Facies and Reservoir Characteristics of the Ngrayong Sandstone in the Rembang Area, Northeast Java (Indonesia)

Abstract

The Rembang area is a well-known prospective region for oil and gas exploration in Northeast Java, Indonesia. In this study, the reservoir characteristics of the Ngrayong Sandstone were investigated based on outcrops in the Rembang area. Petrological, mineralogical, petrophysical and sedimentological facies analyses were conducted. These sandstones are grain-and matrix-supported, and composed of very fine to medium, sub-angular to poorly-rounded, moderately-to very well-sorted sand grains. These sandstones are mainly composed of quartz, orthoclase, plagioclase, and micas with minor amounts of clay minerals, and therefore are predominantly classified as sub-lithic arenite and sub-felds pathicarenite. Petrographic observations and grain size data indicate that these sandstones are texturally quite mature, based on their good -sorting and the occurrence of minor amounts of matrix clays. Common clays in the samples include illite, smectite, kaolinite, and gibbsite. The porosity of the Ngrayong sandstones ranges from 25.97% to 40.21%, and the permeability ranges from 94.6 to 3385 millidarcies. Thus, these sandstones exhibit well to excellent reservoir qualities. Eight lithofacies were identified from five measured stratigraphic sections, and are dominated by foreshore and tide-dominated shoreface facies. The Ngrayong sequence shows a single transgressiveregressive cycle. Cross-bedded sandstone and massive sandstone are identified as the most promising potential reservoir facies based on their characteristics in outcrops, their lateral and vertical distributions, their sedimentological characteristics and their petrophysical properties.

Cenozoic Basin History of the Cepu Area Based on Calcareous Nannofossil Biostratigraphy in Eastern Java, Indonesia

“…The NN7 sequence "Ngrayong Formation" of Kedungtuban-1 well between unconformities 2 and 3 is considered a single Transgressive-Regressive cycle. This opinion is supported by the result of the facies analysis of Ngrayong sandstone by Khaing et al [16]. Based on nannofossil biostratigraphy, unconformity 3 is correlated to the cooling event of Mi5 [17].…”

“…10,16,17 indicate the age from the middle Miocene to early Pliocene (NN6 to NN14) are present in 1100m/1180m. This evidence indicates that the big unconformity between the middle Miocene to early Pliocene is present in 1100m/1180m.…”

The sedimentological reservoir characteristics of the Jurassic Sangonghe Formation, Southern Mahu Slope, Junggar Basin, Northwestern China

“…The sequence stratigraphic framework, sedimentary facies, and diagenetic processes are the significant factors that control reservoir heterogeneity and quality in river‐dominated deltaic sandstones (Dutton & Loucks, 2010; Halisch, Weller, Sattler, Debschütz, & El‐Sayed, 2009; Hammer, Mørk, & Næss, 2010; Makeen, Abdullah, Ayinla, Hakimi, & Sia, 2016; Morad, Al‐Ramadan, Ketzer, & De Ros, 2010; Nichols, 2009; Umar, Friis, Khan, Kassi, & Kasi, 2011). Previous studies predominantly focus on reservoir heterogeneity and quality within sequence stratigraphic framework (Morad et al, 2010; Nichols, 2009; Yassin et al, 2018), sedimentary facies (Hammer et al, 2010;Makeen et al, 2016; Nichols, 2009; Khaing, Surjono, Setyowiyoto, & Sugai, 2017), and diagenetic process (Dutton & Loucks, 2010; Gier, Worden, Johns, & Kurzweil, 2008;Makeen et al, 2016; Umar et al, 2011). The reservoir heterogeneity and quality of river‐dominated deltaic sandstones in different sequences usually vary significantly due to interplay of tectonics and sedimentation (Morad et al, 2010).…”

“…The river‐dominated deltaic sequencesare usually among the most comprehensive and heterogeneous depositional systems in lacustrine rift basins with favourable reservoirs below seismic resolution or outside seismic coverage (Al‐hasani et al, 2018; Benayad et al, 2019; Kassab, Hassanain, & Salem, 2014; Khaing et al, 2017; Mahgoub et al, 2016; Richard & Kenneth, 2003; Wang, 2000; Wu, Wu, Qu, Ma, & Guo, 2010; Xia et al, 2018, 2018, 2018, 2020; Xia, Lin, Du, Li, & Li, 2020; Yassin et al, 2018; Zhang et al, 2020). In addition, the reservoir characteristics have long been of great interest in hosting potential petroleum reserves and developing petroliferous petroleum plays.…”

The sandstone reservoir characteristics and controlling factors of Shanxi Formation and Lower Shihezi Formation in Southeastern Ordos Basin

“…Generally, the sandstone reservoirs are mainly resulted from fluvial‐deltaic deposits and developed in responses to sediment supply, palaeoclimate, lacustrine fluctuations, and tectonic movements (Al‐hasani et al, 2018; Allen & Allen, 2013; Gier, Worden, Johns, & Kurzweil, 2008; Halisch, Weller, Sattler, Debschütz, & El‐Sayed, 2009; Hammer, Mørk, & Næss, 2010; Umar, Friis, Khan, Kassi, & Kasi, 2011). However, the factors controlling the development, characteristics (macro and micro), and evolution (horizontal and vertical) of sandstone reservoirs are complex and integrative (Benayad et al, 2019; Dutton & Loucks, 2010; Khaing, Surjono, Setyowiyoto, & Sugai, 2017; Morad, Al‐Ramadan, Ketzer, & De Ros, 2010). The interaction of the factors influencing the characteristics of sandstone reservoirs and revealing associated controlling factors in different tectonic settings or under different sedimentary environments or at various diagenesis stages will generate different sandstone reservoir characteristics and clarify different controlling factors (Hakimi, Shalaby, & Abdullah, 2012; Kassab, Hassanain, & Salem, 2014; Mahgoub, Padmanabhan, & Abdullatif, 2016; Makeen, Abdullah, Ayinla, Hakimi, & Sia, 2016).…”