Source Rock Evaluation and Reservoir Characterization of Early Jurassic Formations in Selected Wells, in Duhok Governorate, Iraqi Kurdistan Region
Abstract
Three wells: Atrush-1 (AT-1), Shaikhan-1B (SH-1B) and Mangesh-1 from Atrush, Shaikhan, and Sarsang Oilfields respectively, in Duhok Governorate, Iraqi Kurdistan Region were selected for studying Source Rock and Reservoir Characterization of Early Jurassic Formations. Well Logs and cuttings samples data from these wells were used to achieve this research.
The executed Pyrolysis analysis for the studied samples has shown that the Total Organic Carbon (TOC) content in Alan Formation at well AT-1 and SH-1B indicated Excellent and Good source rock respectively. The organic matter of this formation is identified as Type I kerogen. Mus Formation is considered Very Good and Good source rock in wells AT-1 and SH-1B respectively, based on the TOC content, and its organic matter is identified as Type I kerogen in well AT-1, and kerogen Type II in well SH-1B. The studied samples of Adaiyah Formation, in wells SH-1B and Mangesh-1, showed Good and Very Good source rock, with kerogen recognized as Type II in these two wells. While, Butmah Formation expressed Fair to Very Good source rock, with kerogen belonging to Types I, II, and II-III in well AT-1. The same formation, in well SH-1B, obtains a value of total organic carbon that indicated Fair source rock, with Type IV kerogen. Butmah Formation, in well Mangesh-1, showed Poor to Good source rock, its organic matter is recognized as Types II-III, III kerogen. The Tmax values indicated that thermal maturity of the studied formations in three wells are probably in Immature Phase.
The Well Log data are used to study petrophysical properties of the reservoir rocks. This task is accomplished by using Interactive Petrophysics Software Version 3.5, Log interpretation was supportive to: prediction of Lithological characters, calculation of Shale Volume, Total Porosity, Effective Porosity, Secondary Porosity, Water Saturation, water bulk volume, residual hydrocarbon and movable hydrocarbon of each formation in the three studied wells.
The Neutron-Density Cross Plot and M-N Cross Plot were established, and depending on the mud log provided by the operating oil companies to construct General Composite column of formations for three wells. This was intended to show the changes in lithology of Alan, Mus, Adaiyah, and Butmah Formations between the wells. In wells AT-1 and SH-1B, Alan and Mus Formation are consistently Limestones, while at well Mangesh-1, these formations become Dolomite, Calcareous Dolomite with some units of Anhydrite. Adaiyah Formation changes from Anhydrite in wells AT-1 and SH-1B to Dolomite in well Mangesh-1, that means these formations appear to be replaced by the equivalent Sehkaniyan Formation in well Mangesh-1.
Pulished: 26/02/2017 Sunday