Global inversion of gravity data using the principle of general local isostasy for lithospheric modeling
AssigneeExxonMobil Upstream Research Company
InventorsRobert J. Ferderer, John Mariano
Life of this patent
Estimating the term…
Abstract
A method including: defining a model space within which all subsurface models are in general local isostatic equilibrium; generating a representative set of trial models which span the model space, wherein a requirement that all of the trial models be in isostatic equilibrium provides a constraint that narrows a range of solutions that fit observed gravity data, wherein the trial models provide scenarios of Earth's crustal geometry, and crust and mantle rock properties; and determining, within an inversion process, a model solution based on minimizing a misfit between the observed gravity data and synthetic gravity data generated from at least one of the trial models.
Claims16
A method, comprising:
- defining a model space within which all subsurface models are in general local isostatic equilibrium such that within each subsurface model one or more of a crustal density, a mantle density, and a depth to a top and base of the crust vary laterally while local isostatic equilibrium is maintained;
- generating a representative set of trial models which span the model space where each trial model has a unique set of parameter values and provides a scenario of Earth's crustal geometry and crust and mantle rock properties, and wherein generating each of the trial models comprises creating a lithospheric column that is in general local isostatic equilibrium, where the lithospheric column comprises a crustal layer having a crustal thickness (C) determined using the following equation:
- C=Cref−T−S−[Cref(ρcref−ρc)+Tρc−S(ρs−ρc)]/(ρmref−ρc)
- wherein
- Cref is the thickness of the crust at a reference location;
- T is the vertical distance between Earth's rock surface and sea level;
- S is the vertical thickness of sedimentary section of the Earth;
- ρs is the density of sediment;
- ρc is the density of crust;
- ρcref is the density of the crust at the reference location;
- and
- ρmref is the density of the mantle at the reference location;
- and
- determining, within an inversion process, a solution for the model space based on minimizing a misfit between observed gravity anomaly data and synthetic gravity anomaly data generated from the set of trial models.
A method comprising:
- defining a model space within which all subsurface models are in general local isostatic equilibrium such that within each subsurface model one or more of a crustal density, a mantle density, and a depth to a top and base of the crust vary laterally while local isostatic equilibrium is maintained;
- generating a representative set of trial models which span the model space where each trial model has a unique set of parameter values and provides a scenario of Earth's crustal geometry and crust and mantle rock properties, and wherein generating each of the trial models comprises creating a lithospheric column that is in general local isostatic equilibrium, where the lithospheric column comprises a sediment layer having a sediment thickness (S) determined using the following equation:
- S=[Cref(ρcref−ρc)−T(ρw−ρc)−M(ρm−ρc)]/(ρs−ρc)
- wherein
- Cref is the thickness of the crust at a reference location;
- T is the vertical distance between Earth's rock surface and sea level;
- M is the vertical distance between the top of the mantle and the depth to the top of the mantle at the reference location;
- ρs is the density of sediment;
- ρw is the density of water;
- ρc is the density of crust;
- ρcref is the density of the crust at the reference location;
- and
- ρm is the density of the mantle;
- and
- determining, within an inversion process, a solution for the model space based on minimizing a misfit between observed gravity anomaly data and synthetic gravity anomaly data generated from the set of trial models.
Dependencies are inferred from the claim text.