Formation Testing Below 20,000 Feet
Authors: Edwards A.G. , West E.R. 
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
This paper was prepared for the Deep Drilling and Production Symposium of the Society of Petroleum Engineers of AIME, to be held in Amarillo, Texas, Sept. 8–10, 1974. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.
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Abstract
Better knowledge of the lithology and improved equipment has greatly increased the success of Formation Testing below 20,000 feet. Careful examination of well conditions and equipment used on Ellenburger, Arbuckle and Hunton tests has been the key to eliminating many problems. problems. Experience in these formations shows that it can be predicted, with a substantial degree of accuracy, when the testing tools will be stuck. Fishing time, the few occasions when the testing tools are stuck, has been substantially reduced by using the correct equipment and techniques.
Packer seats in these fractured formations can be a problem. Some unusual approaches to this problem such as minimum water and gas cushions has proven helpful. Tandem packers with a proven helpful. Tandem packers with a pressure distribution valve between has pressure distribution valve between has aided significantly in getting and maintaining good packer seats. Selection of the packer seats in the Ellenburger, Arbuckle and Hunton is of utmost importance due to the natural fractures. Specific conditions of each well dictate the type packer element to be used. Packer packer element to be used. Packer elements capable of setting and maintaining a seat at the temperature and pressures normally encountered in these formations are available.
Confidence in the ability of obtaining mechanically successful tests, has permitted focusing attention on obtaining permitted focusing attention on obtaining maximum data. Again, experience has proven the best teacher. Better data is proven the best teacher. Better data is being obtained by one or two longer flow and closed-in periods than had been obtained with multiple flows of short duration. Reliability of the packer seat and reaction of the well during the flow periods are the major influences on the duration of the test.
Using the procedures discussed in the paper, information to aid in evaluating the wells' potential such as: Production Rate, Transmissibility, Average Production Rate, Transmissibility, Average Effective Permeability, Damage Ratio, Theoretical Potential with Damage Removed, Radius of Investigation and Potentiometric Surface is being obtained Potentiometric Surface is being obtained on these tests.

Introduction
Formation Testing below 20,000 feet in the early sixties encountered many problems.