Early gas detection system for a drill stem test

摘要

A method for testing earth formations informs the operator of the density of the formation fluid being produced before it reaches the surface. In the method, a bypass sub is secured to the drill string. The bypass sub has a bore for receiving a wireline tool that has sensing instruments. The wireline tool also has arms that will shift a sleeve to open and close the bypass sub. The wireline tool has a density measuring device for measuring the density of the formation fluid and providing a concurrent surface indication. A reversing valve is located above the bypass sub and is of a type that provides a port for reverse circulation while the wireline tool is still downhole. Preferably, the reversing valve is shifted by the wireline tool to the open position.