Safety of Casing Shoe Test and Casing Shoe Integrity After Testing
- N. Morita (Conoco Inc.) | G-F. Fuh (Conoco Inc.) | P.A. Boyd (Conoco Inc.)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- December 1997
- Document Type
- Journal Paper
- 266 - 274
- 1997. Society of Petroleum Engineers
- 7.2.1 Risk, Uncertainty and Risk Assessment, 4.3.4 Scale, 2.7.1 Completion Fluids, 1.15 Fundamental Research in Drilling, 1.11.2 Drilling Fluid Selection and Formulation (Chemistry, Properties), 1.11 Drilling Fluids and Materials, 4.1.3 Dehydration, 3 Production and Well Operations, 1.6 Drilling Operations, 2.2.2 Perforating, 5.8.2 Shale Gas
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Increased injection volume during a casing-shoe test is needed to gather data, but it increases the possibility of lost circulation or reduced casing-shoe strength after testing. These hazards often encourage drilling engineers to halt casing-shoe tests prematurely just to confirm the casing-shoe strength. This paper addresses drilling-engineering concerns regarding lost circulation during a casing-shoe test, the extent of fracture propagation, the amount of data obtainable as a function of the drilling-fluid volume injected, and the casing-shoe integrity expected after testing. Laboratory data and a numerical model are used to illustrate phenomena that occur during casing-shoe tests. Analysis of the data yields guidelines for safe casing-shoe tests.
Ongoing improvements in drilling fluids have minimized API-filtrate loss, while providing a thin and impermeable mudcake. Lostcirculation problems are often encountered when using the expensive mineral-oil-based muds, which have otherwise good mud properties, including thin cake formation and reduced filtrate loss. The potential for lost circulation often discourages drilling engineers from conducting proper casing-shoe tests. A guideline is needed to resolve the drilling engineer's concern. To give a guideline for safe casing-shoe testing, this study examines information obtained from several types of casing-shoe tests, casing-shoe integrity after testing, lost circulation during testing, partial lost circulation during drilling, and field examples.
A lost-circulation-simulation model is constructed to study the circumstances under which lost circulation occurs during and after a casing-shoe test. The model reveals the magnitude of lost circulation under various conditions. It analyzes the fracture-propagation resistance, fracture-reopening pressure, and partial lost circulation with the input parameters obtained during the fracture experiments by the Drilling Research Laboratory (DRL) in Salt Lake City, Utah. The results should be applied with caution to a formation with significantly low permeability, because the results are derived from several sandstones (with permeability more than 1 md) and Mancos shale (with permeability more than 0.001 md). These results would not be applicable to those impermeable formations that cannot form any mudcake on the fracture surface. This work, in an effort to quantify lost-circulation problems associated with induced fracture and to establish a risk-assessment procedure, is the first attempt of its kind to appear in literature.
|File Size||372 KB||Number of Pages||9|