Method for permanent emplacement of sensors inside casing

Abstract

An array of sensors is disposed on an umbilical cable attached to tubing extending into a well. The sensor array includes a series of evenly spaced three-component accelerometers individually mounted on biasing members, such as bowspring centralizer fins, which clamp the accelerometers to an outer casing to establish a mechanical coupling between the accelerometers and the surrounding formation. The accelerometers are lightweight such that the biasing members provide sufficient clamping force to ensure mechanical coupling, thereby facilitating the emplacement of the sensor array. The umbilical cable coupling the accelerometers and extending to the surface may include a crush resistant metal coil wrapped around an inner transmission cable which carries power and/or telemetry information from downhole to the surface. The metal coil provides a higher crush resistance and a higher flexibility than comparable solid metal tubing. A wire wrap similar to that used for wireline cables may be provided outside the metal coil for added tensile strength, and an abrasion-resistant plastic coating may also be employed to enhance the longevity of the umbilical cable.

Dependencies are inferred from the claim text.