Distributing petrofacies using analytical modeling

A computer system comprising:

• a processor;
• a memory coupled to the processor;
• the memory storing a program that, when executed by the processor, causes the processor to:
• create a geocellular model of an underground formation, the geocellular model including a plurality of cells, each cell representing a portion of the underground formation at a location corresponding to that cell's location in the geocellular model;
• receive, from a downhole tool communicatively coupled to the processor, measurements of rock properties of the underground formation measured by the downhole tool;
• read, from the memory, a first measured value of a first rock property from a first well log including the measured rock properties associated with a portion of the underground formation corresponding to a first cell of the geocellular model;
• associate the first measured value of the first rock property with the first cell of the geocellular model;
• read, from the memory, a second measured value of the first rock property from a second well log including the measured rock properties for a portion of the underground formation corresponding to a second cell of the geocellular model, the second well log being distinct from the first well log;
• associate the second measured value of the first rock property with the second cell of the geocellular model;
• assign a value of the first rock property to each cell of the plurality of cells for which no measurement of the first rock property is available, based on an interpolation of the first rock property from the first measured value associated with the first cell, the second measured value associated with the second cell, and a datum of information representing a value of the first rock property for a portion of the underground formation corresponding to a third cell of the plurality of cells, wherein the first and second cells are equidistant from the cell for which no measurement of the first rock property is available;
• obtain, by seismic receiving devices coupled to the processor, seismic data derived from a seismic survey of the underground formation;
• refine, on a cell-by-cell basis, rock property values assigned to each cell of the geocellular model, based at least partly on the seismic data obtained for the portion of the underground formation corresponding to that cell;
• and
• determine a rock type for the portion of the underground formation corresponding to each cell of the refined geocellular model, based on a distribution of rock property values among the plurality of cells.

A non-transitory computer-readable medium storing a program that, when executed by a processor, causes the processor to:

• create a geocellular model of an underground formation, the geocellular model including a plurality of cells, each cell representing a portion of the underground formation at a location corresponding to that cell's location in the geocellular model;
• receive, from a downhole tool communicatively coupled to the processor, rock properties of the underground formation measured by the downhole tool;
• read a first measured value of a first rock property from a first well log including the measured rock properties associated with a portion of the underground formation corresponding to a first cell of the geocellular model;
• associate the first measured value of the first rock property with the first cell of the geocellular model of an underground formation;
• read a second measured value of the first rock property from a second well log including the measured rock properties for a portion of the underground formation corresponding to a second cell of the geocellular model, the second well log being distinct from the first well log;
• associate the second measured value of the first rock property with the second cell of the geocellular model;
• assign a value of the first rock property to each cell of the plurality of cells for which no measurement of the first rock property is available, based on an interpolation of the first rock property from the first measured value associated with the first cell, the second measured value associated with the second cell, and a datum of information representing a value of the first rock property for a portion of the underground formation corresponding to a third cell of the plurality of cells, wherein the first and second cells are equidistant from the cell for which no measurement of the first rock property is available;
• obtain, from seismic receiving devices coupled to the processor, seismic data derived from a seismic survey of the underground formation;
• refine, on a cell-by-cell basis, rock property values assigned to each cell of the geocellular model, based at least partly on the seismic data obtained for the portion of the underground formation corresponding to that cell;
• and
• determine a rock type for the portion of the underground formation corresponding to each cell of the refined geocellular model, based on a distribution of rock property values among the plurality of cells.