bluuebunny/crossref_metadata_2025_split huggingface dataset:
Successful Application of Clusterization Development Strategy for Small and Scattered Fields
Authors: Wang Ruifeng , Xiaoling Yi , Xintao Yuan 
Published: February 2021

ABSTRACT
This paper demonstrates an innovative clusterization approach to define development strategy for small and scattered fields in T Basin, which is located in landlocked central Africa. As a rifted basin, T basin is around 250 km long and 80 km wide under sub-Saharan desert environment. The operator started exploration in 2008 and had discovered over 40 oil fields scattered over the whole basin but with limited size. 30 small oilfields occupy only 20% of total OOIP. Therefore the discovered fields in T basin belong to small and scattered fields. To realize fast track development in landlocked desert and achieve economic robustness meanwhile is the huge challenge for the operator. Clusterization development strategy had been put forward to realize integrated asset development.
Clusterization is to define several oil field clusters based on the criteria of adjacency, reservoir characteristics etc. Each oil field cluster should have one and/or two relatively bigger oil field as the central fields. Satellite fields are grouped into adjacent central fields thus forming oil field clusters. The whole basin development optimization could be carried out on a two-tier level: 1) for the intra cluster level, central fields will be commissioned first and satellite fields could be ranked to substitute production plateau, satellite fields facilities could be skid-mounted and shared among satellite fields to reduce Capx. 2) for the oilfield cluster level, clusters could be ranked according to criteria of OOIP scale, productivity projection and commissioning complexity. Relatively concentrated oilfield clusters could be prioritized to arrive at long term production projection. The remaining clusters could serve as plateau maintenance purpose afterwards.
Five oilfield clusters had been defined under the guidance of clusterization strategy. Three oilfield clusters had been recommended for Phase I production after optimization on the inter-cluster and intra-cluster level. 60 KBOPD of productivity with longer plateau is expected from clusterization development with convincing economical parameters, which fully satisfy the requirement of long distance pipeline.
This paper had proposed an innovative clusterization approach to define development strategy for small and scattered oilfields in a landlocked basin. The two-tier optimization process inherent in the clusterization approach could be of strong reference value to similar marginal blocks and basins.
Petroleum Exploration Potential on Abu Gabra Formations in Fula Sub-basin, Muglad Basin, Sudan
Authors: Weili Ke , Guangya Zhang , Aixiang Liu , Yonglin Zheng , Yongjun Yu 
Published: February 2021

ABSTRACT
Fula sub-basin is one of chasmic structure units with rich petroleum accumulation within Muglad basin. In the past, thick sandstones of Bentiu was considered as main petroleum accumulation targets sealed by faults and anticlines, and most petroleum generated by AG source kitchen has migrated to upper formations along big faults, and furthermore, sandstones inside AG formation of are thin with poor permeability and porosity caused by compaction. Recently, some works have been done specially on AG formation, including small fault interpretation, seismic sedimentary analysis and thin layer inversion, resulting in new petroleum discoveries within middle AG formation, which reveals that AG formation has also good petroleum accumulation abilities.
Comprehensive study shows that there developed many small faults within AG period, which could seal sandstones of AG formation laterally, forming effective faulted block within AG formation. Sandstones of delta and sub-water channel could be found. Within AG4 and AG2 formations, there are mainly lacustrine facies. Channel sandstones occurred regression and the area of alluvium fan decreased AG shale has high matter abundance, high hydrocarbon generating potential and kerogen type I, II with middle to high mature, showing good hydrocarbon generation ability. Although sandstones of AG formation have relatively low permeability and porosity, these sandstone have good logging response on hydrocarbon could be sealed by local surrounding mudstones and. All above reveals that AG combination is near-source reservoir combination.
Low-amplitude anticline and structure-lithology reservoir models are favorite reservoir models in Fula sub-basin. In the west slope, especially the lower places of the slope are the areas of huge sedimentary accumulation should be favorite prospects. As for the east slope, low-amplitude anticline bounded by small faults that developed during AG period should be the favorite area for exploration, which has been proved by successful drilling activities.
In Fula sub-basin, AG structure-lithology complex reservoir combination should be the favorite type for drilling as per under these two key factors, the petroleum could be well accumulated. Currently, there have two important petroleum discoveries of channel sandstone and delta sheet sandstone in AG formation, proving that AG formation still has good potential for drilling.
Appraising Carbon Geological Storage Potential in Unconventional Reservoirs Using Well-Testing Method: Engineering Parameters Analysis
Authors: Chen Z. M. , Liao X. W. , Zhao X. L. , Li X. J. , Jiang W. L. , Zhu L. T. , Wang L. , Xia Y. H. 
Published: February 2021

ABSTRACT
Most of work focus on influences of reservoir parameters of depleted shales on carbon storage capacity. This is useful for selecting a good candidate as a repository. However, engineering parameters of shales are also important factors for carbon sequestration. So, necessary work is still needed.
Following a detailed introduction of a trilinear flow model for carbon sequestration (Chen et al., 2016), this paper continues to study impacts of engineering parameters on carbon storage potential. Firstly, the methodology for appraising carbon sequestration potential was introduced, containing (1) introducing the conceptual model, (2) developing the mathematical model, (3) obtaining the wellbore-pressure solution, (4) determining the injection time, and (5) appraising the carbon sequestration capacity. In the conceptual model, the shale formation were divided into two subsystems and three regions, including matrix subsystem, natural-fracture subsystems, hydraulic-fracture region, inner region, and outer region. With basic equations, a mathematical model was developed in those subsystems and regions. Then, based on the mathematical model, CO2 storage potential in abandoned shales was investigated at different values of fracture conductivity, fracture number, fracture length, inner permeability, and wellbore length. This meaningful work provides a guideline to select wells and monitoring facilities for storing CO2 in residual depleted shale reservoirs.
Regional Geological Study and Potential Prediction of the Rio Del Rey Basin (RDR), Offshore Cameroon
Authors: Altayeb Khalid O. , Yushan Su , Shixiang Wu , Zhankun Chen 
Published: February 2021

ABSTRACT
Located in the eastern end of Niger delta; the Rio Del Rey (RDR) basin has a unique, complex multi-staged geological features and different types of Structures. This study has aimed to better understand the different structural and stratigraphic setting of the fields within the RDR basin and the way they control the hydrocarbon occurrences. To do that, an integrated 2D and 3D seismic interpretation was done targeting the toe thrust boundary, the upper Cretaceous unconformity and four key horizons of different depth levels in the Tertiary formations. Twelve regional profiles of contrastive orientations that cover the whole basin were interpreted to identify the regional structures; well correlation was done to identify the shallower tertiary settings while additional detailed grids of interpretation at the northeastern and southwestern corners and the seismic facies analysis of the whole RDR study area were used to classify the stratigraphic setting at the deeper regions. The results have revealed that the RDR basin is mainly controlled by thrusting, diapirism and detachment fault structures. The major toe thrust zone is found southern of Ngosso and trends in the northeast-southwestern direction. Gravitational tectonism becomes the primary deformation process shaping the structures as the sediments accumulation increases to the south and consequently, several shale ridges were formed. These ridges and their lateral movement from North to South along with the whole sediments increasing have caused a slope instability of the lower ductile Akata shale formation; what caused the forming of the detachment faults zone in the Northern and middle parts of the RDR basin. The Oongue Turbidites of Eocene were deposited in the northeastern part of the basin in deep water fans by the main sediments supply from the North and the East with various sand thicknesses due to the structural system. The hydrocarbon potential accumulations are found in the mid to upper Tertiary formations and the deeper Upper Cretaceous, but most of the oil and gas fields are located in shallower deltaic reservoirs associated with fault-bounded traps related to shale ridges and diapir structures. Considerable amounts of hydrocarbons were also found within the turbidites sands of Oongue (NE) and Isongo (SE).
Application of Analytic Hierarchy Process to Identify the Most Influencing Human Factors (HFs) and Performance Influencing Factors (PIFs) in Process Safety Accidents
Authors: Theophilus Stephen C. , Abikoye Olayinka G. , Arewa Andrew O. , Ifelebuegu Augustine O. , Esenowo Victor 
Published: February 2021

ABSTRACT
Numerous studies suggest that 80% of accidents in hydrocarbon processing industries are as a result of human factors (HFs). While a lot is known of human factor influence to process accident, the effects of performance influencing factors (PIFs) on human factors in process accidents is not yet well understood. This study examined HFs and PIFs which influences the propagation of undesired occurrences in hydrocarbon processing industries. An illustrative case study of the Tesoro refinery accident was analysed. To affirm consistency in judgments, Analytic Hierarchy Process AHP – a multi-criteria decision-making method was used in identifying HFs and PIFs of critical events. BPMSG AHP computer program was also used to validate results obtained from the manual calculations. Three critical events namely non-routine operations (Event 1), manual manipulation of several isolation block valves (Event 2) and automated start-up operations of Naphtha Hydro-Treating unit (Event 3) were identified. The ranking of PIFs revealed that Procedures, Level of Supervision, Task Characteristics, and Skill Level were major influencing factors to the event. Analysis of human factors revealed that Job Factors had the most significant influence (41%), while the Individual Factors and Organisational Factors had (31%) and (28%) influence respectively. The consistency index (CI) and consistency ratios (CR) of the PIFs were 0.174 and 0.193 for critical Event 1; 0.170 and 0.120 for critical Event 2; and, 0.037 and 0.033 for critical Event 3 respectively. This showed consistency in judgments of the study on PIFs selected for the critical events identified. The Tesoro refinery accident was due to latent organisational and cultural failures.
United States Experience Regulating Unconventional Oil and Gas Development
Authors: Allison Edith 
Published: February 2021

ABSTRACT
In the midst of aggressive anti-drilling campaigns by environmental organizations and well-publicized complaints by citizens unaccustomed to oil and gas operations, rigorous studies of unconventional oil and gas development show that there are no widespread or systemic impacts on drinking water resources in the United States. In addition, air pollution and greenhouse gas emissions have significantly declined with the growth in natural gas production and its use in power generation. Furthermore, induced seismicity from subsurface waste disposal has plummeted in response to industry initiatives and new regulations. This record of environmental protection reflects the fact that U.S. hydraulic fracturing, like other oil and gas operations, is highly regulated by the states. In addition, air emissions, operations on federal lands, and subsurface injection are subject to federal regulation.
Academic and government researchers have documented that chemicals and gas produced by hydraulic fracturing are not contaminating drinking water. However, as an added complication, methane occurs naturally in drinking water aquifers in some producing areas. In 2015, the U.S. Environmental Protection Agency (EPA) completed a four-year study of potential aquifer contamination from hydraulic fracturing and associated industry operations. The report found some impacts on drinking water including contamination of drinking water wells; however, the number of cases was small compared to the number of wells hydraulically fractured. The scientific peer-review and public critique of the study, which continues after more than a year, may recommend additional research.
The emotionally charged, anti-fracking campaigns provided important lessons to U.S. operators: pre-drilling, baseline data on water and air quality are essential to answering public concerns; infrastructure issues such as increased truck traffic on small, local roads are important to residents; and the initial failure to disclose the composition of hydraulic fracturing fluid intensified public concern.
Cost Reduction Strategies in Workover operations in the Face of Low Oil Price: The Agbada Workover Project
Authors: Eze Joy , Onakomaiya Oluwarotimi , Ogunrinde Ademola , Adegboyega Olusegun , Wopara James , Timibitei Fred , Ideh Matthew 
Published: February 2021

ABSTRACT
The current low oil price has resulted in several continuous improvement drives particularly focused on capital efficiency. With over 60 producing oil fields and approximately 700 producing wells, some of which date back to the 60s, work over operations in Shell Petroleum Development Company (SPDC) is imperative. Having completed over twenty (20) Work Over operations in the last six years in SPDC, the importance of Work Over operations as a means to sustain production especially for relatively old, dysfunctional or non-compliant wells and keep the production funnel full at a relatively lower cost compared to new drills is more evident. Work over operations, defined as the repair and/or stimulation of existing wells in order to improve production performance presents the opportunity to maximize short term gains from already existing facilities.
The objective of the workover operations on Agbada ABC and XYZ was to restore well integrity with the installation of sub surface safety valves and gas lift mandrels instead of insert orifice while assuring the development of oil and associated gas. The insert orifice had been installed on both wells to enable gas lift operations from the Agbada Associated Gas Gathering (AGG) plant since they were unable to sustain natural flow. However, due to epileptic AGG, both wells quit frequently requiring nitrogen lift with an average Non-Productive Times (NPT) of 6 months per year while Agbada XYZ was put on cyclic production and had been a pressure build-up well with at least two weeks down time per month. The workover operation was therefore proposed to replace the existing (punched) tubing, install proper gas lift mandrels for optimum performance, reduce well operating cost arising from AGG outage and/or compressor failure and restore production in the reservoir.
This paper aims to discuss the cost reduction strategies such as collaboration, re-use, program optimization and operational efficiency applied in driving down Non-Productive Times (NPT) in the efficient delivery of these workover operations which resulted in &lt;6% NPT, &gt;30% time savings, ca. 40% cost savings and early return of wells to production.
Annular Barrier as an Alternative to Squeezes in Challenging Wells: Technology Review and Case Histories
Authors: Bagal Joseph , Onadeko Gbenga , Hazel Paul , Dagestad Vibjørn 
Published: February 2021

ABSTRACT
The drilling industry has always relied on cement as a primary barrier. Although the cement represents about 5% of the well cost, when squeezes are required, cementing averages 17% of the well cost. Only 50% of the squeezes achieve the objective of establishing a barrier for well integrity. A little bit more than half of the failures can be attributed to operational challenges (pump failure, cement contamination), or design oversights (cement recipe, centralizers). However there are still cement failures with perfect design and field execution. These failures typically exhibit some of the following characteristics: high deviation, high pressure, washouts, natural fractures, long casing section, heterogeneous sands.
For these specific conditions, it is beneficial to add an assurance that would maintain the integrity of the well even in case of bad cement. Some of the assurances used include port collars, external casing packers (ECP) and swell packers. Port collars allow a squeeze above the first stage cement, while ECP serves as a base for a second stage cement, and swell packers provides a baffle for sustained casing pressure. A more recent technology is the well annular barrier that can form a combined barrier with cement, and can also be used as a stand-alone primary barrier.
The well annular barrier is a metal-expandable barrier that is expanded with hydraulic pressure. It is full bore, highly customizable, and qualified to ISO 14310. The metallurgy allows the packer to shape fit into either an open hole with irregular geometry or inside a casing to preclude annular pressure build up by giving a life-of-well reliable seal. The well annular barrier has been deployed in a variety of wells to achieve well integrity with and without cement, protect the B-annulus from sustained casing pressure, or serve as a barrier between reservoirs that cannot be commingled.
This paper performs a review of the technologies used for cement assurance, their advantages and disadvantages. Case histories of well annular barrier deployments are presented, including a case where the well annular barrier was used as a stand-alone well barrier element without the need for dispensation. This paper also discusses how the well annular barrier fits into the regulatory requirements for well construction providing to the drilling industry an alternative to cement for the purpose of well integrity.
Diagnosis patterns of sickle cell disease in Ghana: a secondary analysis using cohort data
Authors: Sims Alexandra M. , Bonsu Kwaku Osei , Urbonya Rebekah , Farooq Fatima , Tavernier Fitz , Yamamoto Marianna , VanOmen Sheri , Halford Brittne , Gorodinsky Polina , Issaka Rachel , Kpadenou Tulana , Douglas Rhonda , Wilson Samuel , Fu Clementine , Canter Danielle , Martin Duña , Novarra Austin , Graham Lewis , Sey Fredericka , Antwi-Boasiako Charles , Segbefia Cathy , Rodrigues Onike , Campbell Andrew 
Published: February 2021

Abstract
Background:

Despite having the highest prevalence of sickle cell disease (SCD), Sub-Saharan Africa lacks a robust screening program. We sought to capture the diagnosis patterns of SCD, particularly age and mechanism at SCD and age of first pain crisis, in Accra, Ghana.
Methods

We administered a survey to parents of offspring with SCD between 2009–2013 in Accra as a part of a larger cohort study and analyzed a subset of the data to determine diagnosis patterns. Univariate analyses were performed on diagnostic patterns; bivariate analyses were conducted to determine if patterns differ by offspring’s age, or their disease severity. Pearson’s chi-squared were calculated.
Results

Data was collected on 354 unique participants from parents. 44% were diagnosed with SCD by age four; 46% had experienced a pain crisis by the same age. 66% were diagnosed during pain crisis, either in acute (49%) or primary care (17%) settings. Younger (< 18 years) offspring were diagnosed with SCD at an earlier age (74% by four years old); in the adult ( > = 18 years) group, 30% were diagnosed by four years (p < 0.001). Few were diagnosed via newborn screen. Half with severe disease were diagnosed by age four, compared to 31% with mild disease (p = 0.009).
Conclusions

These findings reflect a reliance on diagnosis in acute settings, and a relative underutilization of systematic screening programs. By understanding current patterns, opportunities remain to more effectively detect and treat SCD in this high prevalence population.
Multiscale imaging of the rat brain using an integrated diceCT and histology workflow
Authors: Gignac Paul M. , O’Brien Haley D. , Sanchez Jimena , Sanroman Dolores Vazquez 
Published: February 2021

Abstract
Advancements in tissue visualization techniques have spurred significant gains in the biomedical sciences by enabling researchers to integrate their datasets across anatomical scales. Of particular import are techniques that enable the interpolation of multiple hierarchical scales in samples taken from the same individuals. This study demonstrates that two-dimensional histology techniques can be employed on neural tissues following three-dimensional diffusible iodine-based contrast-enhanced computed tomography (diceCT) without causing tissue degradation. This represents the first step toward a multiscale pipeline for brain visualization. We studied brains from adolescent male Sprague-Dawley rats, comparing experimental (diceCT-stained then de-stained) to control (without diceCT) brains to evaluate neural tissues for immunolabeling integrity, compare somata sizes, and distinguish neurons from glial cells within the telencephalon and diencephalon. We hypothesized that if experimental and control samples do not differ significantly in quantitative metrics, brain tissues are robust to the chemical, temperature, and radiation environments required for these multiple, successive imaging protocols. Visualizations for experimental brains were first captured via micro-computed tomography scanning of isolated, iodine-infused specimens. Samples were then cleared of iodine, serially sectioned, and prepared again using immunofluorescent, fluorescent, and cresyl violet labeling, followed by imaging with confocal and light microscopy, respectively. Our results show that many neural targets are resilient to diceCT imaging and compatible with downstream histological staining as part of a low-cost, multiscale brain imaging pipeline.
Examining of the countries in terms of water resources along with the effect of climate change by time series clustering
Authors: akay özlem 
Published: February 2021

Abstract
Today, the problem of climate change is addressed in many ways. The most important effect of climate change is the disruption of the water cycle. Therefore, the location and timing of the water resources in the world are changing. Water is an indispensable resource that connects all living things together and directly affects their lives. Water is not only a biological requirement for man, but also for economic, social, and cultural life itself. However, this resource, which is of vital importance, exists unfortunately in a limited amount on earth. This study aims to identify similar countries in terms of water resources by taking into account the changes in precipitation amounts together with climate change. For this purpose, a time series clustering analysis was conducted to precipitation amounts of 21 countries between 2009-2017 with the Hierarchical clustering and Partitioning Around Medoids (PAM) clustering methods. Countries are divided into two clusters and they were evaluated according to their water risk levels and populations. It should be noted that countries with low precipitation, high risk of water, and a high population should take urgent measures for climate change.