Downholed system and method for determining formation properties

Abstract

In this invention, drill pipe or tubing is attached to a sampling tool that is suspended in a borehole. A wireline cable also connects the tool to surface equipment and establishes electrical communication between the tool and the surface equipment. A valve located in the docking head assembly controls fluid flow between the borehole and the drill pipe through a port located within the drill pipe assembly which is opened and closed as required. During operations, the tool takes fluid samples from the formation and analyzes them for contamination levels. Unacceptable fluid is pumped or flowed through the tool via a flowline and into the drill pipe where it is stored until it is disposed of at the surface. Once the flowing fluid reaches acceptable levels of contamination, this fluid is pumped or flowed into a sample chamber(s) in the tool. Once sampling is completed the contaminated fluid is forced to the surface by opening the port and pumping a different fluid down the borehole annulus, through the port and into the tool below the contaminated fluid and thereby filling the drill pipe and forcing the contaminated fluid up the drill pipe and to the surface, instead of discarding the fluid into the borehole or storing the fluid in the tool. This invention allows for larger amounts of fluid to be retrieved from the formation which results in cleaner fluid samples and better information about the formation. Moreover the nature of the pressure data acquired both during periods of flow and shut-in can be used to deduce formation permeability and permeability anisotropy.