加拿大萨斯喀彻温省Bakken组致密油生产特征及甜点分布预测

Production characteristics and sweet-spots mapping of the Upper Devonian-Lower Mississippian Bakken Formation tight oil in southeastern Saskatchewan, Canada

为对加拿大萨斯喀彻温省东南部Williston盆地中Bakken段致密油产区"甜点"进行预测,在大量生产数据分析基础上,根据致密油生产井产量与成藏要素间的定量关系,提出了一套识别潜在"甜点"的多元统计方法。在筛选和分析控制油气"甜点"地质要素的过程中,发现一些制约常规油气成藏的地质因素同样适用于中Bakken段致密油区,这些因素包括:(1)北东走向的Torqunay-Rocanville构造带可能是连接Williston盆地南部成熟烃源岩灶和研究区内Bakken组致密储集层之间的主要油气运移通道;(2)美国和加拿大边界Bakken段致密储集层中的油可能由当地局部成熟的Bakken组烃源岩提供;(3)正向构造有利于油气聚集;(4)顶部盖层和侧向封堵有利于油气的聚集与保存,从而增加单井产量;(5)单井最终可采储量方向变差函数的空间连续性方向与最大水平应力方向一致,水平井的走向对致密油的产量有实质影响。

A workflow that helps identify potential production sweet spots in the Middle Bakken tight oil play is proposed based on analysis of large amounts of production data. The proposed approach is a multivariate statistical model that extracts relevant information from a training dataset of production wells to facilitate geological similarity comparison between economic and sub-economic production wells. The model is applied to the Middle Bakken tight oil play in southeastern Saskatchewan. Data screening for diagnostic geological indicators for sweet spots reveals that several geological factors indicative for conventional oil reservoirs seem to work for the Middle Bakken tight oil play as well. These factors include： a） the NE trend Torqunay-Rocanville structural belt serving as a preferred regional migration path for connecting mature source rock in southern Williston Basin and the Middle Bakken tight reservoir in southeastern Saskatchewan; b） the oils in the Bakken tight reservoirs along the U.S. and Canada border are more likely from local matured Bakken source rocks; c） subtle structural components enhancing the convergence of dispersed hydrocarbons over a large area; d） top seal and lateral barrier improving preservation, thus favouring oil productivity; e） orientation of maximum horizontal stress coincident with the direction of the variogram spatial continuity in ultimate recoverable reserves, so the direction of horizontal well has a significant impact on the oil productivity.