Progress review of geothermal exploratory drilling in Roseau Valley

Dominica News Online has obtained the full report on the completion of drilling on two test wells at Laudat, which according to Energy Minister,  Rayburn Blackmore, means that Dominica is moving closer to realizing its geothermal potential.

Blackmore addressed the media last week, on the status of the geothermal project.

Government signed a contract to the tune of $17-million last year for the exploration of geothermal energy in the Roseau Valley.

Blackmore said that with drilling of two test wells completed, the site for the third well, located between Wotton Waven and Trafalgar, was being prepared.

The ongoing work said the Energy Minister, would help determine the size  and quality of the geothermal resource thought to exist in the Roseau Valley.

The following is the entire progress review of exploratory drilling for geothermal energy in the Roseau Valley:

The Exploratory Drilling Project emanated from the findings of the European INTERREG IIIB Géothermie Caraïbes or “Geothermal Energy in Caribbean Islands” Programme of the Wotten Waven resource area which was undertaken during April, 2008 and November, 2008.

As part of the detailed geological studies and investigation carried out under this Géothermie Caraïbes Project, it was estimated that the Laudat-Wotten Waven geothermal field was about 15 square kilometres with temperature in the range of 250 – 300°C and the potential power capacity to generate 120 Mega-Watt of electricity. In order to verify the reservoir capacity and the quality of the geothermal fluid it was suggested then that a minimum of four (4) strategically located exploratory wells of depth ranging from 1,000 to 2,000 metres would be needed to prove that resource. After further consideration by the geologists and drilling experts it was recommended that the drilling of three (3) exploratory wells in a triangulated formation would more cost-effective.

Hence the main goal of the in progress Drilling of the Three (3) Geothermal Exploratory Wells in the Roseau Valley is to better assess the potential of the Laudat-Wotten Waven geothermal field and to estimate its capacity for power generation. It will provide data on:
 the depth of the reservoir
 the reservoir temperature conditions;
 the reservoir pressure conditions;
 the permeability within the reservoir;
 the fluid(s) chemistry;
 the fluid flow model;

The drill rig and other ancillary equipment for the contractor, Iceland Drilling Company (IDC) arrived in Dominica on November 20, 2011 and drilling of the first well started on Well Site #2 (Aerial Tram, Laudat) on December 15, 2011. On January 28, 2011 the drilling contractor successfully completed the drilling of the first test well, Well #2 and installed casing to a depth of 1,337 metres, one hundred and thirty-two (132 m) metres short of the initial reach of 1,469 metres.

On March 9, 2012, forty-one (41) days after the successful termination of drilling of the first test well, Well #2, the testing aspect performed by ISOR of Iceland, commenced with the allowing of the gas column on the top of the well to escape until the first water with steam appeared. The gas release activity went on for about seventeen (17) minutes under controlled conditions.

According to the expert advice the well was allowed to continue to flow on its own for cleaning out while monitoring the temperature, pressure and sampling of fluid for chemical analysis. The highest temperature recorded during the monitoring was 240 degrees Celsius and the pressure from a depth of 1100 metres was 67.5 Bars (979 pounds per square inch, psi) which indicates a very viable resource. Further detailed deduction on the characteristics of the reservoir based upon the current findings will be produced by the end of the week by the Technical Assistance consultant, ELC.

Meanwhile, the drilling operation on Well #3, near the DOMLEC Balancing Tank, Laudat started on February 14, 2012 and is progressing remarkably well. As of March 14, 2012 the operation has been trouble-free and the final depth of well was 1,613 metres (about 1 mile) which the contractor and consultant believe is well within the reservoir based upon earlier total circulation losses experienced. The key activity on Well #3 over the next two days will involve the placing of the well casing and cementing to stabilize and secure the walls of the well.

The Drilling Supervisor, Geothermal Resource Group (GRG), has advised that the current depth of 1,613 metres is sufficient to permit proper geological/geothermal analysis and determination of the resource within Well #3. Furthermore, it is expected that the necessary drill pad preparation work on the final site, Well #1 in Wotten Waven-Trafalgar will be ready by Monday 19th March, 2012 to permit the timely transfer of drilling equipment to that site for drilling of Well #1.

The drilling contractor and drilling supervisor remains confident that the final drilling operation on Well #1 should proceed satisfactorily. This position is also regarded by the PMU and the Technical Assistance as the expected outcome based upon the improved performance and lessons learnt on Well #3 which were very insightful and rewarding. The successful completion and testing of the 3rd well will provide the required data to determine whether the geothermal reservoir in the Laudat-Wotton Waven area poses the requisite quality and magnitude for large-scale generation of electricity.