Method and apparatus for isolating and testing zones during reverse circulation drilling

Abstract

A zone isolating and testing apparatus comprising an isolation tool and a downhole flow control means and a method of using such apparatus is disclosed. The zone isolating and testing apparatus is particularly useful for testing zones during reverse circulation drilling using concentric drill string such as concentric drill pipe or concentric coiled tubing. The isolation tool of the zone isolating and testing apparatus comprises an expandable packer means and is adapted to connect to concentric drill string near the drilling means. The downhole flow control means of the zone isolating and testing apparatus comprises two valves, one for closing off the annulus between the inner tube and outer tube of the concentric drill string and the other for closing off the inner space of the inner tube. The downhole flow control means is also adapted to connect to concentric drill string near the drilling means. During testing, the isolation tool seals off the annulus between the concentric drill string and the walls of the wellbore and the downhole flow control means seals off either the annulus between the inner tube and outer tube of the concentric drill string or the inner space of the inner tube of the concentric drill string.

Description

[0001] This application claims the benefit of U.S. Provisional Application No. 60 / 521,051, filed Feb. 11, 2004.FIELD OF USE [0002] The present invention relates to an apparatus and method for isolating and testing individual zones in a vertical, directional or horizontal wellbore during drilling. More particularly, the present invention relates to a zone isolating and testing apparatus and method of use thereof to allow testing of isolated zones for flow of hydrocarbons, formation fluids and drill cuttings during vertical, horizontal or directional reverse circulation drilling of wellbores using concentric drill pipe, concentric coiled tubing, or the like. BACKGROUND OF THE INVENTION [0003] The oil and gas industry uses various methods to test the productivity of wells prior to completing a well (see, for example, U.S. Pat. No. 4,898,236). After drilling operations have been completed and a well has been drilled to total depth or prior to reaching total depth in the case of multi-zo...

AI Technical Summary

Benefits of technology

[0007] The isolation tool of the zone isolating and testing apparatus comprises an expandable packer means and is adapted to connect to concentric drill string near the drilling means. When the packer means of the isolation tool is in the expanded position, the isolation tool is in the “closed position” and when the packer means is in the contracted position the isolation tool is in the “open position”. In a preferred embodiment, the expansion of the packer means is controlled by an electric current for quicker opening and closing of the isolation tool.

[0014] The disclosed invention has one or more of the following advantages over conventional isolation packer technology and drill stem testing:

[0018] easier to measure the flow of formation fluids into a zone;

Problems solved by technology

Current technologies used for testing reservoirs such as drill stem testing (DST) are often too expensive to test multi-zone reservoirs, particularly at shallow depths.

Furthermore, isolating and testing zones using conventional packer technology can be slow, expensive and sometimes difficult to set and then release.

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