Productive Horizons Research Articles

Improving the Efficiency of Managing the Development of the West Siberian Oil and Gas Province Fields on the Basis of Differentiation and Grouping

Abstract —Using image recognition methods (principal component method (PCM) and discriminant analysis) made it possible to group and identify more than 500 research objects developed in five oil and gas areas of the West Siberian oil and gas province (WSOGP), which are confined to 13 large tectonic structures and 10 productive horizons. The grouping was made according to 19 parameters characterizing the mode of oil and gas occurrence and the geologic–physical and physicochemical properties of the reservoirs and hosted fluids exerting a prevailing influence on the recovery of oil reserves and used on projecting the development of research objects. The performed study has identified 19 relatively homogeneous groups of objects, each having a specific set of geologic–physical properties. It is shown that the parameters reflecting the geologic–physical and physicochemical properties of the reservoirs and fluids within the identified groups of objects exert different effects on the recovery of oil reserves. This requires differentiation and grouping of the objects during the solution of various development problems. It has been established that the specific features of groups of objects are determined primarily by areal, tectonic, and stratigraphic factors and that grouping must be performed separately in each stratigraphic system. Algorithms are proposed for grouping the developed oil and gas fields and for searching for groups of analogous objects in fields out of exploration that are most similar to the developed ones. The performed grouping and the results obtained provide the necessary information about the research objects and increase its reliability, thus making it possible to improve the efficiency of managing the oil company assets, i.e., the WSOGP oil fields.

ON THE QUESTION OF AFRON-CONTAINING BOREHOLE MUD APPLICATION FOR DRILLING WELLS UNDER COMPLICATED CONDITIONS ON BLACK SEA SHELF FIELDS

Currently, the development of hydrocarbon deposits on the Black Sea shelf, characterized by difficult mining and geological conditions, requires the development of new effective technological solutions in the field of well drilling. An urgent task is to select the optimal drilling fluids to prevent loss of circulation, minimize the likelihood of stuck and damage to productive horizons. Drilling fluids containing aphrons are well known in the world drilling practice, but they have not yet found wide circulation in the Russian market. These drilling fluid systems are designed to solve these problems at lower costs than technologies that require expensive equipment and relevant competencies, and are also a promising solution that can make a significant contribution to the development of Russian drilling technologies. This article highlights the results of generalization and analysis of scientific literature on the study of drilling fluids, the development of compositions and technology based on the use of aphron systems.

Tectono-magmatogenering structures in zones of increased geodynamic instability as priority objects for exploration of hydrogen fields

Based on comparison of the migration activity of hydrocarbons, helium and hydrogen, the paper substantiates the types of cap rocks for hydrogen accumulations (pools), which most of all contributes to its partial shieldingat steady feed. Such cap rocks are represented by predominantly smectite clay, pure (without inclusions) salt at depths over 1—2 km, non-fractured quartz sandstone at depths over 4 km, effusive and hypabissal intrusive rocks, as well as basement rocks undisturbed by metamorphic decomposition processes. Endogenous hydrogen isconsidered as the main factor of dissipative structures formation. Occurrence of hydrogen, hydrocarbon and ore macro accumulations is a kind of energy, information-geochemical fluctuations, which are intermediate states of dissipative structures subordinated to the planetary heat and mass transfer processes caused by the deep Earth degassing. In this context, the nature of geodynamic instability (activation of vertical movements, shifts, tensile and compressive stresses) can be considered as a growing sequence of dissipative processes associated with the energy percolation role of endogenous hydrogen. In the hierarchy of ring structures (RS) (from minor depressions to large structures of dozens kilometres in diameter) special attention should be paid to Sribne RS within the Dnieper-Donets Basin and Kaluga RS within the SW part of the Voronezh anteclisepericline. These ring structuresare genetically related to explosion or volcanic calderas, and characterized by ancient origin (Proterozoic) and long-term development, including neo- and actuotectonic stages. Intensity of hydrogen degassing in the Sribne RSis confirmed by micro- and nano-inclusions in the black-shale domanicoid rocks of the productive horizons in the form of particles of native metals(including oxyphile elements Al, Zn, W and others), natural alloys and intermetallids, which are tracers of ascending flows of deep reduced fluids. It is reasonable to assume the occurrence of a large hydrogen or helium-hydrogen field (group of fields) within the Sribne RS in the Lower Visean, Lower Bashkirian and Lower Permian aged rocks, which are shielded by the Lower Permian salt deposits.

Technological feature of water shutoff operations

At present, the use of a water flooding pattern in the development of oilfields at the late stage causes the premature water influx. Therefore, in recent years, the problem of eliminating water influx has become urgent. The productive horizons of the studied deposits are merged into a single object and exhibit a sharp heterogeneity in combination with a dense well pattern. This leads to the natural water influx and, as a result, to high water cut oil reserves. In conditions of a high level of water cut, a significant number of wells are idle and require geological and technological measures for recommencing, demulsification of the produced oil and disposal of the produced water. Therefore, oil companies suffer significant losses. The aim behind this paper is to analyze and evaluate the existing water shutoff techniques for the Vereisk and Bashkir carbonate sediments in the field studied.

Lithogenetic preconditions of reservoirs and reservoir rocks formation in the Middle Devonian sediments of the Skhidnosaratske deposit (Dobrudja Foredeep)

The lithological features of the Middle Devonian sediments of the Skhidnosaratska structure of the Dobrudja Foredeep in the aspect of their influence on the formation of reservoir rocks and hydrocarbon reservoirs have been considered. Nine lithocycles of regressive nature (e-1 – e-5; g-1 – g-4), characterized by a two-membered structure have been identified in the section. Each lithocycle represents a separate productive horizon. The lower parts of the latter are composed of porous and fractured reservoir rocks (limestones, dolomites, siltstones, sandstones), and the upper parts are composed of fluid-resistant packs (marls, anhydrites).Features of cyclic sedimentation conditions caused spatial-age variability of trap localization and morphology, nature of distribution of reservoir rocks of various types, and post-sedimentation processes caused spatial heterogeneity of petrophysical properties of rocks, which entailed different prospects for individual areas of the Skhidnosaratske deposit. The vaulted traps of the productive horizons of the Eifelian deposits tend to the area of borehole 2, and the Zhivetian deposits to the borehole 1. Consequently, in the first case, the most perspective horizons are e-2 and e-3, in the second – g-2 – g-4. Often more powerful packs of better-quality reservoir rocks are developed outside the vault, which leads to the formation of lithological traps in the e-1 and e-2 horizons. It has been shown that the complex structure (presence of layers of carbonate and terrigenous rocks) of fluid-resistant marl-sulfate packs could cause dispersion of hydrocarbons and thus reduce the prospects of individual horizons, in particular, e-2 and e-3. The established heterogeneity of the structure of the productive horizons, the pinching out of individual packs of both pore and fractured reservoirs, the spatial uneven development of the limestones anhydritization and dolomitization processes give possibilities to suggest the formation of separate deposits with different hypsometry of water-oil contacts.

Allocation of a deep-lying brine aquifer in the rocks of a chemogenic section based on the data of geophysical well logging and 2D seismic exploration

Advancement in the production of potassium fertilizers is an important strategic task of Russian agricultural industry. Given annually growing production rates, the reserves of discovered potassium-magnesium salt deposits are noticeably decreasing, which creates the need to ensure stable replenishment of the resource base through both the discovery of new deposits and the exploitation of deep-lying production horizons of the deposits that are already under development. In most cases, deposits of potassium-magnesium salts are developed by underground mining. The main problem for any salt deposit is water. Dry salt workings do not require any additional reinforcement and can easily withstand rock pressure, but with an inflow of water they begin to collapse intensively – hence, special attention is paid to mine waterproofing. Determination of spatial location, physical and mechanical properties of the aquifer and water-blocking stratum in the geological section represent an important stage in the exploration of a salt deposit. The results of these studies allow to validate an optimal system of deposit development that will minimize environmental and economic risks. On the territory of Russia, there is a deposit of potassium-magnesium salts with a unique geological structure – its production horizon lies at a considerable depth and is capped by a regional aquifer, which imposes significant limitations on the development process. To estimate parameters of the studied object, we analyzed the data from CDP seismic reflection survey and a suite of methods of radioactive and acoustic well logging, supplemented with high-frequency induction logging isoparametric sounding (VIKIZ) data. As a result of performed analysis, we identified location of the water-bearing stratum, estimated average thickness of the aquifers and possible water-blocking strata. Based on research results, we proposed methods for increasing operational reliability of the main shaft in the designed mine that will minimize the risks of water breakthrough into the mine shaft.

Methods for intensification of borehole uranium mining at the fields with low filtration characteristics of ores

Purpose. Improving the efficiency of borehole uranium mining and the selection of special decolmating solutions to improve the filtration characteristics of the seam due to effective destruction, as well as by preventing the sedimentation in the productive horizon, depending on the mineralogical composition and structure of sediment-forming materials. Methods. The advantages and disadvantages of the main methods used for improving the filtration characteristics of the productive horizon, when mining the uranium deposits by the borehole method, have been studied. Samples of sedimentation from the productive horizon are taken at the uranium deposit of the Shu-Syrasu depression. The quantitative and qualitative parameters, as well as the peculiarities of the mineral compositions have been determined by the X-ray phase method. A methodology has been developed and laboratory experiments have been conducted on the treatment of sedimentation samples by the drop method using various compositions of selected decolmating solutions. The microscopic method is used to determine the structure and peculiarities of sedimentation before and after treatment with various decolmating solutions. Findings. The effectiveness of the main methods used to improve the filtration characteristics of seams in the uranium deposits, mined by the borehole method, has been determined. The structure and composition of sedimentation, which causes a decrease in the filtration characteristics of the productive horizon, have been determined. To destroy and prevent the sedimentation in the productive horizon, an effective composition of a special decolmating solution using ammonium hydrogen fluoride with the addition of sulphuric acid and surfactants has been selected. An effective method for increasing the filtration characteristics of the productive horizon with the use of special decolmating solutions has been developed and scientifically substantiated. Originality. The use of special decolmating solutions based on ammonium hydrogen fluoride with the addition of sulphuric acid and surfactants according to the developed methodology allows to effectively destroy and prevent sedimentation in the productive horizon of borehole uranium ore mining. Practical implications. The use of the developed decolmating solution and a special methodology for the intensification of borehole uranium mining can reduce the operating costs of its production. This increases the ecological and industrial safety of the work to intensify the leaching of uranium ores.

One-sided Shewhart control charts for monitoring the ratio of two normal variables in short production runs

Monitoring the ratio of two normal random variables plays an important role in several manufacturing environments. In addition, the traditional control charts that have been developed for infinite production horizons can not function effectively to detect anomalies in short production runs. In this paper, we tackle this problem by proposing two one-sided Shewhart-type charts to monitor the ratio of two normal random variables for a finite horizon production. The statistical performance of the proposed charts is investigated using the truncated average run length as a performance measure in short production runs. In order to help the quality practitioner to implement these control charts, we have provided ready-to-use tables of the control limit parameters. An illustrative example from the food industry is given for illustration.

So you want to express your protein in Escherichia coli?

Recombinant proteins have been extensively employed as therapeutics for the treatment of various critical and life-threatening diseases and as industrial enzymes in high-value industrial processes. Advances in genetic engineering and synthetic biology have broadened the horizon of heterologous protein production using multiple expression platforms. Selection of a suitable expression system depends on a variety of factors ranging from the physicochemical properties of the target protein to economic considerations. For more than 40 years, Escherichia coli has been an established organism of choice for protein production. This review aims to provide a stepwise approach for any researcher embarking on the journey of recombinant protein production in E. coli. We present an overview of the challenges associated with heterologous protein expression, fundamental considerations connected to the protein of interest (POI) and designing expression constructs, as well as insights into recently developed technologies that have contributed to this ever-growing field.

Effect estimation of variations of petrophysical and lithological-facial characteristics on the quality of reservoir rocks

The paper presents the results of researches on the specification of clay components, as well as the zones of intra- and interstratal fluid flows in the formation processes of oil-gas fields. The investigations have been carried out in the context of Sangachal-Duvanny-Khara-Zira (SDKhZ) field, located in Baku archipelago of South Caspian basin (SCB). It was defined that the presence of clayey chlidolite in the reservoirs are observed more effective in the values of permeability rates. The zones of intra- and interstrata of fluid flows in the reservoirs were specified based on the lithological model of productive horizons. Therefore, the presence of closed migration-flow (drainage) system both within productive horizons and in the scale of reviewed field was supposed. In support of these assumptions, 2D and 3D variation models of flow zones indicator values for intrastrata levels of productive horizons and for the section fragment of SDKhZ field have been developed.

Intrastratal regimes and reservoir properties of productive horizons in Sangachal-deniz–Duvanny-deniz–Khara-zira adasy fields

The paper reviews the intrastratal regimes and reservoir properties of V, VII and VIII horizons in Sangachal-deniz–Duvanny-deniz–Khara-zira adasy fields. As a result of studies of core samples taken from 1700–5750 m depth, lithological-reservoir characteristics of the rocks have been analyzed, the changing intervals of parameter values shown as well. Therefore, instratal regimes of productive horizons have been analyzed, the dependence of initial formation pressure on hydrostatic and saturation pressures specified. Considering all mentioned above, 3D models of deep structure of SDKhZ (by VII horizon) field have been developed, corresponding vector directions in structural form of studied area defined as well.

A comprehensive evaluation of the productive formation collector of the Kanevskoye field

At the present stage, the development of the oil and gas industry of the Russian Federation is impossible without replenishing the resource base, and therefore an urgent task is to conduct research, prospecting and evaluating petroleum potential in undiscovered areas of fields. The aim of the study is to conduct a comprehensive assessment of the reservoir of the productive formation of the Kanevskoye field. We have carried out mineralogical and petrographic studies, laboratory studies to assess the effective porosity of the core sample by the saturation method, particle size analysis, X-ray diffraction analysis. Our studies have shown that the considered initial sands under consideration, which formed the reservoir rocks of the productive horizon of the Kanevskoye field, were formed by coastal or beach type marine sediments. This is confirmed by the poorly rounded shape of the grains and the presence of glauconite in the rocks. The studied core sample is a fine-grained glauconite-feldspar-quartz sandstone with an admixture of aleurite fraction, with semi-rounded grains, pelitic cement, basal and porous-basal, silt-psammitic structure. The total porosity is 14.3 %. A comprehensive assessment of the reservoir of the productive formation of the Kanevskoye field has been carried out. The reservoir is productive. Therefore, it is necessary to make a project for conducting geological exploration.

Deep Sequential Surrogate Model Enables New Work Flows

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 201775, “An End-to-End Deep Sequential Surrogate Model for High-Performance Reservoir Modeling: Enabling New Work Flows,” by Jiri Navratil, IBM; Giorgio De Paola, SPE, Repsol; and Georgos Kollias, IBM, et al., prepared for the 2020 SPE Annual Technical Conference and Exhibition, originally scheduled to be held in Denver, 5–7 October. The paper has not been peer reviewed. Despite considerable progress in the development of rapid evaluation methods for physics-based reservoir simulators, a significant gap still exists in the acceleration and accuracy needed to enable complex optimization methods. The complete paper describes an end-to-end deep surrogate model capable of modeling field and individual-well production rates given arbitrary sequences of actions (schedules), including varying well locations, controls, and completions. Results provide concrete measures of the efficacy of the deep surrogate model as an enabling technology for the development of optimization techniques previously out of reach because of computational complexity. Introduction Recent advances in machine learning, particularly in deep learning, have enabled breakthroughs in technically challenging areas such as computer vision, natural language processing, and speech processing. The authors expand on these powerful algorithms to develop a deep neural network (DNN) surrogate model for reservoir dynamics. The objective of the DNN surrogate model is to predict field rates and individual well rates. The field rates typically include aggregate oil and water production and water-injection rates reported at equidistant timesteps over a desired production horizon. Economic metrics such as net present value are computed using the field rates. The individual well rates are optional, and, typically, the oil production per well is the desired output. The contribution of this paper is twofold: It expands on the sequence-to-sequence approach by capturing additional varying inputs, namely well controls and completions, and it presents a thorough experimental analysis and validation on a publicly available synthetic reservoir model (SPE9) as well as a real large-scale reservoir model. Methods and Procedures Reservoir Models. SPE9 is a standard benchmark to validate and compare simulations of the black-oil model. The reservoir is described by a 24×25×15 grid, having a 10° dipping angle in the x direction and a heterogeneous geostatistically based permeability field. The grid has a uniform size of 300 ft in the x and y directions and is nonuniform along the z direction. The porosity values for each layer are constant and vary across layers. In this work, the original SPE9 benchmark has been modified to be suitable for field development plan (FDP) optimization. Different well-completion data and ranges have been used for the number of producer and injector wells. The areal well locations, the number of wells, and the well-drilling sequence are variables specified by a suitable FDP. A fixed well control has been used in all SPE9 simulations. In the original SPE9 benchmark, the field operating conditions led to free-gas formation and most of the wells switched from rate control to pressure control. The conditions that trigger the switch in well controls are provided as inputs to a reservoir model and are determined on the basis of operational logistics and geomechanical stability criteria. Neglecting such switches in well controls is disastrous in the real world. However, this is benign from the point of view of a numerical benchmark to test FDP optimization.

Experience in conducting multi-zone hydraulic fracturing on the oilfield of PJSC «Tatneft»

The paper presents the possibilities of expanding production opportunities in the oil company PJSC Tatneft. For this purpose, the well No.xxx7g with an inclined pilot borehole was drilled at the Bavlinskoye oil field and oriented core samples were taken to study the lithological cross-section and the geological structure of the subsurface horizons. The horizontal wellbore itself is located in the dankovo-lebedyansky horizon, where multi-zone hydraulic fracturing was carried out through ports with packers there. The following methods will increase the share of recoverable oil reserves in the oldest oil-producing Volga region by starting the development of new productive horizons and increase the oil recovery factors for these reservoirs. The methods used in this work will reduce the unit costs of increasing oil production and achieve a cost-effective level of work on wells of this type. The work had its own peculiarities. One of the reasons for the difficulty in interpreting the hydraulic fracturing Minifrac (Meyer software package) was the rather long time of closing fractures in domanic deposits during the registration of pressure drop. In turn, during the minifrac analysis of the Nolte G Time Test graph showed that the fracture did not close, and therefore it is impossible to determine the closing pressure (the pressure gradient of the gap) with reliable accuracy. Note that when interpreting the flow test results, the best match of the experimental and calculated curves is achieved when using the model of a horizontal well operating a homogeneous reservoir. Also, the deterioration of the bottom-hole zone may be associated with a weak opening of the created fractures. Keywords: oil; well; hydraulic fracturing; unconventionals; fracture; core.

DRILLING OF COMPLEXES WITH HYDRAULIC TRANSPORT OF A CORE FOR INCREASE OF EFFICIENCY OF GEOLOGICAL EXPLORATION WORKS

On the basis of an in-depth analysis of domestic achievements and the results of experimental and methodological works and practice the expediency of widespread use of improved technical means and technologies for drilling geological exploration wells with complexes counterflush coring (CCD) till the depth of 300 m upon sedimentary strata is substantiated. During the exploration of brown coal deposits and titanium placers, which convincingly confirm the high efficiency of CCD with appropriate modifi cations of equipment, technology and testing methods for specific productive horizons and host rocks. The best results of industrial application of CCD were obtained during the exploration of the Paromivske ilmenite placer deposit (2016). High technical and economic indicators of completion of work in difficult socio-economic and geological and technical conditions were achieved thanks to CCD application. The main argument in favor of CCD is undoubtedly proven by ultra-high productivity with a significant reduction in cost and improved quality of the work. The operational geological informational content of the method allows timely adjustments and responsibly choose the most optimal flexible schemes and methods of geological research. Due to the significantly reduced timing of drilling operations, field research can be carried out shorter at the most favorable climatic conditions and seasons of agricultural activity. The mobile circulation system excludes the construction of earthen sedimentation tanks, which signifi cantly reduces the size of disturbed soils, their contamination and prevents the loss of flushing fluid. The peculiarities of the technology and organization of work promote close cooperation, mutual control and understanding of technical, geological, geophysical and other personnel serving and actively mobilize for high-quality and highly efficient performance of geological tasks. A reduction of heavy operations in the technological process significantly improves the working conditions for the service personnel, increases the production culture, and contributes to the attractiveness of the drilling profession. Ukraine has sufficient production facilities (at Kiev Drilling Equipment Plant, Dnepropetrovsk Drilling Equipment Plant, Discovery - Drilling Equipment. Ukraine LLC, etc.), which are capable of providing geological exploration companies with modern CCD. The main reasons that hinder the development of modern highly efficient geological exploration technologies are recognized and the optimal ways to solve the problem of widespread introduction of CCD are featured.

Petrophysical analysis of the messinian Qawasim Formation in El Tamad Field (Nile Delta)

The onshore Nile Delta has shown promise in oil and gas production in Egypt. However, exploration activities in the past decade indicated conspicuous spatial changes in the quality and geometry of reservoirs. Therefore, petrophysical traits of the productive horizons must be monitored continuously. Based on detailed logging data of five wells, the spatial changes in the reservoir quality and geometry of the Messinian (Late Miocene) Qawasim Formation in El Tamad Field (Northeast Nile delta) was reevaluated. All integrated petrophysical analyses (i.e. lithology, porosity, net pay thickness, shale volume, water saturation, and hydrocarbon saturation) indicated a high spatial variability, where up to 12 different zones have been identified in the Qawasim Formation. Indeed, the Qawasim Zone 2 has the highest potentiality of hydrocarbons (i.e. Main Pay Zone) with good porosity (19.1–27.8%), low shale volume (14.9–22.1%), and low water saturation (22.1–44.4%). The constructed cross-plots (i.e. Neutron-Sonic, Neutron-Bulk Density, and M-N plots) showed that the reservoir is composed mainly of quartz arenite. The dia-porosity cross plot (density porosity ‘ØD’-neutron porosity ‘ØN’) indicated that the pore spaces are interpenetrated with dispersed shale of minor laminated types. To identify the free water-level and the contact with gas or oil, the hydrostatic pressure gradient using pressure-depth plot was implemented. The gas gradient ranges from 0.07 to 0.08 psi/ft with an average 0.075 psi/ft, while the oil pressure gradient ranges from 0.26 to 0.24 psi/ft with an average 0.25 psi/ft and the water gradient is about 0.45 psi/ft. Future exploration and production in the area should take in account that the Qawasim Formation represents a good reservoir but with marked spatial heterogeneity in the reservoir quality and geometry.

Identification of nonstructural type traps within the limits of northern side of Dnieper-Donets Depression according to the data of AVO analysis and seismic inversion

Nonstructural type traps in the sedimentary cover of the northern side of the Dnieper-Donets depression are poorly studied by seismic methods due to many factors among which are the following: complicated geological structure and not so high quality of given data of geological-geophysical studies of last years. Identification of lithologically screened gas-saturated object has been demonstrated based on the studies of elastic dynamic characteristics by the methods of AVO-analysis and elastic seismic inversion. Acoustic and elastic properties have been analyzed in the wells with cross-dipole real and synthesized acoustics. Gas-saturated intervals have been identified based on the ratios VP /VS and acoustic impedance. According to AVO-studies within the northern side of DDD in the stratum of productive horizons of the moscovian horizon a positive answer has been obtained to the question «if AVO analysis works correctly in general within the limits of the northern side of DDD deposits». Determining factors that influence on the result during the application of AVO-analysis at the most part of gas condensate field of the northern side of DDD are effective thicknesses, depths of occurrence, lithology, poro-sity and quality of given seismic data and data from geophysical surveys of wells. Taking into account minor effective thicknesses, small values of porosity, significant depths of occurrence of productive layers typical for the northern side of DDD, the majority of gas-saturated intervals are not at all identified in the wave field by dynamic characteristics of seismic signal. All the seismic anomalies analyzed had effective thicknesses from 6 to 20 m. Within the limits of deposits of the northern side of DDD, AVO-anomalies of the 2nd class are modeled. Along with positive experience of identification of dynamically cont-rasting objects in the wave field limitations to use methods of AVO-analysis and elastic seismic inversion are generalized for the northern side shown in particular and the whole Dnieper-Donets depression.

The Influence of Trap Magmatism on the Geochemical Composition of Brines of Petroliferous Deposits in the Western Areas of the Kureika Syneclise (Siberian Platform)

Abstract —We present the results of study of the influence of trap magmatism on the geochemical composition of brines and on the geothermal regime of the Earth’s interior in the western areas of the Kureika syneclise. The Siberian trap province, which unites all cutting and layered tholeiite–basic magmatic intrusions and erupted basaltic lava, is the world’s largest Phanerozoic continental basalt province. Brines, hydrocarbon deposits, and organic matter of the sedimentary cover were subjected to a significant thermal impact as a result of the Permo-Triassic trap magmatism. During the trap intrusion, the maximum paleotemperatures in major Silurian (D’yavolskii), Ordovician (Baikit), and Cambrian (Deltula–Tanachi, Abakun, and Moktakon) productive horizons reached 650 °C. The Paleozoic and Proterozoic deposits of the study area contain brines with TDS = 50–470 g/dm3. By chemical composition, they are of Na, Na–Ca, Ca–Na, Ca–Mg, and Ca chloride types (according to the classification by S.A. Shchukarev), with mixed Ca–Na and Na–Ca chloride brines dominating. The studied brines can be divided into three groups according to the degree of metamorphism: low (S1), medium (S2), and high (S3). The first group includes mainly sodium chloride brines with TDS = 50–370 g/dm3 (rNa/rCl = 0.60–0.95; S ≤ 100). The second (dominating) group comprises Na–Ca, Ca–Na, Ca, and Ca–Mg chloride brines with TDS = 150–470 g/dm3 (rNa/rCl = 0.10–0.87; 100 ≤ S ≤ 300). The third group is Ca–Na and Ca chloride brines with TDS = 223–381 g/dm3 (rNa/rCl = 0.12–0.45; S ≥ 300). We have first established changes in the hydrogeochemical field (major- and trace-component and gas compositions) with distance from the contacts of intruded dolerite sills and dikes. Hydrocarbons (CH4, C2H6, C3H8, i-C4H10, n-C4H10, i-C5H12, n-C5H12, and C6H14) and water-soluble components I, B, and NH4 were most actively subjected to destruction. For example, at a distance of 100 m from the intrusion zone, the water-dissolved gases are dominated by CO2 (>90 vol.%), and CH4 amounts to 5 vol.%, whereas at a distance of 250 m, the concentration of CO2 decreases to 30 vol.%, and that of CH4 increases to 60–70 vol.%. In addition to the negative effect on the hydrocarbon preservation in the contact zone (≤400 m), the intrusive trap magmatism favored the formation of hydrocarbons in remote horizons. The reaction of intruding traps with brines of the sedimentary cover led to the saturation of the latter with iron, aluminum, and silica, which suggests extraction of metals in the form of salts from magmatic melts into an ore-bearing fluid.

Optimization of steam injection in SAGD using reinforcement learning

Conventional steam injection strategies or policies in SAGD are typically not a result of a formal optimization process but rather empirically found. However, finding the steam injection policy that maximizes cumulative performance over the entire production horizon represents a major challenge due to the complex dynamics of the physical phenomena. To address this challenge one alternative is to use a reinforcement learning (RL) approach; here an agent is trained to find the optimal policy only by continuous interactions with the reservoir simulation model (environment). In this work, the RL-SARSA on-line on-policy learning algorithm is used to find the optimal steam injection policy and offer insight in the physics of the SAGD process. Net Present Value (NPV) is used as a performance measure of objective function, the action-value function is approximated using a stochastic gradient regression strategy, and the state vector is featurized using radial basis kernels. The action space is discrete, three (3) possible actions: increase/decrease/no change on the steam injection rate w.r.t the previous value, and the state space is continuous and is made up of cumulative values for water and oil production and steam injection. Additionally, the environment is represented by a one well pair reservoir simulation model built using data from a reservoir located in northern Alberta and a production horizon of 250 days is considered. For the considered case study, the agent showed a significant improvement on the cumulative NPV value after 200 episodes or simulations and the optimal policies are characterized by three distinct regions, (1) constant rate to increase the average reservoir pressure and allow the steam chamber reach the overburden, (2) sharp increase to increase average reservoir temperature and abrupt decrease and (3) constant minimum value to maintain the average reservoir temperature. • Reinforcement learning with function approximation has been successfully applied to the optimization of steam injection in a SAGD process. • The optimal steam injection policy is characterized by three distinct regions: constant rate, sharp increase and abrupt decrease, constant minimum rate. • For optimum SAGD operations, pressure plays a key role until the steam chamber reaches the overburden, afterwards temperature dominates.

A new species of crested pterosaur (Pterodactyloidea, Anhangueridae) from the Lower Cretaceous (upper Albian) of Richmond, North West Queensland, Australia

ABSTRACT Pterosaur fossils from Australia are exceptionally rare. Since the discovery of the continent’s first pterosaur some 40 years ago, fewer than 20 specimens have been described. The Lower Cretaceous (upper Albian) Toolebuc Formation of North West Queensland is the most productive horizon for Australian pterosaurs. Herein, we describe a new species of pterosaur, Thapunngaka shawi gen. et sp. nov., from the Toolebuc Formation, near Richmond, North West Queensland. The specimen (KKF494) comprises the rostral portion of a crested mandible and represents the largest pterosaur yet described from Australia. The new species presents features that indicate an affinity with Anhangueridae, which is consistent with their reported cosmopolitan distribution during this period. Thapunngaka shawi can be distinguished from other anhanguerids through the possession of a mandible with a smooth dorsal surface medially and uniquely sized alveoli that are positioned laterally along the jaw. Phylogenetic analysis reveals a close relationship among all Australian anhanguerids and points to an endemic Australian radiation within Anhangueridae. Thapunngaka shawi has the largest mandibular crest of any anhanguerian worldwide, and provides further evidence for the existence of an increasingly diverse range of large crested pterosaurs in the Australian part of eastern Gondwana during the Cretaceous.