Inversion Technique For Fracture Characterization In Highly Inclined Wells Using Multiaxial Induction Measurements

摘要

A method uses multiaxial electromagnetic measurements corresponding to measurements made along two mutually orthogonal axes perpendicular to and parallel to an axis of a wellbore corresponding to at least one receiver spacing from a transmitter. An initial orientation of a fracture with respect to the axis of the wellbore and a distance from the fracture are calculated using the multiaxial electromagnetic measurements. An initial model of subsurface formations is made using the initial orientation, distance and formation resistivity adjacent the fracture. An expected response of an electromagnetic instrument to the initial model is generated. The expected response is compared to measurements made by the electromagnetic instrument and a parameter of the initial model is adjusted. The expected response is repeated and the model adjusted until a difference between the expected response and the measurements either (i) falls below a selected threshold or (ii) exceeds a predetermined number of repetitions.

主权项

1. A method for determining an orientation of formation fractures with respect to a wellbore axis, comprising:
(a) accepting as input to a computer multiaxial electromagnetic measurements corresponding to measurements made along two mutually orthogonal axes perpendicular to and parallel to an axis of the wellbore, the measurements corresponding to at least one receiver spacing from a transmitter; (b) in the computer estimating an initial orientation of a fracture with respect to the axis of the wellbore and a distance from the fracture to a position from which the electromagnetic measurements are obtained using the multiaxial electromagnetic measurements; (c) in the computer generating an initial model of a subsurface formation using the estimated initial orientation and distance and data related to at least one formation resistivity adjacent to the fracture; (d) in the computer, generating an expected response of an electromagnetic well logging instrument to the initial model; (e) in the computer, comparing the expected response to measurements made by the electromagnetic well logging instrument; and (f) in the computer, adjusting at least one parameter of the initial model and repeating (d) and (e) until a difference between the expected response and the measurements either (i) falls below a selected threshold or (ii) exceeds a predetermined number of repetitions of (d) and (e) and; (g) in the computer either (i) displaying the model after (f)(i) or (ii) displaying an indication of non-convergence after (f)(ii).