Vertilog - A Down-Hole Casing Inspection Service
- John N. Haire (Dresser Atlas) | Jearald D. Heflin (Dresser Atlas)
- Document ID
- Society of Petroleum Engineers
- SPE California Regional Meeting, 13-15 April, Bakersfield, California
- Publication Date
- Document Type
- Conference Paper
- 1977. Society of Petroleum Engineers
- 4.3.4 Scale, 3 Production and Well Operations, 2.2.2 Perforating, 4.2.3 Materials and Corrosion, 2 Well Completion
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American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
In California the shortages and resulting economics of new oil has intensified the search for new sources. With casing and drilling costs increasing, this search has resulted in a renewed interest and re-evaluation of many existing wells.
A knowledge of the condition of the existing casing is necessary for repairs, workovers, and possible developement of additional zones.
The Vertilog is a casing inspection service which is now available to the oil and gas industry to determine the condition of the casing in existing wells. It is a quantitative measurement of corrosive damage, indicating if the metal loss is internal or external, and if it is isolated or circumferential. Holes in the casing can be identified as well as parted casing. This survey in conjunction with other measurements, can be used to detect, monitor, and establish preventive techniques for corrosive problems.
This paper is intended to familiarize the industry with tool specifications, theory of operations, calibrations, applications, interpretation principles, and field examples.
The Vertilog is a downhole casing inspection service. The recordings produced allow identification of damaged intervals and severity of corrosion. Measurements taken determine if corrosion or damage is internal or external and if it is isolated or circumferential.
Due to instrument design, casing inspection covers the full circumference and minor elongation does not elect the reliability of the measurements. Anomalies as small as 1/8" in diameter with as little as 20% penetration of the nominal bodywall of the casing penetration of the nominal bodywall of the casing can be detected.
All casing sizes, weights, and grades from 4-1/2" O.D. through 8-5/8" O.D., except 6-5/8" O.D., can be inspected at the present time.
The tools are temperature rated at 250 deg. F and pressure rated at 10,000 PSI. pressure rated at 10,000 PSI. The logging speed is 125 feet per minute and no special borehole fluids are required for the survey. It is recommended that the casing be scraped just prior to the survey for the most definitive measurements.
PRESENTATION PRESENTATION The data is presented in a standard log format, however, the usual depth scale is 10" per 100 feet of borehole for improved definition. The measurements are presented on a four track log grid as illustrated in Figure 1.
Track one and two are designated as Flux Leakage-1 (FL-1) and Flux Leakage-2 (FL-2) and correspond to the two rings of shoes on the Vertilog instrument. Recorder deflections in these tracks indicate the severity of corrosion that has taken place and also the location of the collars.
|File Size||4 MB||Number of Pages||14|