Process for constructing three-dimensional geologic models having adjustable geologic interfaces
AssigneeExxonMobil Upstream Research Company
InventorsCraig S. Calvert, Thomas A. Jones
Life of this patent
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Abstract
A process for constructing a three-dimensional geologic model of a subsurface earth volume in which the positions of geologic interfaces within the model are adjusted as the model is being constructed. The resulting geologic model should be consistent with all available geologic and geophysical information regarding the subsurface earth volume, including information regarding the spatial attributes of geologic interfaces within said subsurface earth volume.
Claims20
A process for constructing a three-dimensional geologic model of a subsurface earth volume containing one or more geologic interfaces, said process comprising the steps of:
- (a) generating a tentative geologic model of said subsurface earth volume, said tentative geologic model comprising a three-dimensional array of contiguous model blocks, each model block having tentative values for one or more rock properties assigned thereto, said tentative geologic model containing tentative positions for said one or more geologic interfaces;
- (b) specifying training criteria which define the spatial attributes of geologic interfaces and the characteristics of rock properties in said subsurface earth volume;
- (c) calculating statistics that describe the spatial attributes of said tentative geologic-interface positions and the characteristics of said tentative rock-property values in said tentative geologic model;
- and
- (d) comparing statistics calculated in step (c) with corresponding training criteria specified in step (b) and either
- (1) if said statistics do not match said training criteria within specified limits, perturbing the tentative position within said tentative geologic model of at least a portion of at least one of said geologic interfaces, updating said tentative geologic model, and repeating steps (c) and (d), or
- (2) if said statistics match said training criteria within said specified limits, accepting said tentative geologic model as the three-dimensional geologic model for said subsurface earth volume.
A process for constructing a three-dimensional geologic model of a subsurface earth volume containing one or more geologic interfaces, said process comprising the steps of:
- (a) generating a tentative geologic model of said subsurface earth volume by
- (1) specifying initial positions within said tentative geologic model for said one or more geologic interfaces,
- (2) defining a three-dimensional array of contiguous model blocks to represent said subsurface earth volume, and
- (3) assigning initial rock-property values to each of said model blocks;
- (b) specifying training criteria that define the characteristics of rock properties in said subsurface earth volume and the spatial attributes of geologic interfaces in said subsurface earth volume, and specifying desired values for said training criteria;
- (c) calculating statistics comparing the characteristics of rock properties in said tentative geologic model and the spatial attributes of geologic interfaces in said tentative geologic model to the desired values for corresponding training criteria;
- (d) combining the statistics calculated in step (c) into an objective function and calculating an initial value for said objective function;
- (e) randomly selecting at least one model block and tentatively perturbing the value of at least one rock property thereof;
- (f) if said selected model block is within a preselected distance from a geologic interface, determining whether or not to tentatively shift the position of said geologic interface to the opposite side of said selected model block;
- (g) calculating tentative statistics and a tentative value for said objective function based on said rock-property perturbation and said geologic-interface position shift, if any;
- (h) determining whether to accept or reject said rock-property perturbation and said geologic-interface position shift, if any, based on a preselected optimization procedure;
- (i) if either or both of said rock-property perturbation and said geologic-interface position shift are accepted, updating said tentative geologic model and said objective-function value;
- and
- (j) repeating steps (e) through (i) until a preselected number of perturbations have been attempted or predetermined criteria for said objective function have been attained.
Dependencies are inferred from the claim text.