Formation Evaluation While Drilling

Abstract

A sample module for a sampling while drilling tool includes a sample fluid flowline operatively connectable between a sample chamber and an inlet, for passing a downhole fluid. A primary piston divides the sample chamber into a sample volume and a buffer volume and includes a first face in fluid communication with the sample volume and a second face in fluid communication with the buffer volume. A secondary piston includes a first face in fluid communication with the buffer volume having buffer fluid disposed therein and a second face.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a continuation-in-part of prior application Ser. No. 11 / 313,004, filed Dec. 19, 2005.FIELD OF THE DISCLOSURE [0002] The present disclosure relates to techniques for evaluating a subsurface formation. More particularly, the present disclosure relates to techniques for collecting and / or storing fluid samples acquired from a subsurface formation. BACKGROUND OF THE DISCLOSURE [0003] Wellbores are drilled to locate and produce hydrocarbons. A downhole drilling tool with a bit at an end thereof is advanced into the ground to form a wellbore. As the drilling tool is advanced, a drilling mud is pumped from a surface mud pit, through the drilling tool and out the drill bit to cool the drilling tool and carry away cuttings. The fluid exits the drill bit and flows back up to the surface for recirculation through the tool. The drilling mud is also used to form a mudcake to line the wellbore. [0004] During the drilling operation, ...

AI Technical Summary

Benefits of technology

[0019] According to another aspect of the disclosure, a method of obtaining a fluid sample with a sampling while drilling tool is disclosed. The method includes lowering a tool that includes a sample chamber having a first volume and a second volume in a wellbore; flowing a sample fluid through an inlet of the tool into the first volume of the sample chamber; moving a first piston disposed between the first and second volumes, thereby increasing the first volume; moving a buffer fluid from a first position to a second position with at least one of the first and a second piston; and moving the second piston disposed between the second and a third volume, thereby decreasing the third volume.

Problems solved by technology

Such shocks may cause the pistons used in sample chambers to move.

Unnecessary movement of the pistons causes the seals carried by the pistons to diminish, thereby leading to sample contamination.

Conventional sample chambers also do not preserve the integrity of the sample in its travel from the point of collection don hole to surface, in particular, they do not adequately maintain the sample fluid in a single phase.

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