Play-based exploration (PBE)

Shell evaluation experts use play-based exploration, or PBE, to build a full understanding of the geological basins that we are exploring and to reassess familiar ones to find new plays. This is a technically rigorous method, which demands time and skill in the early stages of an exploration project. But it is a consistent approach which Shell explorers use across the globe – it enables us to concentrate our evaluation resources efficiently and it gives us increased confidence in our decisions.

A pyramid approach

The PBE approach can be represented as a pyramid. At the base, forming the foundation, we look at the basics – defining the regional context and the framework of basins to understand the working petroleum systems they contain. In the middle of the pyramid, we focus on the plays within the basin and quantify various aspects of the system. For this, Shell’s specialist geologists use methods such as common-risk segment mapping to highlight the sweet spots, those areas with the best chance of containing commercial hydrocarbons. At this stage we make estimates of volumetrics and risk, and we can grade the potential of specific locations within the plays. Finally, once these are mapped, we make more detailed geological and geophysical analyses to define each prospect further.

Once we have mapped the framework of a basin, the analysis is valid for the whole area. This is vitally important when we are bidding for licenses to explore for new fields.

PBE in new ventures

Shell’s new ventures team has added substantial new areas to the exploration portfolio, and PBE has been essential in their evaluation. For example, in the Mackenzie delta in the Canadian Arctic, we used PBE to build our confidence for making initial drilling tests in new plays. Using existing 2D seismic data, and regional and geological maps as a starting point, we applied PBE approaches to define risk segments and were able to be more confident about potential test drilling.

In deepwater provinces

Shell was an early entrant in the exploration of the deepwater province off the coast of Nigeria, and this work resulted in the large discovery of the Bonga field, which is now in production. Such a discovery boosts the urgency of further exploration in the surrounding waters.

Much of the uncharted area was in even deeper water than Bonga field, and the subsurface geology contained various different structures that the deepwater evaluation team needed to understand. These include mini-basins, folds and thrust-belts. PBE provided enough information for the team to prioritise the areas and focus on the most valuable blocks, so that Shell was able to bid for new licences with confidence. Intensive exploration during 2005 and 2006 led to several additional discoveries in the area.