Hydrocarbon production from fractured basement formations

Proceedings of Indonesian Petroleum Association 41st Annual Convention & Exhibition, Jakarta - Indonesia, 2017

Exploration of fractured basement reservoirs has become a great subject of interest in oil and gas industries due to depleting hydrocarbon reserves in many conventional sources. In 2013, PetroChina Intl. Jabung Ltd. successfully drilled the Northeast Betara (NEB) Base-1 well located in South Sumatra Basin to 3000' MD / 2000' TVD through the basement, primarily targeting a fractured basement reservoir. Barefoot test showed that gas and condensate flowed from the fractured basement. Following the success of NEB Base-1 well drilling, NEB Base-2 well was drilled in 2015 at a greater depth than NEB Base-1 well to reach the basement. Interestingly, the barefoot test in NEB Base-2 well showed no indication of influx from the well. Therefore, further investigation on the fracture characteristics from both wells was conducted to better understand their effects on hydrocarbon accumulation. Mudlog and gamma ray log data suggested that both wells have similar granitic basement lithology. However, image log data showed resistivity contrast enhancement for NEB Base-1 well which was associated with open fractures. On the other hand, limited resistivity contrast was observed in NEB Base-2 well, suggesting that the fractures were closed or filled with minerals. The fracture orientation of NEB Base-1 well also indicated that the fracture azimuth is oriented towards ENE-WSW, which is in the direction of compressional tectonics. In contrast, the fractures observed in the NEB Base-2 well are oriented towards NNE-SSW orientation, which is in the direction of extensional tectonics. In addition, compressional sonic data from NEB Base-1 well showed more cycle skipping compared to NEB Base-2 well and NEB Base-1 resistivity log is lower than in NEB Base-2 well. The differences in fracture characteristics of both wells were attributed to the difference in their stratigraphic succession during the syn-rift phase of basin evolution. Palinspastic reconstruction in the NEB area suggested that the area of NEB Base-1 experienced inversion or uplift in the post-rift phase. However, there is no indication of inversion after the syn-rift phase around the NEB Base-2 area. Hence, tectonic inversion played an important role in determining the location of hydrocarbon accumulations in the fractured basement.

Георесурсы, 2018

The shale revolution and the great progress in the US in the development of deposits in tight, ultra-low-permeable, shale strata put the issues of studying and developing unconventional deposits on the agenda. The special geological structure of the deposits of unconventional oils makes it necessary to use new (different from traditional) methods of prospecting, exploration and development of such deposits. And this, in turn, requires a new approach to studying the features of the geological structure and the creation of geological and hydrodynamic models, taking into account the fracturing fields and heterogeneity in the distribution of the reservoir's oil content and the productivity of producing wells. The article deals with the problems of studying the fracturing of rocks and the need to take it into account in the geological and hydrodynamic modeling of oil and gas deposits. The obligatory use of innovative seismic technologies in studying the geological structure of fields and new technologies for studying sludge during drilling is the key to a successful study of unconventional reservoirs and shale strata at various stages of geological exploration and development of oil fields.

Proceedings of the Indian National Science Academy, 2020

India is endowed with twenty six sedimentary basins covering an area of 3.36 million sq. km spread over Onland, Shallow water (down to 400m isobaths) and Deep water (400m isobaths to EEZ) sectors. The aerial extent of Onland, Shallow water and Deep water are 1.63 million sq. km, 0.41 million sq. km. and 1.32 million sq. km. respectively. A large portion of the basinal area is still to be appraised in terms of knowledge building efforts for evaluating hydrocarbon prospectivity of the basin through Geological studies, Geophysical surveys and exploratory drilling. The National Seismic Programme (NSP) introduced by MoPNG, GoI for Geo-Scientific Data generation in Indian Sedimentary Basins is intended to assess the un-appraised onland areas in 26 sedimentary basins. The project relating to Acquisition, Processing and Interpretation (API) of 48,243 LKM of 2D Seismic Data is being implemented through National Oil Companies: ONGCL and OIL. With the increase in exploration spread and quantum jump in availability of geo-scientific data generated under the New Exploration Licensing Policy (NELP), a need was felt to revisit the Hydrocarbon Resource assessment of India which was last carried out during 1995-96. The Reassessment exercise has been carried out during 2015-17. In order to intensify exploration activities and bring investments in Indian sedimentary basins Govt. of India (GOI) has taken a number of measures in recent times. The Hydrocarbon Exploration Licensing Policy (HELP) permits operators to explore and extract all types of hydrocarbon resources from a single acreage. It has also announced fiscal incentives for unconventional hydrocarbon production through this policy. A number of Indian sedimentary basins possess huge volume of organic rich shale rocks deposited through wide geological time. The unconventional hydrocarbon reservoirs include shale oil/gas, tight oil/gas, heavy oil, Coal Bed Methane etc. which are capable of providing a cleaner source of energy than other fossil fuels albeit with appropriate safeguards.

Elements, 2014

2012

Oilfield Review Summer 2012: 24, no. 2. Copyright © 2012 Schlumberger. For help in preparation of this article, thanks to Art Bonett and Ismail Haggag, Abu Dhabi, UAE. FMI and PowerV are marks of Schlumberger. Over the last decade, oil and gas companies have had increased success placing wells within productive zones—sweet spots—of fractured reservoirs. These fracture zones often display subtle expressions in seismic data, but recent advances in seismic attributes and visualization techniques are helping geophysicists identify and characterize them. By combining these geophysical results with geologic and engineering data, companies are reducing risk and increasing their drilling and production successes. Optimal well placement requires the operator to factor the predominant trend of natural fractures into the selection of wellbore orientation. Production may be enhanced by intersecting multiple fractures. Fractures may also redirect the path of injected fluids, thus limiting the fl...

2003

There are no technical and technological problems concerning oil shale mining, therefore the section" Oil Shale Resources, Geology and Mining" concentrated mainly upon resources and mining impact on the environment. The problems were analyzed and discussed basing mainly on the ample experience of Estonia.