勘探阶段由于钻井及其他相关资料较少,页岩气的资源评价和选区评价工作具有一定的特殊性,应根据阶段特点选择相适应的评价思路和评价方法.基于五峰组-龙马溪组海相页岩气勘探工作实践,系统梳理了勘探阶段页岩气资源评价和选区评价的内容和思路,明确了该阶段相适应的资源评价和选区评价方法.将页岩气勘探阶段划分为区带评价、目标评价和气藏评价等3个次一级评价阶段.资源评价中区带评价阶段的主要方法为含气量类比法、资源丰度类比法、成因法和综合法,目标评价阶段的主要方法为含气量体积法、含气量类比法、资源丰度类比法和综合法,气藏评价阶段的主要方法为含气量体积法、含气量体积法+含气饱和度容积法和综合法.以四川盆地焦石坝地区五峰组—龙马溪组作为类比标准区,建立了总含气量和资源丰度2个关键参数的类比参数体系.勘探阶段页岩气选区评价方法可归纳为2种:综合参数叠合分析法(叠图法)和参数归一化定量评价法.针对区带评价阶段建立了"地质条件-工程条件"双因素区带评价参数体系,针对目标评价阶段建立了"地质条件-工程条件-经济条件"3因素目标评价参数体系.建立的区带评价和目标评价参数体系更能体现评价阶段特点,很好地满足了相应的评价需求.

Due to the relatively limited drilling and other relevant data during the exploration stage,the resource and favorable area evaluation of shale gas have certain specificity.Suitable evaluation ideas and methods should be sorted out based on the characteristics of the stage.According to the practice of marine shale gas exploration,the content and ideas of shale gas resource and favorable area evaluation in the exploration stage are systematically sorted out,and the corresponding resource and favorable area evaluation methods for this stage are clarified.The shale gas exploration stage is divided into three secondary evaluation stages:play evaluation,target evaluation,and gas reservoir evaluation.It is believed that the main methods for resource evaluation in the play evaluation stage are gas content analogy,resource abundance analogy,genesis method,and comprehensive method.The main methods for target evaluation stage are gas content volume method,gas content analogy method,resource abundance analogy method,and comprehensive method.The main methods for gas reservoir evaluation stage are gas content volume method,gas content volume method+gas saturation volume method and comprehensive method.Taking the Wufeng Formation-Longmaxi Formation in the Jiaoshiba area as an example,a system of analogy parameters for the total gas content and resource abundance of marine shale gas is established.This system can further improve the important aspects of analogy that still have shortcomings.The methods for shale gas favorable area in the exploration stage can be summarized into two main methods:comprehensive parameter superposition analysis method(stacking map method)and parameter normalization quantitative evaluation method.The two favorable area evaluation methods are applicable for both play evaluation and target evaluation,with the main difference of the differences in parameter types and quantities in the evaluation parameter system.In view of the emphasis on the evaluation of shale gas formation and enrichment conditions(geological conditions)and fracturing high production conditions(engineering conditions)in the play evaluation stage,a dual factor play evaluation parameter system of"geological conditions-engineering conditions"has been established.In the stage of target evaluation,it is necessary to consider the evaluation of economic benefits and further enrich the parameters.A three factor target evaluation parameter system of"geological conditions-engineering conditions-economic conditions"has been established.At the same time,the evaluation parameters in terms of hydrocarbon generation,preservation,resources,and geostress have also been further deepened.The established play evaluation and target evaluation parameter system can better reflect the characteristics of the evaluation stage and meet the corresponding evaluation needs.