Abstract:

Polyurethe grouting has been successfully applied to a lost circulation zone in a geothermal well at Rye Patch, NV. Previously, this zone had resulted in the temporary abandonment of the well after conventional cement plugs had been unsuccessful. The techniques applied to grouting with polyurethane were adapted from civil engineering technology where polyurethane is becoming the grout of choice for sealing boreholes with large voids and high cross flows.

Abstract:

Foam cement i s a versatile and economical light weight cementing slurry that can be used in geothermal wells. Ultralight foam cement slurries develop useful compressive strength and can be used for primary cementing infragile formation intervals and lost circulation areas. Successful circulation of a full column of cement is practically assured with the proper use of foam cement. Geothermal foam cementing success is dependent upon proper applications, slurry design, and cementing procedures. These points will be covered along with the result s of foam cementing at The Union Geothermal Of Indonesia, Gunung Sal ak Project, West Java, Indonesia.

Abstract:

Three wells were drilled at Puna Geothermal Venture, Hawaii in 2005 – a production well redrill, a new production well, and a new injection well. Several innovative procedures were used to deal with difficulties and successfully complete the wells. A casing patch was used to repair parted casing. Foam cement was used for the intermediate casing and foam cement was reverse circulated for the production casing. Mud motors were used for most of the drilling to increase rate of penetration. Micronized cellulose lost circulation material (LCM) was used to protect moderate permeability zones in the injection well and a hydrostatic bailer was used to swab cuttings and mud back out of the zones.

Abstract:

Geothermal wells in the Blue Mountain area of Nevada have experienced problems caused by losses during primary cementing of well casings, often requiring top jobs to
complete. Conventional cement designs were not effective in solving the problem. Also, as deeper casing setting depths were required because of reservoir characteristics, the risk of not achieving good cement jobs increased. Analysis of cement jobs in this geothermal field led to the need for developing nontraditional cement designs. This paper documents the analysis, planning, and execution of foamed-cementing operations used to successfully perform primary 13 3/8-in. casing cement work. Previous cementing practices are presented, as well as the advantages and design of foamed cementing for this application. A post-job analysis and cost comparison of foamed versus conventional cementing is also presented.

Abstract:

In 2009, Peppermill Resort Casino expanded its use of geothermal waters by drilling at depth into the Moana geothermal resource. The geothermal resource is of meteoric origin and is assumed to be heated by an intrusive body at depth. Past production of fluids from the resource was limited to shallow, Neogene clastic sediments. The first well drilled into the deeper Kat Peak formation was completed in 1988 and was completed as an injection well. In 2007, with the beginning of a large expansion to the facility, it was decided to make geothermal an integral part of the development plan. Two new deep wells were drilled in 2009 and 2010 to provide additional production and injection capacity. These wells demonstrated a significant improvement in temperature and flow over the earlier shallow wells. The use of acoustic and microresistivity logs, combined with other wireline logs and cuttings analysis, helped to develop a more detailed view of the resource. An intensely fractured zone occurs in the highly permeable andesite from approximately 2,500 ft to 3,400 ft. The majority of fractures in the Kate Peak trend northerly with a dip to the west. This data, with existing structural data, allows hypotheses regarding underlying controls of the Moana geothermal resource, as well as a foundation for further economic evaluation for commercial use.

Abstract:

The PUNA Geothermal Venture wells are located on the Big Island of Hawaii. The project site is close to the Kilauea Volcano with a high geothermal gradient resulting in static bottom hole temperatures above 600˚F. As with most geothermal projects, lost circulation can be a problem in drilling these wells, as it is costly, resulting in drilling delays, hole instability and stuck pipe. These associated drilling problems can ultimately jeopardize the hole. By controlling mud losses, the amount of time combating lost
circulation is reduced, providing a more stable wellbore. Controlling mud losses has also been helpful with logistics since Hawaii is 2,000 miles away from the closest drilling infrastructure. The drilling, as with most geothermal wells, is conducted with unweighted drilling mud containing few solids to bridge the formation and limit fluid losses. To minimize lost circulation when drilling the intermediate hole intervals, micronized cellulose material is introduced into the mud system, which stops lost circulation and/or reduces mud losses to seepage. This ability to control mud losses in the intermediate sections provides improved wellbore conditions for directional drilling and benefits cementing operations. To minimize losses and protect the reservoir, the production interval is drilled with a high-temperature copolymer drilling fluid conditioned with micronized cellulose. The micronized cellulose material being used is a unique fibrous material that has been developed for controlling seepage and lost circulation while drilling depleted, fractured or other permeable zones. This paper will discuss the drilling operation, drilling fluid and the application of micronized cellulose on these geothermal wells.