地质建模中净毛比场的精细表征

Fine Characterization Method of Net to Gross in Geological Modeling

三维地质模型中的净毛比参数场,直接关系到地质储量的客观评估。目前常规方法主要采用优选的测井参数截断值定义布尔数(0或1)分布的净毛比场,具有较大的片面性。大量实践证明:沉积特征不同,表征净毛比参数场的方法也应有所不同。针对沉积环境较为稳定、砂地比较高的三角洲前缘相或深水浊积体系中水道主体和朵叶主体相,可采用离散型非连续的布尔数(0或1)表征;针对砂泥薄互层,如浅水三角洲沉积体系中薄层砂或深水浊流沉积中水道体系发育砂泥薄互层的天然堤相,适用连续型非布尔数分布的净毛比场(0~1)表征。联系油田实际,采用与泥质含量相关的指示曲线获取连续性的净毛比曲线的方法,可极大提高净毛比场的精度。

In 3D geological modeling, the uncertainty of NTG directly affects the assessment of reserves. At present, it is usually unilateral to define Boolean number distribution (0 or 1) by using preferred logging parameter cut-off. Lots of practice has proved that the method of characterizing NTG should also be different based on different kinds of sedimentary characteristics. Regarding the front delta in delta system and main channel and main lobe in deep water turbidity system with relatively stable sedimentary environment and relatively high sand content, discrete non-continuous Boolean numbers (0 or 1) can be adopted. Otherwise, in terms of thin sand-shale interbed in the shallow-water delta sedimentary system, or shale and sandy levee in deep-water turbidity sedimentary system, it should be characterized by the continuous non-Boolean distribution (0~1). In combination with the actual oilfield, the author firstly proposes the indicator curve related to the shale content to obtain the continuity NET curve, which greatly improves the accuracy of geological model.