济阳坳陷待发现生物气资源量预测新方法

New method of predicting undiscovered biogas resources in Jiyang Depression

生物气是特殊成因天然气,由于生成机理尚未明确,成因法难以准确预测其资源量。在对生物气成因类型和生成条件分析的基础上划分了评价单元,提出了基于统计学的待发现生物气资源量预测的新方法,即应用截头移位帕雷托分布模型预测各评价单元待发现生物气藏的规模分布,然后构建三角分布函数预测待发现生物气藏数量,最后用Monte Carlo法预测研究区待发现生物气资源量。应用上述方法预测济阳坳陷待发现生物气资源量,研究表明,待发现生物气藏规模服从对数正态分布,下一勘探阶段最可能发现生物气藏储量（0.2~1.2）×108 m3,在惠民凹陷北部和东营凹陷浅层可能发现储量规模较大的原生生物气藏,在沾化凹陷、陈家庄凸起、滨县-林樊家凸起可能发现规模小、数量多的原油降解气藏,预测济阳坳陷待发现生物气藏资源量约424.74×108 m3。

Biogas is a kind of natural gas with special generation process.Because the formation and accumulation mechanism has not been defined,it is difficult to predict the resources of biogas accurately using the genetic methods.In this paper,a new statistics method for predicting the undiscovered biogas resources was developed based on the analysis of biogas genetic types and formation conditions,and the evaluation units were divided,that is to predict the size distribution of undiscovered biogas reservoirs with truncated shifted Pareto distribution model,build the triangular distribution function to predict the number distribution of undiscovered biogas reservoirs,finally use Monte Carlo method to estimate the undiscovered biogas resources in the study area.The resources of undiscovered biogas in Jiyang Depression were found.The results show that the size distribution of biogas in Jiyang Depression belongs to log-normal distribution,most likely to find biogas reservoirs whose reserves is about 0.02-0.12 billion cubic meters.In the shallow formation of Dongying and north of Huimin Sag,it is possible to find large primary biogas reservoirs,but in Zhanhua Sag,Chenjiazhuang and Binxian-Linfanjia Uplift,there are small oil-degradation biogas reservoirs to be found.The undiscovered biogas resources in Jiyang Depression are about 42.474 billion cubic meters.