M. D. Wood, Inc.

Fracture Technology, Inc.

Milton D Wood

Daniel Silverman

This invention relates to a method of determination of the change in subsurface structure of the earth resulting from the application of fluid pressure at a selected point, at a selected depth, in the earth, by measuring at least one physical parameter of the contour of the surface of the earth above the point of application of fluid pressure. The method involves positioning a plurality of tiltmeters on the earth above the point of application of fluid pressure arranged in a known array, and measuring the change in angle of tilt of the earth's surface at the point of placement of each sensor while varying the pressure and flow rate of fluid into the earth at the selected point. This invention further teaches how the individual values of incremental tilt at selected points on the earth's surface can be processed to provide indication of the azimuth of the vertical fracture in the earth, and an estimate of length of the fracture.

Method of determining the azimuth and length of a deep vertical fracture

An underground combustion operation in which combustible material, in a selected geologic formation at a selected depth, is burned by forcing air under pressure down a first well into the formation, and collecting products of combustion at a second well, a selected distance away from the first well. The overburden above the formation is supported, in part, by the combustible material, which might be viscous oil, tar, etc. This material is ignited at the first well and a flame front is formed which burns in the form of a circular front, which moves radially outwardly as a function of time and the rate of air supply. A plurality of electronic tilt meters are positioned at or near the surface of the earth, in at least one linear array directed along the radius from the first well to the second well. Combustion air is provided and the outputs of the tilt meters are amplified and recorded as a function of time. As the flame front progresses, the overburden behind the front will slump, which will be selected by a corresponding slump and tilting of the earth surface, which will be reflected in the corresponding readings of the tilt meters.

Method and apparatus for monitoring the position and movement progress

This invention relates to a method of determination of the change in subsurface structure of the earth resulting from the application of fluid pressure at a selected point, at a selected depth, in the earth, by measuring at least one physical parameter of the contour of the subsurface of the earth above the point of application of fluid pressure. The method involves positioning a plurality of tiltmeters on the earth above the point of application of fluid pressure arranged in a known array, and measuring the change in angle of tilt of the earth's surface at the point of placement of each sensor while varying the pressure and flow rate of fluid into the earth at the selected point.

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Portola Valley, CA, United States of America

Milton D Wood