涠西南凹陷WZ11-7N-3井涠洲组流体包裹体研究

Study and Application of Fluid Inclusion in Petroleum Exploration in Weizhou Formation in Weixinan Depression of Beibuwan Basin

涠西南凹陷是一个复杂断陷型富生烃凹陷,发育了一系列断裂带,涠洲组多以小型断块型油藏为主,构造极其复杂,一批断块圈闭的高部位是否成藏仍很难落实。WZ11-7N-3井涠洲组未见油气显示,圈闭高部位侧钻井WZ11-7N-3Sa,涠洲组三段见68 m油斑显示,油层62.1 m。对WZ11-7N-3井岩屑资料进行流体包裹体化验,证实与3Sa井油层对应的砂组,含烃流体包裹体含量明显高于水层含烃类包裹体,均在30%以上;与3Sa井水层对应的砂组盐水包裹体含量明显高于油层对应砂组的盐水包裹体,均在80%以上,勘探实践证实在高部位已经成藏。复查老井,通过流体包裹分析,可以落实一批类似的断块型圈闭高部位是否成藏,增加储量,提高探井的成功率,短期内就可以指导勘探评价,该研究思路值得推广使用。

Weixinan depression is a complex faulted depression with rich hydrocarbon,and a series of fault-zones have been developed in this depression.Weizhou formation is mainly small faulted oil reservoirs,and the structure is very complex.Therefore,it is very difficult to confirm petroleum entrapment.In Well WZI1-7N-3,no oil and gas shows were found in Weizhou formation.In sidewell WZ1 l-7N-3Sa,68 m oil spots and 62.1 m oil layer were found.It has been confirmed through analysis on fluid inclusion of cuttings from well WZ11-7N-3 that in sand sets corresponding to the oil layers in WZ1 l-7N-3Sa,the content of hydrocarbon fluid inclusion is much higher than that in oil layers,over 30%.In sand sets corresponding to the water layers in WZ11-7N-3Sa.water layers and salty fluid inclusion is much higher in water layers than oil layers,over 80%.It has been proved through exploration practice that oil reservoirs formed at the structural high place.Reexamining old wells by analyzing fluid inclusion can ascertain analogous faulted traps and find if hydrocarbon accumulation at the structural high place.In addition,the reserves can be increased,and the success rate of exploration can be improved.The study results can be used to guide exploration evaluation,and the study thinking is worth promoting.