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OMV and ADNOC commissioned WesternGeco to acquire a high fold, high density seismic program in the Foreland of the Oman Mountains, west of the city Al Ain. The objective of the survey was to acquire high quality 3D seismic data for a proper delineation and reservoir characterisation of structural and stratigraphic trapping geometries in order to identify potential exploration drilling locations. The acquisition commenced Mid-2014 and was completed by early 2015. The program included two separate 3D areas covering 1800km². In addition, 700km of infill 2D lines were recorded to connect the two 3D surveys with modern 2D seismic and to complement the existing vintage 2D seismic grid. The seismic surveys were recorded with a Single Source Single Sensor design (4S) using WesternGeco's UniQ seismic acquisition system with single sensor geophone accelerometers (GACs) and single 80,000lb DX-80 vibrators. A Maximum Displacement Sweep was designed to enhance especially low frequencies resulting in a broadened amplitude spectrum. Operating up to 15 vibrators simultaneously allowed a very efficient seismic data acquisition but needed the implementation of the correct separations and slip times to ensure the data was not contaminated. The 18sec custom designed broad bandwidth sweep (1–120Hz) enhanced the S/N ratio in general and improved the data quality of the deeper target levels due to the input of low frequencies (below 10 Hz). Sufficient azimuth, high fold, long offsets, broad bandwidth as well as optimum random noise reduction and increased spatial resolution was required to improve data quality. Therefore gaining more value with advanced seismic attribute analysis and enhancing the illumination of deeper zones in order to meet the objectives of the seismic. On the logistical side, high flexibility was needed to allow complex and dynamic fleet grouping to maximize productivity. Any cross-talk noise between two different sources was managed using Managed Source and Spread (MSS) time and distance rules, which were based on the target characteristics. Acquiring dense 4S seismic required detailed planning to ensure operational safety and to achieve the planned fold coverage, especially in areas of dense infrastructure. The processing sequence for the high fold, high density 4S pre-stack seismic totalling 160 TB of data – 16 billion traces, was designed to effectively remove noise and preserve signal fidelity in the pre-stack data to ensure an optimal imaging and resolution of the geological targets. Due to the dune environment in the area, the application of optimal static solutions was an essential processing step. The good sampling of the noise in the raw data by the high density and high fold acquisition enabled a successful noise suppression performance and resulted in improving the image of the geological signal.

3D pre-stack depth migration (PSDM) reprocessing was conducted in 2003 on a portion of the Onnia 3D seismic cube, located in exploration permit AC/P-21, Timor Sea.The main objective of the reprocessing was to obtain the best seismic depth image and the most realistic structural reconstruction of the sub-surface to mitigate the risk factors associated with trap definition (trap retention and trap efficiency). This represents one of the main challenges for oil exploration in the area.The 3D PSDM methodology was chosen as the most appropriate imaging tool to define the correct sub-surface geometry and fault imaging through the use of an appropriate velocity field. An integrated approach to building the final velocity model was adopted, with a substantial contribution from the regional geological model.Several examples are given to demonstrate that the 3D PSDM reprocessing significantly improved the seismic image and thus the confidence in the interpretation, contributing strongly to the definition of the exploration targets.The interpretation of the new seismic data has resulted in a new structural picture in which higher confidence in seismic imaging has improved fault correlation. This has enabled better structural definition at the Middle Jurassic Plover Formation level that has reduced the complexity of the large Vesta Prospect, in the centre of the Swan Graben to the northwest of East Swan–1. Improved understanding of the fault reactivation mechanism and the structural elements of the trap (trap integrity) were eventually incorporated in the prospect risking.In the Swan Graben 3D PSDM has proved to be a very powerful instrument capable of producing significant impact on the exploration even in an area with a complex geological setting and a fairly poor seismic data quality.

OMV and ADNOC signed a study agreement in 2013 to explore for hydrocarbons in a large (10,000km2) under-explored onshore area, named East Abu Dhabi. The objective of the work programme was to evaluate the conventional and unconventional hydrocarbon potential within multiple play types and structural settings, via the analysis of existing vintage data, acquisition of new seismic followed by exploration drilling. To date 1,800km2 3D (4S) and 700km 2D seismic have been acquired focused on two principal play types; namely, the ‘Pabdeh’ stratigraphic play and the ‘Thamama’ combined structural/stratigraphic play. Additional studies completed include fluid inclusion stratigraphy using data from nearby vintage wells, and the completion of an unconventional study covering the wider area of interest. The first OMV operated exploration well reached its TD in the Jurassic in March 2017. Two tests have been performed in Lower Cretaceous and Jurassic resulting in a dry sour gas discovery. The main results of the well that have an impact on the understanding of the regional geology can be summarized as follows: 1) Source Rock, three potential source rock intervals have been penetrated (Middle and Lower Cretaceous & Jurassic). 2) Reservoir, The middle Cretaceous has been found in a back-shoal facies with its suggested corresponding platform margin being located in close proximity to the South-West. The Aptian is represented by the classical Lower Shuaiba fm. and overlain by the Bab shales. No isolated platform has been encountered. 3) Clear stratigraphic and structural evidence supporting structural deformation of the Thamama Group during the Lower Cretaceous. Several distinct fault trends are evidenced from both the well data and 3D seismic depth slices. Understanding these faults and related fracture systems will be fundamental in understanding the play potential in the wider area. This is the first exploration well to be drilled in the area since the ‘80s. Multiple intervals of regional interest have been encountered spanning the massive loss circulation intervals of the Palaeocene, conventional and unconventional reservoir within the Middle Cretaceous, the entire Lower Cretaceous sequence and the Asab equivalents of the Upper Jurassic.

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