QUANTIFYING FINE GRAINED ROCKS FROM LOGS AND THEIR RELATION SHIP WITH PORE PRESSURE AND STRATIGRAPHY

On this project work on the title “Quantifying fine grained rocks from logs and there relation ship with pore pressure and stratigraphy” there are two main parts. The first part in literature review on shaly sands and shale which are normally used for the entire class of fine-grained sedimentary rocks that contain substantial amount of clay minerals. Since the presence of low density overpressure is derived for the porosity within the unit in the fine grained rocks in the subsurface which includes shales or mudstone in a sedimentary sequence which influences the operations of petroleum exploration, drilling and production, their relation ship with the pore pressure has also been conducted in this part. During the exploration phase such low density fine grained rocks also influence the interpretation of seismic and gravity surveys. In addition to the immediate influence of high pressures and compaction phenomenon on the petroleum industry, fine grained rocks including shales are thought to have been the source of petroleum found in permeable reservoir rocks. There fore a better understanding of these fine grained rocks in the subsurface is very important. A common method for evaluating the fine grained rocks in the subsurface using the known interpretation techniques which includes the different logging tools measurements is also studied on this part of the report.
The second part presents a study conducted on the real data from GELAMA MERAH field to evaluate the effect of the fine grained rocks on the hydrocarbon occurance, pore pressure, and stratigraphy.How the presence of clays in the formation affects resistivity reading by lowering it which will lead for miss – interpretation of the oil – bearing zone as a water – bearing zone because of the excess conductivity due to the presence of clay minerals is also evaluated.
Proper pore pressure prediction and determination is important and crucial for the purpose of optimizing casing and drilling fluid programs, to improve well control and to increase drilling efficiencies, to reduce drill time/costs per well. There fore, it is important to understand the fine grained rock which usually is the shale that will lead to abnormal pressure and cause well bore instability and since the shale effect depends on shale content, the estimation of Vsh is of prime importance.