Print this pageAAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Development of Architecture Elements in Deepwater Depositional System from Canyon to Distal Lobe: A Comparison Example
(1) PetroChina Hangzhou Research Institute of Geology, Hangzhou, China.
Deepwater depositional systems represent an important frontier of petroleum exploration, because deepwater architecture elements, which have been studied extensively using seismic reflection data, cores and outcrop analogs et al, control hydrocarbon reservoirs. This study attempts to reveal the difference of architecture elements between two types of deepwater depositional systems that develop in different tectonic settings on the basis of regional and local seismic reflection data as well as partly wireline-log data and cores.
The first type of deepwater depositional system is a sand-rich system and located at Rio Muni passive continental margin basin. It is characterized by 2D and 3D attributes of numerous canyons, channel complexes, individual channels, lobes and sheets. The distribution of a channel system is recognized from proximal channel complexes to channelized lobe, distal lobe and individual channel. The migration of channel complexes and channelized lobes shows that the forming geomorphology controls the distribution of later deposition. It has been verified that channel complex sand is favorable thick reservoir with high porosity and permeability, whereas channelized lobe sands tend to be thinner and more widely spread in unconfined settings.
Another type of deepwater depositional system- the eastern part of Bengal Fan is a mud-rich system and developed at Bengal remnant ocean basin. The Bengal Fan has been evolving basinwards of the shelf break since the Eocene, and is now the largest deep-water fan in the world, with a length of about 3000 km, a width of about 1000 km and a maximum thickness of 16.5 km. A series of architecture elements, more complex than the first system, are identified such as canyon, channel-levee systems, channel complexes and complex sets, mass-transport complex, individual channel with sinuous and straight shape, crevasse lobe as well as mouth and distal lobe. It has been discovered that sheet sand in levee and lobe are favorable reservoir in offshore Myanmar, whereas it is possible that channel complex sands will be an important reservoir with more exploration activity and are the main type of deepwater reservoir in offshore India.