂尔多斯盆地天然气主要赋存于古生界砂岩地层内,具有低孔隙度、低渗透率、低含气丰度、气水关系复杂等特点,导致录井解释符合率仅为75%。为了解决解释符合率低的难题,引入了对油、水信号响应灵敏的核磁共振录井技术,通过一样三谱的分析方法,评价储层的有效性及流体的可动性,建立了压裂条件下的干层划分标准及可动水评价标准。基于气体具有较强的可压缩性,在常温常压条件下,含氢分子数较低,核磁共振测不到含气信号,为此提出了视含气孔隙度、可动气水比指数两个概念,消除了饱和样与新鲜样谱图之间的空白区即为含气孔隙度的传统认识,实现了核磁共振与气测两项录井技术的优势互补,建立了谱图解释、图版解释两种解释方案,将致密砂岩气藏的解释符合率提高到90%以上。经过验证,所建立的思路与方法可靠,对优化试气选层、提高压裂效果具有重要参考价值。
The natural gas in Ordos Basin is mainly in the Paleozoic sandstones,which has the characteristics of low porosity,low permeability,low gas abundance and complex gas-water relationship,so that the coincidence rate of logging interpretation is only 75%.In order to solve the problem of low coincidence rate,the nuclear magnetic resonance(NMR)logging technique that is sensitive to oil and water signals is introduced.Through the analysis method of tri-spectrum for one sample,the effectiveness of reservoir and the mobility of fluid are evaluated,and the division standard for dry formation and the evaluation standard for movable water are made under the conditions of fracturing.Hydrogen molecules number is low and gas signal can’t get through NMR at room temperature and atmospheric pressure for strong compressibility of the gas,two concepts of apparent gas-bearing porosity and producible gas-water ratio index are proposed.The traditional understanding that the blank area between the spectrograms of saturated sample and fresh sample is the gas-bearing porosity changed,and NMR and gas logging are supplemented mutually.Two interpretation plans by spectra and chart are set up to increase the coincidence rate to above 90%in the tight sandstone gas reservoir interpretation.It has been verified that the thought and method established are reliable and have important reference value for optimizing layer selection for gas testing and improving fracturing effect.
作者
孙红华
范伟
孟庆峰
于海军
乔德民
戴广阔
张明扬
李毅逵
胡洋
王金友
陈玉蓉
Sun Honghua;Fan Wei;Meng Qingfeng;Yu Haijun;Qiao Demin;Dai Guangkuo;Zhang Mingyang;Li Yikui;Hu Yang;Wang Jinyou;Chen Yurong(No.2 Mud Logging Companyof BHDC,CNPC,Renqiu Hebei 063552)
出处
《中外能源》
CAS
2021年第4期38-43,共6页
Sino-Global Energy
关键词
鄂尔多斯盆地
致密砂岩气藏
核磁共振
有效储层
含水识别
Ordos Basin
tight sandstone gas reservoir
nuclear magnetic resonance
effective reservoir
water-bearing identification
