Advanced Determination of Heat Flow Density on an Example of a West Russian Oil Field

Reliable geothermal data are required for basin and petroleum system modeling. The essential shortcomings of the methods and results of previous geothermal investigations lead to a necessity to reappraise the data on the thermal properties and heat flow. A new, advanced experimental basis was used to provide reliable data on vertical variations in the thermal properties of formation and heat flow for the area surrounding a prospecting borehole drilled through an unconventional hydrocarbon reservoir of the Domanik Formation in the Orenburg region (Russia). Temperature logging was conducted 12.5 months after well drilling. The thermal properties of the rocks were measured with continuous thermal core profiling on all 1699 recovered core samples. Within non-cored intervals, the thermal conductivity of the rocks was determined from well-logging data. The influence of core aging, multiscale heterogeneity and anisotropy, in situ pressure and temperature on the thermal properties of rock was accounted for. The terrestrial heat flow was determined to be 72.6 ± 2.2 mW·m−2—~114% larger than the published average data for the studied area. The experiment presents the first experience of supporting basin modeling in unconventional plays with advanced experimental geothermal investigations.

Lithological and Geochemical Heterogeneity of the Organo-Mineral Matrix in Carbonate-Rich Shales

The paper discusses the issues of interaction of the organic matter and the siliceous-carbonate mineral matrix in unconventional reservoirs of the Upper Devonian Domanik Formation of the Upper Kama Depression of the Volga-Ural Basin. The Domanik Formation is composed of organic-rich low-permeability rocks. Lithological and geochemical peculiarities of rocks were studied using light microscopy, X-ray diffraction analysis (XRD), scanning electronic microscopy (SEM), and evaporation method. Organic matter was examined by the Rock-Eval pyrolysis with quantitative and qualitative evaluation of generation potential and maturity degree. Integrated analysis of results of lithological and geochemical studies allowed identifying intervals in the studied section where organic matter can form a complex association with the siliceous-carbonate matrix. It was fixed experimentally that in some cases the mineral carbonate matrix and the organic matter form a one-whole high-molecular compound. The authors supposed that in the course of sedimentation, organic matter is immobilized into the structure of the mineral carbonate matrix. At the deposition and diagenesis stage, the carbonate matter interacts with acids of the organic matter and forms natural organo-mineral polymers. Special physicochemical properties of such organo-mineral associations shed new light onto the problems of producing from hard-to-develop nonconventional carbonate reservoirs and evaluating the associated risks.

Early-Middle Frasnian (Late Devonian) carbon isotope Event in the Timan-Pechora Basin (Chernyshev Swell, Pymvashor River section, North Cis-Urals, Russia)

Details of the Early-Middle Frasnian boundary interval of the Pymvashor River section (Timan-Pechora Basin, Cis-Urals, in the far north of European Russia) are revealed by biostratigraphically constrained carbonate (δ13Ccarb) and organic carbon (δ13Corg) stable data. The studied interval corresponds to the lower part of the Domanik Formation, which consists of interbedded limestone and shale beds. Organic-rich black shale that lacks bioturbation and benthic organisms indicates an oxygen-depleted depositional environment. Detection of isorenieratene derivatives in organic matter indicates that anoxia was present in the photic zone during deposition. The Pymvashor River section contains δ13Ccarb and δ13Corg isotope records related to the Early-Middle Frasnian isotope Event. The similarity between the Cis-Uralian (this study) and the Chinese δ13Ccarb and δ13Corg oscillations, including the twostep pattern of the recorded major positive excursions, suggests a robust correlation of the Late Devonian Early- Middle Frasnian isotope Event and minor intra-event excursions. Magnitude of variations and values of δ13Corg and δ13Ccarb in the punctata Zone in the Pymvashor River section are minor than those observed in the North American, Polish, and Chinese successions. Such difference may reflect specific variation of the local environments.

Timan-Pechora Composite Tectono-Sedimentary Element

Timan-Pechora Composite Tectono-Sedimentary Element represents a significant part of the Timan-Pechora petroleum province, which is the second largest in the Circum-Arctic. It contains as much as up to 10 km of Paleozoic and Mesozoic strata hosting world-class hydrocarbon source rock, the Domanik Formation, and a variety of hydrocarbon plays prolific for both, oil and natural gas. Complex tectonic structure of the composite tectono-sedimentary element formed as result of several tectonic phases: two extensional events, post-rift thermal sag in a passive margin setting, and a series of late Paleozoic and early Mesozoic compressional events. The latter modified the extensional fabric and led to the formation of a number of inverted swells and smaller anticlinal structures providing the major trapping capacities. The deposition of source and reservoir facies occurred during the extensional tectonic phases, while the main reservoir-prone sedimentary units were deposited during late Paleozoic and early Mesozoic orogenic phases.

Lithological-geochemical characteristics of natural outcrops of the Domani sediments in the areas of the Pre-Urals regional trough of the Volga-Ural oil and gas basin

Replenishment of oil reserves requires searching, exploration and production of new unconventional objects. Among these objects is Domanik formation, which is widespread in the Volga-Ural basin. The Domanic high-carbon formation is presented by thin-layered carbonate-siliceous rocks with a high content of organic matter, capable of both producing hydrocarbons with its own oil and gas potential, and concentraring them in reservoirs [Stupakova et al., 2017]. Study of lithological composition of rocks help to obtain information about the nature of hydrocarbon accumulations and understand possibilities of estracting hydrocarbon of them. The lithological and geochemical characteristics of rocks are an integral part of the study such types of deposits.

Experimental study of gydrotermal production of oil from Domanik Formation rocks

The experimental results on the synthetic oil production from Domanik Formation rocks under hydrothermal conditions are given. Oil fractions extracting potential of the rocks under hydrothermal was shown to be up to 60 mg/g or 6,0 wt.%. Inorganic additives (sodium carbonate or silica) incorporation does not influence on the oil recovery factor. Meanwhile the amount of recoverable oil products depends on the mineral composition of the rock. The dependence between the percentage of hydrocarbons emission and mineral composition of the rocks was determined. Clay minerals and silica increase the yield of synthetic oil, carbonates, conversely, inhibit the process.