Using an integrated interpretation approach, utilizing structural interpretation, attribute analysis, seismic stratigraphy, regional geology, acoustic impedance from inversion and well calibration, a model of potential Mishrif reservoirs was developed for the area of exploration interest. The integrated interpretation resulted in a Mishrif model that was consistent with regional geology, local stratigraphy, well control and detailed geophysical studies and interprtation. Based on the final integrated interpretation a new seismic program was proposed and justified. The new seismic will provide essential information over potential leads and prospects to better quantify the structural size and help confirm the presence of porous reservoir facies.
The Upper Creatceous Shilaif, Mishrif, Tuwail, and Ruwaydah formations, shown in Figure 1, are interpreted to correspond to three third-order depositional sequences (Sequence 1, Sequence 2, and Sequence 3) as well as a third-order composite sequence (Sequence 4).
The three third-order depositional sequences illustrated in Figure 2, are interpreted to correspond to the Shilaif and Mishrif formations, whereas the third-order composite sequence is interpreted to comprise the Tuwayil and Ruwaydha formations. Regional geologic information indicates that the Shelf margin, reefal build-ups of the eastern basin margin of Abu Dhabi, were prograding towards the west. Well control shows that in the inner platform position, the Ruwaidha and Tuwayil formations, as well as the upper part of the Mishrif Formation are missing due to erosion and non-deposition. Reefal build-ups with their shoal complexes represent areas where good Mishrif reservoir has the highest exploration potential.
The integrated interpretation approach was able to overcome difficulties associated with poor seismic data quality and the final Mishrif interpretation fit with regional models based on well control. Quantitative well-to-seismic ties were used to identify the Mishrif seismic events for mapping. Figure 3 is a representative well-to-seismic tie quality control display. The seismic traces around the well are in the left panel and the synthetic from the well data and estimated wavelet is shown in the center. The synthetic shows what the seismic image should look like if no noise was present. Comparing the seismic to the synthetic it is possible to identify events that are primary reflections because of the good agreement.
