核磁共振录井技术在鄂尔多斯盆地上古生界岩性气藏解释评价中的应用
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摘要
鄂尔多斯盆地天然气主要赋存于古生界地层内,其中作为主要产层的上古生界砂岩气藏具有低孔隙度、低渗透率、低丰度的特点,成藏演化类型为"先致密后成藏"。此类气藏由于非浮力成藏,流体通常没有经历长距离的二次运移,所以气水分布关系一般较为复杂,甚至不存在明显的气水分异,这给传统的、适用于构造气藏解释评价且效果较好的气测解释带来了较大的困难和挑战。针对该问题,中国石油渤海钻探第一录井公司联合长庆油田盆地东部天然气勘探项目组,利用核磁共振录井技术在评价储集层物性、流体性质方面的独特优势,通过定义新参数(有效含气系数),将该系数与反映储集层有效性的孔隙度交会建立图板,划定不同流体性质区间,实现对鄂尔多斯盆地上古生界致密砂岩气藏流体性质的精准解释,有效提高了录井解释评价符合率。
Natural gas in Ordos Basin mainly occurs in Paleozoic strata.The Upper Paleozoic sandstone gas reservoirs,as the main producing pay,have the characteristics of low porosity,low permeability and low abundance.The reservoir-forming evolution type is first compaction and then reservoir-forming.This type of gas reservoir is formed by non-buoyancy,and the fluids usually do not undergo long-distance secondary migration.Therefore,the gas-water distribution relationship is generally more complex,even there is no obvious gas-water differentiation,which brings great difficulties and challenges to the traditional gas logging interpretation,which is suitable for the interpretation and evaluation of structural gas reservoirs.To solve this problem,No.1 Mud Logging Company,BHDC together with Changqing Oilfield Basin East Natural Gas Exploration Project Team,defined a new parameter of effective gas-bearing coefficient by utilizing the unique advantages of NMR mud logging technique in evaluating reservoir physical properties and fluid properties.The coefficient was combined with the porosity reflecting reservoir effectiveness to establish a chart and to divide different fluid property intervals.Accurate interpretation of fluid properties of the Upper Paleozoic tight sandstone gas reservoirs in Ordos Basin.The coincidence rate of mud logging interpretation and evaluation has been improved effectively.
Natural gas in Ordos Basin mainly occurs in Paleozoic strata.The Upper Paleozoic sandstone gas reservoirs,as the main producing pay,have the characteristics of low porosity,low permeability and low abundance.The reservoir-forming evolution type is first compaction and then reservoir-forming.This type of gas reservoir is formed by non-buoyancy,and the fluids usually do not undergo long-distance secondary migration.Therefore,the gas-water distribution relationship is generally more complex,even there is no obvious gas-water differentiation,which brings great difficulties and challenges to the traditional gas logging interpretation,which is suitable for the interpretation and evaluation of structural gas reservoirs.To solve this problem,No.1 Mud Logging Company,BHDC together with Changqing Oilfield Basin East Natural Gas Exploration Project Team,defined a new parameter of effective gas-bearing coefficient by utilizing the unique advantages of NMR mud logging technique in evaluating reservoir physical properties and fluid properties.The coefficient was combined with the porosity reflecting reservoir effectiveness to establish a chart and to divide different fluid property intervals.Accurate interpretation of fluid properties of the Upper Paleozoic tight sandstone gas reservoirs in Ordos Basin.The coincidence rate of mud logging interpretation and evaluation has been improved effectively.
引文
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