Exploration Wells Research Articles

A radiation safety assessment in aquatic ecosystems formed by self-discharging wells: a case study of the watercourse: the well No. 36-RG — a stream — the Aremzyanka River

This article investigates the impact of geothermal water from the Cherkashinskaya No. 36-RG self-injection exploration well on ecosystem watercourses. The well was drilled in 1965 to investigate deposits of iodine-bromine water. This article presents estimations of the acceptable levels of radiation hazard content in the water and near-bottom sediments of gravity-flow hydrogeological wells. The radiation safety of working with these materials for personnel in geological exploration and national economic enterprises is also evaluated. The article provides information on the study of the natural radiation background, as well as results on the natural radioactivity of the bottom sediments and the volumetric radium content of the water. Natural radioactivity in the bottom sediments of potassium (40K) and thorium (232Th) is analyzed in this study. The relevance of this research originates from over fifty years of pollution by highly mineralised iodine-bromine water within the catchment area of one of Western Siberia's largest transboundary rivers, the Irtysh River. The Aremzyanka River is first-order tributary of the Irtysh River, and it receives water from a stream originating from exploration well No. 36-RG.

Machine learning application for prediction of sonic wave transit time - A case of Niger Delta basin

Sonic wave transit times are the major logs for estimating pertinent geomechanical parameters including overburden stress, pore pressure, effective stress, and unconfined compressible strength among others. These logs contain much important information about subsurface formation. However, in most oil and gas exploration wells, these logs are not usually acquired in all the wells which can be attributed to the high cost involved in logging. The application of the data-driven ML model has rarely been used for compressional and shear sonic logs (DTP and DTS) prediction within the Niger Delta basin where many reports of geomechanical instabilities have been reported. In this study, seven machine learning algorithms namely linear regression (LR), K-nearest neighbour (KNN), support vector regressor (SVR), random forest regressor (RFR), Extreme Gradient Boosting (XGBoost), Categorical Boosting (CatBoost), and back propagation artificial neural network (BPANN) were employed for prediction of DTP and DTS from conventional wireline logs data and their results were compared. For DTP prediction, the best model achieved a coefficient of determination (R2) value of 90 % using CatBoost. Also, CatBoost produced the model for DTS prediction with an R2 value of 95 %. A comparison results of the seven ML algorithms showed that six models performed really well for DTP and DTS predictions with a value of R2 > 80 % and 90 % respectively. In contrast, the worst performance models are LR for DTP prediction and SVR for DTS prediction. The blind testing carried out on some selected wells affirmed the efficiency of the proposed technique producing R2 values ranging from 92 to 94 % for DTP prediction and 94–99 % for DTS prediction. This present study confirmed the ability of building efficient ML models for estimating and predicting DTP and DTS which can be used to estimate geomechanical parameters in wells where both are not available.

Implications of Timanian thrust systems in the Barents Sea and Svalbard on using paleontological constraints for plate tectonics reconstructions.

The Svalbard Archipelago is commonly believed to have been located at comparable latitude and, possibly, to have been attached to Laurentia in the early Paleozoic (500-420 Ma) based on trilobite assemblage similarities. Trilobite assemblage differences and lack of mixing between Laurentia-Svalbard and Baltica were further used to propose that these continents were separated by the Iapetus Ocean at that time. However, recent structural correlation of Timanian (650-550 Ma) thrust systems throughout the Barents Sea show that Svalbard was already attached to Baltica in the latest Neoproterozoic and remained so during the Phanerozoic. The present study presents a new interpretation of seismic reflection data from the DISKOS database, which were tied to nearby exploration wells. The study uses recently acquired knowledge of the seismic facies of intensely deformed pre-Caledonian rocks and principles of seismic stratigraphy to interpret the data. The present study reconciles the proximity of Svalbard and Laurentia with the early accretion of Svalbard to Baltica in the latest Neoproterozoic. It also describes the influence of Timanian thrust systems on paleoenvironments and possible effects on trilobite assemblages, e.g., the lack of mixing between those of Laurentia-Svalbard and Baltica. The identification of elongate, emerged topographic highs in the Barents Sea and Svalbard in the late Neoproterozoic-early Paleozoic suggest that paleontological constraints should be considered with greater care when discussing continent separation since thrust systems may act as major faunal barriers within a single tectonic plate. Other factors to consider when discussing plate separation include paleoclimatic belts.

Cretaceous-Paleogene rifting on the NW margin of the Australian continent, SE Banda Arc region

The Banda Terrane successions of Timor Island and correlative units in Sumba are widely considered allochthonous with respect to the Australian continental margin successions that form the main part of the Banda arc-continent collision complex. A new interpretation is proposed for the Banda Terrane, which suggests that these units originated on the outermost (northern) edge of the Australian continent. Volcanic successions in the Banda Terrane, which date to the Cretaceous and Paleogene (Aptian/Albian to Eocene), are interpreted as originating in a backarc/marginal basin setting behind a northward-facing arc that rifted away from the NW margin of Australia through this period. The Banda terrane successions are interpreted as representing the southern, continent-attached portion of the marginal basin, and occupied a position on the distal edge of Australia up to the onset of Banda arc-continent collision in the Miocene.Supporting evidence for an Australian margin origin of the Banda Terrane includes very similar age ranges for zircons dated to the Cretaceous in Sumba and Timor (Banda Terrane) and in sandstones of the Ungar Formation in Tanimbar, the latter forming an element of the Australian margin succession. In Timor there is also previously reported evidence for continental margin rifting during the Late Cretaceous, while contemporaneous Late Cretaceous-Paleogene volcanism is also recognised in the Bird’s Head-Misool region of eastern Indonesia, which forms part of the Australian continental margin. In addition, a number of stratigraphic links between the Banda Terrane and the Australian continental margin successions in Timor are summarised in this study.The effects of the Cretaceous-Paleogene rifting event are also apparent in subsidence curves derived from petroleum exploration wells drilled on the northern ‘passive’ continental margin of Australia from SW of Timor to the Bird’s Head-Misool region of eastern Indonesia. Inferred rift-related subsidence commenced in the Aptian-Albian on the Australian palaeo-margin immediately east of Timor and developed sporadically but in regionally consistent groupings throughout the Late Cretaceous and Paleogene.

Thermal conductivity of sediments from well-logs and its application to determine heat flow density in the Pannonian Basin, Hungary

The thermal conductivity of rocks can be deduced from available data of exploration wells such as core samples, cuttings, lithological descriptions and geophysical well logs. We present a methodology for determining the thermal conductivity of the Neogene and Quaternary clastic sediments in the Pannonian Basin using geophysical well logs and thermal conductivity data measured in laboratory. The lithological composition consisting of shale, sand and water was identified and the volumetric fractions of these components were derived from wireline logging data that included natural gamma ray, resistivity, bulk density and neutron porosity logs. The bulk thermal conductivity was computed by applying an appropriate mixing law using the thermal conductivity values of the lithological components. The thermal conductivities of the lithological components were determined by the best fit of the calculated bulk thermal conductivity values to the laboratory data. Different mixing models are recommended to calculate thermal conductivity of shales and sandstones. The thermal conductivity of shales was calculated with the weighted harmonic mean of the constituents, where the volumetric fractions and the porosity were the weights. The thermal conductivity of sandstones can be equally well estimated by the weighted geometric mean and the three component lower Hashin-Shtrikman bound. The geometric mean was used in calculations due its simplicity. Shale to sand ratio was utilized to separate shaly and sandstone samples. Heat flow density determination was carried out using the Bullard-plot technique with thermal conductivities calculated by our method. Heat flow density calculated by our method is in the range of heat flow density values previously conducted but with substantially lower uncertainties. The significance of the method is that it allows the harmonization of the heat flow density in the countries lying in the Pannonian Basin, because the Neogene and Quaternary sedimentary cycle resulting in the filling of the basin was uniform throughout the basin.

Environmental radiological baseline in unconventional oil and gas areas of Mexico

Abstract Environmental radioactivity study was performed in unconventional hydrocarbons areas for the first time in Mexico, where four unconventional hydrocarbon exploratory wells (UHEW) are planned. This study assesses natural radiological conditions in areas around UHEW. Equivalent dose rate distribution displayed in Geographic Information System (GIS) had a maximum of 1.83 mSv a−1 and minimum of 0.04 mSv a−1, GIS was also used for introducing land usage, water resources and population occupancy. Measurements of gross alpha and gross beta in water were below the national permissible limits for drinking water 0.5 and 1.0 Bq L−1 respectively, even though samples do not correspond to drinking water. Evaluation of 238U and 226Ra in groundwater were below minimum detectable concentration 1.3 and 1.0 Bq L−1, respectively. This study provides a radiological baseline for the impact of future industrial activities, especially if exploitation of unconventional hydrocarbons produces naturally occurring radioactive material.

Utility of fluid inclusion paleo-temperature in petroleum system modelling: A case study from western offshore, India

The paleo-temperature (Th) data from fluid inclusions are utilized for thermal history modelling using PetroMod software. Generally, bottom hole temperature (BHT) and vitrinite reflectance (Ro) measurements are widely used in petroleum system modelling (PSM) in the oil industry for calibration purposes. Th representing the minimum temperature of fluid entrapment estimated from fluid-inclusion study provides extra support to build the thermal models for PSM. Fluid inclusion parameters along with Rock-Eval pyrolysis analysis have been used to predict the maturity of oil in terms of API gravity as well as the maturity of source rocks respectively. Two exploratory wells RV-1 (Mumbai Offshore Basin) and KK4C-A-1 (Kerala-Konkan Offshore Basin), India were examined and the Th from most of the fluid inclusions of wells RV-1 and KK4C-A-1 fell in the oil window range of 60–140 °C suggesting thermal conditions favourable for oil generation in both of the wells. Th of coeval aqueous inclusions along with the Hydrocarbon Fluid inclusions (HCFIs) was used to calibrate PSM. Vital parameters show that source rocks of well RV-1 are mature and that of well KK4C-A-1 are immature. Two sets of PSM are created in terms of generation and expulsion for the dry wells RV-1 and KK4C-A-1 and calibrated each well using fluid inclusion Th and BHT. From the fluid inclusion analysis method, it is evident that hydrocarbon generation happened in both wells and the paleo-temperature indicates that the formations of both wells were subjected to temperatures in the oil window range, even though it was designated as dry wells in the present scenario. The present study highlights the application of fluid inclusion paleo-temperature (Th) during calibration instead of commonly used methods. We could obtain desirable and accurate data output from PSM using Th calibration.

The history of palynology in Egypt

This contribution marks the achievements made in the past decades by a group of mainly Egyptian palynologists. The data generated covers a long-time span from the Precambrian to the Holocene of Egypt. Previously published results are devoted primarily to the study of many exploration wells and outcrop sections. Comprehensive studies were carried out on a range of palynomorph groups including spores and pollen, algae and prasinophytes, dinoflagellate cysts, acritarchs, scolecodonts, chitinozoans, and other miscellaneous forms as well as palynofacies. Particular attention is given to the history of palaeopalynology. This study has identified three main phases. The results of the first phase were limited, as the knowledge of palynology in Egypt was poorly known from 1959 until 1979. Between 1980 and 2000, which represents the second or shaping phase, an intensive study of surface and subsurface material was carried out. The third phase (2000 until now) provides the academic and commercial expansion of palynological research in Egypt, where palynology can have immediate application in petroleum exploration studies. In the first phase, the application of palynology was seriously hampered by the limited extent of the published data. Only 27 works emerged by the end of 1979. A considerable acceleration was noted in the second phase when palynological research was established in many national institutions and started to play a considerable role in petroleum exploration. Beyond academia, some of the operating oil companies started to set up palynological laboratories and staff as part of biostratigraphy teams. These included, for example, GPC, Khalda Petroleum Company with a focus on the north Western Desert, and GUPCO with a focus on the Gulf of Suez, and most of the results obtained were incorporated with the internal data on the well files. During the period 2000–2009, especially when palynofacies studies were incorporated, the progress and the direction of palynological research changed. This allowed for a more accurate reconstruction of the depositional process and eventually a palaeobiogeographical history mainly for the Cretaceous, which is an important target for hydrocarbon exploration in Egypt. From 2010 onwards, the number of publications has clearly grown and reached 23 publications in 2020. Such a high pace of development seems to have been at the expense of basic research comprising taxonomy and biostratigraphy, something that might negatively impact the quality of research and also researchers, especially early career researchers. The change brought about through this phase by integrating organic geochemistry, sedimentology, and other disciplines may, however, have left a positive impact, principally in terms of international collaborations and expansion of palynological applications beyond the standard academic cluster. Important highlights and outputs, and prospective forthcoming developments and recommendations pertaining to Egyptian palynology generally (and in each phase) are discussed.

Evidence of new diapiric structures in the southern Adria Plate (Eastern Margin of Tethyan Ocean): Implications for Triassic paleogeography and evaporites remobilization during subduction/collision (Northern Ionian Sea, Central Mediterranean)

It has long been recognized that the Adria Plate, as well as the Dinaric-Hellenic sector, contains a large volume of Triassic salt associated with diapirism, and it is well known that Triassic evaporites in the Mediterranean Sea region were deposited over epicratonic platforms surrounding the Mesozoic passive margin of Tethys Ocean. However, the real extent of these evaporites is still unknown; especially in the deep-water offshore area where publicly available seismic reflection profiles are scarce and petroleum exploration wells are missing. Several authors highlighted the presence of Triassic salt structures, mostly triggered by Meso-Cenozoic compressions and associated with fold-and-thrust belts. Both the lack of data and the later compressions contribute to hiding how a diapiric structure, formed in a passive margin and characterized by dome's geometry, is remoulded to assume a teardrop geometry typical of diapirs in fold-and-thrust belts. Two end members of diapiric structures are discussed: extensional structures formed in a passive margin, and compressional structures formed in a fold-thrust belt. The transformation of one end-member into the other is not well known. In the Northern Ionian Sea, the Apulian foreland, belonging to the southernmost termination of the Adria Plate and considered one of the largest preserved Mesozoic passive margin block of the Tethys Ocean, is a deep-water area associated with the opposing fronts of the nearby Calabrian Arc/Apennines and Dinaric-Hellenic Chains since the Cretaceous. Therefore, it represents an ideal area for investigating both the real extent of Triassic evaporites and the transformation of the diapiric structures under different regional geodynamic contexts.Based on seismic reflection profiles but no petroleum exploration wells, we present evidence of Triassic evaporites in the deep-water portion of the Apulian foreland, as indicated by the interpretation of two diapiric structures never described previously. These two new diapirs likely formed from inherited Mesozoic salt structures such as pillows and/or salt domes. The identification of halokinetic-related sequences affecting the Plio-Quaternary foreland sediments allows constraining the polyphaser evolution of the two diapirs. We suggest they are reactivated in response to the compressive stresses transmitted by the nearby Calabrian Arc/Southern Apennines and Hellenides. But, after the Middle Pleistocene, extensional tectonics, related to Adria Plate flexuring, acted again, and the diapirs were cross-cut by normal faults. These observations and findings are integrated into the geological context that controls the fundamental features of the diapirs, providing new insights on the fate of diapiric structures formed in a passive margin, later involved in a subducting and colliding plate, and before they become part of a fold-and-thrust belt. Furthermore, the study provides new constraints on the Triassic paleogeographic reconstruction of the Northern Ionian and Central Mediterranean Seas at the continental margin of the Tethys Ocean.

METODOLOŠKI PRISTUP PROUČAVANJU UZROKA I MEHANIZMA AKTIVIRANJA KLIZIŠTA OGORELICA U OPĆINI TEOČAK (BOSNA I HERCEGOVINA)

The paper analyzes the causes and mechanisms of landslide activation in the Ogorelica settlement, Teočak municipality. This was when there was a danger to the property and the lives of the people living there. To determine the main causes of landslide activation, detailed engineering geological research was conducted (exploratory drilling with ten exploratory wells, detailed geological and engineering geological mapping of the terrain, and slope stability analysis). Based on the obtained data, urgent remedial measures were implemented on the said landslide, which consisted of filling cracks with material from the excavation, removing labile parts and mitigating the angle of the natural slope, leveling (ironing) the terrain to prevent the penetration of atmospheric precipitation into the sliding surface, making drainage ditches above the face of the landslide to drain the surface water and pumping out water from the body of the landslide.

Analysis and countermeasures of drilling challenges in complex ultra-deep exploration wells in thrust structural belt with multiple salt layers

The deep and ultra-deep zones of Bokhtar oilfield in Tajikistan are the critical blocks for future exploration and development, which are imbedded between two salt layers, accompany with four reservoir and cap assemblages of middle and upper Jurassic, Lower Cretaceous, Upper Cretaceous and Paleogene. The reservoir and cap assemblages of pre-salt carbonate and salt-gypsum cap have great potential. The complicated geological structure, uncertain formation and non-developed pre-salt formations made the critical challenges for drilling operation, including: (1) The difficult casing program design caused by peripheral compression and thrust of the basin, the complicated geological structure, the large geological difference above and below the salt layer, the unfaithful prediction of multiple sets of salt layer, great formation pressure uncertainty, and many sealing points; (2) The upper salt formations are featured by developed thrust belt and large dip angle, the contradiction between deviation prevention and drilling acceleration in high steep structure is prominent, and the wellbore quality is difficult to control; (3) Due to the mud loss in upper salt layer, loss coexisted with blow out in the salt layer and inaccurate prediction of salt bottom, the drilling complexes such as mud loss, overflow and well collapse are occurred frequently; (4) Ultra-deep well depth (over 7000m), HTHP (180°C,140MPa), multiple salt layers and long open hole section made high requirements on high temperature resistance of drilling fluid, cementing slurry and downhole tools, as well as high drilling risk and cost. It is necessary to carry out the drilling difficulties investigation of ultra-deep exploration well under the consideration of pertinence, safety, applicability and economy, then formed the suitable drilling engineering plan for Bokhtar Block through the optimization of domestic and foreign advanced and mature deep and ultra-deep well technologies, which is used to provide the technical support for the first pre-salt ultra-deep exploration well in this Block to be drilled successfully.

Assessment of the probability of success and risking in hydrocarbon exploration: A case study from Zindapir Anticline, Sulaiman Foldbelt, Indus Basin, Pakistan

Role of the statistical calculation is very important in petroleum exploration business. It is used to calculate the associated risk and determines the chances of geological success prior to drilling of an exploratory well in mapped prospect area. This manuscript is focusing on the geological modelling of Zindapir Anticline, Sulaiman Fold Belt, Indus basin, Pakistan using mainly based on the concept of probability developed by Coordinating Committee for Coastal and Offshore Geoscience Program (CCOP) in East and Southeast Asia in 2000. Study area comprises of Zindapir Anticline with two abandoned wells Well X-1 and Zindapir-1 which were drilled and declared as dry holes. Detailed geological modelling indicates that Zindapir structure is still virgin to flow hydrocarbons, and there are ample chances of compartments, which were developed as result of transpressional movement at the periphery of the structure. Interpreted seismic line also supports the presence of different compartments in structure. These compartments may host hydrocarbon, generated and migrated either from Bharti Syncline and Sulaiman Foredeep or generated by indigenous source rocks possibly deposited in the south of Zindapir-1 and Well X-1. Presence of trap, hydrocarbon charge and reservoir in Zindapir structure indicates there is better probability of success for hydrocarbons, and good chances for the development of traps because of transpressional movement. Traps may contain the hydrocarbon, possibly generated from Bharti Syncline in west and Sulaiman Foredeep in east whereas southern part of Zindapir Anticline was not considered, and northern part of Zindapir Anticline was mapped with very open grid size. Present seismic data is limited which is the major reason that due to poor probability of effective trap it is recommended to acquire additional seismic data for further detailed picture structure of Zindapir Anticline. An equation for the calculation of geological chances success for new development well is also proposed in this manuscript.

Subsidence and Uplift History of the UAE and the Western Flank of the UAE‐Oman Mountain Range

AbstractThe western flank of the UAE‐Oman mountain range offers a unique geodynamic setting to study the development of a cratonic rift into a mature passive margin and its subsequent flexure under orogenic load. However, the geodynamic processes driving this evolution are not fully understood. In this study, seismic and biostratigraphic data from 283 exploration wells were utilized to assess the regional subsidence and uplift history of the United Arab Emirates (UAE) and neighboring areas of the western flank of the UAE‐Oman mountain range. Three major sequences have been identified: pre‐Permian, Permian‐Turonian rifted margin, and Coniacian‐Pleistocene active margin. Backstripping of biostratigraphic data reveals Early Permian (ca. 272 Ma) and Late Jurassic (ca. 160) rift phases, that have been linked to Gondwana's early and final fragmentation. A NE‐SW‐oriented basin in central UAE suggests a Jurassic intracratonic rift that has been influenced by pre‐existing structures. Compressional phases were identified during the Late Cretaceous and in the Oligocene‐Miocene, coinciding with the emplacement of the Semail ophiolite and the Arabian‐Eurasian plates collision, respectively. These events caused additional subsidence and flank uplift, forming the Aruma foreland basin in the east and the Pabdeh foreland basin in the eastern and northern UAE. Crustal thickness following the rift episodes ranges from 30 to 36 km, resulting in a sedimentary cover thickness of 11–14 km. These estimates are in accord with Moho depths derived from teleseismic receiver functions and gravity inversion. These findings can be used to better understand Gondwana fragmentation and the opening and closing of the Neo‐Tethys Ocean.

The cambrian gog quartzite and deadwood formations of alberta: lessons for subsurface carbon sequestration

Injecting carbon dioxide into reservoirs has been undertaken since the 1940s, mostly as a method to enhance oil recovery. With the recognition of the impact of climate change, interest in carbon sequestration has increased exponentially, with hundreds of projects in progress around the globe. Many of these projects focus on Cambrian quartzites, which meet the requirements for carbon dioxide injection (CCS). Several CCS projects in Alberta, Canada, currently focus on using these reservoirs, including the Basal Cambrian Sandstone and Deadwood Formations, for injection and storage.A series of spectacular outcrops of the Cambrian Gog Quartzite are available for study in the area around Lake Louise in the Canadian Rockies of Alberta. These outcrops provide compelling analogues to other clastic Cambrian formations in the province that have been utilized for CCS. As an example, the Gog Quartzite was used by Shell as a direct reservoir analogue when modeling CO2 injection into the Basal Cambrian Sandstone in the QUEST Project. The Gog Quartzite also has potential to act as a CCS reservoir in its own right and may reach 2 kilometres in thickness.Outcrops of the Gog Quartzite were studied at Sink Lake, Spiral Tunnels and in the vicinity of Lake Louise in Alberta. They include fluvial and shallow marine, high net:gross sandstone beds with stacked trough cross-bedded sandstones. These are commonly interbedded with thin mudstone beds. Sedimentary structures include planar and trough cross-beds, wave ripples and contorted horizons interpreted as seismites with associated dewatering. Some units of the Gog Quartzite are heavily bioturbated with burrows including Arenicolites and Skolithos as well as other marine traces such as trilobite related ichnofacies.The Cambrian Deadwood Formation is also a target for carbon dioxide sequestration and provides the main reservoir for the Aquistore Project in Saskatchewan. It has been targeted by exploration wells in eastern Alberta and a new core study has demonstrated its suitability as a CO2 reservoir. Facies ranging from regolith overlying igneous basement, through alluvial fan and tidal deposits, and out into shallow marine settings with well developed parasequences, are all seen in the cores.The outcrop and core studies provide new data on Cambrian reservoirs which can be applied directly to potential Cambrian CCS targets in the subsurface of Alberta. The data can also be used to identify other potential Cambrian CO2 sinks around the world.

An integrated approach to the study of Achimov deposits within the South Tambey field (Western Siberia)

In order to clarify the structure of promising oil and gas objects in the South Tambey field (Western Siberia), an integrated approach to the study of Achimov deposits has been developed. The oil and gas potential level includes layers from PK1 to Yu9 at depths from 1000 to 4000 meters. Despite the fifty-year history of drilling wells in the area, the Achimov objects are currently poorly explored in the study area and may have significant potential for development. The purpose of this work was to clarify the geological structure of the Achimov deposits, which became possible thanks to the acquisition of new geological exploration data during the study of the underlying Jurassic complex. CDP 3D seismic exploration work was completed using a modern full-azimuth observation system, and active drilling of exploration wells for Jurassic deposits in the slope parts of the main structures began. The objectives of the study were the interpretation of a 3D seismic cube covering most of the area of the site, seismic geological linking of data from the Achimov interval of the field with neighboring areas, including using the sequence stratigraphy method, accounting for the results of drilling wells for the pilot development of the Jurassic complex and the transit fund of prospecting and exploration wells, as well as the inclusion of the results of a petrophysical model in a first approximation for the Achimov reservoir interval of the South Tambey field. The results of full-azimuth CDP 3D seismic surveys made it possible to obtain reliable correlations between well data and seismic data, including analysis of AVO attributes (Amplitude Variation with Offset). Based on sequence stratigraphic analysis, the stratification of the section was clarified, correlation with neighboring territories was made, and a conceptual model of the clinoform complex was created. For each layer, system tracts within the sequences were determined. There is strong relationship existing between the formation conditions, geometry of objects and reservoir properties.

Organic contaminants in the groundwater of the Kerio Valley water basin, Baringo County, Kenya

Currently, groundwater is largely becoming the main source of fresh water in most developing countries. However, various deleterious impacts resulting from anthropogenic activities beneath the earth’s surface have significantly affected groundwater quality, as evidenced in several areas endowed with mineral and hydrocarbon deposits, agricultural activities, and industrial processes. The possible etiological impacts may include cancer and genetic aberrations which result from the toxic effects of organic waterborne contaminants ingested by humans and animals over time. The motivation behind this study was to identify and determine the concentration profiles of various organic pollutants in the wells located along the Kerio Valley water basin near the exploratory wells for hydrocarbons and mining activities. Therefore, this study is necessary in unraveling the level of organic contaminants in the sampled borehole water, which can then be extrapolated to cover other boreholes within the Kerio Valley basin. The study was carried out during the dry season of December 2022. The water samples from the boreholes were extracted using a solid phase extraction procedure and characterized using a gas chromatograph interfaced with a mass selective detector. The findings indicate that benzene derivatives which were mainly xylenes, 1,3,5-trimethylbenzene, 1-ethyl-3-methylbenzene, 1-methyl-2-propylpentylbenzene and polycyclic aromatic hydrocarbons such as naphthalene, phenanthrene, fluoranthene, azulene, and pyrene were found in most of the boreholes sampled. Furthermore, long-chain hydrocarbons were present in all groundwater samples with varying concentrations. The concentration of benzene derivatives ranged from 2.84 to 20.47 ppm. However, polycyclic hydrocarbons exhibited the highest concentrations of all organic pollutants, with pyrene giving a concentration of 23.14 ppm, fluoranthene (18.54 ppm), phenanthrene (14.13 ppm) and anthracene (11.06 ppm). According to the findings reported in this study, most of the borehole water in the Kerio Valley basin is contaminated and may be unsafe for drinking. Most of the reported concentration levels were several times higher than the standards of the U.S. Environmental and Protection Agency. However, it is necessary to develop a policy framework on the assessment and monitoring of water quality in the region and propose urgent measures to ensure a clean water supply for the benefit of residents.

Analysis of structural-tectonic and petrophysical features of productive horizons of Mishovdag fold


 
 
 The article analyzes the geological structure, lithofascial, tectonic, and morpho- logical features of the Mishovdag oil field, which is a productive area in terms of oil content. Morphologically, it represents a brachianticlinal fold located in the north-west and south-east directions. The Mishovdag fold is located on the Kalamaddin-Bandovan anticline zone between the Kichik Harami (in the northeast) and Galmaz (in the northwest) structures. The Mishovdag-Galmaz part of the anticlinal zone extends in the sub-southern direction. The structures included in the zone are represented on the surface mainly by Aghjagil, Absheron, and ancient Khazar sediments. Productive layer sediments come to the surface in few areas. The tectonic movements and activity of mud volcanoes (active or buried) have left characteristic traces in the geological structure of the research area. Brachianticlinal and other types of structures were formed here. Under the strong influence of tectonic movements, the layers forming them were deformed and broken into blocks by regional tectonic faults. The anticlinal structures of the zone are complicated by longitudinal and latitudinal faults. The Mishovdag fold is represented by a brachianticline, 20-25 km long and 4-6 km wide. Brachianticline has a sharply asymmet- rical structure. The southwestern limb is steep, and inclined at an angle of 25-450, while the northeastern limb is flat and characterized by an inclination angle of 7-250. As a result of the analysis of the cross-sections of deep wells drilled in the field, it was determined that Mesozoic, Paleogene-Miocene, and Pliocene-Anthropogenic sediments are developed in the section of the fold. Sediments repre- senting the cross-section are characterized by high reservoir properties. Geological-geophysical works are carried out in the field. Core materials were taken from wells. The lithological-petrophysical characteristics – carbonate, porosity, and permeability of reservoir rocks have been determined according to core samples taken from exploration wells drilled in the field. The lithological-petrophysical characteristic regularities of change were investigated depending on depth.
 
 

The pre-Jurassic Meng-Shaan paleochannel and its control on the accumulation model of Yan 10 reservoir in Central Ordos Basin

In the setting of the increasing density of exploration wells, and the decreasing scale and increasing difficulty of discovering Jurassic paleogeomorphology reservoirs, it is urgent to deepen the fine depiction of pre-Jurassic paleogeomorphology features and to analyze their controlling effect on reservoirs. Based on abundant logging data combined with indoor microscopic observation and experimental testing, the paper applies the theory of reservoir configuration analysis for the first time to the single-channel period division of the pre-Jurassic Meng-Shaan paleochannel which deposited with the braided channel sand bodies. Meanwhile, it reveals the controlling effect of hydrocarbon accumulation and the distribution characteristics of the Yan 101 reservoir as ' paleogeomorphology and sedimentary facies combination' to determine the type, 'migration channel' to determine the distributing range, and 'low-amplitude structure' to determine the trap in the study area, and also the reservoir accumulation modes in different channel ranges have established. In conclusion, the single-channel boundary of the Meng-Shaan paleochannel in different periods controls the path of oil and gas migration, thus controlling the distribution range and reservoir type of the Yan 10 reservoir. Moreover, depending on the production data we derived that it should prefer the composite trap reservoir of the Fuxian period and the Yan 102 period, as well as the structural reservoir on the periphery of the Yan 102 period single-channel for the further exploration of the Yan 10 paleogeomorphology reservoirs within the development range of the Meng-Shaan ancient river. In particular, the lithologic trap reservoirs within the Fuxian period channel and the Meng-Shaan main channel, such as the reservoirs of the 'Source' of the secondary channel type and the paleochannel type, which could as a replacement accumulation model for increasing reserves and production.

Leisure practices of geological explorers of Western Siberia based on the narratives of pio-neers (1950s–1960s)

In this paper, the main leisure activities of the geologists, identified by the author on the basis of collected inter-views with those involved at the initial stage of geological explorations in Tyumen Oblast during the 1950s–1960s, are presented. The organisation of the leisure activities, as well as the complex development of the social and do-mestic sphere amongst the geological prospectors, in one of the perspective regions in terms of the availability of hydrocarbons, was not amongst the priorities of the state at the dawn of the oil exploration and was a prerogative of the geological community. The trade unions of geologists, who were overseeing social matters, including leisure activities, due to low funding and a lack of adequate personnel and material-and-technical potential did not always successfully cope with the tasks set. The leveling of the shortcomings in this development was imposed on the initia-tive of the oil prospectors themselves, who were interested in improving conditions of their stay at the work sites. It is noted that the initiatives of the geologists expanded the possibilities of organized forms of leisure activities both at stationary places of residence and ’in the field’. The variability of leisure activities at the locations of geological par-ties, including residential places, was significantly higher than in the places of work ― ‘in the field’. However, even in conditions of remoteness from the centres of ‘culture’, oil prospectors carried out improvement of the quality and diversity of their leisure time on their own. The demand for and variability of the leisure practices were taking place in line with the ‘concept of culture’, depended on the degree of qualification and level of education of the specialists, personal development and attitude of the employees, and their environment. The implementation of leisure practices was necessitated by the need for compensating limited opportunities of the socio-cultural environment against the background of the dominance of the strenuous daily work, as well as the confrontation in the archaisation of the daily routine due to the prevalence of the deviant forms of behaviour. Many changes emanating from the oil prospectors and taking place in the socio-cultural sphere later took root and became an asset of the local population. The initia-tive of the geologists made it possible to expand and diversify leisure practices under the lack of opportunities and financial support of the social sphere, which facilitated positive changes in the daily life of the geologists themselves and population of the places where the oil prospectors were staying.

2022 Exploration & Appraisal Year in Review

Petroleum exploration activity in Australia decreased in 2022. The total number of exploration wells drilled and expenditure across Federal offshore and state jurisdictions decreased from 2021 levels. The number of exploration permits awarded and acreage made available for exploration was also lower than that of 2021. However, more appraisal wells were drilled in 2022. Onshore exploration expenditure in Australia has exceeded that of the offshore since 2019 and remains the focus of exploration activity. Exploration activity and expenditure has not followed the increase in oil and gas prices of recent years, suggesting external factors are suppressing and impeding exploration activity.