bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Distribution Controlling Factors of Reef and Shoal, and Their Favorable Plays Analysis: Changxing(Permian)-Feixianguan Formations(Triassic),Sichuan Basin
Authors: Long Wen , Yu Yang , Qi Zhang , Yi Liu , Xian Zeng Yun , Liang Xu 
Published: March 2015

Abstract
Reef and shoal gas reservoirs in the Permian-Triassic Changxing-Feixianguan formations, Sichuan Basin, are typical representative of the marine carbonatite gas reservoirs in china. Breakthroughs in exploration make it necessary to know the distribution controlling factors of reef and shoal. Based on the comparative analysis of various well data and 3D seismic, the impact of various factors is studied on the distribution of reef and oolitic shoal, such as the geometry of the Kaijiang-Liangping trough, Late Permian regional palaeogeomorphologic framework, tectonic extension, system tracts of the Longtan-Feixianguan formations. The following conclusions were drawn. (1) At the end of Late Permian, the palaeogeomorphologic framework of the Sichuan Basin was "three depressions separated by three uplifts" which played a key role in controlling the distribution of reefs and oolitic shoals. (2) Transgressive systems tract (TST) deposits dominated the Longtan-early Changxing period, mid-late Changxing period has a highstand system tract (HST) deposits feature. Highstand system tract (HST) deposits dominated Feixianguan period. The change of system tracts made it possible to develop multistage reefs near the platform margin. Oolitic shoals may occur on the progradation slope margin in the Kaijiang-Liangping trough, while the aggradational platform margin is the most favorable development zone of Oolitic shoals. (3)The unevenness of extension caused the differences in the development of platform margin palaeogeomorphologic, which influenced the development time, continuity and their superimposed relationship of reef and oolitic shoal. (4)The methods, based on 3D seismic, are studied for characterizing the bioherms distribution along the platform margin. The distribution and shape of Bioherms along the platform margin can occur as curved belt, moniliform and atoll, or occur as echelon belt oblique to the platform margin. Favorable Plays are analyzed based on the study results.
Seismic Velocity Uncertainty Analysis In An Underexplored Basin
Authors: Bacenetti R. , Andreoletti C. , Capponi G. , Martera M. Della 
Published: March 2015

Abstract
In areas characterized by complex geology, Depth Velocity Analysis is the mandatory instrument to estimate the sharp velocity variations that can be expected; seismic data and processing tools are necessary but not sufficient ingredients for successful depth imaging results, so sound a priori information must be retrieved from well information and from the geological knowledge of the area of study, as well as a close integration between the geophysical and geological contexts. A proper estimation of seismic velocities is not only fundamental to obtain good imaging quality and correct depth positioning, but it can also be a key input for detecting the presence of overpressures: usually, overpressured areas are associated with seismic velocity inversions. Moreover, in areas where anisotropy is unknown because of lack of well information, seismic velocities are affected by uncertainty: this must be taken into account in order to quantify the consequent uncertainty both in depth positioning of the target and in pore pressure prediction. In this paper a case history from Offshore Ghana is presented, dealing with the above mentioned issues: the intimate correlation that exists between anisotropy and velocity analysis is investigated, and the impacts of the uncertainty that affects them is considered.
Geological Interpretation of a Weakly Confined Channel Complex Integrating Seismic Amplitudes and Elastic Inversion Attributes (Offshore Ghana)
Authors: Care Davide , Cavanna Giorgio , Capponi Giulia , Fonnesu Franco , Knezaurek Gabriella , Piva Andrea , Torricelli Stefano 
Published: March 2015

Abstract
During the last decade, seismic-based studies have become fundamental for detailed and objective descriptions of reservoir depositional elements, a necessary condition for building robust stratigraphic frameworks and sedimentological interpretations unbiased by questionable analogues or existing models. A close integration of sedimentary geology and geophysical interpretation is presented here to demonstrate that these two disciplines can support each other to provide a powerful tool for predicting reservoir sandstones architecture.
The work was carried out on the deep-water sequences of the Ghanaian offshore, which have been interpreted as weakly confined channel complexes (WCCC) deposited at the base of slope. WCCC are approximately 150–300m thick and 10–15km wide and made of stacked, laterally amalgamated channels and lobes vertically separated by shale-prone intercalations.
Detailed interpretation of individual seismic reflections followed by an elastic inversion and Bayesian facies classification calibrated with 3 wells allowed to identify several distinct small-scale composite channel fills and lobes forming sand bodies 1–2km wide and 15–25m thick. High and low-sinuosity sand bodies compensate each other and stack vertically, migrating progressively from West to East. Furthermore, some channel-fills show a marked aggradational pattern. The overall depositional pattern is believed to represent a progressive decrease in sediment supply leading to the de-activation of the system.
Despite the key sand bodies were correctly identified on seismic amplitudes and well-logs through conventional, "qualitative" approaches, their subsequent "quantitative" imaging by elastic inversion and facies (shale, brine and gas) probabilities allowed to clarify many uncertainties in the stratigraphic and sedimentological framework, particularly where the marked AVO fluid effect inevitably interfered with the initial, purely sedimentological interpretation. High-res biostratigraphic data further confirmed the inferred physical-stratigraphic and litho-fluid framework established through the integration of seismic sedimentology and quantitative geophysics.
Evaluation of Chelating-Hydrofluoric Systems
Authors: Al-Harbi B.G. , Al-Khaldi M.H. , Al-Dahlan M.N. 
Published: March 2015

Abstract
Different chelating agent-HF mixture systems have been used to stimulate deep hot sandstone formations. Typically, chelating agents are used as a substitute for HCl and organic acids in HF based systems to stimulate hot and exotic oil and gas sandstone formations. Apart from reducing the risk of corrosion, secondary and tertiary reactions, the system can be deployed in formations containing high clays and carbonates as well as iron and zeolite bearing sandstone formations. However, several fields' cases indicated precipitation of aluminum-based scale following acid treatments that include these systems. The focus of this paper is to identify the type of precipitations that occur during the reaction of chelating-HF systems and determine the factors that affect these precipitations.
Solutions of different ethylenediaminetetraacetic acid EDTA containing two ammonium bifluoride ABF concentrations of 0.5 and 1.0 wt% were examined in this study. Aluminum chloride or calcium chloride was added separately to each chelating-HF solution to contain various concentrations of aluminum or calcium. The filtered liquid was analyzed using inductively coupled plasma ICP, while formed solid precipitate was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).
The main type of precipitate in solutions containing aluminum was identified as AlF3. The amount of precipitate was found to be dependent on solution initial aluminum and free fluoride concentrations. In other words, the main factor that controlled the aluminum-fluoride precipitation was found to be F/Al ratio and above a critical F/Al value, AlF3 precipitates.

Introduction
Hydrofluoric based acids have been extensively used to stimulate sandstone formations with variable success rate. The poor results are mainly attributed to the rapid spending rate, subsequent precipitation, and decomposition of sensitive clays and matrix unconsolidation (Smith and Hendrickson, 1965; Gidley, 1985; Brady et al., 1989; Simon and Anderson, 1990; Shuchart, 1995; Gdanski and Shuchart, 1996; Thomas et al., 2001). Hydrofluoric based acids went through several optimization and development processes to overcome these potential limitations and the main drivers were developing acidizing fluids with low corrosivity, retarded reaction rate and without undesirable reactions by-products (Rae and Di-Lullo, 2003). In terms of regular mud acid, in order to avoid undesirable reactions by-product, HCl/HF ratio is recommended to be maintained high i.e. 9/1 (Gdanski and Shuchart, 1996). Nevertheless, strong acids such as HCl decompose sensitive clays i.e. illite and chlorite by extracting aluminum resulting in amorphous silica precipitation and fines migration (Simon and Anderson, 1990; Thomas et al., 2001).
Geomechanical Technology for Seal Integrity Analysis: The Three-Step Approach
Authors: Davison J.M. , van den Bogert P. , Schutjens P. , Ita J. , Fokker P. 
Published: March 2015

Abstract
A clear understanding of the subsurface pore pressure and the presence of geological seals are significant considerations when designing safe wells and optimal production strategies for oil and gas resources. This paper highlights geomechanical techniques and tools which have been developed to assure injection operations for large scale EOR projects in South-East Asia. A key concern is if depletion or injection will lead to reservoir or seal failure by tensile fracturing or shear faulting. If so, will these fractures and faults "grow" upwards and provide a pathway for fluids to escape to the seafloor? First, a 1D-model is made of the total stresses and pore fluid pressures and how these change as a function of depth and depletion/injection. This empirical approach helps to highlight the zones of relatively low minimum effective stress where there is greater risk of rock deformation which will impact operations. Where more detail and refinement is required in terms of the identified risks, we analytically describe the reservoir and overburden deformation with the theory of poro-elasticity, Mohr-Coulomb-type shear faulting, and tensile fracturing. Analytical geomechanics aims at a mechanistic understanding using simplified geology and simplified pore pressure patterns, but with realistic mechanical rock properties. The third step delivers greater detail of the technical complexity using a 3D finite-element simulator. These numerical techniques can simulate the effects of complex structural geology or intra-reservoir compartmentalization, inhomogeneous depletion, and spatial variation in rock mechanical properties. It makes sense to start simple and gradually bring in more complexity whilst adjusting geomechanics support accordingly. We demonstrate the above three-step approach with examples from projects in the South China Sea, offshore Malaysia, which illustrate the multi-disciplinary aspect of geomechanics and its impact on safety, efficiency (costs), and the technical reputation of our company and industry.
Optimal Infill Drilling Using Simulation and Cross-Functional Integration-Ubit Field Example
Authors: Krukrubo G.J. , Nwakwue J.E. , Babafemi O.A. , Young R.H. , Ogunnusi H.O. 
Published: March 2015

Abstract
The Ubit Field, located southeast of the Niger Delta, is a Nigerian National Petroleum Corporation (NNPC)/Mobil Producing Nigeria (MPN) Joint Venture (JV) asset that has been on production for more than 40 years (September 1970). Ubit has approximately 2.4GBO OOIP, with production peaking at ~137,000 BOPD in 1997, and is currently at ~85,000 BOPD. With much of the reserves yet to be produced, it is important that an optimized field development plan be implemented to maximize recovery. Guided by reservoir simulation models, a revised Ubit Field re-development plan was approved in December 2009. Infill development has proceeded as designed, and the first infill drilling program is underway.
Integration of results from reprocessed seismic, geologic interpretation, core, log and reservoir simulation studies, coupled with state of the art technology in well completions, were critical in developing an optimized depletion plan. Reservoir simulation results consistently indicate higher reserves capture with increased well density from infill drilling that targets unswept locations around and down-dip of abandoned completions. Results from the integrated studies suggest varying the optimum well spacing requirements for the different sections of the reservoir. The recovery factor in the lower quality reservoir section (Disturbed Biafra) could be vastly improved by increasing well density.
The multidisciplinary study for field development indicates that approximately 100 additional wells should be drilled to tap unswept resource in the field. This aggressive approach will maximize ultimate recovery, but requires closer well spacing than minimum regulatory specification. The technical basis for this strategy, primarily reservoir simulation models anchored in measured hard-data, is the core focus of this paper.
Variable Nozzle-Based Inflow Control Device Completion: Inflow Distribution Comparison, Analysis, and Evaluation
Authors: Abd Elfattah Mahmoud , Al-Yateem Karam , Qahtani Hassan , Rajabian Behzad 
Published: March 2015

Abstract
This paper presents a study of horizontal well completions equipped with inflow control devices (ICDs) in a large, unconsolidated sandstone reservoir in Saudi Arabia. The focus is the improved production performance gained through a completion using ICDs with variable nozzle settings across the openhole section vs. that from a cemented, perforated liner completion and uniform nozzle setting ICD completion performance. Discussion includes an overview of ICD and intelligent completions and their components, and the advantages and limitations of both uniform/variable types of ICDs completion design methods. Results from two wells in Saudi Arabia show that the major advantages of completions using ICDs with variable nozzle settings are the operator's ability to make adjustments at the wellsite; to balance the inflow from areas of differing permeability; to reduce the pressure drop across the completion; and to better controls water production compared with uniform nozzle setting ICD completion.
Inflow Control Device (ICD) technology has been developed to overcome horizontal well production/injection challenges. ICD completion with packers segregates openhole (OH) horizontal section into compartments to balance inflow/outflow along the well and control undesirable water/gas production.
There are various types of ICDs such as tube, helical, orifice and nozzle ICDs. The advantages of orifice/nozzle ICDs (Fig. 1) are their viscosity independence and the nozzle installation at the wellsite according to the attained while drilling properties/openhole logs that might change ICD completion design optimization. The optimum ICD completion is one which balances influx from heterogeneous reservoirs and control water/gas production and simultaneously without creating a huge pressure drop across the completion.
Safety Enhancements Using Wireless Technology in Gas Plants
Authors: Al-Hashim Najeeb S. , Al-Deraa Abdulrazaq H. 
Published: March 2015

Abstract
The motive force behind this advanced concept in implementing "Wireless Technology Using Solar Powered" instruments is to get hydrogen sulfide (H2S) and lower explosive level (LEL) signals from an unreachable location where hazardous waste is being handled to a safe centralized control room. Implementing this would reduce the cable cost and the maintenance. This solar power is eco-friendly. With wireless communication, allowing more sophisticated data to be transmitted to the centralized control room; appropriate steps have been taken to install wireless devices in remote location. Such technology plays a progressively essential role in up-to-date industries. The wireless solar powered sensors provide a cost-effective alternative and are being used increasingly for equipment and other applications in a diversity of industrial processes. In addition, its improved remote diagnostics makes plants and operations safer. In this paper, we will cover the benefits and challenges we experienced at the Haradh gas plant while implementing wireless technology to prevent massive threats and destruction to persons, property and equipment.

Introduction
Wireless technology has been growing exponentially over the years. Consequently, wireless technology developments are providing numerous advantages in gas plants and the operating plans for refineries. These developments are providing new opportunities for enhancing plant performance, reliability and safety while reducing installation and maintenance/operating costs. In Saudi Aramco's business, the safety of employees is at the top of its priorities. Since the lower explosive level (LEL) gas or hydrogen sulfide (H2S) could be present in most of Saudi Aramco's operation facilities, it is mandatory to install LEL/H2S sensors in every location where the hazardous gases are expected. For gas plants and refineries there are a lot of challenges related to monitoring H2S and LEL gas releases. The biggest challenge for monitoring releases of gas in plants is to cover isolated remote field locations such as the oily sumps area outside the plant fence. To overcome this challenge, a new solution was designed to fit this application. This solution can be achieved by installing standalone wireless H2S and LEL detectors powered by solar cells plus batteries, beacon and horn. The system consists of different equipment that is using Saudi Aramco standards as well as international standards. The International Society of Automation (ISA) standard for wireless systems - Process Control and Related Applications - is ISA 100.11a [3, 5].
This paper reviews the use of H2S and LEL solar powered wireless sensors for safe operation in gas plants and refineries. The paper also addresses the system design and integration.
Drill Pipe Riser Intervention System Successful Experience in Offshore West Africa
Authors: Rohart Christophe , de Fonvielle Henri , Bordet Laurent , Campbell William , Susak Nenad 
Published: March 2015

Abstract
While offshore intervention on subsea equipments is quite common, the increasingly deeper water operations require light weight intervention systems while meeting safe and stringent operating specification. For these new deep offshore challenges, the conventional risers are becoming a more costly and less desirable solution.
Starting with a recollection of the main drivers that motivated the development of drill pipe riser intervention systems (DPRIS[i]), the paper details the technical and economical challenges in West Africa that have led to the design of such a solution. When non productive time and financial aspects are taken into account, it makes sense to develop a dedicated system in order to provide fast and reliable intervention.
Depending on the field requirements, two different types of drill pipe riser systems using a proprietary double shoulder connection were used by operators. A first solution was developed in 1999 featuring a seal ring close to the external shoulder. Subsequently, a new solution featuring a gas-tight metal to metal seal on the pin nose was developed in order to address increasingly demanding and challenging operations.
Intensively used in West Africa since 1999, the solution using the seal ring has shown robustness and reliability while being used for several projects in Angola such as Girassol and Rosa and now GirRI. The paper draws a summary of these operations and the feedback on the field use and maintenance. Also it emphasises the successful qualification process for the metal to metal seal solution that has been used in offshore Nigeria since 2010 for the USAN project.
Imaging Velocity of Pre-Stack Depth Migration in Steep and Complicated Structures
Authors: Xiaoyun Dai , Xiaoxia Luo , Tiemin Wen 
Published: March 2015

Abstract
During the processing of pre-stack depth migration (PSDM) of seismic data in complex structures in western China, an anomaly of interval velocity inconsistent with geological features appears, even when the CRP gather is flattened and the residual velocity (or the residual moveout) returns to zero(Reshef, 2001). The model data analysis in this paper suggests that velocity errors in the shallow layer lead to these anomalies. In order to improve PSDM results of near-surface complicated zones, the velocity variation trend of the deep layer is restrained by geological constraints and residual spectra and afterwards an updated velocity modeling method using the corrected shallow layer velocities is applied. The crucial point in this paper is to understand the reasoning for velocity anomalies and to build a relatively correct velocity model using the PSDM velocity analysis.

Introduction
The pre-stack depth migration technique has recently been widely used to obtain better structural images of overthrust nappes in the piedmont zone of western China. Since the surface conditions are complex, poor shooting and receiving conditions result in a low signal-to-noise ratio (SNR) of seismic data and as a result, it is hard to identify effective seismic reflection information of shallow layers data. The very low SNR makes PSDM velocity modelling difficult.
The PSDM velocity model is derived from the initial interval velocity by velocity iteration and the interval velocity is converted from pre-stack time migration (PSTM) RMS velocity according to the DIX formula. Whether the iteration velocity is correct or not depends on if CRP gathers are flattened and reflection stack energy reaches a maximum. Using this rule, the accuracy of picking velocity is not guaranteed when CRP events can't be identified. There are more picking velocity errors of shallow layers in continental piedmont zone. The main reason is that piedmont lithology and the velocity of shallow layers is various in transverse and longitude. At the same time, the precision of the velocity spectrum is affected by poor shooting and receiving conditions, less valid multiple stacks and a low SNR of shallow seismic data. This paper focuses on the deep velocity error of complex structures affected by incorrect shallow velocity models that may cause structural deformation of PSDM results.