Prediction of the formation pore pressure is considered as a significant simulation process during the drilling and production phases of the carbonate reservoir. The deficiency in this prediction allows for the occurrence of many troubles like blowouts, kicks, hole washouts, wellbore breakout, and stuck pipe. The most common conventional methods for the pore pressure prediction are Eaton's and Bower's methods which depend mainly on the normal compaction trend and commonly applied on Shales. The objective of this work is the prediction of the formation pore pressure by the application of the modified Atashbari prediction model upon the wireline logging data. This method depend on the porosity and the compressibility attribute of the rocks for the estimation of the pore pressure without any need for the normal compaction trends. The method was applied on the carbonate reservoir of the Middle Eocene Apollonia Formation, Abu El-Gharadig basin, Egypt. It is a gas bearing reservoir which characterized by its high porosity and low permeability. The results were compared with the other commonly used methods and show an improvement in the pore pressure estimation. It can be used as an individual method or in complement with other available methods.
The Abu Gharadig basin in the Western Desert (NW Egypt) is a mature hydrocarbon province with over 95% of the oil and gas fields in the Upper Cretaceous reservoirs. JG and JD fields are producing fields; JG is producing from the Jurassic reservoirs, while the JD field is producing from the shallower Tertiary reservoir. Both fields lie on the footwall of the main bounding fault of Abu Gharadig basin trending E-W and NW-SE. Four dry wells have been drilled into the deeper Jurassic reservoir, and this paper will try to figure out the possible reasons for the failure of Jurassic reservoir in JD compared to JG field 2002. Two main geological cross sections have been created. The first cross section ties the JD field to the Abu Gharadig basin and the second one ties the JG field to same depocenter. The restoration has been carried out using 2D Move (Midland Valley software) to restore the two sections to their original tectonic status. Since the Eocene-Miocene is the common time for the hydrocarbon expulsion in Abu Gharadig basin, both JG and JD traps were formed at that time. The restoration clearly showed the juxtaposition of the Jurassic reservoirs against Abu Roash and Khoman (shale, limestone and chalk) in JG. In contrary, the Jurassic reservoir is juxtaposed with Kharita and Alam El Bueb (Sandstone) in JD. Fault juxtaposition has been carried out also and concluded the juxtaposition of Abu Roash F member and Masajid flip East of JD well so no chance of Abu Roash F member charging JD.
Sandstone channels are one of the best stratigraphic traps for hydrocarbon accumulation, and their depositional and composition make them difficult to detect on ordinary seismic data, especially in structurally affected onshore areas like the Western Desert of Egypt. The Western Desert of Egypt has many hydrocarbon-bearing reservoirs of various compositions like carbonates and sandstones with high production rates, and thus the Western Desert of Egypt is recognized as a hot spot for oil and gas exploration. One of the important reservoirs in the Lower Cretaceous “the Aptian sand” produced around 285 MBBLS cumulative oil of 22° API and still produces 102 BOPD. This reservoir has a channel-type depositional environment, and the dimensions of this channel could be resolved by good quality 3D seismic data in the moderately deep basins as the basins become deeper, the detection of the channel becomes increasingly challenging. This study aims to delineate the geometry of this reservoir and reveal the exposure from the Aptian sand channel in the Alamein area using the seismic attributes analogy on the re-processed 3D seismic data to determine the best drilling location for increasing the production from this reservoir. In this context, the relative acoustic impedance (RAI), iso-frequency components, and sweetness stratigraphic attribute analyses were conducted on the optimized seismic data and attested as important as they resolved the stratigraphic geological mystery in the structurally affected study area. These attribute analyses revealed the exposure from the distinctive meander channel of the Aptian sand for the first time in the study area nearby the producing Alamein field, where this channel was hard to be distinguished by the ordinary seismic interpretation methods and there is no drilled well penetrated the detected channel’s body. Upon the results, the conclusion and recommendation summaries to intensify the efforts to test the productivity of the detected channel to increase the production from this motivating reservoir by drilling a new well targeting the best structural locations of the channel body.
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