Calibrated Impression Packers Define Perforation Size, Shape and Connection To Permeability In Situ
Authors: Anderson Glen W. 
Published: December 2007

Calibrated Impression Packers Define Perforation Size, Shape and Connection Perforation Size, Shape and Connection To Permeability In Situ
American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
This paper was prepared for the Society of Petroleum Engineers of AIME Symposium on Formation Damage Control, to be held in Houston, Tx., Jan 29–30, 1976. Permission to copy is restricted to an abstract of not more then 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 presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal, provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
The eight critical parameters for the accurate calibration of inflatable impression packers are defined and discussed. The development and use of calibration charts are illustrated. The ability to accurately measure perforation size and shape in situ permits an effective evaluation of perforating equipment and permits an effective evaluation of perforating equipment and stimulation techniques. To be effective, a perforation must be properly sized to allow fluid entry but keep out sand and must be properly sized to allow fluid entry but keep out sand and must be connected to permeability. The very low differential extrusion pressures used in the inflatable impression packers cannot displace pressures used in the inflatable impression packers cannot displace the fluid from a perforation which is not connected to a permeable formation, thus, the effectiveness of perforations can be detected.
Preliminary field data indicates that less than 50% of new jet perforations are effective in the low pressured, unconsolidated sands of California oil fields. However, after stimulation by acid washing, 90% to 100% may be effectively connected to permeability.

Introduction
Inflatable impression packers are not new they have been around for a number of years. However, their use has been very limited probably due to one or more of the following limitations:high differential pressure was required to squeeze impressionable material into cracks or perforations which necessitated an inflatable packer which was expensive to manufacture and difficult to make longer than about 10 feet.the inflation pressure often had to be held for up to 10 hours in order to be able to retain an impression.the inflatable packer had to be returned to its manufacturing plant to be repaired or redressed.
A new field redressable, 30' long, low differential pressure inflatable impression packer system has been developed. Also, new impression materials which are oil resistant and which can make and retain in situ impressions in 10 minutes or less have been developed.
During the development and field testing of this inflatable impression packer system, the minute detail and consistency of the impression retrieved on the new impression material suggested that with careful calibration accurate correlations could be made between impression size and actual in situ hole size.