![]()
ABSTRACT Afghanistan is well endowed with natural gas and has economically viable oil deposits. Hydrocarbon exploitation began in the 1960s and continues today, although production has been significantly disrupted due to decades of war and conflict. These resources are in the Amu Darya and Afghan-Tajik Basins in northern Afghanistan. Petroleum reservoirs exist in Upper Jurassic, Cretaceous, and Paleogene strata. Drilling challenges in these basins include; washing out of shales, mud caking in boreholes, dissolution of salt strata, overpressure zones, and high water pressures. The government of Afghanistan is seeking partners to help develop the petroleum resources and modernize the energy infrastructure in the country.
1. INTRODUCTION Oil and gas exploitation in Afghanistan began in the 1960s with help from the former Soviet Union. Soviet assistance continued until 1988 after which time production and processing was done entirely by Afghans. Producing fields are limited to the northern part of the country although the Afghanistan Geological Survey has conducted exploration efforts in Central and Southern Afghanistan [1]. A recent evaluation of reserves by the US Geological Survey (USGS) estimates that there are 0.2 billion tonnes of crude oil and 0.4 trillion cubic meters of natural gas that are technically recoverable [2]. Figure 1 shows the existing known fields and the areas where there is potential for additional exploration and development. Current gas production is from the Shebarghan field in Samangan Province. The equipment and facilities are old and productivity is low. The Afghan Ministry of Mines and Industry is currently seeking companies who would like to acquire leases to explore and develop the petroleum resources of northern Afghanistan. This paper reviews the geological conditions of the oil and gas deposits, the petrophysical aspects of the drilling environment, and technical challenges specific to oil and gas operations in this environment.
2. NORTHERN AFGHANISTAN BASIN The northern Afghanistan area consists of two main basins, the Amu Darya (Oxus River) Basin and the Afghan-Tajik basin (Figure 1). Marine strata of these basins were deposited prior to the closing of the Tethys seaway in early Cenozoic time [3]. Extractable oil deposits are in Paleocene carbonates and Eocene clastic sedimentary rocks in anticlines and faulted structures. Extractable gas occurs in Cretaceous sandstones andUpper Jurassic and Lower Cretaceous stratigraphic traps. The Jurassic gas is trapped by reef structures and capped by salt. The gas from Jurassic reservoirs is largely sour gas (with a high H2S content). The Cretaceous gas is generally low in H2S. 2.1 Stratigraphic Column and Generalized Cross Sections The deep gas reservoir is a transgressive sequence with carbonate sedimentary rocks and reefs on the basin margins. The cap of this reservoir rock consists of Upper Jurassic evaporite deposits. Source rocks beneath this reservoir consist of Lower to Middle Jurassic carbonaceous rocks with a few coal beds. Oil and gas reservoir with shale cap rock exists in Eocene strata. The Neogene was a time of compressional deformation associated with uplift of the Pamir and Hindu Kush Ranges.
Site News