Feature, origin and distribution of calcareous interlayers: A case of Carboniferous Donghe sandstone in Hade Oil Field, Tarim Basin, NW China

The Reservoir potential of Middle Jurassic sedimentary deposits in the Imhotep Field, Matruh Basin, North-Western Egypt

“…Although the calcareous inter-layers are usually thin, they can be identified by combining conventional logging curves with dip logging curves, as explained by Rubing (2014). In this method, the well log responses of these thin calcareous layers can be identified as showing long and stable drilling times without hole enlargement.…”

Determination of Formation Time of Calcareous Cements in Marine Sandstone and Their Influence on Hydrocarbon Accumulation: A Case Study of the Carboniferous Donghe Sandstone in the Hadexun Oilfield, Tarim Basin

“…Previous studies also identified phase IV carbonate cements, which are composed mainly of ferruginous calcite and ferruginous dolomite, show nonluminescence or dark orange-red cathodoluminescence, and are typically characterized by replacement of feldspar grains [8,13]. Complete replacement of feldspar grains is observed, indicating that the phase IV carbonate cements formed in the middle burial stage (middle diagenetic phase A) [8,10].…”

“…The isotope ratios were reported relative to the Pee Dee Belemnite (PDB) standard, and the accuracy of the isotope measurement was less than 0.03%. In the Donghe sandstone in Well HD4 in the southern part of the Hadexun area, the average δ 13 C PDB values of carbonate cements from five measurements ranged from −4.4‰ to −3.1‰, and the average δ 18 O PDB values ranged between −10.6‰ and−6.9‰. In the Donghe sandstone in Well HD17 in the northern part of the area, the average δ 13 C PDB values of carbonate cements from five measurements ranged from −7.8‰ to −4.5‰, and the average δ 18 O PDB values ranged between −9.8‰ and 6.9‰ ( Table 2).…”

“…Some important progress in the study of the interlayers in the Donghe sandstone has been made. There are three types of septums in the Donghe sandstone, namely, the calcareous septum, the argillaceous carbonate septum, and the argillaceous septum, which are sedimentary and diagenetic [1,[13][14][15]. These septums have small thickness, ranging narrowly from 0.02 m to 0.6 m, with an average of about 0.2 m, and occur mainly in masses, spots, beddings, and quasilamellae or lamellae.…”

“…Because the original clumped isotopes within the lattice of a carbonate mineral are retained well during the process of acid digestion, mass-47 CO 2 ( 13 C 18 O 16 O (Δ47)) can be used as an approximation of isotopologue 13 C 18 O 16 O 2− in carbonate rocks, and the abundance of mass-47 CO 2 can represent the abundance of 13 C- 18 O bonds in a carbonate mineral [28]. The carbonate cluster isotope thermometer is based on the exchange reaction between 13 C and 18 O, which depends mainly on temperature [20,21]. In recent years, many scholars have found that the carbonate clumped isotope information would change with increasing formation temperature under certain conditions; however, it can be predicted quantitatively by corresponding models [29,30].…”