Comparison and Contrasts in Geothermal Drilling at Ngawha and Broadlands

Abstract

two years ago in the Broadlands Investigation Report of June 1977. Drilling has since followed made in that report to drill wells on major inferred subsurface faults the southeast part the field to identify fracture zone permeability and so add to the overall resources of the field. Both wells (BR 35 and 36) were sited to intersect these faults a to r near the top of the greywacke basement and both were highly successful in intersecting fissures near the anticipated depths and so producing reliable well discharges. The two wells averaged 70 steam at W.H.P. 16 bars, effectively doubling the resources east of the Waikato River to a present of Deepening of three non-productive wells 24, 14 and 30) was also recomnended and the G.C. r i g deepened BR 24 in late 1977. Unfortunately, the strayed offline in the wrong direction (to the northwest by about 10 ) from and was abandoned when drill pipe became stuck. The well is now being redrilled and deviated to the southeast to search for a possible continuation of one of the steep faults in the basement greywacke. A further well (Br 26) was J r l l l e d in the northeast lobe of the resistivity 400 of BR 1 in an area of known high temperatures and low primary permeability. The well intersected greywacke at without encountering any significant losses of circulation; once more the importance of locating subsurface faul t-determined fissures for successful production in the Broadlands Field.