Method for constructing a geologic model of a subsurface reservoir

The present invention is a method for constructing a geologic model of a subsurface reservoir which is a composite sedimentary body ( 30 ) composed of many smaller fundamental sedimentary bodies ( 32 ). In one embodiment, the fundamental sedimentary bodies ( 32 ) within the composite body ( 30 ) are specified by the properties of the flow which built them, including the flow properties that existed at the local inlet ( 36 ) of each fundamental body ( 32 ). The statistical distribution of these local inlet properties is characterized throughout the composite sedimentary body ( 30 ) using either outline forms of some of the fundamental sedimentary bodies ( 32 ) or a well penetration which samples the composite sedimentary body ( 30 ). The geologic model is constructed by placing an appropriate statistical distribution of the fundamental sedimentary bodies ( 32 ) into the outline form of the composite sedimentary body ( 30 ) so that the grain size distribution and/or other geologic properties are specified at each point within the composite sedimentary body ( 30 ).