Diagenetic controlled reservoir quality of South Pars gas field, an integrated approach

Abstract

The Dalan-Kangan Permo-Triassic aged carbonates were deposited in the South Pars gas field in the Persian Gulf Basin, offshore Iran. Based on the thin section studies from this field, pore spaces are classified into three groups including depositional, fabric-selective and non-fabric selective. Stable isotope studies confirm the role of diagenesis in reservoir quality development. Integration of various data show that different diagenetic processes developed in two reservoir zones in the Kangan and Dalan formations. While dolomitisation enhanced reservoir properties in the upper K2 and lower K4 units, lower part of K2 and upper part of K4 have experienced more dissolution. Integration of RQI, porosity-permeability values and pore-throat sizes resulted from mercury intrusion tests shows detailed petrophysical behavior in reservoir zones. Though both upper K2 and lower K4 are dolomitised, in upper K2 unit non-fabric selective pores are dominant and fabric destructive dolomitisation is the main cause of high reservoir quality. In comparison, lower K4 has more fabric-selective pores that have been connected by fabric retentive to selective dolomitisation.

3d Basin Modelling in the Central Persian Gulf, Offshore Iran

“…At the base of the Triassic succession is the Kangan Formation, which, together with the Dalan Formation, consists of shallow-marine limestones and dolostones (Szabo and Kheradpir, 1978;Insalaco et al, 2006;Tavakoli et al, 2011); interbedded evaporitic rocks are assigned to the Nar Member. Massive anhydrites, shales and tight dolomitic carbonates of the Dashtak Formation rest on the Kangan Formation (Szabo and Kheradpir, 1978).…”

Paleoenvironmental, diagenetic, and eustatic controls on the Permo–Triassic carbonate–evaporite reservoir quality, Upper Dalan and Kangan formations, Lavan Gas Field, Zagros Basin

“…The dolomitization process was dominant, especially in the Upper Dalan (Amel et al, 2015) and the Kangan formations (Abdolmaleki et al, 2016;Tavakoli et al, 2011), playing the main diagenetic role in increasing the reservoir quality. A number of differing dolomitization processes are evident, including sabkha evaporation, hypersaline seepage reflux, meteoric/seawater mixing ("Dorag model"), and bacterial action (Badiozamani, 1973;Luczaj, 2006;Read, Husinec, Cangialosi, Loehn, & Prtoljan, 2016;Ward & Hally, 1985;Warren, 1989).…”

“…In the Zagros Basin (Iran), the Upper Dalan and Kangan formations hold one of the largest gas reserves in the Middle East and also the world. Considering this importance, a sizable number of studies on the sedimentology, diagenesis, and reservoir quality have been done on the Permo–Triassic strata of the region (e.g., Abdolmaleki, Tavakoli, & Asadi‐Eskandar, ; Amel, Jafarian, Husinec, Koeshidayatullah, & Swennen, ; Bordenave, ; Esrafili‐Dizaji & Rahimpour‐Bonab, ; Haase & Aigner, ; Insalaco et al, ; Kashfi, ; Peyravi, Rahimpour‐Bonab, Nader, & Kamali, ; Rahimpour‐Bonab, Asadi‐Eskandar, & Sonei, ; Rahimpour‐Bonab, Esrafili‐Dizaji, & Tavakoli, ; Sharland et al, ; Tavakoli, Rahimpour‐Bonab, & Esrafili‐Dizaji, ). The sedimentologic, stratigraphic, and diagenetic attributes of the Upper Dalan (K3) and Kangan (K1, K2) formations of the Lavan Gas Field (Figure ) however, did not receive enough consideration to understand their depositional setting, diagenetic properties, and the effect of the sea‐level fluctuations on the reservoir qualities of the strata.…”

“…In the Zagros Basin (Iran), the Upper Dalan and Kangan formations hold one of the largest gas reserves in the Middle East and also the world. Considering this importance, a sizable number of studies on the sedimentology, diagenesis, and reservoir quality have been done on the Permo-Triassic strata of the region (e.g., Abdolmaleki, Tavakoli, & Asadi-Eskandar, 2016;Amel, Jafarian, Husinec, Koeshidayatullah, & Swennen, 2015;Bordenave, 2008;Esrafili-Dizaji & Rahimpour-Bonab, 2013;Haase & Aigner, 2013;Insalaco et al, 2006;Kashfi, 1992;Peyravi, Rahimpour-Bonab, Nader, & Kamali, 2015;Rahimpour-Bonab, Asadi-Eskandar, & Sonei, 2009;Rahimpour-Bonab, Esrafili-Dizaji, & Tavakoli, 2010;Sharland et al, 2001;Tavakoli, Rahimpour-Bonab, & Esrafili-Dizaji, 2011). (Goldhammer, Dunn, & Hardie, 1990;Husinec & Jelaska, 2006;Koeshidayatullah, Al-Ramadan, Collier, & Hughes, 2016;Salad Hersi, Abbasi, & Al-Harthy, 2016;Salad Hersi, Lavoie, & Nowlan, 2002), and these repeated shallowing-upward cycles may record important information on spatio-temporal changes of reservoir quality in the studied sequence.…”

Flow Unit Characterisation in the Permian‐triassic Carbonate Reservoir Succession at South Pars Gasfield, Offshore Iran

“…South Pars gasfield and its extension within Qatari territorial waters (North field) comprises the world's largest offshore gas accumulation (Halbouty, 2003; studies have focused on depositional and diagenetic characteristics, palaeo-environmental conditions and geochemical properties and on factors governing reservoir quality (e.g. Insalaco et al, 2006;Ehrenberg, 2006;Rahimpour-Bonab, 2007;Ehrenberg et al, 2008;Rahimpour-Bonab et al, 2009Rahimpour-Bonab, 2009, 2013;Tavakoli et al, 2011;Tavakoli and Rahimpour-Bonab, 2012;Aleali et al, 2013). In a recent study (Rahimpour-Bonab et al, 2014), barrier units within the Upper Dalan and Lower Kangan succession (intrareservoir barriers) were evaluated using petrographic, petrophysical (SMLP) and geochemical approaches.…”