页岩气成藏条件与评价体系

为了更好地对我国页岩气进行勘探开发,完善页岩气评价各环节,有必要对页岩气成藏和评价进行研究。在已有的页岩气勘探开发基础上,结合国外开发技术资料,通过对比分析各评价指标与页岩气成藏特征之间的联系,弄清成藏规律以及评价指标量化大小,结果表明页岩气成藏应具备地层以泥/页岩为主,单层厚度≥30 m,泥质含量≥10%,TOC≥0.3%,Ro≥0.4%等条件,页岩气开发目标区地质条件更为苛刻;体积法是现阶段计算我国页岩气资源量的主要方法;对页岩气储层评价影响的因素有很多,利用综合评价方法建立评价模型,确定各因素对储层质量的影响权重,进而对储层进行等级划分,其中结构方程模型和层次分析法已有进行应用,评价结果准确度很高;我国南方地区页岩气勘探开发潜力巨大,上述评价体系在南方勘探开发中的应用,可为开发页岩气的决策者提供定量的指标,有助于页岩气的开发。

Shale gas accumulation condition and evaluation system

In order to make a better exploration and development on shale gas,perfect the shale gas evaluation in each link,it is necessary to make a study on shale gas accumulation condition and evaluation system.Based on existing shale gas exploration and development,combined with foreign development technical data,through the contrast analysis between each evaluation index and shale gas accumulation features,the accumulation regularity and quantitative size of evaluation indexes have been made clear.The results indicate the shale gas accumulation should have conditions of mud/shale formation,single-layer thickness of 30m or higher,shale content of 10% or higher,TOC≥0.3%,Ro≥0.4% and etc.and the geological condition for shale gas target area is more demanding.At present,the volume method is the main method to calculate shale gas resource.There are many factors influencing shale gas reservoir evaluation.By using comprehensive evaluation method,to establish evaluation model,to determine the weights of factors on the reservoir quality,and to divide the reservoir hierarchies.Among them,the structural equation model and analytic hierarchy process(AHP)has been applied,and the evaluation results are of high accuracy.In south China,there exists great potential in shale gas exploration and development.The evaluation system mentioned above can be applied there,which can provide quantitative indicators for policy makers and be helpful for shale gas exploration and development.