New Growth in an Old Basin: Successful Implementation of PDO's Exploration Strategy in a Downturn
Authors: Feast Nicholas , Rawahi Salim , Mazrui Mohammed 
Published: November 2019

Oman Block 6 is in a mature hydrocarbon province with a long history. Exploration is key to sustaining production growth. However, creamed plays and an oil price downturn posed a challenge for exploration in recent years. Following falling oil prices, global exploration investment reduced significantly, as companies focused on production and cash flow. In response, the following strategy was implemented in PDO: 1) short term reduction in oil exploration drilling; 2) focus on rapid hook-up and early monetization to partially fund exploration; 3) sustain investment in, and improve efficiency of, advanced seismic acquisition and processing.

Despite the challenges, success through both oil and gas exploration was achieved. Enhanced short-term cash flow and improved capital efficiency resulted while discovering significant commercial oil and gas volumes, and laying a foundation for future investment. During 2016-2018 1.3 bln boe were discovered, dominantly in subtle and stratigraphic traps, and over 22000 km2 of new 3D WAZ was acquired.

Focused activity in the Shammar play added volumes while early hook-up and production provided cash flow repaying all Shammar drilling and testing costs within the year. The Mabrouk North-East Giant Gas discovery lies close to three large gas fields. The novel field-trapping configuration was not visible on conventional seismic, requiring a step change in acquisition/processing and aggressive exploration to outline the field. A success rate of 100% in exploration and appraisal wells proved the potential of better seismic imaging in pursuing more complex stratigraphic traps in deep reservoirs. In excess of 4 Tcf cCR and test rates &gt; 1 million m3/d gas and 500 m3/d condensate were achieved.

Early monetization focus, while implementing new seismic acquisition techniques with fast processing turnaround also opened new oil play potential. Discoveries in the Permo-Carboniferous Haushi reservoir between 2016 and 2017 delivered in excess of 80 million barrels UR through imaging of truncations beneath Nahr Umr sealing shales. These low Unit technical Cost (UTC) developments are under accelerated development programmes with follow-up potential.

Cost management, timely delivery, and data quality remain focus areas. Ultra-High Productivity (UHP) seismic acquisition techniques were implemented, leading to significant enhancements in acquisition volumes and speed. In 2018, over 7000 km2 of fine sampled Wide Azimuth (WAZ) survey was completed, achieving &gt;35000 vibrator points/day (VP/d) and providing a firm basis for future exploration. Improvements in seismic processing delivered products a couple of months after last shot and final products quicker than before and made quantitative interpretation feasible.

Improved seismic quality in a mature basin continues to add value through enabling new discoveries from old ideas. Thus, the strategy of maintaining investment in seismic during a downturn, coupled with a focus on stratigraphic and subtle traps, and achieving cash flow from early production has proven to be robust and a solid basis for future success.