Schlumberger Technology Corporation

Services Petroliers Schlumberger

Schlumberger Holdings Limited

Prad Research and Development Limited

John Tombari

Terizhandur S Ramakrishnan

Nikita Chugunov

Andrew John Duguid

Terizhandur S Ramakrishan

Nikita V Chugunov

Andrew Duguid

A cased hole pressure test tool is used to determine the integrity of cement between two points in a borehole in terms of permeability or transmissibility. The test tool drills at least one probe hole through the casing up to the cement. In one embodiment, two probes are set and the dissipation of a pressure pulse through the cement initiated by the first probe is observed by the second probe. In another embodiment, one probe hole is in hydraulic communication with the borehole fluid and a single offset probe is set in another probe hole. Fluid (water) is then added to the borehole to cause a pressure increase in the borehole fluid. Detection of the pressure increase through the cement by the offset probe is indicative of a loss of hydraulic isolation. Packers may be used to isolate the portion of the borehole under test. A mechanism for generating a pressure pulse of known magnitude is also described.

Pressure interference testing for estimating hydraulic isolation

The permeability of the cement annulus surrounding a casing is measured by locating a tool inside the casing, placing a probe of the tool in hydraulic contact with the cement annulus, measuring the change of pressure in the probe over time, where the change in pressure over time is a function of among other things, the initial probe pressure, the formation pressure, and the permeability, and using the measured change over time to determine an estimated permeability. By drilling into the cement and making additional measurements of the change of pressure in the probe over time, a radial profile of the cement permeability can be generated.

Method and tool for evaluating fluid dynamic properties of a cement annulus surrounding a casing

The permeability of the cement annulus surrounding a casing is measured by locating a tool inside the casing, placing a probe of the tool in contact with the cement annulus, measuring the change of pressure in the probe over time, where the change in pressure over time is a function of among other things, the initial probe pressure, the formation pressure, and the permeability, and using the measured change over time to determine an estimated permeability. The estimated permeability is useful in determining whether carbon dioxide can be effectively sequestered in the formation below or at the depth of measurement without significant leakage through the cement annulus.

Tool and method for evaluating fluid dynamic properties of a cement annulus surrounding a casing

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Spring, TX, United States of America

John Tombari