Journal of Nanomedicine & Nanotechnology

Petrographic, petrophysics and seismic integration: An approach to delineation of diagenetic trap, in the mishrif formation, the Persian Gulf

26^th International Conference on ADVANCED NANOSCIENCE AND NANOTECHNOLOGY

December 05-06, 2022 | Dubai, UAE

Alireza Bashari

Iranian Society of Petroleum geology, Iran

Posters & Accepted Abstracts: J Nanomed Nanotechnol

Abstract:

This oilfield is located in the central Part of the Persian Gulf, is an anticline with an approximately North- South trend. The Upper Sarvak Formation is a potential reservoir in this area. Diagenetic processes including (dissolution, dolomitization and fracturing) improved reservoir qualities. As a result of diagenetic process (dissolution), stratighraphic trap (diagenetic) has been created, and zones A and B are shaped into pinch out trap. Weathering dramatically improves the reservoir permeability and thus controls the extent of this diagenetic trap. Petrographic, Petrophysics studies show that local unconformity in the southern flank of Reshadat oilfield, created the highest reservoir zones in this part. Consequently; reservoir quality of zones C and D have been improved. The study has taken the form of an intial interpretation data followed by an inversion to acoustic impedance and sbsequent fine-tuning of interpretation on the impedence data. The advantage of this offers is a reduction of wavelet and tunning effects and the generation of 3D geological model matching the orginal seismic data. The main results of the study are time and depth maps of horizons near top Damam, top Mishrif, top Khatiyah, top Kazhdoumi and etc. Middle Cretaceous reef facies of the Mishrif limestone with good reservoir characteristics forms a key reservoir in this oil field. Mishrif resvoir in this field has been divided into five zones. Zone A, (the uppermost) is recognized the best reservoir zone. The Mishrif reservoir in this area is part of more extensive reef deposition of the Middle cretaceous in the Persian Gulf. Applying reasonable cutoffs for porosity and permeability, reveals valuable zones (A&B) in this portion of field. These zones are located in the west and northwest of Reshadat oil field. The studies show that thickness of the valuable zones are increasing towards the west and the northwest and decreasing in the center and south of this field. Mishrif reservoir contains several lithologies. Each of which exhibits differing sedimentological, and petrophysical properties and each representing a distinct subenvironment. Interfacies boundareis are not clear because adjacent facies grade laterally and vertically into each other.The formation consists of the following facies: Lagoonal/ backreef, rudist biostrom, algal boundstone, shallower sub basinal (or outer reef margin), and deeper subbasinal (slope margin) .The contact between Mishrif shallow marine reef facies and khatiyah deeper marine facies in a gradual transition. There is thining of the Mishrif on the crest of structures. This is largely related to the erosion during early upper Creataceous uplift. It is believed that most of the present structures originated during upper Cretaceous uplift. The Mishrif reservoir have primary remnant and leached porosities. In the leached shelfal grainstones to packstones associated with rudist bioherms, porosity ranges from 10% to 15%. The grainstones associated with the high energy shoals and islands within the carbonate platform have high porosity ranging, with fair to good permeability. Extensive leaching has caused intense solution and brecciation below the pre-Laffan(Coniacian) unconformity Many of the solution features are related to unconformity surface at the top of the formation. The combination of seismic interpretation and seismic inversion togheter with log interpretation and petrographic study has improved our understanding and definition of the reservoir.