scholarly journals Magnetotelluric monitoring of hydraulic fracture stimulation at the Habanero Enhanced Geothermal System, Cooper Basin, South Australia

2016 ◽  
Vol 2016 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Yohannes L. Didana ◽  
Stephan Thiel ◽  
Graham Heinson ◽  
Goren Boran
2016 ◽  
Vol 56 (1) ◽  
pp. 51
Author(s):  
Maxwell Williamson

There have been 13 major inquiries completed during the past few years that have addressed the issue of hydraulic fracture stimulation (fraccing) in Australia. There are two inquiries due to report before mid-2016; namely in SA (Natural Resources Committee, Parliament of South Australia, 2015), and the Senate Inquiry (Parliament of Australia, 2015). These inquiries are in addition to many others conducted in overseas jurisdictions including various states of the US, Canada, and in countries in the European Union, including the UK. Concerns are usually concluded around ensuring there is a proper regulatory environment to confirm that the use of fraccing is conducted using international best practices, and the risk to the environment is minimised. In each and every responsible inquiry the conclusion has been that there is no scientific or public policy reason that would justifiably prevent the use of fraccing as a pre-well completion stimulation technique. This paper attempts to synthesise basic data about fraccing—why the ability to fracture stimulate wells is no longer a luxury but a necessity in deep oil and gas production—to convey factual information and summarise the results of inquiries in Australia to date. Comparisons between hydraulic fracture stimulation operations and results in the US and Australia are intended to provide comfort that some of the potentially more intense (massive) hydraulic fracture stimulation operations routinely conducted in the US (and Canada) on an individual well basis are not contemplated in the immediate future in Australia. The scale of North American fraccing activities may bear little resemblance to what may be proposed or occur in Australia owing to fundamental differences in geology, basin stress regimes, infrastructure, and cost and logistics, among other factors. The author’s conclusion is that fraccing in Australia can and will be carried out in a sphere of safety and regulation that many other countries are likely to aspire to copy. It would, however, be foolish to suggest hydraulic fracturing operations are not without some risk, as with many industrial and other daily activities, but the risks can be managed or mitigated with sound engineering and scientific practices. This is irrespective of the messages by opponents of hydraulic fracture stimulation in oil and gas wells. The modern practice of fraccing has been used now for more than 65 years, albeit with increasing scale commensurate with technological advances, which has caught the public’s imagination. Indeed, the results of inquiries have given no credence to demonising the technology.


2005 ◽  
Vol 45 (1) ◽  
pp. 175
Author(s):  
D. Wyborn ◽  
L. de Graaf ◽  
S. Hann ◽  
B. Nicholson

Geodynamics Limited is nearing the completion of its ‘proof of concept’ hot fractured rock (HFR) program to extract superheated hot water for electricity generation from granite buried beneath the Cooper Basin. Difficult drilling conditions were discovered in the target granite when the Habanero–1 well penetrated permeable sub-horizontal fractures at more than 4,000 m depth. The well was completed at 4,421 m with overpressures in the fractures around this depth exceeding pressures projected from a hydrostatic gradient by more than 5,000 psi. The static rock temperature at the bottom of the well is about 250°C.The overpressures assisted in the development of the world’s largest underground heat exchanger, a volume of rock more than 0.7 km3 defined by more than 11,700 microseismic events located on-site during the injection of 23 ML of fresh water into the granite fracture network. The horizontal heat exchanger is more than 2 km north–south, more than 1 km east–west and more than 300 m thick. During its development there was no evidence of direct upwards growth towards the sedimentary cover, which is at about 3,700 m, though a small number of events were observed above the main cloud of events. From production logging surveys, a major fracture at a depth of 4,254 m is interpreted to have taken most of the flow during the injection.The second well (Habanero–2) was located 500 m southwest of the first. Before intersecting a major fracture, interpreted to be an extension of the dominant fracture in Habanero–1, it was drilled to a depth of 4,325 m. At this depth, total drilling circulation losses were encountered which were only partially overcome with the pumping of calcium carbonate lost circulation material. During the operation the lower 245 m of the drill stem was irretrievably lost, and the well was subsequently sidetracked to a total depth of 4,358 m, just below the main fracture.Flow and circulation testing between the two wells in early 2005 is designed to demonstrate the economic potential of the far-field geothermal system and the heat exchange volume between the two wells.


2015 ◽  
Vol 55 (2) ◽  
pp. 439
Author(s):  
Nicole Ditty ◽  
Dennis Cooke

Unconventional reservoirs such as tight sands and shales require hydraulic fracture stimulation to improve productivity. The success of reservoir stimulation is controlled by the local stress field but decisions are often made knowing only the average stress field. This study uses geomechanical modelling to help explain lateral stress variability using structural geology, lithology contrast and boundary conditions. Changes in vertical and horizontal stresses are related to depth, lithology and structural position, yet these effects are not always accounted for. This is evident in the Cooper Basin, Australia, where, for example, unexpected changes in minifrac pressure are commonly observed in adjacent wells in a field. This study presents results from conceptual geomechanical models to help explain such variations in stress. Model scenarios are constructed using finite element package to investigate the impact of structural position, rock mechanical properties and stress regime on the patterns of horizontal and vertical stress magnitudes in a layered antiform sequence. Key findings suggest that: stress magnitude is affected by structural positioning; different patterns of stress exist across different lithologies; and, stress regime impacts on patterns of stress, especially in combination with curvature of structures. These challenge traditional methods of one-dimensional mechanical earth models and show that, rather than employing methods developed for simple layer-cake geology in extensional basins, geomechanical models should be constructed in two- or even three-dimensions. Results of this study highlight part of the solution to the unconventional resource potential of the Cooper Basin. Improved prediction of field-scale stress variations should enable further optimisation of hydraulic fracture stimulation treatments.


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