scholarly journals Water-free oil reservoirs: origin and morphology

Georesursy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 15-21
Author(s):  
Tatyana A. Kireeva
Keyword(s):  
High Temperature ◽  
Crystalline Rocks ◽  
Secondary Minerals ◽  
Bazhenov Formation ◽  
Iron Aluminum ◽  
Hydrothermal Origin ◽  
South Vietnam ◽  
White Tiger ◽  
Clay Rocks ◽  
Calcium Iron

The features of the morphology and composition of secondary minerals in the reservoir zones of the White Tiger (Bach Ho) deposit (shelf of South Vietnam) and deposits in clay rocks of the Bazhenov formation of the Salym area of Western Siberia are considered. It is shown that the common for these fields is the formation of a reservoir as a result of the leaching effect of high-temperature fluids. The genesis of the reservoir is determined by a complex of secondary minerals, obviously of hydrothermal origin, partially filling caverns and cracks in the rock: native silver – zincous copper – barite – anhydrite – kaolinite – laumontite (White Tiger oilfield) and sulphates of iron, aluminum, sodium and calcium – iron-aluminum alum, alunite, jarosite, mirabilite, melanterite, gypsum (deposit in the rocks of the Bazhenov formation of the Salym area). Diagnostics of secondary minerals was established based on the results of microprobe studies of undisturbed samples and analysis of the composition of water extracts from crushed core samples.The species composition of secondary minerals indicates a high temperature of the affected solutions, which varied from 600 to 200°C in the case of the White Tiger oilfield, and in the range of 350–450°C, in the case of rocks of the Bazhenov formation. Hydrothermal alteration of crystalline rocks with the formation of secondary clay minerals (kaolinite, montmorillonite, hydromica), zeolites and minerals-sulfates, which are crystalline hydrates, occurs with the absorption of huge amounts of water by the rock (up to 4∙108 tons of water per 1 km3 of altered rock). This may be related to the waterlessness (lack of bottom water) of oilfields, the reservoir of which has a hydrothermal origin. It is possible that oil deposits in crystalline rocks with high oil-saturated zones have associated waters of hydrothermal rather than sedimentogenic origin, but they occur at considerable depths and are not penetrated by drilling. This possibility is evidenced by the discovery of hydrothermal water in the basement of the White Tiger reservoir at a depth of 4493 m, which, in terms of chemical composition and mineralization, is close to the waters of sodium chloride hydrotherms of Kamchatka.

scholarly journals Types of Void Space in the Bazhenov Reservoir Rocks

Geosciences ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 269
Author(s):  
Olga V. Postnikova ◽  
Alexander V. Postnikov ◽  
Olga A. Zueva ◽  
Artem E. Kozionov ◽  
Ekaterina V. Milovanova ◽  
...  
Keyword(s):  
Western Siberia ◽  
Distribution Patterns ◽  
Void Space ◽  
X Ray Diffraction ◽  
Bazhenov Formation ◽  
Reservoir Rocks ◽  
Oil Reserves ◽  
Light Oil ◽  
Clay Rocks ◽  
High Degree

The deposits of the Bazhenov formation are a unique reservoir of unconventional oil reserves in Western Siberia. They contain both solid organic matter (kerogen) and liquid light oil. The successful development of these hydrocarbons is largely determined by the adequacy of the void space models. The aim of the study is to identify the types of void space in the sediments of the Bazhenov formation and to identify the distribution patterns across the section of the researched wells. The void space was studied by electron and optical microscopy, and the mineral composition of the rocks was determined by X-ray diffraction analysis. The deposits of the Bazhenov productive formation in the territory of Western Siberia are represented by a wide complex of lithotypes, including various kinds of silicites, carbonate, clay rocks, and mixtites. The reservoir space in the reservoir rocks of the Bazhenov formation is a complex and hierarchically subordinated system, which includes voids and fractures of various sizes, configurations, and genesis. The void space of the Bazhenov formation is characterized by a fairly high degree of spatial heterogeneity, which is controlled by lithological, facies, and tectonic factors, as well as the direction of catagenetic processes.

Application of logging-while-drilling spectroscopy to evaluate volume of clay, grain density, and porosity in a low porosity, high temperature environment—offshore Western Australia

2014 ◽  
Vol 54 (2) ◽  
pp. 533
Author(s):  
Paolo Bartelucci ◽  
Mauro Firinu ◽  
Anthony Jones ◽  
Ping Yan
Keyword(s):  
High Temperature ◽  
Gamma Ray ◽  
Water Saturation ◽  
Dry Weight ◽  
Core Data ◽  
Low Salinity ◽  
Petrophysical Model ◽  
Logging While Drilling ◽  
Calcium Iron ◽  
Low Porosity

Formation evaluation in low porosity, low salinity, and high temperature reservoirs poses many challenges. The environment is hostile to many logging tools due to their temperature limits and there is greater uncertainty related to petrophysical parameters compared with conventional formations. Additionally, in low porosity and low salinity reservoirs, resistivity contrast between hydrocarbon and water filled rocks is often missing. This extended abstract presents a case study from offshore WA where a petrophysical model has been created with logging while drilling measurements including spectroscopy data to improve estimation of mineralogy, clay volume and porosity, thereby reducing saturation evaluation uncertainty. Spectroscopy measurements can be analysed to derive dry weight elemental concentrations of various elements such as silicon, calcium, iron, and sulfur. These concentrations have been subsequently used as input to compute a multi-mineral petrophysical model using a least squares inversion technique. We demonstrate that spectroscopy can be used independently to obtain an accurate volume of clay instead of gamma ray, spontaneous potential, or porosity logs. Moreover, matrix properties such as grain density, which enhance the accuracy of porosity estimation derived from bulk density, are also derived from spectroscopy dataset. Good agreement with core validates the petrophysical model. Also demonstrated is how the petrophysical model reduces the uncertainty in clay volume and porosity, from which more accurate water saturation can be derived in these tight reservoirs. Calibrating the spectroscopy information to core data allows the mineralogical and geological model to be extended to the intervals where core data are not available.

Closed Vessel Sample Decomposition by Microprocessor Controlled High Temperature/ Pressure Asher for Elemental Analysis by Inductively Coupled Argon Plasma Emission Spectrometer

1989 ◽  
Vol 72 (2) ◽  
pp. 387-393
Author(s):  
R Thomas White
Keyword(s):  
High Temperature ◽  
Argon Plasma ◽  
Average Recovery ◽  
Inductively Coupled ◽  
Environmental Material ◽  
Sample Decomposition ◽  
Lead Magnesium ◽  
Temperature And Pressure ◽  
Calcium Iron ◽  
Agricultural Food

Abstract A safe, reliable, and efficient method is described for automated acid decomposition of biological samples, agricultural food products, and environmental material under high temperature and pressure. A high temperature/pressure asher that provides temperatures up to 320°C and pressures up to 100 bars (1450 psi) is used to heat 5 mL of ultrapure acid 4 h for complete sample decomposition. The unit is microprocessor-controlled with up to 5 programmable temperature levels and ramp time intervals. These levels and intervals are displayed on a CRT screen. Both temperature and pressure program set points and actual readings inside the autoclave can be monitored by an analyst as the decomposition program progresses. Biological samples and agricultural food products of 1.0 g each are weighed into 70 mL closed quartz vessels for acid digestion. The digested samples are analyzed by using an inductively coupled argon plasma (ICP) emission spectrometer for aluminum, boron, calcium, iron, lead, magnesium, manganese, phosphorus, potassium, sodium, strontium, sulfur, and zinc. Environmental material of 0.2 g each is weighed into 20 mL glassy carbon vessels for digestion and ICP analysis for calcium, iron, lead, magnesium, manganese, nickel, phosphorus, potassium, sodium, strontium, sulfur, titanium, and zinc. The average recovery for 31 elemental standards evaluated by digestion in the high temperature/ pressure asher provided an average recovery of 98.7%.

Wollastonite from hydrothermally altered basaltic rocks in Iceland

1981 ◽  
Vol 44 (333) ◽  
pp. 95-99 ◽  
Author(s):  
H. Kristmannsdóttir
Keyword(s):  
High Temperature ◽  
Geothermal Area ◽  
Basaltic Rocks ◽  
Hydrothermal Quartz ◽  
Hydrothermal Origin ◽  
First Time

AbstractWollastonite is reported, for the first time in Iceland, in hydrothermally altered basaltic rocks in the Krafla high-temperature geothermal area, northern Iceland. Two possible modes of origin are suggested: (1) A contact metamorphic origin at the expense of hydrothermal quartz and calcite near the margins of dykes. (2) A hydrothermal origin at depths below 1000 m where fluid temperatures exceed 300°C.

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