Global Deep Siliciclastic Reservoirs: Distribution Patterns and Geological Features

Abstract

In order to obtain new additional oil and gas reserves and improve energy security, it is of great significance to expand the petroleum exploration and development to deep siliciclastic rocks in petroliferous basins. Based on the latest data of deep siliciclastic reservoirs, this study aims at documenting the distribution patterns and geological features of the global siliciclastic reservoirs. Central and South America hosts 19358.5 million barrel oil equivalent, which are the largest share and amount to 27.31% of the total oil and gas proved and probable reserves in deep siliciclastic rocks. It is followed by North America (excluding the Lower 48 States). North America contains the bulk of oil reserves in deep siliciclastic rocks. Whereas Central and South America has the lion's share of gas and condensate reserves. Of the 74 deep petroliferous basins with siliciclastic reservoirs, the richest petroliferous basins are the Gulf of Mexico, East Venezuela Basin, Arabian, South Caspian, Tarim and Santa Cruz-Tarija Basins and they host 73.7% of the total oil and gas reserves in deep siliciclastic reservoirs. The maximum porosity of deep siliciclastic reservoirs significantly decreases with the buried depth. In contrast, the median value of porosity decreases at shallow and intermediate burial, then increases, and finally decreases again with the burial depth. The variation of porosity with depth implies that anomalously high porosities and permeabilities have developed in deep siliciclastics reservoirs. Their development is associated with the presence of grain coatings, hydrocarbon emplacement, fluid overpressure and formation of secondary pores. In China, deep petroleum exploration should focus on the fairways where oil and gas discoveries have been made at the intermediate and shallow reservoirs. To a large extent, the success of deep petroleum exploration depends upon the delineation of “Sweet Spots” in deep layers where grain coatings, fluid overpressure and well-developed salts might have preserved original primary porosity. Integrated application of diagenetic model, depositional model and 3-D basin modeling will play an important role in accurately forecasting the quality of deep siliciclastic reservoir rocks.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015