Oilwell/gaswell cement-sheath evaluation
- Mobil Technology Co., Dallas, TX (United States). Producing Technical Center
Cement is placed in the casing/openhole annulus for two primary purposes: to isolate producible formation horizons and to support the casing. When one evaluates a cement in an oilwell/gaswell annulus, all one really needs to know is whether cement exists in the annulus (regardless of its strength) and whether the cement occupies 100% of the annulus. If 10-psi cement exists in 100% of the annulus, no portion of it can be removed for replacement by a 1,000-psi cement. If the annulus is packed with settled barite (from the drilling mud) or formation particles, no portion of the particulate matter can be removed and replaced by cement. Only liquids can be removed from the annulus for replacement by squeeze cementing. Acceptance of this basic premise can both simplify evaluation of a cement sheath in a casing/openhole annulus significantly and complicate measurement methods significantly. This leaves one with trying to identify solids or liquids behind the casing, not the difference between 250- and 5,000-psi cement. The paper discusses cement-sheath complications, cement-bond logs, annular segmentation for analysis, cement-evaluation recommendations, and interpretation guidelines.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 580773
- Journal Information:
- JPT, Journal of Petroleum Technology, Journal Name: JPT, Journal of Petroleum Technology Journal Issue: 12 Vol. 49; ISSN 0149-2136; ISSN JPTJAM
- Country of Publication:
- United States
- Language:
- English
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