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Uncertainty analysis of reserves of fluvial reservoir calculated by geological model
Reservoir Evaluation and Development
2018, 8 (4):
1-5.
DOI:
The reserves of the geological model in the offshore fluvial reservoirs are influenced by the uncertain parameters, such as the structure, plane variogram, correlation between reservoir properties and seismic attributes, irreducible water saturation, lower limiting value of effective reservoir, volume coefficient, and oil-water interface. The root that causes these uncertain parameters is analyzed. Meanwhile, taking oilfield-Q in Bohai bay as an example, and by the integrated application of the Monte-Carlo method and stochastic modeling, the effects of the uncertainty parameters on the reserves are estimated quantitatively. The probability cumulative distribution curves of reserves and 3 probability reserve value which are the pessimistic reserves（P90）, expected reserves（P50） and optimistic reserves（P10） are obtained to predict the risk and potential of the reserves. 
Fig. 2
Crossplot of porosity with mud content, porosity and oil saturation
Extracts from the Article
有效储层物性下限是指储集层能够成为有效储层应具有的最低物性,通常用孔隙度、渗透率、含油饱和度的某一确定值来表示,是影响计算储量结果的一个主要因素。目前,国内外确定有效储层下限值一般采有岩心分析法、经验统计法和测试法等三种方法。由于有效储层物性下限值的确定受到储集层岩性、岩石表面性质、胶结物成份及含量、孔隙结构、流体性质、储层压力等内在因素及石油政策、经济指标、开发工艺、试油工艺、测井技术、油层改造技术等外在因素的共同影响,其具有一定的随机性和不确定性[12,13,14]。一种方法确定的有效储层下限值只能从一个方面反映储层的特征,并不能代表储层真正的下限[15,16]。渤海Q油田综合应用DST测试、取样和测压资料将有效储层下限值确定为孔隙度25 %（图2）,考虑到测试、取样及测压过程中可能存在的误差,为了表征有效储层下限值存在的不确定性,在地质建模时可取值为24 %~26 %。
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