History of hydrocarbon exploration in the Kurdistan Region of Iraq

Abstract

The Kurdistan Region of Iraq has witnessed extraordinary levels of exploration activity since the first exploration well to be drilled in over two decades was spudded in 2005. Since then almost 200 wells have been drilled encountering recoverable reserves estimated to be in excess of 15 billion barrels of oil equivalent. Whilst the region is in close proximity to many of the giant and supergiant fields of Iran and Iraq, the reservoirs in which discoveries have been made are largely different. In Iraq a large percentage of discovered reserves reside in Cenozoic and Cretaceous sediments capped by Cenozoic evaporite sequences. Over much of Kurdistan, particularly the north and northeastern parts of the region, Cenozoic strata are absent. A decade ago many were doubtful that significant quantities of hydrocarbons could be trapped in the absence of the Cenozoic evaporite sequences. Furthermore, whilst the presence of large surface structures and significant oil seeps were encouraging to some, to others it fueled concerns about trap leakage. Today the majority of the surface anticlinal features in Kurdistan have been drilled, but remain to be fully evaluated. Almost all of the exploration activity in Kurdistan has taken place on 2-D seismic with vertical exploration wells. In the last few years, a number of 3-D seismic surveys have been acquired and these will undoubtedly lead to production and reserve enhancements in parallel with increased subsurface complexity. Following a decade of exploration, three fields have been fully appraised and have a reasonable early production history: Tawke, Taq Taq and Khurmala. Reserve additions in the Tawke Field have been significant as a result of increased production performance due to better than originally anticipated reservoir properties, better pressure communication and additional reserves found in older reservoirs. It is probable that similar trends will occur in other fields and discoveries. Whilst a small number of horizontal wells have been drilled, advanced techniques used for producing from tight fractured carbonates such as multilateral wells, hydraulic fracturing, selective completions, proping and water injection have not as yet been used in the region. Almost all wells in Kurdistan have been drilled on surface or near subsurface structures within the foreland or the fold belt. Some wells have drilled through thrusts, more often by accident as opposed to on purpose. There have been virtually no dedicated wells for pure sub-thrust plays or stratigraphic traps although hydrocarbons have been found below significant thrusts and also beyond apparent structural closure in some structures. Challenges remain in what is a structurally complex and recently deformed region. High levels of exploration and appraisal activity persist and new pipeline infrastructure is under construction. It is likely that the Kurdistan Region of Iraq will develop to become an important contributor to world oil and gas production. This paper aims to summarise the first decade of exploration and appraisal activity in Kurdistan Region of northern Iraq. Due to the paucity of technical papers on this subject, this document draws upon the authors’ own knowledge and material published by companies operating in the region.