Petrophysical Investigation of areas of hydrocarbon low-resistivity of the Reservoir TAGI Hassi Berkine South field. Berkine basin. Algerian Sahara.

Abstract: The Hassi Berkine South study area is located in the block 404, in the South of the Berkine basin. The lower Triassic clayey - Sandy (TAGI) is the main reservoir, it’s unconformity deposit on the Paleozoic... [ view full abstract ]

Abstract:

The Hassi Berkine South study area is located in the block 404, in the South of the Berkine basin.
The lower Triassic clayey - Sandy (TAGI) is the main reservoir, it’s unconformity deposit on the Paleozoic formations, with an average thickness of 75 m.
The phenomenon of areas of hydrocarbons in low resistivity (LRP) is manifested both in the carbonates and in the sandstone, but it is more common in sandstone reservoirs. Due to the low resistivity, the computed water saturation is high, we can even neglect the area or under - estimate the reserves.
The purpose of this study is to determine the reasons for LRP, review the offerings and validate the result.
A many reservoirs of production have low apparent resistivity values, they are generally characterized by areas that cause deep resistivity curves to read around 0.5 to 5 ohm - m.
This abnormal behavior is often due to a combination of shale content, and the presence of fine sands and diagenetic effects, mineralogy, the microporosity and the thickness of the sandbank.
There are several reasons why LRP manifests: Invasion deep by conductive sludge, presence of clay, fractures, presence of microporosity, high capillary bound water presence, presence of other conductive minerals, wells with angle of relatively high inclination and laminated formations.
LRP zones can be neglected or underestimated oil content.
The result is an estimate less reserves than what really exists.
The stages to follow to achieve the solution are first to establish that the area is a useful area, find the reason for LRP, apply the proper method to resolve the problem, and finally to validate the result.
The identification of the cause of the LRP is the most important part of the process.

Key words: Berkine basin. Hassi Berkine South field. Reservoi TAGI. Petrophysical properties. Resistivity.