Africa (Sub-Sahara) ExxonMobil will drill its first exploratory well offshore Liberia this month, the company announced on 18 October. A deepwater well is planned on the Liberia-13 Block, which is about 50 miles off the coast of the West African country. Solo Oil plans to spud the Ntorya-2 appraisal well in Tanzania next month. The drilling pad is a mile southwest of the 2012 Ntorya-1 discovery well, which was tested at rates of 20.1 MMcf/D of gas and 139 B/D of condensate. An independent report estimated the discovery to hold 153 Bcf of gas in place, of which 70 Bcf is considered a gross best-estimate contingent resource. A gross best estimate of more than 1 Tcf of gas in place has been made for the Ntorya prospect as a whole, in which the company has a 25% interest. Asia Pacific BP has decided to abandon drilling plans in the Great Australian Bight offshore southern Australia, an area in which prospective drilling has long been contested by environmentalists.
The Ceduna Sub-basin is one of the few remaining frontier basins in Australia today. Few exploration wells have been drilled in the basin and none have encountered hydrocarbons. The current study aims to investigate the hydrocarbon prospectivity of an area of interest (AOI) within the distal part of the Ceduna Sub-basin, where no well information is available.
The study uses 3D seismic data and employs principles from geophysics, structural geology, sedimentology, sequence stratigraphy, and petroleum systems analysis in a comprehensive investigation to understand the Ceduna Sub-basin. Multiple 2D basin models were created for the AOI to test different scenarios in a detailed risk analysis of the petroleum system and its major controls. They were identified from a comprehensive literature review and after a thorough interpretation of the 3D seismic survey in the AOI.
Results show that the best reservoir is located within the low stand systems tract (LST) deposits of the Hammerhead Sandstone (Ss) and Top Tiger Ss. The potential source rock occurs in the condensed high stand system tract (HST) deposits in the Base Tiger Ss and White Pointer Ss. 1D modeling showed that these source rocks may have generated hydrocarbons as their depth is <9 km. The critical moment during the source rock history was at 80 Ma coinciding with the deposition of the Hammerhead Ss.
Based on the regional structural framework, faults were initiated after source rock deposition. Several growth faults may pose a risk in terms of hydrocarbon leakage. Different 2D models have advanced the understanding of the petroleum systems in the AOI. The results showed that the most prospective areas are within a rollover anticline play and those areas where intra-formational seals are present. The model confirms that fault integrity represents the prime risk across the basin.
The current study contributes to understanding of the Ceduna Sub-basin by identifying two different plays in the AOI: rollover anticline and tilted fault block. Probability analysis of the different petroleum elements shows that the rollover anticline play has the highest geological probability of success.
AbstractThe Great Australian Bight(GAB) has been subjected to exploration for the past five decades with no major hydrocarbon discoveries, and could be defined as a new frontier for oil and gas development. BP has recently committed to a drilling campaign in the region and establishing key infrastructure indicating potential for a significant hydrocarbon discovery. The key challenges for developing in this area are; ➢Remoteness–Closest population 300km away, nearest oil & gas infrastructure +1,000km away➢Deep water – Area explored range from 1,000m to 3,000m➢Harsh Environment–100yr storm estimate significant wave height 13m, period 12s, andcurrent 1m/s➢Limited information for long term modelling of the environmentThis paper has focused on the evaluating different development options against the challenges, with mostof the data being based upon public information from BP drill sites. The focus of the technical feasibility assessment is on the potential production mechanism used to enable the development i.e. fixed or floating platform or other facility. This conceptual review forms the preliminary basis for concept selection for a field in this new and environmentally highly sensitive area and as such it is expected that several potential offshore development options are to be presented.
Oil wealth can either be a curse or a blessing. However with prudent management oil wealth becomes a primary source for economic transformation. The purpose of this research is to investigate the management of oil revenue in some oil rich countries specifically Angola, Nigeria and Norway and draw some lessons for Ghana's nascent oil industry. These factors were identified in the main work and later categorised under three variables namely; stability, dependency and corruption. Using a qualitative study approach, the effects of these factors on the four countries being studied were analysed using the assessments of working papers by the World Bank, CIDCM and the Corruption Perception Index by the Transparency International. The study revealed that the main cause of mismanagement of oil revenue in Nigeria and Angola was the overdependence of the economies of both countries on their oil revenue, diminishing the effectiveness of good governance in both countries. Norway, on the other hand was successful in managing their resources because of good governance, strengthening their long and stable democracy. It concluded that, though the right policies have been put in place to regulate Ghana's petroleum industry, the judiciary system must be empowered to effectively enforce these policies, and the Government must look at investing its oil rent in sustainable developments. This will help the country in achieving their positive targets and not go down the same lane as the other unsuccessful countries in managing their oil revenue.
Identifying, risking, and maintaining subsurface integrity is of critical importance to a variety of geologic subsurface operations including geothermal, oil and gas production (conventional, unconventional, fractured crystalline, heavy-oil fields), mining, natural gas storage, and sequestration of CO2 and hazardous waste. Predicting and mitigating out-of-zone fluid migration includes but goes beyond maintaining well integrity: it relies on technical understanding of top and fault seals, reservoir and overburden deformation, production/injection-induced stress changes, reservoir management, completions design and engineering, hydraulic fracturing/height containment, wastewater disposal, induced seismicity/fracture reactivation, and reservoir monitoring (e.g., geodetic and downhole measurement and interpretation). Subsurface integrity excludes surface facilities and spill response but includes regulations regarding subsurface activities.
In this paper we present and synthesize examples of subsurface containment loss from oil and gas fields that are documented in the open literature. We then discuss common risk areas or themes in subsurface containment geomechanics that are important to subsurface integrity and illustrate with some general examples how some of these could be investigated by using geomechanical models.
Containment of produced or injected fluids within their intended wellbores or geologic subsurface zones in oil and gas fields is widely recognized as a critical part of exploration and production (E&P) activities in conventional and unconventional plays and reservoirs. For example, it is a primary objective while drilling exploration, appraisal, development, and production wells. Maintaining the integrity of wellbores and subsurface geologic elements can potentially minimize drilling and operational risk. Effectively managing injection pressures, volumes, and rates of fluids in producing fields depends critically on adequately defining the geomechanical limits set by geologic elements such as overburden, caprock, top seals, faults, and evolving in situ stress states (including reservoir pressures). Characterization of the mechanical integrity of the subsurface relies upon obtaining baseline measurements including lithology, petrophysical and mechanical properties, pore pressure, and stress state that are best obtained during field appraisal and development, before production begins. Because the consequences of subsurface containment loss to an operator or partner can be significant, including both direct and indirect costs (e.g., clean-up cost, loss of production, and damage to reputation), even for small events, containment-related activities have assumed a larger share of enterprise risk as technologically more challenging fields are evaluated and placed into production .
Weaver (1965) gave a mathematical formulation that estimates the magnetic signal due to ocean waves and ocean swells. This magnetic effect is a function of many parameters: the wave period, amplitude and direction; seawater properties; the main magnetic field; the aircraft altitude, speed and heading. Ochadlick (1989) reported magnetic field measurements made both from an oceanographic research tower and from an airborne magnetic survey flown at seven different altitudes ranging from 57 m to 210 m, and he concluded that field observation results are consistent with the theory of Weaver (1965). Luyendyk (1997) noticed that a magnetic survey at a flying height of 80 m detected wave noise from ocean swells of 1.5 nT. To design an offshore airborne magnetic survey, Lilly and Weitemeyer (2004) wrote that "a helpful strategy may be to direct the aircraft so that the component of its speed in the direction of swell travel is close to the speed of the swell".
Righetto, G. L. (ATHENA) | Lautenschläger, C. E. R. (Computational Geomechanics Group, GTEP) | Inoue, N. (Group of Technology in Petroleum Engineering, PUC-Rio) | da Fontoura, S. A. B. (Pontifical Catholic University of Rio de Janeiro)
Aiming to increase hydrocarbon production, the oil industry has developed recovery methods whose purpose is to get more production. Thus, several problems may be encountered when making use of these techniques, mainly the conventional one. In addition, consideration of geological structures in reservoir engineering, such as fault zones, has fundamental character for determining realistic response for the production of hydrocarbons. In the case of faults zones, its consideration in the model has significant importance currently, especially with regard to the possibility of reactivation and possible loss of tightness of the reservoir. Thus, the aim of this study was assess reservoir models with a fault zone using partially coupled hydro-mechanical simulations. The methodology considers a fault zone whose behavior is given by the Mohr-Coulomb yield criterion. The plasticity model showed consistent results with the process of reactivation for the models. Thus, for the case where the objective is to determine the maximum flow rate of injection as well as its spatial configurations aimed at maintaining the field production, it is possible to establish the flow rate that may result in the initiation of the fault reactivation. Furthermore, the effect of surrounding rocks had a great influence in the time required to initiate the process of reactivation. As a general conclusion, it is stated that the consideration of fault zones in reservoirs, as well as surrounding rocks, must be taken into account to obtain more accurate response to the field behavior.
The exploitation of petroleum began from the drilling of the first well of petroleum in the XIX century in the United States. From this point, aiming increase the petroleum recovery, the oil industry developed recovery methods whose objective is to obtain a higher production than that which would be obtained only as a result of the natural energy of the reservoir (Thomas 2001). In this context, several problems can be faced when one uses recovery techniques, mainly through the fluid injection, in geologically complex reservoirs.
Besides that, the consideration of geological structures in the reservoir engineering, for instance faults, has fundamental importance for determining realistic responses related to oil recovery factor, compaction of reservoir, seafloor subsidence, among others. In the specific case of faults, its consideration and analyses has been reported for several authors (Morris et al. 1996, Wiprup & Zoback 2000, Mildren et al. 2002, Streit & Hillis 2004, Chiaramonte et al. 2006, Færseth et al. 2007, Rutqvist et al. 2007, 2008, Soltanzadeh & Hawkes 2008, Zhang et al. 2009, Cappa & Rutqvist 2010, Ducellier et al. 2011, Jain et al. 2012, McDonald et al. 2012; Leclère & Fabbri 2012), due, mainly by its reactivation possibility. In the fault reactivation perspective during the field development, the objective is to prescribe the highest injection flow rate or the highest bottom hole pressure that can be applied in injector wells in order to maintain the reservoir pressure, without the failure of the faults. The process of fault reactivation, due the stress state variation, can result in an emergence of a preferential path for the hydrocarbon, implying in the most critical cases, in the leakage of fluid and possible loss of tightness of the reservoir.
Bradshaw, Marita (Geoscience Australia, GPO Box 378, Canberra A.C.T., 2601, Australia Email: email@example.com) | Foster, Clinton (Geoscience Australia, GPO Box 378, Canberra A.C.T., 2601, Australia Email: firstname.lastname@example.org) | Willcox, Barry (Geoscience Australia, GPO Box 378, Canberra A.C.T., 2601, Australia Email: email@example.com) | Struckmeyer, Heike (Geoscience Australia, GPO Box 378, Canberra A.C.T., 2601, Australia Email: firstname.lastname@example.org)
AUSTRALIA'S FRONTIER BASINS AND PROSPECTS FOR NEW PETROLEUM PROVINCES. Marita Bradshaw, Geoscience Australia, GPO Box 378, Canberra A.C.T., 2601, Australia Clinton Foster, Email: email@example.com Barry Willcox, Heike Struckmeyer Abstract Within Australia's marine jurisdiction (AMJ) there are at least ten deepwater basins related to Mesozoic rifted margins that have the potential to contribute at least one new petroleum province of global significance. Current offshore exploration activity in Australia is focussed around giant fields in the north west (North West Shelf) and in the south east (Bass Strait) quadrants of the AMJ, representing less than one percent of the prospective acreage. Frontier basins in deepwater along Australia's southern and eastern margins are vastly under-explored with only three exploration wells having been drilled in water depths beyond 500 metres and limited, sometimes only regional, seismic coverage. Despite this minimal exploration, active petroleum systems are indicated by remote sensing techniques (SAR, ALF), seismic evidence of bottom simulating reflectors (BSRs), flat spots and gas escape structures, beach strandings of asphaltites, and oil and gas shows in the few wells in this region. Key prospects for hydrocarbon exploration in the future include the basins of the Great Australian Bight, the west Tasmanian margin and the Lord Howe Rise. Australia's southern margin is conjugate with Antarctica and was the site of a major Mesozoic rift valley system approximately 4,000 kilometres long. At its eastern end the giant Gippsland Basin fields were discovered in the 1960s, but the western two-thirds of the margin is essentially unexplored. A giant Late Cretaceous delta complex is apparent even on present day bathymetry. It is comparable in area to the Niger Delta, with prograding sequences up to 5,000 metres thick. These sand-rich sequences overlie mobile units representing Albian and Turonian marine shales; and the total sedimentary section is up to 15,000 metres thick. Along the western margin of Tasmania and on the South Tasman Rise the break-up had a strong trans- current component producing a series of strike-slip basins up to 6,000 metres thick. Restricted marine environments were maintained along this part of the margin until the final separation of Australia and Antarctica in the Oligocene. The Lord Howe Rise is a large continental fragment lying between Australia, New Caledonia and New Zealand in the Tasman Sea. It covers an area of 740,000 square kilometres in waters shallower than 3000 metres. It is underlain by a number of sedimentary basins, some in excess of 4,000 metres thick. BSRs indicative of gas hydrates, flat spots and diapiric features have been observed on the limited seismic coverage. BLOCK 1 -- FORUM 2 157 AUSTRALIA'S FRONTIER BASINS AND PROSPECTS FOR NEW PETROLEUM PROVINCES Introduction Australia's marine jurisdiction covers 14.2 million square kilomet
Continental margin sedimentation (COMSED) has recently become an area of emphasis within the National Oceanic and Atmospheric Administration. In a combined Government-university-industry operation off the northeast U.S., quantitative parameters f sediment flux and dispersion are being studied. Previous geological investigations on the Atlantic continental shelf have described bottom sediments and current directions on a regional scale; C0MSED will define detailed bottom morphology, shallow stratigraphy, bottom sediment movement, and geochemistry.
The initial area of interest is the continental shelf from Long Island, N.Y., to Cape Hatteras, N.C. Some university studies of the North Carolina, Virginia, and Delaware coasts have already been done. Investigations are now being under taken on New York-New Jersey shelf as part of NQAA' s Marine Ecosystems Analysis (MESA) environmental study. NOAA's initial plans in the NewYork sector call for three shelf transects from the shoreline to the upper continental slope off Long island ,new york harbor, and new Jersey. Each transect contains three study areas of approximately 300 square nautical miles each representative of the nearshore, mid-shelf, and shelf-edge environments. However, due to budget restrictions, work in 1973 will be confined to an intensive study of the apex of the New York bight centered around Ambrose Light.
The program is planned in three phases: I. Description of sediment parameters: grain.size and composition, bottom morphology, shallow stratigraphy and geochemistry; II. Analysis of the hydraulicregime by current meter and wave refraction studies, and III. Examination of the bottom sediment flux and the flux ofsignificant geochemical parameters by radioactive tracers and other dynamic measurement techniques.
Continental shelf studies are increasingly attracting geologisis as they attempt to define more precisely the distribution of sediments and track their movement. The increased environmental and ecological interest in the marine area by the general public has added considerable emphasis to this work such that community problems may be studied in addition to working on long-standing questions in the basic research area. The COMSED (continental margin sedimentation) project will attempt to provide geological data by serving as the focus of cooperative work between several government agencies, universities, and private contractors.
The Atlantic continental shelf is presently used as a source of mineral resource (sand and gravel), living resource (shellfish and finfish), waste disposal (sewer-sludge, dredge spoil, cellar dirt, and acid waste dumpsites), recreation (swimming, boating and fishing) , and more recently, as proposed sites for offshore nuclear power plants and deep-water ship terminals. The northeast Atlantic shelf was chosed for the initial area of study because of population demands for these often conflicting multiple uses. The New York bight area, extending from the-eastern tip of Long Island southward to Cape May, New Jersey, wait chose-n-in particular because of high demand for basic environmental data. The area is unique geoiogically in having the Hudson shelf valley cutting across the entire shelf from its edge to nearly the shoreline.