bluuebunny/crossref_metadata_2025_split huggingface dataset:
First evidence of the early cretaceous oceanic anoxic events (MBE and OAE1a) in the southern Tethyan margin (NE-Tunisia): biostratigraphy and shale resource system
Authors: Talbi Rachida , Amri Ahlem , Boujemaa Abdelhamid , Gabtni Hakim , Spiller Reginal , Levey Raymond 
Published: December 2021

AbstractThe Jebel Oust region (north-eastern Tunisia) recorded two levels of marine black shale in the Lower Cretaceous marly series. Geodynamic evolution, biostratigraphic and Rock–Eval analysies allow classifying those black shales as unconventional shale oil resource systems that were deposited during two oceanic anoxic events: the Middel Barremian Event "MBE" and the Early Aptian Event "OAE1a". Paleogeographic evolution highlights two transgressive–regressive cycles: the first one is Valanginian-Early Barremian, and the second is Late Barremian–Early Aptian. Each black shale deposit occurs at the end of the transgression that coincides with the highest sea level. During the Barreman–Aptian interval, sedimentation was controlled by extensional faults in a system of tilted fault blocks which were reactivated several times. Kerogen is of type I, II origin in black shales and of type III origin in marls. Tmax values indicate "oil window" stage. Average transformation ratio is around 67% and 82%, respectively, in the Lower Aptian and Middel Barremian source rock related to the relatively high thermal maturity degree due to the deep burial of the later. Estimated initial hydrocarbon generation potential is moderate to high. Oil saturation index records an "oil crossover" indicating expelled and migrated hydrocarbons from the organic-rich to the organic-poor facies. The petroleum system of the two mature source rocks with a high hydrocarbon generation potential enclose all elements characterizing a "shale oil hybrid system with a combination of juxtaposed organic-rich and organic-lean facies associated with open fractures".
Mitigation capacity of an eco-friendly locally sourced surfactant for gas hydrate inhibition in an offshore environment
Authors: Elechi Virtue Urunwo , Ikiensikimama Sunday Sunday , Ajienka Joseph Atubokiki , Akaranta Onyewuchi , Okon Okon Efiong 
Published: December 2021

AbstractGas hydrate inhibition is very key and has become more sensitive as oil and gas exploration goes into deeper terrains especially deep offshore as a result of technological advancement. Use of chemicals has been the most efficient and cost effective in these areas. These chemicals add to the cost of doing oil and gas business and also cause harm to the environment; hence, research has been going on for more eco-friendly and cost-efficient inhibitors. This study takes a look at a locally sourced surfactant as one of such inhibitors. Varying weight percentages of the LSS were screened in a locally fabricated laboratory mini flow loop of 39.4 m with an internal diameter of 0.5 inch mounted on an external frame work. The various pressure plots (pressure vs. time, change in pressure vs. time, initial and final pressures vs. time) show that the LSS used in very small percentages performed better than the synthetic inhibitor methanol (MeOH) used in higher weight percentage than the LSS. The final pressures for MeOH for 1–5 wt% were 104, 111, 123, 120 and 123 psi while those of the LSS were 115, 128, 125, 127 and 131 psi, respectively, for 0.01–0.05 wt%, respectively. This means that the system with LSS had more stable pressure values than those of MeOH. Similarly, the change in pressure at the end of 120 min for MeOH was 46, 39, 27, 30 and 27 psi against 35, 22, 25, 23 and 19 psi for LSS. This was an indication that more gas was used up in the system with MeOH than in the system with LSS. The mitigation capacity of the LSS in percentage was calculated to be 69.30, 80.71, 78.07, 79.82 and 83.3% for 0.01–0.05 wt% while MeOH had values of 59.65, 65.79, 76.32, 73.68 and 76.32% for 1–5 wt%, respectively. This showed that the LSS inhibited hydrates better than MeOH in all the weight percentages considered. There is need to harness and develop the LSS for gas hydrate mitigation because it performed better than MeOH which is a known toxicant to man, terrestrial and aquatic habitat.
Seismic expression of miocene carbonate platform and reservoir characterization through geophysical approach: application in central Luconia, offshore Malaysia
Authors: Bashir Yasir , Faisal Muhammad Amir , Biswas Ajay , Babasafari Amir abbas , Ali Syed Haroon , Imran Qazi Sohail , Siddiqui Numair Ahmed , Ehsan Muhsan 
Published: December 2021

AbstractA substantial proportion of proven oil and gas reserves of the world is contained in the carbonate reservoir. It is estimated that about 60% of the world’s oil and 40% of gas reserves are confined in carbonate reservoirs. Exploration and development of hydrocarbons in carbonate reservoirs are much more challenging due to poor seismic imaging and reservoir heterogeneity caused by diagenetic changes. Evaluation of carbonate reservoirs has been a high priority for researchers and geoscientists working in the petroleum industry mainly due to the challenges presented by these highly heterogeneous reservoir rocks. It is essential for geoscientists, petrophysicists, and engineers to work together from initial phases of exploration and delineation of the pool through mature stages of production, to extract as much information as possible to produce maximum hydrocarbons from the field for the commercial viability of the project. In the absence of the well-log data, the properties are inferred from the inversion of seismic data alone. In oil and gas exploration and production industries, seismic inversion is proven as a tool for tracing the subsurface reservoir facies and their fluid contents. In this paper, seismic inversion demonstrates the understanding of lithology and includes the full band of frequency in our initial model to incorporate the detailed study about the basin for prospect evaluation. 3D seismic data along with the geological & petrophysical information and electrologs acquired from drilled wells are used for interpretation and inversion of seismic data to understand the reservoir geometry and facies variation including the distribution of intervening tight layers within the Miocene carbonate reservoir in the study area of Central Luconia. The out-come of the seismic post-stack inversion technique shows a better subsurface lithofacies and fluid distribution for delineation and detailed study of the reservoir.
Velocity anisotropy and trend in Niger Delta, Nigeria
Authors: Aniwetalu Emmanuel , Anakwuba Emmanuel , Ilechukwu Juliet 
Published: December 2021

AbstractIn geophysical data interpretation, matching the vertical velocity direction from seismic data with borehole-derived velocities is a challenging task because seismic-derived velocities are faster than borehole recorded velocities. This geophysical phenomenon is caused by velocity anisotropy. In this study, we used an empirical approach to estimate the degree of velocity anisotropy in the study area. The results showed that the delta anisotropy in sandstone beds varies from − 2.5% to 7.2% while most of them concentrate between 3.2% and 6.1%. The epsilon ranges between -6.4% and 9.3% while many of them concentrate between 3.2% and 7.2%. The gamma varies from − 6.3% to 7.3% while most of them concentrate between 1.2% and 5%. At shale beds, delta anisotropy varies from − 11.2% to 11.1% but most of them concentrate between 4.3% and 10.5%. The epsilon varies from − 7.2% to 14.5% while most of them concentrate between 4.5% and 10.5%. The gamma varies from 6.4% to 8.2% while majority of them concentrate between 2% and 5.3%. The results indicate that the study area is weakly to moderately anisotropic with shale beds having higher anisotropy values than sandstone beds. This probably results from preferential alignment of clay mineral orientations which also affect in situ velocity propagation. Three distinct velocity gradients (low, moderate and very high) were identified in the study area. These velocities vary erratically but showed northeast–southwest increase in velocities. Thus, the need to derive correction factors for individual wells for improved exploration success.
Numerical simulation of formation damage by drilling fluid in low permeability sandstone reservoirs
Authors: He Weiwei , Liu Zhiqiang 
Published: December 2021

AbstractUnderstanding the formation damage surrounding the well during the drilling operation is the key to predict damage degree and protect the formation in oil/gas reserviors. Based on the core drainage results, we obtained an empirical relationship between the invasion volume of drilling fluid and permeability reduction of formation. Furthermore, the equation is incorporated into a commercial reservior numerical simulation simulator to characterize the behaviors of drilling fluid invasion process. The results show that, although the invasion depth in low permeability reservoirs is short with the range of 1.7–2.5 m, the effect on recovery factor is significant due to the narrow seepage area in the near fracture region. When considering the formation damage, the pressure in the near-fracture damage region drops sharply, leading to a three-stage shape in pressure distribution curve. In addition, we found that high viscosity and low density oil-based slurry and shorter soaking period are conducive to decrease the formation damage during drilling operation. This work reveals the fundamental mechanisms of formation damage in low permeability reservoirs, which is a theoretical basis in formulation drilling fluids and optimization operation parameters.
Banana peel and mango kernel-based polymers and their suitability in enhanced oil recovery
Authors: Fadairo Adesina , Adeyemi Gbadegesin , Temitope Ogunkunle , Kegang Ling , Vamegh Rasouli , Enuice David , Temitope Ilusemiti , Ayoo James 
Published: December 2021

AbstractThis study reports the extraction and performance evaluation of two bio-derived polymers for enhanced oil recovery applications. The oil displacement processes were conducted using six (6) unconsolidated sandstone core plugs. Reservoir permeability tester was used to simulate real reservoir conditions in order to evaluate the suitability of the formulated biopolymers for oil displacement applications at laboratory conditions. The experimental results indicate the effectiveness of the biopolymer solutions in enhanced oil recovery in terms of their superior incremental oil recoveries after conventional waterflood with percentage oil recovery of 30.9–39.3% for banana peel derived polymer and 40.6–50.8% for mango kernel derived polymer compared to conventional waterflood with percentage recovery of 16.2–32% of the initial oil in place. This work identified the potential suitability and use of bio-derived polymers for enhanced oil recovery applications with emphasis on their biodegradability.
Experimental study of shale drillability with different bedding inclinations under varying wellbore pressure conditions
Authors: Chen Shuai , Shi Xiangchao , Bao Heng , Gao Leiyu , Wu Jie 
Published: December 2021

AbstractIn the practice of shale gas development engineering, it is important to understand the physical and mechanical properties of shale. The bedding inclinations of shale are known to significantly influence its physical and mechanical properties. This study mainly examined the influence of bedding inclinations on drillability under different wellbore pressures. The bedding inclinations used in this study varied from 0° to 90°, with a gradient of 15°. The wellbore pressure values used varied from 0 to 25 MPa, with a gradient of 5 MPa. The results show that the drillability index of shale increases exponentially with increasing wellbore pressure at different bedding inclinations. The proposed exponential empirical model can describe the relationship between the drillability index and wellbore pressure. When the wellbore pressure is less than 15 MPa, bedding inclinations significantly influence the drillability index, and the drillability index of shale shows a “W”-type variation trend as the bedding inclinations increase in the range of 0° to 90°. The influence of bedding inclinations on drillability decreases gradually with increasing wellbore pressure. When the wellbore pressure increases to 25 MPa, the impact of bedding inclinations on drillability is virtually undetectable. The results of this study can provide reasonably insight into the effect of bedding inclinations on shale deformation under the drill bit, and useful prediction for the drillability index under in situ conditions.
Integrated rock typing and pore facies analyses in a heterogeneous carbonate for saturation height modelling, a case study from Fahliyan Formation, the Persian Gulf
Authors: Ranjbar-Karami Rasoul , Tavoosi Iraj Parisa , Mehrabi Hamzeh 
Published: December 2021

AbstractKnowledge of initial fluids saturation has great importance in hydrocarbon reservoir analysis and modelling. Distribution of initial water saturation (Swi) in 3D models dictates the original oil in place (STOIIP), which consequently influences reserve estimation and dynamic modelling. Calculation of initial water saturation in heterogeneous carbonate reservoirs always is a challenging task, because these reservoirs have complex depositional and diagenetic history with a complex pore network. This paper aims to model the initial water saturation in a pore facies framework, in a heterogeneous carbonate reservoir. Petrographic studies were accomplished to define depositional facies, diagenetic features and pore types. Accordingly, isolated pores are dominant in the upper parts, while the lower intervals contain more interconnected interparticle pore types. Generally, in the upper and middle parts of the reservoir, diagenetic alterations such as cementation and compaction decreased the primary reservoir potential. However, in the lower interval, which mainly includes high-energy shoal facies, high reservoir quality was formed by primary interparticle pores and secondary dissolution moulds and vugs. Using huge number of primary drainage mercury injection capillary pressure tests, we evaluate the ability of FZI, r35Winland, r35Pittman, FZI* and Lucia’s petrophysical classes in definition of rock types. Results show that recently introduced rock typing method is an efficient way to classify samples into petrophysical rock types with same pore characteristics. Moreover, as in this study MICP data were available from every one meter of reservoir interval, results show that using FZI* method much more representative sample can be selected for SCAL laboratory tests, in case of limitation in number of SCAL tests samples. Integration of petrographic analyses with routine (RCAL) and special (SCAL) core data resulted in recognition of four pore facies in the studied reservoir. Finally, in order to model initial water saturation, capillary pressure data were averaged in each pore facies which was defined by FZI* method and using a nonlinear curve fitting approach, fitting parameters (M and C) were extracted. Finally, relationship between fitting parameters and porosity in core samples was used to model initial water saturation in wells and between wells. As permeability prediction and reservoir rock typing are challenging tasks, findings of this study help to model initial water saturation using log-derived porosity.
Evaluation of environment friendly micro-ionized litchi leaves powder (LLP) as a fluid loss control agent in water-based drilling fluid
Authors: Prakash Ved , Sharma Neetu , Bhattacharya Munmun , Raina Ashok , Gusain Man Mohan , Sharma Kiran 
Published: December 2021

AbstractThis work investigates the efficacy of a biodegradable natural product, litchi leaves powder (LLP) as a filtration loss control agent in the water-based drilling fluid formulations. In order to evaluate the potential of litchi leaves powder (LLP), a strict protocol of experimentations according to API (American Petroleum Institute) standard has been followed. The experimental outcome showed that before hot rolling and after hot rolling of mud samples at 100 °C it was observed that 3–5% Concentration of LLP significantly increased the rheological parameters such as PV, YP and gelation of drilling fluid as compared to reference mud. Also, LLP reformed the filtration loss control characterization, suggesting a better biodegradable fluid loss reducing agent. After hot rolling at 100 °C for 18 h, the water-based drilling fluid with LLP as an additive showed a marked reduction in filtration control property as compared to reference Mud (RM). Experimental results concluded that 5% concentration of LLP significantly reduced the filtration loss of drilling fluid by 70.6% as compared to reference mud under the influence of 100 psi pressure. However, the conventional fluid loss additive CMC (LVG) reduced the filtration loss by maximum 67.5% as compared to reference mud. Therefore, LLP can be used as an alternative to CMC (LVG) in water-based drilling fluid with a maximum subsurface temperature of 100 °C.
Well integrity management in mature fields: a state-of-the-art review on the system structure and maturity
Authors: Yakoot Mostafa S. , Elgibaly Ahmed A. , Ragab Adel M. S. , Mahmoud Omar 
Published: December 2021

AbstractNowadays, oil and gas (O&G) fields are maturing and creating new threats. This urged the operating companies and industry researchers to have intensive focus on well integrity (WI). Building Well Integrity Management System (WIMS) establishes standardized criteria to guarantee that integrity of all wells is preserved during their lifespan, functions properly in healthy condition, and is able to operate consistently to fulfill the expected production/injection demands. Moreover, exploration and production (E&P) companies put Health, Safety, and Environment (HSE), assets, production, local and public image as top priority in their businesses. Having effective WIMS at all times and throughout all well phases reduces the frequency of major integrity failures and thus helps companies to be on track regarding the aforementioned considerations. In this paper, we present a comprehensive review on the system structure and maturity of WIMS in mature fields. This state-of-the-art review highlights the efforts made by different O&G operators all over the world to develop and start application of WIMS, which varies widely due to differences in the main WI challenges that are recurring in each field or concession. Moreover, it lists the goals and expounds the stages of launching effective WIMS. In addition, the key elements, around which the WI program is structured, are discussed and presented for various O&G operators. The major five elements of accountability and responsibility, well operations procedures, well intervention procedures, tubing and casing integrity program, and wellhead and X-tree maintenance are overviewed. Furthermore, this paper assesses WIMS sustainability through demonstration of WI maturity models, scrutiny of maturity levels, and analysis of transformative elements to convert WIMS into strategic framework. Risk management systems as well as application of analytics in WIMS are also covered and thoroughly discussed. In reviewing the literature covering different assets—all over the world for the last 15 years—it was found that real progress was made in WI area, and WIMS established in many operating companies through different approaches. However, the introduced systems lack universality and few of them are applying artificial intelligence as powerful tool for boosting the system. The most obvious finding to emerge from the analysis is that WIMS is crucial system that must be implemented and matured for well lifecycle. The findings of this study can help operating companies for better framing of key pillars to have robust and operable WIMS throughout different fields and concessions, hence improving the well integrity performance worldwide.
Proximity politics in changing oceans
Authors: Foley Paul 
Published: December 2021

AbstractHow will ocean governance actors and institutions handle a future where the abundance and spatial distribution of marine life changes rapidly and variably? The answer, this paper argues, will be influenced by inherited and changingocean proximity politics, whereby institutions and actors use spatial proximity or adjacency to legitimize particular forms of resource control, conservation and use. Focusing on United Nations and Canadian institutional contexts and recognizing state and non-state actors as agents of policy change, the paper documents and examines why and how spatial proximity has been invoked (i) as a principle for claiming, defining and implementing use rights, privileges and responsibilities for not just nation-states but also for other entities such as coastal communities and small-scale fisheries; (ii) to justify and legitimize rights, privileges and responsibilities for their interest and benefit; and (iii) to inform and challenge global and local discussions about principles such as conservation, sustainability and distributive equity. The future practical use of spatial closeness/distance for guiding policies of access and exclusion under conditions of change will likely be influenced by challenges associated with applying multiple and conflicting governance principles, accommodating diverse interests and interpretations of principle definition and application, and multiple forms of biophysical and social mobilities. The conclusion highlights four areas of further research and policy engagement for the study of ocean proximity politics.
The Pursuit of Effective Working Memory Training: a Pre-registered Randomised Controlled Trial with a Novel Varied Training Protocol
Authors: Ritakallio Liisa , Fellman Daniel , Jylkkä Jussi , Waris Otto , Lönnroth Nelly , Nervander Reidar , Salmi Juha , Laine Matti 
Published: December 2021

AbstractWorking memory (WM) training, typically entailing repetitive practice with one or two tasks, has mostly yielded only limited task-specific transfer effects. We developed and tested a new WM training approach where the task paradigm, stimulus type, and predictability of the stimulus sequence were constantly altered during the 4-week training period. We expected that this varied training protocol would generate more extensive transfer by facilitating the use of more general strategies that could be applied to a range of WM tasks. Pre-post transfer effects following varied training (VT group, n = 60) were compared against traditional training (TT group, training a single adaptive WM task, n = 63), and active controls (AC, n = 65). As expected, TT evidenced strong task-specific near transfer as compared to AC. In turn, VT exhibited task-specific near transfer only on one of the measures, and only as compared to the TT group. Critically, no evidence for task-general near transfer or far transfer effects was observed. In sum, the present form of VT failed to demonstrate broader transfer. Nevertheless, as VT has met with success in other cognitive domains, future studies should probe if and how it would be possible to design WM training protocols that promote structural learning where common features of specific tasks would be identified and utilised when selecting strategies for novel memory tasks.