Diagenetic controls on the reservoir quality of the tight gas Collyhurst Sandstone Formation, Lower Permian, East Irish Sea Basin, United Kingdom

Abstract

The Lower Permian Collyhurst Sandstone Formation is an important gas reservoir both offshore and onshore in the East Irish Sea Basin of north-western UK, and is considered to be a tight gas reservoir. Diagenetic processes have significantly influenced the reservoir quality of the sandstone. This study employs petrographic, mineralogical, and stable isotopic analyses on two different onshore core successions to investigate the composition and texture, the diagenetic history, and the impact of lithology and diagenesis on reservoir quality. The Collyhurst Sandstone Formation consists of fine-to very coarse-grained, poorly to well-sorted, sub-arkosic to lithic arenite sands. The reservoir properties of the sandstone are relatively poor, with average porosity and permeability of 6.6% and 0.387 mD respectively. On the basis of petrographic analyses, five sandstone lithofacies were identified: fine-grained, conglomeratic, carbonate-cemented, quartz-cemented and matrix-free.Contrasting characteristics between the reservoir units suggest the development of divergent diagenetic pathways. Features observed during early diagenesis include compaction, growth of pore-filling early carbonate cements (calcite I, dolomite and siderite I) and vermicular kaolinite. Late diagenetic features include: further carbonate cementations (ferroan dolomite/ankerite, calcite II and siderite II-III), clay mineral cementation (illite and chlorite) with both grain-coating and pore-filling textures. Also common in late diagenesis are syntaxial quartz overgrowths. Albite, barite and anhydrite are minor late diagenetic cement phases. Compaction processes rather than cementation accounts for the major destruction of

Reservoir variations and heterogeneities under valley‐monadnock palaeo‐geomorphology in hinterland area of the Junggar Basin, northwestern China: Sedimentary characteristics and diagenetic alterations

“…During the progressive burial, most smectite changes into illite via mixed layers of illite/smectite (Boles & Francks, 1979; Gutierrez Paredes, Catuneanu, & Hernandez Romano, 2018). Therefore, the mixed layer ratio together with other parameters (e.g., Ro, temperature, burial depth) can be used to identify the diagenetic stage of the reservoirs (Morad et al, 2000; Oluwadebi, Taylor, & Dowey, 2018; Worden & Burley, 2003; Zhou, Ji, Zhang, & Wan, 2016). Accordingly, the diagenetic stage of the K 1 q reservoirs spans from early eodiagenesis to early mesodiagenesis with a mixed layer ratio of 15–76% (Figure 12).…”

Origin and Sources of Minerals and Their Impact on the Hydrocarbon Reservoir Quality of the PaleogeneLulehe Formation in the Eboliang Area, Northern Qaidam Basin, China

“…The type and contents of carbonate cements were determined on the basis of carbon and oxygen isotopic analysis of thin sections from 31 sandstone samples, which are plotted in Figure 12a. Both the carbon and oxygen isotopes (i.e., Vienna Pee Dee Belemnite normalized isotopes: δ 13 C PDB and δ 18 O PDB ) spanned a wide range of values ( Table 2) Theδ 13 C values indicate that sparry carbonate cements were influenced by organic matter (the model modified after Rahman [37]). (b) Ternary plot of Fe-Mg-Mn element compositions of carbonate cements,data from Table 1.…”

“…Authigenic chloritetypically develops at temperatures of >60 or 70 • C [12], corresponding to a depth of about 2400-2800 m (Figure 3) and belongs to eodiageneticstages. During the early diagenetic stage, volcanic rock fragments can be easily transformed into smectite, as burial depth and temperature increase, illitization of smectite will occurat a temperature around 70 • C [13], corresponds to a depth of about 2700 m in study area (Figure 3). In addition, the onset of authigenic quartz was interpreted at about 70-80 • C [45], corresponding to the burial depth from 2700~3200 m (Figure 3).…”

“…However, the reservoir quality and heterogeneity have been strongly affected by various parameters, such as depositional parameters (e.g., primary depositional textures, detrital composition, grain size and sorting) and different types and sequences of diagenesis [8][9][10]. Depositional parameters have a significant effect on primary reservoir quality (i.e., porosity and permeability) and consequently on diagenetic alteration, which, in turn, results in complex spatial and temporal patterns of reservoir quality and heterogeneity [11][12][13][14]. Diagenesis, including physical processes of mechanical compaction and chemical action of mineral dissolution and precipitation, has a great influence on subsequent evolution paths of porosity and permeability [15][16][17].…”

Multiphase carbonate cementation in the Miocene Pétervására Sandstone (North Hungary): implications for basinal fluid flow and burial history

“…In the case of clastic deposits, the depositional facies is commonly the major control on reservoir architecture, but diagenetic cementation can be an effec tive modifying factor. Carbonate cement in sandstones plays a substantial role in reservoir quality evolution (e.g., Morad 1998;El-ghali et al 2006;Gier et al 2008;Karim et al 2010;Oluwadebi et al 2018). Concretionary calcite cementation of various origins was reported from numerous sandstone formations (e.g., McBride et al 1994;El-ghali et al 2006;Van Den Bril & Swennen 2008;Wanas 2008;Bojanowski et al 2014).…”