System and method for two dimensional gravity modeling with variable densities
AssigneeCgg Services SAS
InventorsXiong Li, Barry Wiggins
Life of this patent
Estimating the term…
Abstract
Systems and methods for to two dimensional gravity modeling with variable densities are disclosed. The methods may include a method of modeling the density of a subsurface formation is disclosed. The methods may include generating a plurality of cells in a cross section of density values corresponding to a subsurface formation. The methods may further include assigning a density value to each cell. The methods may further include calculating a gravity effect for each cell based upon the density value. The methods may further include recording the gravity effect for each cell in a data structure.
Claims20
A method for generating a density model of a subsurface formation, the method comprising:
- receiving observed gravity data acquired over the subsurface formation;
- defining polygonal bodies in a cross section, based on subsurface geophysical information;
- generating an overlay of cells for cross section wherein each cell pertains to one and only one of the polygonal bodies;
- assigning a density value to each cell, wherein one of the polygonal bodies with variable density includes plural cells, at least two of these plural cells having assigned different density values;
- calculating a gravity effect for each cell using the assigned density value thereof;
- recording the gravity effect for each cell in a data structure;
- comparing a gravity response calculated based on the gravity effect of each cell with the observed gravity data;
- and
- if a difference between the gravity response and the observed gravity data is larger than a predetermined threshold, altering the density value assigned to one or more cells in the cross section,
- wherein changes in density values reveals geological changes in the subsurface formation.
A method for generating a density model of a subsurface formation, the method comprising:
- receiving gravity data acquired over the subsurface formation;
- defining polygonal bodies in a cross section, based on subsurface geophysical information of the subsurface formation;
- generating an overlay of cells for the cross section wherein each cell pertains to one and only one of the polygonal bodies;
- assigning a density value to each cell, wherein one of the polygonal bodies with variable density includes plural cells, at least two of the plural cells having assigned different density values;
- approximating a line mass for each cell based upon the density value and a size of the cell;
- determining a gravity effect for each cell based on the line mass;
- comparing a gravity response calculated based on the gravity effect of each cell with the gravity data;
- and
- if a difference between the calculated gravity response and the observed gravity data is larger than a predetermined threshold, altering the density value of one or more cells,
- wherein changes in density values reveals geological changes in the subsurface formation.
A modeling system for generating a density model of a subsurface formation, the modeling system comprising a computing system configured to:
- receive observed gravity data acquired over the subsurface formation;
- define polygonal bodies in a cross section, based on subsurface geophysical information;
- generate an overlay of cells for the cross section wherein each cell pertains to one and only one of the polygonal bodies;
- assign a density value to each cell, wherein one of the polygonal bodies with variable density includes plural cells, at least two of these plural cells having assigned different density values;
- calculate a gravity effect of each cell based upon the assigned density value thereof;
- record the gravity effect of each cell in a data structure;
- compare a gravity response calculated based on the gravity effect of each cell with the observed gravity data;
- and
- if a difference between the gravity response and the observed gravity data is larger than a predetermined threshold, alter the density value assigned to one or more cells,
- wherein changes in density values reveals geological changes in the subsurface formation.
Dependencies are inferred from the claim text.