Exploration History and the Application of New Technologies Contributes to the Discovery of New Reserves in a Marginal Field in a Mature Basin, Abu Dhabi

Abstract

Abstract In 2021 INPEX/JODCO, successfully produced oil, gas, and condensate through drill string tests (DSTs) from Well-L located in Onshore Block 4, Abu Dhabi (INPEX, 2021). Two major factors contributed to the discovery: (1) application of new technological advances to exploration; (2) analyzing and integrating past geological interpretations. Onshore Block 4 is near existing oil and gas production infrastructure, which raised expectations for early-stage development and reduced time to market for any potential discoveries. Given the successful exploration results, further analyses of data collected from the well logs, core, and produced hydrocarbons will support continued exploration activities and play de-risking. Historically, exploration in Abu Dhabi has focused on large closure present-day anticline trends. Over time, new oil and gas discoveries have become scarcer and the discovered volumes smaller. One strategy to open new plays and unlock larger possible reserves is focused on drilling low-relief structures. Well A was drilled in 1956 in the Onshore Block 4 area. Following this 1st well, 6 wells were drilled up until the mid-1970's. These wells were located using early stage 2D seismic and geological surface investigations. In the mid-1970's, due to the development of 2D seismic, it was possible to extract the top structure and a further 5 wells were drilled from the mid-1970's to 1990's. Most of the Onshore Block 4 area is located within a transition zone between sea and land, therefore, it was difficult to detect the top of the structure, even with 2D seismic. In 2017, mega-3D seismic was acquired across Abu Dhabi by ADNOC. Based on interpretation of the newly acquired 3D seismic, certain anticline axis trends were identified that were drilled by deviated wells because of surface limitations. Generally, if the source rock potential is high in the center of the intra shelf basin in Abu Dhabi, it is possible that hydrocarbons are charged to any porous zone. In addition, past geologists identified and drilled the major anticlines with limited information. It is important to know the related exploration history and apply new technologies to existing knowledge to find new reserves. Dry Hole analysis is a crucial evaluation method to understand the thoughts and rationale of previous geoscientists and used to augment the exploration and de-risking of various plays. Based on using this dry hole analysis, in 2021 oil, gas and condensate successfully flowed from an exploration well.