Limits...
A hybrid method for inversion of 3D DC resistivity logging measurements.

Gajda-Zagórska E, Schaefer R, Smołka M, Paszyński M, Pardo D - Nat Comput (2015)

Bottom Line: The computational cost of misfit evaluation by hp-FEM depends strongly on the assumed accuracy.Moreover, tree structure of demes as well as branch reduction and conditional sprouting mechanism reduces the number of expensive local searches up to the number of minima to be recognized.The common (direct and inverse) accuracy control, crucial for the hp-HGS efficiency, has been motivated by precise mathematical considerations.

View Article: PubMed Central - PubMed

Affiliation: AGH University of Science and Technology, Krakow, Poland.

ABSTRACT

This paper focuses on the application of hp hierarchic genetic strategy (hp-HGS) for solution of a challenging problem, the inversion of 3D direct current (DC) resistivity logging measurements. The problem under consideration has been formulated as the global optimization one, for which the objective function (misfit between computed and reference data) exhibits multiple minima. In this paper, we consider the extension of the hp-HGS strategy, namely we couple the hp-HGS algorithm with a gradient based optimization method for a local search. Forward simulations are performed with a self-adaptive hp finite element method, hp-FEM. The computational cost of misfit evaluation by hp-FEM depends strongly on the assumed accuracy. This accuracy is adapted to the tree of populations generated by the hp-HGS algorithm, which makes the global phase significantly cheaper. Moreover, tree structure of demes as well as branch reduction and conditional sprouting mechanism reduces the number of expensive local searches up to the number of minima to be recognized. The common (direct and inverse) accuracy control, crucial for the hp-HGS efficiency, has been motivated by precise mathematical considerations. Numerical results demonstrate the suitability of the proposed method for the inversion of 3D DC resistivity logging measurements.

No MeSH data available.


Related in: MedlinePlus

HGS tree and corresponding coding meshes for binary implementation
© Copyright Policy - OpenAccess
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4541716&req=5

Fig3: HGS tree and corresponding coding meshes for binary implementation

Mentions: In other words, for a given reference logging curve, geometry of the formation layers and resistivities of the borehole and top and bottom formations, we seek for resistivities of the formation layers. The reference logging curve is usually obtained from the field measurements. The idea of the inverse logging curve problem was illustrated by the simple example of finding 3 parameters being the constant value of the resistivity function (see Fig. 3).


A hybrid method for inversion of 3D DC resistivity logging measurements.

Gajda-Zagórska E, Schaefer R, Smołka M, Paszyński M, Pardo D - Nat Comput (2015)

HGS tree and corresponding coding meshes for binary implementation
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4541716&req=5

Fig3: HGS tree and corresponding coding meshes for binary implementation
Mentions: In other words, for a given reference logging curve, geometry of the formation layers and resistivities of the borehole and top and bottom formations, we seek for resistivities of the formation layers. The reference logging curve is usually obtained from the field measurements. The idea of the inverse logging curve problem was illustrated by the simple example of finding 3 parameters being the constant value of the resistivity function (see Fig. 3).

Bottom Line: The computational cost of misfit evaluation by hp-FEM depends strongly on the assumed accuracy.Moreover, tree structure of demes as well as branch reduction and conditional sprouting mechanism reduces the number of expensive local searches up to the number of minima to be recognized.The common (direct and inverse) accuracy control, crucial for the hp-HGS efficiency, has been motivated by precise mathematical considerations.

View Article: PubMed Central - PubMed

Affiliation: AGH University of Science and Technology, Krakow, Poland.

ABSTRACT

This paper focuses on the application of hp hierarchic genetic strategy (hp-HGS) for solution of a challenging problem, the inversion of 3D direct current (DC) resistivity logging measurements. The problem under consideration has been formulated as the global optimization one, for which the objective function (misfit between computed and reference data) exhibits multiple minima. In this paper, we consider the extension of the hp-HGS strategy, namely we couple the hp-HGS algorithm with a gradient based optimization method for a local search. Forward simulations are performed with a self-adaptive hp finite element method, hp-FEM. The computational cost of misfit evaluation by hp-FEM depends strongly on the assumed accuracy. This accuracy is adapted to the tree of populations generated by the hp-HGS algorithm, which makes the global phase significantly cheaper. Moreover, tree structure of demes as well as branch reduction and conditional sprouting mechanism reduces the number of expensive local searches up to the number of minima to be recognized. The common (direct and inverse) accuracy control, crucial for the hp-HGS efficiency, has been motivated by precise mathematical considerations. Numerical results demonstrate the suitability of the proposed method for the inversion of 3D DC resistivity logging measurements.

No MeSH data available.


Related in: MedlinePlus