页岩油经济可采储量起算标准计算方法:以吉木萨尔凹陷二叠系芦草沟组页岩油为例

Methods of determining commercial oil flow standard in shale reserves estimation:a case study of Permian Lucaogou formation in Jimusar depression

页岩油在储层特性、开发方式、单井生产动态规律等方面与常规油藏相比有显著的差异,常规的储量起算标准计算模型不再适用。基于盈亏平衡原理和现金流量法,结合页岩油“两段式”的产量递减特征并考虑资金的时间价值建立了符合页岩油特点的储量起算标准计算模型。储量起算指标包括了单井最低初期稳定产量、单井最低累计产量和最低经济有效厚度。以吉木萨尔凹陷二叠系芦草沟组页岩油为例,结合其油藏相关物性参数、单井投资及成本费用、油气价格等参数,利用所建立的页岩油储量起算标准计算模型;确定了不同油价、不同水平井段长度条件下的储量起算标准图板。通过分析可知,单井最低初期稳定产量和单井最低累计产量随着水平井段长度的增加而增大,最低经济有效厚度则随着水平井段长度的增加而降低。当油价为70美元/桶时,水平井段长度由1500 m增加至2000 m,单井最低初期稳定产量和单井最低累计产量分别由19.51 t/d和1.92×10^(4) t增加至23.04 t/d和2.27×10^(4) t;最低经济有效厚度则由9.42 m降低至8.67 m。

The shale oil is significantly different from conventional reservoirs in reservoir characteristics,development methods and production performance.The conventional method of determining commercial oil flow standard is no longer applicable.On the basis of break-even principle and cash flow method,a standard calculation model of commercial oil flow for shale oil is established combined with the“two-stage”decline producing pattern and the consideration of time value of fund.The standard commercial oil flow index includes the minimum initial stable production,minimum cumulative production and minimum net pay thickness.A standard plate is built according to the standard calculation model of commercial oil flow,drilling investment,costs,oil-gas price and reservoir parameters of shale oil.This standard plate different commercial oil flow will be determined at different oil price and different length of horizontal well section.The plate shows that the minimum initial stable production,minimum cumulative production will be increased along with the increase of the horizontal section,while the minimum net pay thickness decreased.When the oil price is 70$/bbl,and the horizontal section increased from 1500 m to 200 m,the minimum initial stable production and minimum cumulative production will increase from 19.51 t/d and 1.92×10^(4) t to 23.04 t/d and 2.27×10^(4) t,respectively.The minimum net pay thickness decreases from 9.42 m to 8.67 m.