scholarly journals Hydrogeological characteristics of the Lower Cretaceous terrigenous complex of the Karkinit-Northern Crimean deep in the aspect of its potential for oil and gas presence

Purpose. To substantiate the prospects for oil and gas presence in the Lower Cretaceous sediments of the Karkinit-Northern Crimean deep based on hydrogeological (hydrogeochemical, gas-hydrogeochemical and geobaric) features. Methodology. Investigations of formation waters and water-dissolved gases were based on the methods of chemical, elementary spectral and gas chromatographic analyses executed at the laboratories of subsidiary joint-stock company "Chornomornaftogaz", subsidiary "Crimean Geology" and the Institute of Geology and Geochemistry of Combustible Minerals of NASU. For the comparison of formation pressure we applied the hydrostatic coefficient (Ch). Ch is the ratio of measured formation pressure to conditionally hydrostatic at the depth of the measuring with γ=1.000 (Рf/Рch), which eliminates the influence of uneven depths of measurement and different water densities, that is, to get the reduced value. For processing materials Excell, Corell Draw and Surfer are used. Results. Regional features of formation waters in the Lower Cretaceous complex as well as their chemical composition formation conditions are established. According to retrospective data analysis on the Crimean Plains, using the information received on the Black Sea shelf, we come to a conclusion that formation waters of the Lower Cretaceous complex are mainly sedimentogenic. The sulfate-natrium (S.Na) waters of the basal horizon and the Lower Cretaceous aquiferous complex most likely are infiltrative. This is evidenced by the decrease in the indicators of metamorphism of rCa/rMg, r(Cl-Na)/rMg and the increase in Cl/Br to over 1000, the lowered content of iodine (J) and bromine (Br). Infiltrative (paleoinfiltrative) waters mixed with primary sedimentogenic waters. This was accompanied by the decrease in their mineralization and thalassogenic trace elements contents in them. Modern infiltration from the land of meteoric waters at depths of more than 2000–3000 meters through the hydrodynamic barriers of the elision water drive system is impossible, but it could be realized at the continental infiltration stages of the foreground development and before the late Cretaceous time. This is evidenced by the continuous continental conditions marked by denudation of rocks. The main processes in the chemical composition formation of formation waters of Cretaceous and Lower Cretaceous complexes could have been: leaching rocks, mixing of infiltrative fresh or saline waters with thalassogenic waters; mixing of these waters with waters of the high temperature (>2000C) dehydration of clay rocks with formation of non-infiltrative (S.Na) and (Hyd.Car.Na) waters. Based on the analysis of the hydrostatic coeficient distribution (Ch) in the basal and Lower Cretaceous aquiferous complexes the existence of the elision water pressure system within the Karkinit-Northern Crimean deep is confirmed. The cause of overhydrostatic pressures is most likely to be the dehydration of clay rocks and the intrusion of deep gases. Geobaric conditions and filtration parameters suggest that the water flows of the elision water pressure system can move from the deepest parts of the Karkinit-Northern Crimean deep towards its sides. Originality and practical significance. The nature and forming conditions of formation waters have been substantiated. According to gas-hydrogeochemical and geobaric features it was possible to distinguish localities promising for hydrocarbon prospecting in the Lower Cretaceous deposits.

2019 ◽  
Vol 3 (180) ◽  
pp. 90-99
Author(s):  
Ivanna Kolodiy ◽  
Halyna Medvid

Distribution features of formation waters in Karkinit-Northern Crimean deep were studied; the conditions of chemical composition origin of formation waters have been studied as well. The regional features for the distribution of formation waters and the conditions of their chemical composition forming of the Lower Cretaceous complex are established. The formation waters are salty or saline and commonly have low metamorphism intensity. The formation waters of the Lower Cretaceous complex are salt with often a low degree of metamorphosis. The values of the variation coefficients of five principal components (mineralization, (Na + K), chlorine (Cl), bromine (Br), and the water sampling depths) are estimated to range from 28.73 to 57.14 %, which indicates insignificant variability each of these indicators; this characteristic does not depend on the type of water and place of sampling. The seven objects of the correlation such as mineralization, chlorine, calcium, ammonium, bromine, sulfates and hydrocarbonates are closely associated with each other. The land waters are commonly of calcium chloride (Cl.Ca) or hydrocarbonate natrium (Hyd.Car.Na) type, whereas in the water area all variety of formation waters has been recognized. Formation waters of Late Cretaceous shelf complex as well as formation waters at Tarkhankut peninsula have close relation between chemical components, low variations in the composition of macro- and microcomponents. Therefore, the formation waters of these regions could be formed in quite similar conditions. The characteristic features of the shelf formation waters are high sulfate content, despite the fact that waters complex occurs at great depths. At the same time, a decrease in the metamorphism intensity is observed as well as an increase in the Cl/Br ratio up to 1000 or more, caused by low bromine content. It is apparent that such characteristic can be the result of extrusion of water at the late stages of clay rocks dehydration. Paleoinfiltration processes in Lower Cretaceous complex may be considered as an alternative explanation. High gas saturation in the waters of the folded basin bed has been recognized at Golytsyno area and at the Tarkhankut peninsula (Melova, Oktyabrska, Berezivska and Western Oktyabrska areas). This allows us to predict the prospects of the Lower Cretaceous sediments of the Karkinit-Northern Crimean deep.


Author(s):  
D. A. Novikov

The unique material has been compiled on the hydrodynamics of oil and gas deposits of the Yamalo-Kara Depression for the first time in the last 30 years. The main feature of the region is the wide development of abnormally high formation pressures (Ka to 2.21) in both Jurassic and Lower Cretaceous horizons. Studying the filtration-capacitive properties and hydrodynamic characteristics of the Jurassic-Cretaceous reservoirs allows to established the predominate role of the elision water exchange in the formation of the modern hydrodynamic structure. At the depth of about 2–2.5 km elisional lithostatic system begins to acquire the features of elisional thermo-dehydration system. The extensive zones of piezomaxima (Bolshekhetskaya and Karskaya megasyneclise) at the present stage of development of the water-pressure basin system became internal areas of water pressure (supply) with a maximum degree of hydrogeological closeness. The vast zones of piezomaxima (the Bolshekhetskaya and Karskaya megasyneclises) became the inner regions of water pressuring (feeding) with the maximal degree of hydrogeological closeness of the interior at the current stage of the development of the water-pressure system in the basin. The areas of piezominima extending along the main sites of oil and gas generation are related to the largest zones of oil and gas accumulation (Vankoro-Suzunskaya, Bovanenkovskaya, Urengoyskaya and others). Currently, two types of natural water-pressure systems has been established in the region under investigation: elision in the inner regions (dominating within the Yamalo-Kara depression) and infiltration — in the basin margins of the West Siberian sedimentary basin.


2017 ◽  
pp. 6-10
Author(s):  
V. A. Beshentsev ◽  
R. N. Abdrashitova ◽  
N. K. Lazutin

Hydrogeochemical conditions of the Zapolyarnoye oil and gas condensate field are discussed in the paper. These conditions of Mesozoic basin are important in the formation and preservation of oil and gas deposits. An explanation is given for the presence of the hydrocarbonate-sodium type of waters in the Neocomian hydrogeo-logical complex. It is shown, that the field belong to the Elysion geodynamic a water pressure system - Omsk-Gydansk structural zone, in particular to the northern part - the Yamal-Gydan lineaments.


2018 ◽  
pp. 6-11
Author(s):  
V. A. Beshentsev ◽  
R. N. Abdrashitova ◽  
N. K. Lazutin ◽  
I. G. Sabanina ◽  
A. A. Gudkova

The article considers hydrogeological conditions of the Ety-Purovsky oil and gas field. The authors describe hydrogeological stratification of the field and its hydrogeochemical conditions. These conditions reveal the existence of classical vertical zoning. The research pays attention to the important role of an elution water pressure system in the formation of the hydrogeochemical and hydrogeodynamic fields structure.


2020 ◽  
pp. 20-35
Author(s):  
V. A. Beshentsev ◽  
Yu. I. Salnikova ◽  
S. V. Vorobjeva

The article is devoted to the hydrogeochemical conditions of the Mesozoic hydrogeological basin within the Russkoye oil and gas field. The text gives valuable information on the natural conditions, geological structure, geotemperature regime of the bowels of the Earth and the composition of groundwater of the Aptian-Albian-Cenomanian, Neocomian, and Jurassic hydrogeological complexes. The change in the composition of groundwater in the section of the AptianAlbian-Cenomanian complex has been revealed. Vertical inversion zoning that traces the underlying the Neocomian complex is established. We describe the main features of the regional distribution of reservoir pressures. Hydrodynamic schemes of the Aptian-Albian-Cenomanian, Neocomian, and Jurassic hydrogeological complexes are given in the article. These schemes show that the Russkoye gas and oil field is located in the zone of low reservoir pressures. The above vertical inversion zoning and low reservoir pressures are associated with the location of the field within the elisional hydrodynamic water pressure system of the Yamal-Gydan lineaments. The data of the block-fault model of the considered field were used in the course of the study. The block-fault structure predetermined the migration of hydrocarbons and the formation of tectonically screened deposits.


2018 ◽  
pp. 15-20
Author(s):  
V. A. Beshentsev ◽  
I. G. Sabanina ◽  
O. G. Beshentseva ◽  
R. N. Abdrashitova

Hydrogeochemical conditions of the Yarudey oil and gas condensate field are largely determined by its position within the elysion lithostatic water pressure system and the presence of a large number of faults in the base plate. In the article we explore the main features of the Neocomian and the Jurassic hydrogeological complexes of the field. Underground waters of the Mesozoic hydrogeological basin are characterized by chloride sodium ion-salt composition. They belong to the hydrocarbonate sodium type according to V. A. Sulin’s classification, mineralization is 7,0 g/l in the Neocomian complex and is 11,1 g/l in the Jurassic complex. The existence of complex hydrogeochemical conditions is confirmed by the nature of the change in the genetic sodiumchlorine coefficient (up to 1,4) and boron-bromine coefficients (up to 0,49).


Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4457
Author(s):  
Valentin Morenov ◽  
Ekaterina Leusheva ◽  
Tianle Liu

Construction of oil and gas wells at offshore fields often involves high formation pressure and the presence of swellable clay rocks in the section. In addition, productivity preservation is also an important aspect. For this purpose, it is necessary to reduce the solids content of the drilling mud. The purpose of this work is to develop, improve, and study compositions of weighted drilling muds with low content of solids, on the basis of organic salts of alkali metals and polymers for the construction of wells prone to rock swelling and/or cavings, as well as drilling fluids for drilling-in the formation. In order to achieve the set goal the following is required: Analysis of existing drilling muds of higher density for drilling wells in unstable rock intervals and for drilling in the productive formation; analysis of experience in using drilling systems on the formic acid salts base and substantiation of requirements for flushing fluids during well construction; development and investigation of drilling mud compositions on the formate base; and the evaluation of inhibiting effect of systems containing organic salts, polymer reagents, and calcium carbonate on clay samples. The developed drilling mud is characterized by a high inhibiting ability that allows minimized mud-weighting by the natural solid phase. This reduces the volume of prepared mud and facilitates the regulation of its properties by reducing the dispersion of drilled cuttings; it eliminates problems related to hydration and the swelling of active clay rocks; and stabilizes unstable argillites prone to caving. The low solids content, low filtration rates, and inhibitory nature of the mud allows high stability of the rheological properties of the mud, and preserves oil and gas reservoir productivity under conditions of elevated formation pressure.


SPE Journal ◽  
2022 ◽  
pp. 1-17
Author(s):  
Zhi Zhang ◽  
Baojiang Sun ◽  
Zhiyuan Wang ◽  
Shaowei Pan ◽  
Wenqiang Lou ◽  
...  

Summary The exploration and development of offshore oil and gas have greatly alleviated the tension of global oil and gas resources. However, the abnormal pressure of offshore reservoirs is more common compared with terrestrial oil and gas reservoirs, and the marine geological structure is complex, with the development of faults, fractures, and high and steep structures, which leads to the strong anisotropy of formation pore pressure distribution and uncertainty of pressure system change. In this paper, considering the corresponding characteristics of the randomness of the formation pressure prediction results in the Eaton equation for their respective variables, a formation pressure inversion method based on multisource information, such as predrilling data, bottomhole while drilling data, seabed measured data, and surface measured data, is established. On this basis, combined with the data of a well in the South China Sea, the variation law of the uncertainty of formation pressure prediction results under the conditions of predrilling data, measurement while drilling (MWD) data, and their mutual coupling is analyzed. The simulation results show that the uncertainty distribution of formation pressure prediction based solely on predrilling data shows linear accumulation trend with well depth, and the formation pressure inversion method based on multisource information can significantly curb the increasing trend of uncertainty when MWD data are introduced. Therefore, through the analysis of typical change patterns of monitoring parameters under normal/abnormal conditions during drilling, combined with the method of multisource information, the abnormal pressure information can be accurately predicted and inversed, which provides important support for wellbore pressure regulation under complex formation conditions.


Author(s):  
I. I. Lube ◽  
N. V. Trutnev ◽  
S. V. Tumashev ◽  
A. V. Krasikov ◽  
A. G. Ul’yanov ◽  
...  

At production of pipes of type 13Cr grade steel used at development of oil and gas deposits in areas with aggressive environment, intensive wear of instrument takes place, first of all, piercing mill mandrels. Factors, influencing the resistivity of the piercing mandrels considered, including chemical composition of the material, the mandrel is made of and its design. Based on industrial experience it was shown, that chrome content in the mandrel material practically does not affect on the increase of its resistivity, since the formed thin protective oxides having high melting temperature, are quickly failed and practically are not restored in the process of piercing. To increase the resistivity of piercing mandrels at production of casing tubes of type 13Cr grade steel, a work was accomplished to select a new material for their manufacturing. The chemical composition of steel presented, which was traditionally used for piercing mandrels manufacturing, as well as a steel grade proposed to increase their resistivity. First, molybdenum content was increased, which increases the characteristics of steel strength and ductility at high temperatures and results in grain refining. Second, tungsten content was also increased, which forms carbides in the steel resulting in an increase of its hardness and “red resistivity”, as well as in preventing grains growth during heating. Third, cobalt content was also increased, which increases heat resistivity and shock loads resistivity. The three elements increase enabled to increase the mandrels resistivity by two times. Results of mandrel test of steel 20ХН2МВ3КБ presented, the mandrel having corrugation on the working cone surface, which enabled to reach the resistivity growth to 12 passes without significant change of instrument cost. Microstructure of mandrels made of steels 20Х2Н4МФА and 20ХН2МВ3КБ shown. Application of the centering pin of special design was tested, which provided forming of a rounding edge on the front billet ends, eliminated undercut of mandrel external surface in the process of secondary billet grip and increase the service life of the piercing mill mandrels. At production of seamless pipes of martensite class type 13Cr stainless steels having L80 group of strength, an increase of piercing mandrel resistivity was reached by more than four times, which together with other technical solutions enabled to increase the hourly productivity of the hot rolling section of Volzhsky pipe plant ТПА 159-426 line by more than two times.


Sign in / Sign up

Export Citation Format

Share Document