融合不同地质场景假设的油气区带及圈闭资源量计算方法

An Improved Non-deterministic Volumetric Method for Play or Trap with Quantifying Geological Scenarios

不确定性体积法是国内外区带、圈闭油气资源量计算的主要方法,主流算法实现都很少考虑不同地质模型约束条件对计算参数取值和蒙氏模拟过程的影响。此外,国内三(四)级圈闭资源量计算,基本上都是在假定其所属每个层(次级)圈闭含油气概率为定值的前提下,片面地"简单加和"或"概率加权加和"所有层(次级)圈闭的资源量,二者计算的油气资源量很大程度上与实际地质情况很难吻合。结合油气资源一体化定量评价软件(PetroV)的实际开发与应用经验,设计并实现了一种融合不同地质场景假设的油气资源量计算方法,也可称"概率组合加和"方法——以不确定性体积法的蒙氏模拟为基础,对最新地质上识别出的、不可切分的含油气聚集单元,进行符合不同地质模型约束的取样、组合;同时,在计算过程中直接量化不同地质模型假设对不同含油气单元的"含油气体积"的影响。该方法涉及的地质模型假设主要包括:不同单元各项体积参数之间的相关性影响、不同单元间含油气性风险依赖对不同单元组合的影响、不同单元目的层直接上下叠置对各自厚度的影响、断层封闭性对油水界面的影响等。从实例计算结果分析可以看出,只有在充分考虑了地质多场景的情况下,才能够给出对应合理地质模型解释的不确定性油气资源量分布结果。

Non-deterministic volumetric method is an optimal way to predicate in-place or recoverable resource size of a play or trap,which almost ignore the direct effect of geological model constraints on volumetric parameters and montecarlo simulation process. In addition, the domain resource assessment of the 3^rd or the 4^th tectonic trap is calculated by directly and simply cumulating the resource size of its segments or floor traps given specified success probability weights, this predication value generally doesn＇t honestly reflect the practical geological conditions. In order to let uncertainty resource distribution embody definite and reasonable geological interpretation,this paper presents a heuristic resource predication method concluded from the development of integrated assessment software platform（PetroV）,which is an improved non- deterministic volumetric method quantifying the geological model scenarios. It is also called as ＂probability combination cumulating＂ method. The essential of this algorithm is to sample and composite the 3^rd or the 4^th tectonic trap＇s children undivided segment or floor trap considering geological model constraints. ＂Probability combination cumulating＂ method currently quantifies the following geological scenario：（1） Random value generated are in line with the correlation between two volumetric parameters; （2）Conformable beds assume the height is a constant when segments are stacked vertically; （3）Different compositions of those segments or floor traps are subject to types of discovery risk dependency types among them;（4） Fault sealing or leaking directly changes the water contact depth between two segments or floor traps. With practical demonstration and compared with current volumetric method,＂probability cumulating＂ can explain each quantile value of resource distribution with clear geological scene.