Cenomanian Shilaif Unconventional Shale Oil Potential in Onshore Abu Dhabi, UAE

Van Laer, Pierre (ADNOC) | Leyrer, Karl (ADNOC) | Povstyanova, Magdalena (ADNOC) | Baig, Muhamad Zeeshan (ADNOC) | Makarychev, Gennady (ADNOC) | Al-Marzooqi, Hassan (ADNOC)

OnePetro 

Abstract

The mainly Cenomanian Shilaif formation of Abu Dhabi (UAE) is currently explored and appraised for its shale oil and shale gas potential. The objective is to assess the hydrocarbons resources, the spatial variability of rock and fluid properties as well as highlighting sweet-spots.

The exploration efforts started in 2014, conducting some multidisciplinary regional depositional and petroleum system studies complemented with exploration wells and the acquisition of comprehensive suites of logs, cores and pressured (sidewall) cores.

The Shilaif formation was deposited in a deeper water intrashelf basin and is time equivalent to the adjacent shallow water higher energy Mishrif formation. Non-eroded Shilaif thicknesses vary from 500 to 900 ft from deep basin to slope respectively. The formation can be subdivided into 3-4 composite sequences each with separate source rocks and clean tight carbonates.

The present day structural configuration is inherited from two related regional compressional events; a) a NW-SE compression responsible for the anticline/syncline, lasting from Late Cenomanian to Early Eocene was created by India's continental drift, b) the late Cretaceous (starting in Turonian) emplacement of the Semail ophiolite from NE direction responsible for loading the continental plate and resulting in the creation of a large scale foreland basin. Reactivation of this NE compression occurred during Late Tertiary.

The resulting structuration created two synclines in the south of Abu Dhabi with maximum maturity of 1.1 Vr (TR 0.65). The foreland basin towards the North East has maturity values reaching the dry gas window. The continuous present day stress from a NE direction combined with high overpressures has a strong geomechanical impact with hmin close to overburden in synclinal areas.

Introduction

This study aims to present the unconventional resource potential of the Late Albian to Early Turonian basinal sequences in Abu Dhabi.

Insights into the local and regional stratigraphic framework as well as structural controls of the depot-centers are presented.