Tight Hole and Closed Chamber Testing - A New Technique for Formation Evaluation
- J.A. McAllister (Johnson Testers) | L.I. Jensen (Johnson Testers Ltd.)
- Document ID
- Petroleum Society of Canada
- Journal of Canadian Petroleum Technology
- Publication Date
- September 1964
- Document Type
- Journal Paper
- 124 - 129
- 1964. Petroleum Society of Canada
- 1.6 Drilling Operations, 5.6.4 Drillstem/Well Testing, 5.6.1 Open hole/cased hole log analysis, 4.1.2 Separation and Treating, 4.1.5 Processing Equipment, 5.2 Reservoir Fluid Dynamics, 1.10 Drilling Equipment
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The closed chamber and tight hole methods of well testing described in thispaper are designed to overcome some special drill stem test problems existingat the surface. The primary purpose for conducting this type of drill stem testis to utilize a system that offers maximum secrecy and/or maximum control offluid recovery; therefore, maximum safety.
The problem of secrecy commonly occurs in Canada, and the tight holetechnique was developed so that only authorized personnel would be able todetermine the type of recovery and the pressure involved.
The closed chamber method has application wherever a high degree of controlof the recovery is desired, such as in townsite and night-time testing, neitherof which can be accomplished safely by the conventional drill stem test method.This method also permits a high degree of safety when testing high-pressure gassands.
Experience with closed chamber testing has indicated that the fluid recoverydata may be applicable for empirical analysis to determine reservoir fluidproperties provided that certain problems are recognized.
Static reservoir pressure can be determined by employing the initialshut-in-flow-period method described in the text of the paper. However,problems are encountered when attempting to utilize the pressure buildup curveto determine transmissibility and permeability with the degree of accuracyobtainable from a conventional drill stem test. Examples of pressure curvesfrom tight hole and closed chamber systems are included and discussed.
Tight hole testing was developed to provide maximum secrecy of drill stemtest results in Canada. In order to maximize secrecy, it was necessary toprovide a testing system that would not allow fluid recovery to be exposed tounauthorized personnel on or off the rig floor.
The tight hole assembly consists of a closed chamber which allows the standsof drill pipe forming the chamber to be separated, drained and set aside in thederrick without revealing any recovery, even in the tool joints, tounauthorized personnel. Secrecy requires the elimination of surface indicationsduring the test and the bringing of the recovery to the surface in such amanner that it will not flow freely from tool joints onto the floor or into thederrick. The recovery has to be removed from the chamber with maximum controlin order to provide secrecy. The conditions required for secrecy result in anincrease in the safety of testing.
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