LITERATURE SURVEY ON CEMENTS FOR REMEDIATION OF DEFORMED CASING IN GEOTHERMAL WELLS
- BROOKHAVEN NAITONAL LABORATORY
Brookhaven National Laboratory was requested to conduct a literature survey for the best available cement to use in the proposed casing patch as part of the Geothermal Drilling Organization (GDO) project on remediation of deformed casings. A total of 50 wells has been identified with deformed production casing in Unocal's portion of The Geysers geothermal field. Reduced internal diameter and casing doglegs result in lost production and the possible need for abandonment. The cause of the deformations is believed to be formation movement along fault planes and/or along weaker layers or interfaces between high impedance contrast media. Apparently, it is unclear whether shear or axial compression is the dominant failure mechanism. A procedure to address the casing deformation and avoid abandonment of these wells has been developed as described in the Geysers Deformed Casing Remediation Proposal. The proposed remediation procedure involves isolation of the zone of interest with an inflatable packer, milling the deformed casing and cementing a 7 inch diameter liner to extend approximately 100 ft above and 100 ft below the milled zone. During the milling operation it is possible that the original cement and surrounding formation may slough away. In order to specify a suitable cement formulation for the casing patch it is first necessary to identify and understand the deformation mechanism/s operating in The Geysers field. Subsequently, the required cement mechanical properties to withstand further deformation of the repaired system must be defined. From this information it can be determined whether available cement formulations meet these requirements. In addition to The Geysers, other geothermal fields are at possible risk of casing deformation due to subsidence, seismic activity, lateral and vertical formation movement or other processes. Therefore, the proposed remediation procedure may have applications in other fields. The literature survey focused on published properties for cements used in geothermal and oil well applications and the experiences of well casing deformation occurring in oil and gas fields. Dr. Mike Bruno of Terralog Technologies kindly supplied a reference list from the DEA (Drilling Engineering Association) 99 Project on Analysis of Well Casing Damage Induced by Reservoir Compaction and Overburden Shear.
- Research Organization:
- Brookhaven National Lab., Upton, NY (US)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 758977
- Report Number(s):
- BNL--66071; EB4001; EB4001
- Country of Publication:
- United States
- Language:
- English
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