FORMATION TESTING USING INFLATABLE PACKERS: FROM FOUNDATION GROUTING TO NUCLEAR WASTE DISPOSAL

Packers are down-hole tools that are used to isolate a portion of a well or borehole. Packers are used for many purposes, including well completion, well repair, hydraulic fracturing, grouting, and formation testing. This paper focuses on formation testing using an inflatable packer system, and depending on the industry, may also be called “permeability testing”, “aquifer testing”, “well testing”, “flow testing”, “yield testing” or “formation evaluation”. Regardless of the name, the goal is to characterize the parameters that control fluid flow in a given rock mass. The manner and degree to which these parameters are characterized can vary greatly depending on the purpose of the work, testing methods, and the standards of a given industry. For example, the requirements to design a grouting program for a foundation differ significantly from those for obtaining input data for modeling nuclear waste repository performance.

The purpose of this paper is to describe a variety of packer systems used for formation testing and the capabilities of each system. Factors affecting tool choice and design include the expected permeability range, accuracy requirements, ultimate use of the test results, budget constraints, and drilling methods. The following types of packer systems are discussed:

· Wireline systems for through-the-bit testing

· Tubing-conveyed packer systems for low- to medium-permeability formations

· Tubing-conveyed packer systems for high-permeability formationsPacker systems can include tools , such as down-hole pressure measurement, down-hole shut-in valve, and in-line pumps, which greatly affect the quality of results and evaluation costs. Finding the proper balance between equipment cost and quality of data is critical to any field testing effort. Inflatable packer systems allow for flexibility in project requirements and completion.