基于区间数地质参数的页岩气勘探开发区块优选

Application of a grey target decision model based on interval numbers of geological parameters to optimize shale gas exploration and development target zones

页岩气开发区块的优选是实施勘探开发的基础和前提,以南襄盆地、湘鄂西地区、渝东等地区的5个页岩气试验区块为研究对象,针对地质参数存在的不确定性和复杂性,采用区间数灰靶决策的方法对其开发潜力进行优选排序。系统地分析了不同参数对页岩气富集程度的作用,并选取页岩有效厚度、有机质丰度、热成熟度、埋深、脆性矿物含量、孔隙度、含气量7项指标建立了页岩气勘探开发优选评价指标体系;运用层次分析法和区间中心点距离法确定各指标的组合权重,修正单一方法确定权重对评价指标产生的影响,使权重值达到主观与客观的统一。基于灰色系统理论的方法建立的灰靶决策模型,对评价指标值为区间范围的研究区的勘探开发潜力进行了排序,初步估算了页岩气资源量。评价结果与实际勘探开发信息吻合较好,表明基于组合权重的区间数地质参数特征的页岩气勘探开发区块灰靶决策模型对页岩气区块的可采性进行评价是可行的。

The optimization of target zones is a premise of shale gas exploration and development.This paper aims to rank the devel- opment potential of five shale gas pilot zones in the Nanxiang Basin, western Hunan and Hubei area, eastern Chongqing area, etc., which were taken as case studies. To achieve this goal, the interval grey target decision was adopted according to the uncertainty and complexity of geological parameters. Through a systematic analysis of different parameters and their impacts on shale gas enrich- ment, we established an evaluation system for shale gas exploration and development by selecting seven indexes： effective shale thickness, organic matter abundance, burial depth, content of brittle mineral, porosity, and gas content. Then we determined the combination weight vector of each index by using the analytic hierarchy process （AHP） and interval central point distance method, modifying the impact of evaluation indexes of one single method to determine weight and make the weighted value up to the unity of subjectivity and ohiectivity. Based on the grey system theory, a grey target decision model was established to optimize and rank the shale gas exploration and development potential of the above five pilot zones, the evaluation indexes of which are interval numbers. Thus, the shale gas reserves were preliminarily estimated in the studied area. The evaluation results are in good agreement with the real data from practical exploration and development, which proves the feasibility of this study.