Argillaceous Facies Research Articles

Prospecting and characterization of plastic clays from the state of São Paulo, Brazil, as raw materials for porcelain stoneware tile production

Abstract The present work aims to prospect and study the plastic and superplastic clay deposits in the state of São Paulo, Brazil, as a source of raw materials for the ceramic tile industry and especially for the production of porcelain stoneware tiles. To achieve the proposed objectives, a geological study was carried out through the mapping and identification of the present lithologies, lithogeochemical characterization using X-ray diffraction, inductively coupled plasma optical emission spectrometry, cation-exchange capacity and organic carbon and characterization of the ceramic technological properties, including granulometric analysis by sedigraph and Brunauer–Emmett–Teller specific surface area. According to their geological characteristics, the studied deposits were classified into two types: a detrital sedimentary deposit, restricted to Quaternary alluvial sediments and Neogenic Tertiary formations and composed of silt-sandy clay and plastic, kaolinitic, refractory and silico-aluminous facies; and an alterite type, found in Permo-Carboniferous rocks of the Paraná Basin, composed of laminated/massive weathering siltstones, with the highly plastic, fluxing clay minerals illite, kaolinite and smectites. Among the targets studied in these deposits, argillaceous facies with plastic and superplastic characteristics were identified, which affect their applicability in compositions for producing porcelain stoneware tiles and stoneware.

Geochemical Studies of Rare Earth Elements (REE) in Ion Adsorption Clays (IAC) in Gua Musang, Kelantan

Rare earth element (REE) become the ‘critical metals’ for green technology development that have been rapidly expanded worldwide in these days. REE is mainly originated from granitic rocks. REE in ion adsorption clay (IAC) is the product from weathering of granite. IAC are believed to store high concentration of heavy rare earth element (HREE) and light rare earth element (LREE). Gua Musang is selected for this study because it is located on the three longitudinal belts that composed of acid volcanic igneous rocks from Main Range, Senting and Boundary Range Granites. In this study, the characteristics of ion adsorption clays and REE distribution in Gua Musang have been studied by mineralogy and geochemical analyses. Rocks and soil samples were collected closed to the granite bodies and its surrounding to represent its weathering products. Polarised optical microscopy was used for petrography and mineralogy studies. From fieldwork observation, Gua Musang lithologies composed of carbonate facies, argillaceous facies and pyroclastic facies. X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD) and Inductive Coupled Plasma Microspectrometry (ICP-MS) were used accordingly to characterise the composition of major and trace elements in IAC samples. REE value in Pulai are the highest concentration as iron nodule have been found in the sampling area. Sample from Boundary Range granite also reported store high concentration of REEs in this study.

Performance evaluation of boosting machine learning algorithms for lithofacies classification in heterogeneous carbonate reservoirs

Lithofacies classification from well logs recorded through heterogeneous carbonate reservoirs helps to improve reservoir discrimination with respect to fluid flow and storage capabilities. A novel technique is developed to classify carbonate lithofacies with the assistance of boosting algorithms for a well drilled into the large Majnoon oil and gas field of southern Iraq. Five boosting machine learning algorithms: Logistic Boosting Regression (LogitBoost), Generalized Boosting Modeling (GBM), Extreme Gradient Boosting (XGBoost), Adaptive Boosting Model (AdaBoost), and K-nearest neighbor (KNN) were comparatively implemented to attain the most realistic lithofacies predictions. Data from available cores provide actual lithofacies determination. Additionally, seven standard well logs recorded provide continuous additional information across the complete reservoir section. Random sub-sampling of the well-log dataset was used to train and test the models. Confusion matrices of the results provided Total Percent Correct (TPC) accuracy measures for LogitBoost, GBM, XGBoost, AdaBoost, and KNN with respect to the entire dataset of 97.65%, 96.99%, 97.74%, 97.74%, and 96.74%, respectively, and with respect to the validation subsets TPC was 94%, 96%, 98%, 91%, and 96%, respectively. The XGBoost provided more accurate lithofacies classification than the other five boosting algorithms with respect to the predictions generated for both the entire dataset and testing subset. The lithofacies predictions were then compared with poro-perm interpretations from the Nuclear Magnetic Resonance (NMR) log and oil rate from the Production Logging Tool (PLT). Rudist-rich and argillaceous lithofacies display lower porosity and permeability, respectively. The Rudist-rich lithotype is associated with high-production-rate zones, whereas the argillaceous facies is associated with low-production-rate zones. The boosting machine learning workflow developed efficiently provides accurate lithofacies classification with reduced uncertainty in carbonate lithofacies determinations. The entire workflow was fully implemented and visualized using open-source R computer codes. These codes have the potential to be generalized for the application of facies classification to other clastic and carbonate reservoirs in oil and gas fields.

Development of Foreland Intracratonic Plateaus (Ozark Plateau and Appalachian Plateaus): A Consequence of Topographic Inversion Due To Erosion of Adjacent Fold‐Thrust Belts

AbstractUnlike well‐known plateaus associated with Cenozoic orogens, the Appalachian and Ozark Plateaus of the eastern United States fringe the foreland side of a long inactive and deeply eroded orogen. These foreland intracratonic plateaus (FIPs), which are underlain by sub‐horizontal cratonic‐platform strata and, in places, foreland‐basin strata, now lie 0.5–1.2 km above sea level, notably higher than adjacent fold‐thrust belts. An escarpment lies at or near the boundary between the FIPs and the fold‐thrust belts. Why did the topographic inversion leading to the development of the FIPs take place? To address this question, we built a numerical model, using Landlab, to simulate how topography evolves as foreland lithosphere flexes upward when post‐tectonic erosion causes unloading. In this model, flat‐lying cap‐rock strata (sandstone and limestone) of the foreland have greater resistance to erosion than do the deformed, tilted, cleaved, and fractured strata of the fold‐thrust belt, especially where the fold‐thrust belt contains argillaceous facies. We tested the model by characterizing the development of the Ozark Plateau in the foreland of the Ouachita fold‐thrust belt. Results demonstrate that regional isostatic uplift due to erosion, given reasonable differences in resistance to erosion between the fold‐thrust belt and the foreland, can generate the observed topographic inversion and a distinct escarpment, yielding a plateau. This model may help explain the post‐Paleozoic evolution of the Catskill Mountains, the Deep Valleys Province, and the Cumberland Plateau, highlands which border the Appalachian fold‐thrust belt.

Facies Architecture and Sedimentary Structures in the drill cores of Uranium Bearing Sediments of Banganapalle Formation of Palnad Sub-basin, Guntur District, Andhra Pradesh

The Banganapalle Formation, the lowest member of the Neoproterozoic Kurnool Group of rocks, resting over the basement granites, has been identified as the host rock for uranium in Koppunuru area in the western part of Palnad sub-basin. The uppermost arenite facies of the Banganapalle Formation is exposed on surface and shows only few bedform indicators like ripple marks, planer laminations etc. Down-hole lithological examinations on course of core drilling in Koppunuru and adjoining areas identified five recognizable lithofacies of Banganapalle Formation, viz. basal conglomerate unit, quartzite-shale intercalated facies, and two quartz arenite facies separated by a grey shale dominated argillaceous facies.
 The polymictic conglomerate, with unsorted grit to pebble size clasts of granite, shale, quartzite, vein quartz and dolerite indicate short distance transportation and derivation from nearby granitoids traversed by quartz reef/dolerite dykes. Cyclic repetitions of arenaceous and argillaceous sediments in Banganapalle lithocolumn above the basal conglomerates point to alternate rhythmic marine transgression and regression regimes. These units can also be discriminated based on their sedimentary texture, bedforms and several soft-sedimentary penecontemporaneous deformational structures (PCD) like load structure, convolute bedding/laminations, and slump structures such as micro-slips, gravity faults and folds. These syn-sedimentary structures clearly indicate perturbation and submergence of the basin contemporaneous to deposition. Cross-beds suggests change in current direction/intensity while bi-directional symmetrical ripples in outcrops of upper arenite facies suggests that the Banganapalle sediments are derived from the basement granitoids exposed to the north as well as upper Cuddapah sediments to its west. Overall, the sedimentary structures, textural and composition variation of the lithounits suggest deposition of these sediments in marginal marine, inter- to supra-tidal flat environment. The porous and permeable nature of the quartz arenite and the basal conglomerates and the presence of available reductants in the form of sulphides and carbonaceous matter make them the best suited loci for fluid movement and precipitation of uranium.

Seismic characterization and origin of clinoforms in lacustrine depositional environments: a case study from the Cretaceous of the South Atlantic

Abstract The lacustrine Itapema Formation in the Santos Basin locally comprises 10 2 m thick clinoforms identified seismically and corroborated by several well penetrations. Individual clinoforms, as proven by well penetrations, are composed of 10 2 m thick successions of basinward-dipping molluscan grainstones and rudstones. Manual dip picking of borehole images shows upward-increasing dips consistent with seismic geometries and a predominance of longshore sediment transport. Clinoforms are bound at their top and base by strata with significantly lower dips recognizable on both seismic and borehole images. Elevated gamma-ray log responses together with sidewall core samples indicate that these intervals correspond to more argillaceous facies which are interpreted as lake flooding events. While the existence of bona fide clinoforms is demonstrated by a range of subsurface data, their precise origin remains enigmatic. The majority of the bivalve genera that make up the grain-supported carbonates appear to be infaunal or semi-infaunal. As such the clinoforms represent large bars produced through the re-working of bivalves from lower-energy depositional environments by shore-parallel currents.

Jodhpur Sandstone: an Architectonic Heritage Stone from India

Jodhpur Sandstone, used extensively in several regional heritage buildings in north-western India, geologically belongs to the Ediacaran-Cambrian age Marwar Supergroup. The Marwar Supergroup has been subdivided into Jodhpur (arenaceous facies), Bilara (carbonate facies) and Nagaur (argillaceous facies) groups (in stratigraphically ascending order). The brown, red, pink and creamish pink varieties of Jodhpur Group Sandstone are the most preferred dimension stone varieties, excavated from several open quarries in the region between Jodhpur and Satrava in western part of Rajasthan State, NW India. The region has an old quarrying history, dating back to the use of sandstone in the fourth century temples in Mandor, eighth century Osian Temple Complex (also called as Khajuraho of Rajasthan for its intricate carvings in sandstone) and several historic monuments, such as Mandore Fort, Royal Tombs at Mandore Garden, Mehrangarh Fort, Clock Tower, Jaswant Thada, Umaid Bhawan Palace, etc. Several present day institutions/corporate houses of national eminence, such as the Rajasthan High Court, Indian Institute of Technology (Jodhpur), All India Institute of Medical Sciences (Jodhpur), Umaid Heritage Residential Complex and Hotel Radisson (Jodhpur) etc. exemplify continued use of Jodhpur Sandstone in contemporary times. Buildings of the Karachi Municipal Corporation and Karachi Chamber of Commerce and Industry in southern Pakistan attest to the international usage of Jodhpur Sandstone. The Jodhpur Sandstone can be classified as ‘quartz arenite’ comprising rounded to sub-rounded quartz grains with ferruginous cement. Its mature, mineralogy and moderate to high endurance, resistance to weathering, etc., render it suitable for intricate carving. Owing to these characteristics and its aesthetic appeal, it is used in a range of artefacts and handicrafts within India and overseas. The Jodhpur Sandstone fulfils the criteria laid down by the Heritage Stone Sub-commission for designation as a Global Heritage Stone Resource and we propose a case for its consideration and accreditation as a Global Heritage Stone Resource from India.

Spatial configuration of sand and mud in the lacustrine nearshore sand bar deposits and its geological implications

Different configurational orders of sand bodies and interlayers in lacustrine nearshore sand bar reservoirs frequently interact, causing complicated genesis and distribution of argillaceous sediments, as well as other issues. This paper investigates the spatial configuration of sand and mud in the sand bar reservoir, and analyzes its internal structure. Modern sand bar deposits in the Xiashan Lake, Shandong Province, China, were analyzed and compared with the sand bar reservoirs of the Member 2 of the Paleogene Shahejie Formation in the Banqiao Sag, China. The configurational mode of sand bar deposits was explored from the perspective of the spatial distribution and composition relationships between sand and mud. Based on the alternate deposition characteristics of sand and mud in the longitudinal direction, lacustrine nearshore sand bars can be divided into three sedimentary combination patterns: thin-sand and thin-mud interbed pattern, thick-mud thick-sand pattern, and thin-mud thick-sand pattern. Their mud components manifest as the deposition of fine-grained lithofacies of multiple genetic types. These include (semi-)deep lacustrine mud, sand and mud interbedded beach, argillaceous sediments in the water retention area behind the bar, and fall-silt seams that resulted from flood discharge. By summarizing the specific developmental locations and sequential relationships of each fine-grained argillaceous facies in modern sand bar deposits, a depositional process-based argillaceous sediment composition model is proposed. Based on this, this paper discusses the spatial configuration of sand bodies and argillaceous sediments in sand bar reservoirs, and introduces the typical stratigraphic structures of sand bars in two environments, i.e., vertical superposition and lateral migration. In lacustrine nearshore sand bar reservoirs, the deposition and preservation degrees of mud mainly depend on three factors: accommodation space change, frequency of base-level cycles, and exposure-erosion time. These in turn influence the continuity and relative contents of sand and mud in reservoirs. The distribution of argillaceous sediments forms different orders of interlayers, which affects the heterogeneity and fluid percolation of sand bar reservoirs. Clarifying the space-matching relationship of sand and mud in sand bar deposits provides geological models and information parameters for the refined characterization and modeling of the internal configuration of sand bar reservoirs. Furthermore, this work offers guidance for the optimal adjustment of reservoir development strategies or the optimization of reservoir development plans.

السحنات الرسوبية الرئيسة في تشكيلات الميوسين وعلاقتها بإنتاج النفط في منخفض الفرات المركزي

يتناول هذا البحث, تمييز السحنات الصخرية الرئيسة في التشكيلات الرسوبية العائدة لزمن الميوسين في منخفض الفرات المركزي, ويهدف إلى تحديد طبيعة هذه السحنات, مكوناتها, انتشارها, خصائصها الخزنية ودورها في توليد وخزن النفط والهيدروكربونات الطبيعية. ولتحقيق ذلك, تم اتباع منهجية الدراسة البترولوجيّة على (60) عينة صخرية لبابيّة (Cores) من عيّنات الحفر العميق لآبار حقل المهاش النفطي, خضعت لتفاعلات كيميائية مع الحموض والكواشف لتحديد التركيب الفلزي الأولي للصخر, وتجارب فيزيائية وقياسات بتروفيزيائية لتحديد القساوة والمسامّية, كما أجريت عليها الدراسة البترولوجيّة المجهرية (بالمجهر الاستقطابي) باستخدام (248) شريحة صخرية مجهرية. وتمّ بالمحصّلة عرض وتمثيل مجمل النتائج في سجلّات مركّبة. بيّنت الدراسة وجود ثمان سحنات رسوبيّة رئيسة في تشكيلات الميوسين, بمنخفض الفرات المركزي, هي: السحنات الكلسية, الكلسية الدولوميتيّة, الدولوميتية, الكلسية الغنية بالجص والإنهدريت, التبخرية, المارلية, الكلسية الغضارية والغضارية. وأظهرت الدراسة أيضاً دور كل سحنة صخريّة من هذه السحنات في توليد وتغطية وخزن الهيدروكربونات. شكّلت السحنات الكربوناتية الخازنة للنفط حوالي (29%) من العمود الطبقي العام لتشكيلات الميوسين, وتتركز في تشكيلتي جريبة والانتقالية, بلغت قيم المسامية الكليّة فيها حدود (30%) في بعض مستويات الدولوميت المشققة بشدّة. اقتصرت القدرة التوليديّة على سماكات قليلة ومتفرقة لبعض السحنات الغضاريّة والكلسيّة العضوية, متركزة في أسفل تشكيلتي جريبة والفرات. كما تم تحديد طبيعة الأغطية الصخريّة للمكمن, وهي مؤلفة من المتبخرات التي شكّلت (37%) من سماكة العمود الطبقي العام, متواجدة بشكل محدود في أعلى تشكيلات دبانة, جريبة والانتقالية, وبوفرة كبيرة في تشكيلة الفارس الأسفل. تم رصد تغيرات جانبيّة محدودة جداً في السحنة والسماكة للتشكيلات الرسوبيّة الميوسينيّة على امتداد الحقل, عن طريق مضاهاة الأعمدة الليتولوجيّة, وأظهرت المضاهاة انعكاسات هذه التغيرات على توليد وخزن وإنتاج النفط والهيدروكربونات في رسوبيات الميوسين.

GEOLOGIA E GÉNESE DOS DEPÓSITOS DE CAULIM FLORESTA E CAMBUÍ (FORMAÇÃO CAMPO ALEGRE - SC) - 2. PETROQUÍMICA E MODELO GENÉTICO

The wide compositional band overlap of the Cambui and Floresta mines argillaceous facies preveni the use of chemical composition as indicator of their origins. Despite this fact, the main ore types have chemical peculiarities, and the disseminated green ore is andesitic in composition, the disseminated white ore from the Cambui mine is rhyolitic and the disseminated white ore from Floresta Mine is dacitic. Rock chemical composition also show that besides the low depth ore evolution line represented by the argillaceous facies related to fractures, stockworks veins and supergenic zones, displayed by mineralogy, with strong K 2 O content variations, another evolution line exists, developed at higher depths, with constant or very small K 2 O variations. This high depth hydrothermal alteration changes the rhyolite composition, strongly leaching SiO 2 and moderately leaching K 2 O, Na 2 O, Fe 2 O 3 , CaO and MgO. These chemical changes transform rhyolites in argilised rocks with kaolin and mica. The hydrothermalism developed according to these two lines have changed rocks making easy the later action of supergenic alteration and weathering, responsible for chemical changes that develop up today. It is proposed a genetic model in which hydrothermal alteration has developed in a proximal volcanogenic environment. If hydrothermalism attained the surface, supergenic alterations occurred simultaneously with the hydrothermal alterations. On the contrary, weathering started and continues until today, only after the exhumation of the hydrothermalized rocks. At least three other models could explain the genesis of Cambui and Floresta kaolin deposits: the volcanic porphyry copper model, the volcanogenic high sulfidation model and the autometassomatic model.

Clues for age of Kolhan Basin: tectonic implications

The age of the Kolhan Basin was mysterious. Careful literature review and logical constraints from available data in literature can constrain the age. The maximum age of Kolhan Basin (closing) is 1531 Ma from whole rock Rb/Sr age of Kolhan shale [1] and opening of basin corresponds to Dalma plume (1600 Ma) [2,3]. Hence the duration or life of Kolhan Basin corresponds to 30 Ma. The Dalma plume magmatism was possibly part of a 1600 Ma global tectono-thermal event. This is synchronous to the existence of the Columbia supercontinent. The implied age directly gives the tectonic implication of the basin.\ The Kolhan basin in Singhbhum district is unique in many respects. Its narrow strip-like outcrop pattern, controlled by the NE_SW trend of the much older Iron-Ore Formation synclinorium abuts against the Singhbhum Granite in the east of a greater portion of its trend. A part of eastern and entire western boundary is in contact (fault) with the Iron-Ore Formation rocks. Its age, stratigraphic relationship and tectonic framework is still controvertial. The Kolhan Shale Formation is of course definitely younger than the Iron-Ore Formation as originally suggested by Dunn and is also younger than the Singhbhum Granite as is clear from the field relations. The Kolhan Basin is set in a diversified lithological provenance, so that it exhibits the development of a rudaceous, arenaceous, calcareous and an argillaceous facies within only a few hundred feet of thickness. The various members of the Formation of the formation dip in general uniformly low to the west away from the contact with the Singhbhum Granite.

Isopach, lithofacies changes, and source rocks chracteristics of Khatatba and Alam El Bueib formations of some wells in North East Western Desert, Egypt

ABSTRACTThe present work deals with isopach, lithofacies changes, and source rock chracteristics of Khatatba and Alam El Bueib formations of some wells in North East Western Desert. Isopach and lithofacies changes showed that the thickness of Khatatba Formation increases toward the south western direction and decreases toward northern parts, and the sediments consisting of sandstone and shale facies indicate a shallow marine environment. Alam El-Bueib sediments increase toward the north direction, and argillaceous sandstone facies reflect terrestrial-to-shallow marine environment. The geochemical analysis showed that Khatatba Formation bears a mature source rock and has poor-to-good generating capability for both oil and gas and lie within the early generation window and oil window. Alam El Buieb Formation constitutes a mature source rock and has poor-to-good generating capability for both oil and gas. It can be stated that Khatatba and Alam El Buieb are the main source rock for hydrocarbon accumulations rich with organic sediments and could be considered as effective source rocks for generating hydrocarbons in the the studied wells.

Ongoing Cenomanian — Turonian heterozoan carbonate production in the neritic settings of Peru

The present paper reports on the sedimentological and geochemical record of Albian–Turonian neritic carbonates from the eastern subequatorial Pacific domain in Peru. The focus is on one of the most extreme carbon cycle perturbations of the Phanerozoic, the Oceanic Anoxic Event 2 (late Cenomanian–early Turonian). Thanks to the very expanded and well-exposed sections in Peru, the OAE2 interval was sampled at high temporal resolution for both bulk micrite and bulk organic matter carbon isotopes. Despite the scarcity of significant amounts of organic matter or evidence for oxygen deficiency, the δ13C curve matches well with global published high-resolution data for coeval successions such as those reported from the English Chalk and the Portland # 1 core. Biostratigraphic data and the detailed sequence stratigraphic interpretation of these sections are combined with the carbon-isotope chemostratigraphy documented here. Applying the characteristic peak and trough chemostratigraphic terminology for OAE2 (A–C), the following main environmental and carbon isotope stratigraphic features are observed from the late Albian to the early middle Turonian in Peru: (i) An Albian to early late Cenomanian heterozoan ramp recording the pre-OAE2 δ13C excursions, specifically the Mid-Cenomanian Event. (ii) A late Cenomanian trough of δ13C values (B) showing a progressive deepening leading to the short-lived establishment of middle ramp type sedimentation. (iii) A late Cenomanian to early Turonian δ13C plateau (C) characterised by benthonic inner ramp sedimentation during a sea-level highstand phase. (iv) A recovery of δ13C values at the end of OAE2 associated to a trophic change, increased influx of argillaceous facies and reduced carbonate production. (v) A early to middle Turonian fluctuating δ13C curve, linked to a maximum flooding phase in the Mammites nodosoides Zone and carbonate production during the Collignoniceras woollgari Zone. The data shown here are particularly relevant as they come from very expanded neritic sections in the sub-equatorial eastern Pacific. Many of the features recognized share important similarities with Tethyan and Atlantic sections whilst the ramp system as such did not suffer from a carbonate crisis during OAE2 as recorded, for instance, in Mexico and Tibet.

Facies analysis, glauconite distribution and sequence stratigraphy of the middle Eocene Qarara Formation, El-Minya area, Egypt

The Qarara Formation consists mainly of shale at the base and overlain by limestone at the top. The formation is Middle Eocene (Lutetian) in age. Three sections located at the eastern bank of the Nile River in El-Minya Province have been measured, described, and sampled. These sections from north to south are: Gebel Qarara, El-Sheikh Fadl, and Gebel El-Ahmar.The main microfacies identified in the studied sections are: silty claystone, silty shale, fossiliferous glauconite, glauconitic (green) sand, glauconitic fossiliferous ironstone, glauconitic bioclastic wacke-packstone, glauconitic bioclastic lime-mudstone-wackestone. These microfacies have been deposited in shallow open marine environment.Collectively the studied rocks contain two principal facies: lower argillaceous facies and upper carbonate facies that separated by glauconitic fossiliferous ironstone bed. The lower argillaceous part represents highstand systems tract (HST), whereas the upper carbonate part represents transgressive systems tract (TST). The glauconitic fossiliferous ironstone bed is recognized as a sequence boundary (SB).

Channel Fracturing Applied in Mature Wells in Western Siberia

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 159347, ’First Channel Fracturing Applied in Mature Wells Increases Production From Talinskoe Oil Field in Western Siberia,’ by Rifat Kayumov, SPE, Artem Klyubin, SPE, Alexey Yudin, SPE, and Philippe Enkababian, SPE, Schlumberger, and Fedor Leskin, SPE, Igor Davidenko, SPE, and Zdenko Kaluder, SPE, TNK-BP, prepared for the 2012 SPE Russian Oil and Gas Exploration and Production Technical Conference and Exhibition, Moscow, 16-18 October. The paper has not been peer reviewed. The new channel-fracturing technique is capable of increasing fracture conductivity by up to two orders of magnitude. The channel-fracturing technique allows development of an open network of flow channels within the proppant pack, enabling fracture conductivity by such channels rather than by flow through the pores between proppant grains in the proppant pack. The successful implementation of the channel-fracturing technique in brownfield development is described in detail with the case study of the Talinskoe field in Russia. Introduction The Talinskoe section (for simplicity, referred to herein as the Talinskoe field) is part of the medium-sized, mature Krasnoleninskoe field, located near Nyagan, Russia. Exploration of this section began in 1982. It has more than 5,000 wells completed either in the Middle Jurassic Tyumenskaya suite (Formations JK2 through JK9) or the Early Jurassic Sherkalinskaya suite (Formations JK10 through JK11). More than 1,500 wells have been fractured hydraulically. Approximately 60% of all wells are idle, mainly because of water breakthrough (the average water cut throughout the field is 90%). Most hydrocarbons are found in the Sherkalinskaya suite, but, currently, water cut in many wells producing from the JK10 and JK11 formations already exceeds the economic limit. These wells are recompleted to produce from shallower formations in the Tyumenskaya suite. The Tyumenskaya suite is characterized by a complex geology. It is an argillaceous facies with sandstone sublayers and lenses. Because of low permeabilities in the Tyumenskaya suite, most of the wells cannot be produced commercially without stimulation. To enhance well productivity in such conditions, the greatest possible fracture length is required, but it is not always possible to achieve targeted half-length because of geological limitations and formation mechanical properties. While designing for the greatest length possible, the engineer is frequently limited by low-to-moderate stress contrast between the target formation and the barrier separating the target interval from the possibly watered-out formation. It is usually not a problem in low-permeability reservoirs to achieve target dimensionless fracture conductivity (DFC) greater than 2. But this does not always provide the best productivity results. Thorough analysis of the 3-year fracturing campaign in Nyagan showed that a DFC greater than 15–20 should be targeted for this region. Lower DFC values result in lower productivity. Lack of control over fracture-height growth (with the subsequent reduction in fracture width) is a possible reason for production underachievement.

Facies distribution of post‐impact sediments in the Ordovician Lockne and Tvären impact craters: Indications for unique impact‐generated environments

Abstract— The Lockne and Tvären craters formed in the Late Ordovician Baltoscandian epicontinental sea. Both craters demonstrate similarities concerning near‐synchronous age, target seabed, and succeeding resurge deposits; however, the water depths at the impact sites and the sizes of the craters were not alike. The post‐impact sedimentary succession of carbonates, i.e., the Dalby Limestone, deposited on top of the resurge sediments in the two craters, is nevertheless similar. At least three main facies of the Dalby Limestone were established in the Lockne crater, depending on sea‐floor topography, location with respect to the crater, and local water currents. The dominating nodular argillaceous facies, showing low values of inorganic carbon (IC), was distributed foremost in the deeper and quiet areas of the crater floor and depressions. At the crater rim, consisting of crushed crystalline basement ejecta, a rim facies with a reef‐like fauna was established, most certainly due to topographical highs and substrate‐derived nutrients. Between these facies are occurrences of a relatively thick‐bedded calcilutite rich in cephalopods (cephalopod facies).In Tvären, the lower part of the succession consists of an analogous argillaceous facies, also showing similar low IC values as in Lockne, followed by calcareous mudstones with an increase of IC. Occasionally biocalcarenites with a distinctive fauna occur in the Tvären succession, probably originating as detritus from a facies developed on the rim. They are evident as peaks in IC and lows in organic carbon (Corg). The fauna in these biocalcarenites corresponds very well with those of erratic boulders derived from Tvären; moreover, they correspond to the rim facies of Lockne except for the inclusion of photosynthesizing algae, indicating shallower water at Tvären than Lockne. Consequently, we suggest equivalent distribution patterns for the carbonates of the Dalby Limestone in Lockne and Tvären.

Miocene deep water agglutinated foraminifera from offshore Krishna-Godavari Basin, India

Research Article| January 01, 2004 Miocene deep water agglutinated foraminifera from offshore Krishna-Godavari Basin, India Abiraman Govindan Abiraman Govindan Asian Biostratigraphic Services, H-53, Central Avenue, Chennai - 600 080, India, email: govindan@md2.vsnl.net.in Search for other works by this author on: GSW Google Scholar Micropaleontology (2004) 50 (3): 213–252. https://doi.org/10.2113/50.3.213 Article history received: 15 Sep 2003 accepted: 14 Oct 2004 first online: 06 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Abiraman Govindan; Miocene deep water agglutinated foraminifera from offshore Krishna-Godavari Basin, India. Micropaleontology 2004;; 50 (3): 213–252. doi: https://doi.org/10.2113/50.3.213 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentBy SocietyMicropaleontology Search Advanced Search Abstract The Krishna Godavari Basin is located in the East Coast Indian Peninsula containing 5 to 7 km of Cretaceous through Cenozoic terrigenous clastic sediments. The Miocene-Pliocene section in the offshore is known as the Ravva Formation, a major argillaceous facies with sandstone beds from which oil and gas are being produced. In this sequence, some cutting samples studied from four offshore wells were found to be rich in agglutinated benthic foraminifera, while planktic foraminifera were absent at these levels. These samples were studied in much detail for agglutinated foraminifera. A total of fifty-nine agglutinated foraminiferal species belonging to thirty-five genera have been identified. Two new species, Alveolophragmium indicum Govindan n. sp and Liebusella krishna Govindan n. sp., are described. All these species are reported for the first time from this region. The agglutinated benthic foraminiferal taxa bear close resemblance to those of Miocene agglutinated foraminifera assemblages reported from South Trinidad, the Falcon Basin of Venezuela, and offshore West Africa. The present report of alveolar genera, Alveovalvulina, Alveovalvulinella and Guppyella, and compressed, inner partitioned alveolar genera Pavonitina and Spiropsammia, together with other genera having complex reticulate inner structure as Cyclammina, Reticulophragmium and Alveolophragmium in this region are of great importance for the evaluation of biostratigraphy, paleoecology, paleobiogeography and burial history. Paleoecological analysis reveals three agglutinated foraminiferal biofacies/groupings, which characterize beyond outer shelf through bathyal slope (500 to 1500m) depth regimes in an oxygen minimum deep water setting for the deposition of these turbidite/debris flow sediments.A major marine transgression at the close of the Oligocene probably caused a moderately rich, more uniform distribution of deep water agglutinated species over this deep basin. Additional observations on the agglutinated benthic assemblage such as deformation of the tests, coloration of the tests and stratigraphic markers are also dealt with briefly. You do not currently have access to this article.

SHEARD CLAYEY SHALES OF FLYSCH. THEIR BEHAVIOR DURING THE EXCAVATION OF THE DIVERSION TUNNEL OF GADOURA DAM IN RHODES (GREECE)

This paper deals with the particular geological-geotechnical conditions that predominate in the construction area of the diversion tunnel of Gadoura dam (in Rhodes) and the way these conditions were taken under consideration during the construction of the temporary support system. The intensely sheared geological formation of flysch that is encountered in the construction area of the tunnel, is characterised by the predomination of clayey shales against siltstones and other lithological members (sandstone horizons, occasional gypsum lenses and limited limestone intercalations) and by the absence of a groundwater table. The main features of this argillaceous facies of flysch are: the schistosity-foliation due to tectonic compression and the chaotic structure, in places where it occurs in alternations with sandstone and siltstone, due to differential deformation of the strata. As a result, squeezing phenomena occured during the tunnel advance. According to the engineering geology model, which was proposed after the first excavation works, sheared clayey shales compose a "soil type" rockmass specified by very low geotechnical parameters (GSI=15-20, ITIJ=6, Oci=5-10 MPa, E m =30r>500 MPa, c'=150+250 kPa, φ=13°+18° και oCm=0,400,60 MPa). Performing a declined surface on the tunnel face, shotcrete and fiber glass anchoring, this weak rockmass was behaved well on the face. The applying of a light forpoling system has contributed to the stabilization of the face and of the cylindrical "core" of rock immediately ahead of the advancing face, although it was a conservative measure. Steel ribs incorporated into shotcrete were used for the support of the tunnel behind the face. Lateral forces were further stabilized by the closure of the invert using reinforced concrete. Weep holes were locally opened for the pore pressure relief.

Miocene deep water agglutinated foraminifera from offshore Krishna-Godavari Basin, India

Abstract The Krishna Godavari Basin is located in the East Coast Indian Peninsula containing 5 to 7 km of Cretaceous through Cenozoic terrigenous clastic sediments. The Miocene-Pliocene section in the offshore is known as the Ravva Formation, a major argillaceous facies with sandstone beds from which oil and gas are being produced. In this sequence, some cutting samples studied from four offshore wells were found to be rich in agglutinated benthic foraminifera, while planktic foraminifera were absent at these levels. These samples were studied in much detail for agglutinated foraminifera. A total of fifty-nine agglutinated foraminiferal species belonging to thirty-five genera have been identified. Two new species, Alveolophragmium indicum Govindan n. sp and Liebusella krishna Govindan n. sp., are described. All these species are reported for the first time from this region. The agglutinated benthic foraminiferal taxa bear close resemblance to those of Miocene agglutinated foraminifera assemblages reported...

A laboratory investigation of some factors affecting the stability of a mine in the Eastern Transvaal coalfield, South Africa

Abstract The stability of roofs and floors in pillared coal mines is affected by a number of properties of the strata above and below the coal seam which is worked. These include the lithological character of the rocks, the sedimentary features contained within them, the geomechanical properties of the rocks, notably their strength and deformation moduli, the durability of the rocks on exposure, and the incidence and geometry of discontinuities. Instability also can be associated with the development of excessive methane and water pressures in the strata surrounding a worked coal seam. Accordingly, rock-core material was obtained from a mine in the Eastern Transvaal Coalfield in order to investigate the influence of certain of these properties on the stability of the roof and floor of the mine. The investigation showed the existence of a number of sedimentary facies that had different geological characteristics and geomechanical properties. A large number of compressive and tensile strength tests were carried out on the rock-core material, as was permeability testing. The latter was undertaken using an Ohle cell, a Bernaix cell and a Hoek triaxial cell. The permeating fluids were nitrogen, methane and water, except in the case of the Hoek cell in which only methane was used. The Hoek cell allowed permeability to be determined under different stress conditions. In addition, the geodurability of the rocks of the argillaceous facies also was determined. The compressive and tensile strength of the various facies varied notably and the latter frequently showed significant anisotropy. Permeability tended to increase with increasing grain size in the coarser-grained facies whereas the opposite tended to occur in the fine-grained facies when tested with gas. The application of stress brought about a decrease in permeability. In the Bernaix cell, divergent flow was greater than convergent flow. The tensile stress that developed during divergent flow testing with water caused some specimens to fail. The durability indicated that some of the argillaceous material was of very poor quality.