| Title | Development of a High Temperature Borehole Fluid Sampler and Its Field Experiments in the Larderello Geothermal Field, Italy |
|---|---|
| Authors | Colin Twose, Roger Parker, Takashi Okabe, Koichiro Kirihara, Haruya Nakata, Tayuki Kondo, Hirokazu Karasawa and Guido Cappetti |
| Year | 2000 |
| Conference | World Geothermal Congress |
| Keywords | NEDO, controlled displacement fluid sampler, rupture disk, Larderello, PTFE seal, Brine filter sampler |
| Abstract | The objective of the high temperature fluid sampler development programme is to produce a downhole system capable of capturing a very high quality, representative sample of the borehole fluid and to deliver it to the surface for subsequent analysis. The maximum operating temperature of the system will be 400?C. Minimal sample alteration and zero contamination are required. The development of the high temperature fluid sampler for the New Energy and Industrial Technology Development Organization (NEDO), for the deep seated geothermal resources research programme began in 1993, with the first prototype tool rated at 300?C (Halladay, 1997). Following these tests reported here the second prototype rated for 400?C will be designed, built and tested. The development programme has included extensive high temperature seal performance tests, material corrosion trials and subsystem design studies. Several types of sampler have been identified and the controlled displacement type (CDS), chosen as the one which offers the best potential for the highest quality sample and further development for use at high temperature. A high temperature CDS sampling tool has been designed, constructed and has been tested downhole at 200?C. This paper presents the field experiments with the first prototype tool at the Larderello site of ENEL in Castiglioni-1 borehole. Over the 6 days period of the test the sampler was deployed 9 times. Initially, some difficulty was experienced with the non-return inlet valve seal leaking, and several deployments returned a small volume of non-pressurised sample. This was rectified by a modification to the seal assembly. The final 5 deployments returned complete pressurised borehole fluid samples to the surface from a depth of 1125 metres. The samples were analysed later and the results are presented in Table 1 below. |