Methods for determining formation and borehole parameters using fresnel volume tomography
First Claim
Patent Images
1. A method of determining formation slowness of segments traversed by a borehole comprising:
- generating acoustic waves with a sonic tool having a source and at least one receiver; and
calculating a Fresnel volume wave path for the acoustic waves, wherein an initial model is assigned for the Fresnel volume wave path, the initial model being is non-homogeneous at least in the direction of the axis of the borehole.
1 Assignment
0 Petitions
Accused Products
Abstract
A method and apparatus for determining formation slowness around a borehole are provided. The Fresnel volume concept is applied for traveltime tomography. The Fresnel volume represents a sonic wave propagation path about the borehole. The application of Fresnel volume to sonic data provides for a stable inversion and makes practical 3-D tomography. Inversion is accomplished by an iterative back-projection method.
-
Citations
42 Claims
-
1. A method of determining formation slowness of segments traversed by a borehole comprising:
-
generating acoustic waves with a sonic tool having a source and at least one receiver; and
calculating a Fresnel volume wave path for the acoustic waves, wherein an initial model is assigned for the Fresnel volume wave path, the initial model being is non-homogeneous at least in the direction of the axis of the borehole. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
-
-
21. A method of determining formation slowness of segments traversed by a borehole from data of a sonic tool having a sonic source and a plurality of receivers comprising:
-
a) assigning an initial slowness model for the formation and the bore hole the initial model being non-homogeneous at least in the direction of the axis of the borehole;
b) calculating Fresnel volume(s) representing wave propagation path(s);
c) calculating theoretical first arrival time(s) based an the Fresnel volume wave propagation path for each receiver;
d) calculating a function of a measured first arrival time and the theoretical first arrival time for each receiver, the measured first arrival time for each receiver being determined from data of the sonic tool;
e) back projecting the function along the Fresnel volume wave path of first arrival, thereby providing modifications to the initial slowness model for a plurality of formation segments; and
f) modifying the initial slowness model as a function of the provided modifications. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
-
- 30. A method of determining formation slowness about a borehole comprising applying Fresnel zone tomography to sonic data.
-
42. A formation slowness determination apparatus comprising:
-
a sonic source;
a sonic receiver;
a processor coupled to said sonic source and sonic receiver and programmed to calculate and update a Fresnel zone for sonic waves generated by the sonic source and received by the sonic receiver in a borehole, wherein an initial model is assigned for a Fresnel volume wave path, the initial model being non-homogeneous at least in the direction of the axis of the borehole.
-
Specification