气测烃比值筛选法在渤海低阻油层水平段随钻决策中的应用

Gas logging hydrocarbon ratio screening method for decision making while drilling in horizontal section of low resistivity reservoir in Bohai Sea

渤海Q油田馆陶组新发现的低阻油层电阻率2~3Ω·m,与水层电阻率相近,该油田开发时测井仅为随钻电阻率和自然伽马两条常规测井曲线,且井型为水平井,根据常规测井曲线随钻快速解释油水层难度大,相比而言,区域气测录井资料齐全,能够反映储层的含油气丰度,利于快速判别油水边界。基于油田已钻低阻油层老井气测录井资料复查分析,在水平段钻进时,运用气测录井烃比值筛选法,筛选出C_1/C_2及(C_4+C_5)/C_3两个随钻烃比值评价参数并建立解释标准。经过井场实际应用表明,该录井解释方法的解释结论与实际生产情况吻合,判断符合率高,有效节省了水平段进尺,节约了钻井作业成本,具有较高的应用价值。

The resistivity of newly discovered low resistivity reservoir in Guantao Formation of Q oilfield in Bohai Sea is 2⁃3Ω·m,similar to the resistivity of water layer.During the development of this oilfield,only two conventional logging curves,namely resistivety while drilling and natural gamma,are used for logging.The well type is horizontal well,so it is difficult to quickly interpret oil and water formations while drilling according to conventional logging curves.In contrast,the regional gas logging data are complete,which can reflect the oil and gas abundance of the reservoir and is conducive to the rapid identification of oil and water boundaries.Through the review and analysis of the gas logging data of low resistivity reservoir of the drilled wells in the oilfield,the gas logging hydrocarbon ratio screening method is used to screen out two hydrocarbon ratio evaluation parameters while drilling:C_(1)/C_(2)and(C_(4)+C_(5))/C_(3),and the interpretation standards are established.Through the practical application of the well site,the interpretation conclusion of this method is consistent with the actual production situation,the judgment coincidence rate is high,the footage of the horizontal section is effectively saved,the drilling operation cost is saved,and it has high application value.