Abstract
The requisite of zonal isolation in a highly deviated, ultra-high temperature wellbore placed extraordinary technical demands on slurry design and cementing operations. This paper documents: (1) the project criteria, (2) proposed ultra high temperature and conventional cement slurries, (3) testing considerations, (4) quality control steps, and (5) operational procedures taken to successfully cement six wells. These wells were a critical part of an evaluation process involving two of the foremost in-situ coal gasification techniques.
The Rocky Mountain #1 project tested the Hanna #1 Coal Seam near Hanna, Wyoming. A 100 day controlled burn took place to gather data. This information would allow comparison of two combustion techniques. A water quality control program was implemented postburn in order to ensure non-contamination of the aquifer. The efficiency and effectiveness of the Controlled Retraction Injection Point (CRIP) module was compared with the Extended Link Well (ELW) module. A program was developed to drill and cement to surface three wells in each of the burn and production patterns. The ELW process would require two shallow vertical cased and cemented injection wells. These vertical wells would intersect a medium radius to horizontal cased and cemented production well. The CRIP process required three cased and cemented wells. Two of the wells, medium radius to horizontal, were designed for injection and production purposes. The third well was used for ignition of the CRIP and initiation of the in-situ combustion process.
Hydraulic isolation of all the wells was confirmed by a lack of uncontrolled by-products at the surface, controlled accountability of tracer elements during the burn and good pressure test of the casing shoe. The results of the successful cementing of both the horizontal and the vertical wells contributed to the precise monitoring and comparison of the in-situ burn patterns. In addition, restoration and maintenance of the quality of the aquifer could be recorded for future projects.
