A New Concept in Wireline Formation Testing: Extended Drawdown


R. Desbrandes, H. Xu, Louisiana State University


In medium to high permeability formations, conventional wireline formation testers (WFT) are used extensively with good success to accurately determine the formation pressure, estimate the formation permeabilities, and collect fluid samples. In low permeability formations, however, the results obtained with these testers range from mediocre to very poor. The formation pressure and permeability determinations are inaccurate due to both slow pressure buildups and the supercharging effect. Furthermore, the permeability determination is affected by formation damage due to mud particle invasion. Also, in most cases, no formation fluid can be collected from low permeability formations during these tests.