Numerous carbonate reservoir discoveries were made in Indonesia (
The process involves multiple cycles—from formation evaluation (e.g., geomechanics analysis, design of an effective fracturing method, and production forecasting) through the economic impact to the operator. During the early phase of this integrated study, the uncertainties of all static and dynamic parameters (i.e., geological complexity, rock physics, and stress profile) were considered for fracturing design. Production performances from multiple fracturing stimulation scenarios were then modeled and compared to select the plan that optimizes production for the Berai Formation.
Results demonstrated an effective multidiscipline approach toward a comprehensive strategy to meet the ultimate objective in optimizing production. This project leveraged formation evaluation and fracturing design to deliver integrated solutions from exploration to accurate production forecast. The well stimulations were performed by carefully selecting fluid characteristics based on geological-petrophysical properties, pressure, and stress profiles within the area. Results yielded excellent production gains—for the best case, up to 50% with an average of 40% in comparison with initial production by using an acid that provides optimum fracture geometry and permeability.
This opportunity demonstrated the importance of understanding formation behavior and the parameters that aid the selection of an appropriate fracturing design for a low porosity/permeability carbonate reservoir.
Africa (Sub-Sahara) Oil was discovered at the Ekales-1 wildcat well located in northern Kenya. The well has a potential net oil pay in the Auwerwer and Upper Lokone sandstone reservoirs of between 197 ft and 322 ft. Tullow (50%) is the operator in partnership with Africa Oil (50%). Drillstem tests on the Pweza-3 well offshore Tanzania flowed at a maximum rate of 67 MMscf/D of gas. The tests confirmed the excellent properties of the Tertiary-section reservoir. BG Group (60%) is the operator in partnership with Ophir Energy (40%). Asia Pacific China National Offshore Oil Corporation issued a tender to invite foreign firms to bid for oil and gas blocks in the east and south China Sea. Twenty-five offshore blocks will be offered, including 17 in the South China Sea, three in the East China Sea, and five in the Yellow and Bohai seas.
Africa (Sub-Sahara) A drillstem test was performed on the Zafarani-2 well--located about 80 km offshore southern Tanzania. Two separate intervals were tested, and the well flowed at a maximum of 66 MMscf/D of gas. Statoil (65%) is the operator, on behalf of Tanzania Petroleum Development Corporation, with partner ExxonMobil Exploration and Production Tanzania (35%). The FA-1 well--located in 600 m of water in the Foum Assaka license area offshore Morocco--was spudded. The well targets Eagle prospect Lower Cretaceous resources. Target depth is 4000 m. Kosmos Energy (29.9%) is the operator, with partners BP (26.4%),
Nugroho, Bayu (Ophir Energy Indonesia) | Guritno, Elly (Ophir Energy Indonesia) | Mustapha, Haryo (Ophir Energy Indonesia) | Darmawan, Windi (Ophir Energy Indonesia) | Subekti, Ari (Ophir Energy Indonesia) | Davis, Carey (Ophir Energy Indonesia)
The long-held view and general understanding on the source rock within the Upper Kutai Basin is that it comes from the fluvial-deltaic facies. This deltaic coals and carbonaceous source rock has been proven generating gas with oil in Western Indonesian tertiary basins such as the Miocene Balikpapan Formation in the Lower Kutai Basin, Tanjung Formation in the Barito Basin and TalangAkar Formation in the South Sumatra Basin. The Oligocene carbonate play in the Upper Kutai Basin is under-explored, with exploration historically focusing on the Miocene deltaic and turbidite plays. These carbonates mainly consist of the UjohBilang or Berai equivalent Formation which outcrops along the southern and western margin of the basin, and is seismically imaged in the subsurface, forming on isolated basement highs and large platform areas. Ophir Energy's Kerendan Gas Field in the Bangkanai PSC is the only Oligocene carbonate gas producer in the Kutai Basin. Development drilling on the Kerendan Field and the West Kerendan-1 exploration well has provided new information which, together with a reevaluation of the existing carbon isotope and other geochemical data has led to a reinterpretation of the source rocks for Kerendan gas. The gas was previously postulated to be generated from Eocene terrestrial source rocks similar to the source rocks that generated oil and gas in the neighboring Tanjung Field in the Barito Basin, 100 kms to the South. The recent carbon isotope data from the Kerendan wells reveals that the gas in the Oligocene carbonate reservoir in Kerendan was generated from a marine source rock and is not terrestrial in origin. In addition there is also a terrestrial component within the gas found at the younger stratigraphic interval.
ABSTRACT: The study is conducted in a coal mining which elongated at South Kalimantan to East Kalimantan covering Tanjung Formation and Kampungbaru Formation. As the area is an open-pit mine, a rapid assessment is required in order to determine slope stability. One of the assessment methods is by using SMR (Slope Mass Rating) based on Bienawski’s RMR. SMR has been studied and formulated by a lot of researchers. However, those SMR results might be inappropriate for some field condition, including the study area. Therefore, in order to get the optimal value of SMR, a correction must be done to all value of obtained SMR. The correction provides modified SMR formula as follow: SMR = 7.2251 RMR0.5207; R2 = 0.89. Based on the formula, slope stability can be determined and applied to slope design for rock slope with following criterions: (1) Very poor rock: slope will stable with dip-slope <35°; (2)Poor rock: slope will stable between 35°-49°; (3)Fair rock: slope will stable between 50°-61°; (4) Good rock: slope will stable between 61°-71°; (5) Very good rock: slope will stable between 71°-79°.
The research area is an open-pit mine, a rapid assessment is required in order to determine slope stability. One of the assessment methods is by using SMR (Slope Mass Rating) based on Bienawski’s RMR (Rock Mass Rating). Slope Mass Rating is a method that can provide quick suggestion for determining stable slope angle in mining engineering (open-pit mining). Some researchers proposed different formulas of SMR, therefore to get optimum value of SMR, an approach was carried out through modification (Zakaria et al. 2015). Geomechanics classification is based on Rock Mass Rating (Bieniawski, 1989). The study is conducted in a coal mining which elongated at South Kalimantan to East Kalimantan covering Tanjung Formation and Kampungbaru Formation. Tanjung Formation at Satui and surrounding is located in South Kalimantan, and Kampungbaru Formation at Sangasanga located at East Kalimantan (Fig. 1).
Putra, Rieza R. (Pukesmigas Trisakti University) | Larasati, Dian (NEGT Pertamina Upstream Technology Center) | Ardi, Sunarli (NEGT Pertamina Upstream Technology Center) | Fiqih, Fikri Muhammad (Pertamina Hulu Energi) | Ramdani, Hilman (Pertamina Hulu Energi) | Widarto, Djedi (NEGT Pertamina Upstream Technology Center) | Guntoro, Agus (Pukesmigas Trisakti University) | Usman, Alfian (NEGT Pertamina Upstream Technology Center)
Integrated from regional studies, geomechanical test from WCBF outcrop sample, conducted to determine where exactly placement of effective coal cleat accumulation. However, this paper focusly on structural and geomechanical aspect and which deformation phase that causing effective cleat accumulation.
Macroscale approach based on three stopsite of WCBF obtained major of west-east trending face cleat and north-south trending of butt cleat. The major trend of coal cleat respectively correlate with regional west-east shortening deformation phase due to tectonic inversion by Meratus Mountain during pliocene-pleistocene. Number of permeability value based on macroscale technique using outcrop matchsticks and cubes formula run widely in 7-46 darcy interval. Mesoscale approach using FMI analysis shows similar west-east coal cleat in subsurface (Coal Zone A) and strongly correlate with downward coal zone (B and C). Permeability value of mesoscale technique at 7.05 md and 5.2% of porosity based on CT Scan analysis from WCBF outcrop sample (TJ-11). The value of mesoscale permeability shows good negative exponential relationship through subsurface permeability test using IFO Test from 414-616 m of depth with range of permeability 3.3-0.23 md. Microscale measurement using SEM analysis from TJ-09, TJ-10, TJ-11 have values range from 0.6, 18.53, 17.824 md. As tested by mesoscale permeability integrated to IFO Test, each of approximation parameter would be respectively following the mesoscale exponential power law.
Geomechanic test was directly tested to SPL-03 sample from WCBF shows number elastic moduli; Young Modulus at 2652.74 MPa, Bulk Modulus 1163.48, Poisson Ratio 1069.65. Hydrostatic crossplot between depth against pressure (confining pressure from uniaxial test) clearly shows that overburden stress (SV) have no influence to create effective stress-driven cleat prior to deformation (Shmax and Shmin).
Fault Facies gave a brief classification of the area surrounding the fault which accomodate most effective cleat abundance in damage zone of the fault. Using weight factoring correlation between paleogeographic and strain partitioning by observe the geometry changing between bisected σ1 and σ3 trajectories. The most effective types of cleat occurs in distributed conduit and combine conduit barrier fault area with tensional-rotational and contractional-rotational strain region.