New Techniques for Oriented-Density Evaluation
- A.E. Holm (El Paso Natural Gas Co.) | J. Kleinegger (Blue Jet, Inc.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- October 1976
- Document Type
- Journal Paper
- 1,151 - 1,156
- 1976. Society of Petroleum Engineers
- 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 4.6 Natural Gas, 1.14.3 Cement Formulation (Chemistry, Properties), 2.4.3 Sand/Solids Control, 1.6 Drilling Operations, 5.6.1 Open hole/cased hole log analysis, 1.14 Casing and Cementing, 2.2.2 Perforating
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By using a digital readout panel, a quantitative evaluation of the densities surrounding casing strings was made with a motorized oriented-density tool. Subsequent drilling-out alongside the casing confirmed the log evaluation.
Since earlier tools could give only a qualitative evaluation of the densities surrounding the casing, a digital readout panel with some electronic modifications was used with the motorized oriented-density tool. This tool now can be used to quantitatively evaluate the wellbore and to orient perforations in dual or multiple casing-string wells.
A simulated-well calibrator was built to calibrate the oriented-density tool while looking through neat cement. Correlation of the calibrator with the actual well logs was excellent. The effective depth of investigation of this tool was also determined using the simulated-well calibrator.
By plotting tool counts per second vs bulk density, this tool can detect other casing strings, neat cement, pozmix cement, mud, water, and gas with reliable results.
Well Conditions Used
Casing: 2 7/8-in., 6.4-lb, J-55, NU, 10 round tubing; two strings cemented nonconcentrically in an 8 3/4-in. wellbore using rubber turbilizers.
Completion cement: Class B neat cement mixed at 15.6 ppg; 1.96-gm/cc bulk density when set up; pumped as tail-in slurry.
Filler cement: 65/35 Class B pozmix cement with 12-percent get added; mixed with 15.56 gal of water per sack at 11.3 ppg; 1.48-gm/cc bulk density when set up; pumped as lead-in slurry. pumped as lead-in slurry. Motorized oriented-density tool: 1-11/16-in.-OD collar locator and motor sections above a 2 1/8-in.-OD window-type detector and radioactive source sections, which can be installed above a 2-in. cased gun for oriented perforating (Fig. 1).
Tool Calibration Simulated-Well Calibrator
To accurately determine the response to neat cement, a calibrator was built to simulate a single string of 2 7/8-in. casing cemented in a wellbore with neat cement. The calibrator is a 14 1/2-in.-ID, 36.71-lb, Grade B line pipe with a pup joint of 2 7/8-in., 6.4-lb, J-55 tubing capped on the bottom end and cemented adjacent to the inner wall of the line pipe. The 2 7/8-in. tubing was then filled with water (Fig. 2).
A 5-counts/sec statistical variation resulted. Logging was performed without tool rotation; then the detector performed without tool rotation; then the detector window was placed looking directly toward the neat cement (180 degrees ) and was recorded on the chart. An average 115 counts/sec was recorded. with an over-all statistical variation of 5 counts/sec.
The effective depth of investigation was 4.5 in. Logging with tool rotation in the calibrator, a sweep of 154 degrees was observed in the neat cement before encountering the 14 1/2-in. line pipe (Fig. 3).
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