Deep stratum heat conductivity coefficient three-dimensional prediction method and device based on Krylov subspace

Abstract

The invention provides a deep stratum heat conductivity coefficient three-dimensional prediction method and device based on a Krylov subspace, and the method comprises the following steps: constructing a heat conductivity coefficient abnormal body in a uniform half-space research region, setting the boundary condition of the research region, carrying out the finite element temperature numerical simulation, and obtaining an underground space three-dimensional temperature field dobs; the method comprises the following steps: constructing an initial prediction model and a regularization objective function, and solving a product of a Jacobian matrix and any vector by adopting a Jacobian-freeKrylov subspace technology in a prediction process to avoid solving and storage of a large dense Jacobian matrix; a Gaussian-Newton algorithm and an L-BFGS algorithm are utilized to construct a Hessian matrix and approximately solve an inverse matrix of the Hessian matrix to reduce storage requirements and calculation amount and obtain a model correction amount delta m, a model step length is searched based on a Wolfe criterion to update model parameters, a fitting difference between actually measured data and simulated data is enabled to be smaller than a preset value through cyclic prediction, and an optimal prediction result is output. The method can quantitatively characterize the distribution characteristics of the heat conductivity coefficient of the deep medium, and is high in prediction precision, wide in range and high in practicability.

Description

technical field [0001] The invention relates to the field of thermal conductivity prediction, in particular to a method and device for three-dimensional prediction of thermal conductivity of deep formations based on Krylov subspace. Background technique [0002] As a kind of stable and sustainable renewable clean energy, geothermal resources are currently receiving unprecedented attention from the whole society. The development and utilization of geothermal resources has important practical significance and far-reaching impact on helping the "dual carbon" goal. The thermal properties of deep rocks, such as thermal conductivity, specific heat capacity, and radioactive heat generation rate, directly affect the heat generation, heat storage and heat transfer of rocks between various circles in the earth, and are indispensable for the study of surface and interior temperature distribution and heat transfer. parameter. Rock thermophysical properties are also a prerequisite for q...

AI Technical Summary

Problems solved by technology

However, these methods can only describe the point-scale or line-scale thermal conductivity of rocks, and cannot predict the distribution characteristics of regional thermal conductivity.

However, the three-dimensional prediction of the thermal conductivity of deep formations is still in the blank stage, which directly restricts the interpretation of the thermal genetic mechanism of geothermal resources in the study area and the site selection of high-temperature geothermal targets.

Images