Method and apparatus for measuring formation pressure
AssigneeSchlumberger Technology Corporation
InventorFran.cedilla.ois M. Auzerais
Life of this patent
Estimating the term…
Abstract
An earth formation tool measures pressure from within a borehole. A portion of the borehole wall is isolated from surrounding borehole fluids by placing a chamber of a borehole tool against the borehole wall. The chamber comprises a recess in an exterior surface of a borehole tool. Mudcake present on the isolated portion of the borehole wall is disintegrated by an ultrasonic transducer within the chamber. In this manner, there is no resistance to fluid flow from the chamber to the formation. A pressure gauge measures pressure of the chamber to indicate pressure of the earth formation. This approach can be used to make moving or stationary measurements of earth formation pressure.
Claims20
A method for evaluating a characteristic of a formation comprising:
- placing a tool in a borehole in a formation;
- isolating a portion of the formation by placing a chamber of the tool against a wall of the borehole;
- producing vibrations within the chamber and loosening material from the borehole wall within the chamber while maintaining isolation of said portion of the formation by the chamber of the tool;
- measuring pressure within the chamber and producing a corresponding first signal;
- and
- using the first signal in evaluating a characteristic of the formation.
Method of indicating an earth formation characteristic, the steps comprising:
- isolating a portion of a borehole wall of a formation with a borehole tool, the isolated portion containing fluid and material;
- using the borehole tool, and while maintaining isolation of said portion of the borehole wall with the borehole tool, moving the material into fluid suspension;
- producing a signal with the borehole tool representing a parameter of the formation adjacent the isolated portion of the borehole wall;
- and
- indicating an earth formation characteristic based on the produced signal.
Method of indicating an earth formation characteristic, the steps comprising:
- defining a volume by isolating a portion of a borehole wall of a formation with a borehole tool, fluid and mudcake being adjacent the borehole wall within the volume;
- fluidizing the mudcake within the volume while maintaining ioslation of said portion of the borehole wall with the borehole tool;
- detecting pressure of the volume and producing a signal with the borehole tool related to pressure of the formation adjacent the isolated portion of the borehole wall as pressure of the formation and on the volume reach equilibrium;
- and
- indicating an earth formation characteristic based on the produced signal.
Apparatus for evaluating an earth formation characteristic, comprising:
- a body for passage within a borehole in a formation, the borehole containing fluid and having a wall;
- the body having a chamber for isolating some of the fluid and a portion of the borehole wall;
- an element associated with the chamber for moving material within the chamber into suspension with the fluid while said chamber maintains isolation of said some of the fluid and a portion of the borehole wall;
- and
- a pressure sensor for producing a signal related to pressure with the chamber, the signal indicating an evaluation of a characteristic of the formation.
Dependencies are inferred from the claim text.