Hydrocarbon potential and porosity types of the Geli Khana Formation (Middle Triassic), Northern Iraq

Abstract

Hydrocarbon generation potential and porosity types of the Middle Triassic Geli Khana Formation in Jabal Kand-1 (JK-1) well and from outcrop section at Ora of northern Iraq are investigated. Total organic carbon, pyrolysis, and maturation assessment such as thermal alteration index (TAI) and vitrinite reflectance (Ro%) for 19 shale samples are conducted. The analyses showed a sufficient amount of organic matter (OM) occurs in JK-1 specifically. According to the obtained samples from the pyrolysis analysis of the studied samples, the existing organic matters in well (JK-1) are composed of a mixed of kerogen type II–III and III; while type IV in outcrop section which found in post mature state, indicating dry gas window. The estimated TAI for the studied section ranged between 3.3 in and 3.7 in JK-1 and 3.3–4 in Ora section. Additionally, the maturity derived information from vitrinite reflectance supported that the Geli Khana Formation is in dry gas window and post mature stage in both sections due to the average ratio of (Ro %) which is between 1.35 and 2 %. The porosity types in the carbonate successions of the formation include; fracture, moldic, intergranular, intramatrix, vuggy, intercrystalline, channel and fenestral birds-eye porosities. These types enhance the reservoir characteristics of the carbonate succession of the formation.