bluuebunny/crossref_metadata_2025_split huggingface dataset:
Insight on the Exploration Potential of the Ordovician Gas Play in Tunisia Ghadames Basin, North Africa
Authors: Troudi Habib , Chevalier Francis , Alouani Wael , Mzoughi Wala , Abdelkader Omri 
Published: November 2018

Abstract
In Tunisian Ghadames sag basin, a significant portion of natural gas resources are looked within low permeability Ordovician sandstones deposited immediately below the Early Silurian Tannezuft world-class source rock.
The objective of this study was to develop an integrated approach to better estimate the amount of gas stored in this emerging play via the analysis of four fundamental elements: 1) the thermal maturity of the Silurian ‘hot shales’ source rock, 2) the trapping mechanism and the architecture of Upper Ordovician paleo-valleys, 3) the impact of diagenesis-lithofacies association on petrophysical properties, and 4) the fracture distribution/density and their contribution in the production.
The Early Silurian hot shales constitute the essential ingredient for the development of a pervasive gas accumulation play. The gas generated at the deeper part of the basin has charged the underlying Ordovician low-permeability sandstones mainly through complex faults system inherited from the basement. During hydrocarbon maturation and charging, pore pressure increases at rates that exceed the normal gradients, leading to local over-pressure as seen in several wells drilled down to the Ordovician reservoirs. Lateral migration via regional faults is confirmed by numerous discoveries at the edges of the basin far away from the gas kitchen.
Besides the structural closures accumulations, more complex structural/stratigraphic or purely stratigraphic traps are deemed within the Late Ordovician, and documented for instance by the development of incised paleovalleys filled with multiple fluvio-glacial and marine clastic sediments (i.e Algeria, Libya). The discovery of hydrocarbon pay zones outside of structural closures and the result of the long term tests confirm this hypothesis.
Based on seismic data it is generally very hard to recognize the paleorelief marking the base of the Late Ordovician sequence. Key elements from core studies, regional correlations, isochore maps and sequence stratigraphy have been combined accordingly, leading to a conceptual model within the observed framework. It is then possible to identify the multiple incision surfaces associated with reservoirs of Jeffara and M'Krata Formations.
The reservoir quality is considered as a major risk in deep areas (&gt;4 km). Although, the primary pores space have been occluded by quartz overgrowths and clay cementation or lost by lithostatic compaction. The substantial gas rates observed in several wells drilled in the junction of NE-SW and NS fault trends constitute an evidence of the contribution of open fracture into the flow.
This new insight into this play has been used by OMV to identify in Ghadames basin the area with possible "Tunnel Valley features", analogues to those drilled in Libya Murzuk basin (Ghienne, 2003).
Hydrocarbon Accumulation Model of Upper Cretaceous Mishrif Formation and Oilfield Discovery in Western Abu Dhabi
Authors: Lv Mingsheng , Al Suwaidi Saeed K. , Ji Yingzhang , Swain Ashis Shashanka , Al Shehhi Maryam , Luo Beiwei , Mao Demin , Jia Minqiang , Zi Douhong , Zhu Jin , Ji Yu 
Published: November 2018

Abstract
Western Abu Dhabi locates in the west of Rub Al Khali Basin, which is an intra-shelf basin during the Late Cretaceous. The Shilaif source, Mishrif reservoir and Tuwayil seal forms one of the Upper Cretaceous important petroleum systems in the western Abu Dhabi Onshore. However, less commercial discoveries have been achieved within Mishrif Formation during the past 60 years since the large scale structures were not developed in western Abu Dhabi and the stratigraphic traps have not been attracted attention.
This study aims to investigate the exploration potential of both Mishrif structural and stratigraphic traps. It provided detailed study on Shilaif source rock, Mishrif shoal/reef reservoir and Tuwayil seal capability. Oil-source rock correlation, reservoir predication and basin modeling have been carried out for building Mishrif hydrocarbon accumulation model by integration of samplings, wire loggings and 2D&3D seismic data. Shilaif Formation is composed of laminated, organic-rich, bioclastic and argillaceous lime-mudstones and its generated hydrocarbon migrated trending to high structures. Three progradational reefs/shoals in Mishrif Formation were deposited along the platform margin, which are characterized by high porosity and permeability. Tuwayil Formation consists of 10-15ft shale interbedding with tight sandstone, acting as the cap rock of Mishrif reservoirs.
Mishrif hydrocarbon accumulation mechanism has been summarized as a model of structural background controls on hydrocarbon migration trend and shoal/reef controls on hydrocarbon accumulation. It is consequently concluded that Mishrif reefs/shoals overlapping with structural background are the favorable exploration prospects, and oil charging is controlled by heterogeneity inside a reef/shoal, the higher porosity and permeability, the higher oil saturation. Two wells have been proposed based on the hydrocarbon accumulation model, and discovered a stratigraphic reservoir with high testing production. This discovery encourages a new idea for stratigraphic traps exploration, as well as implicates the great exploration potential in western Abu Dhabi.
Pushing the Limits of Coiled Tubing to Address the Challenges of Matrix Stimulation in Multi-Lateral Extended Reach Power Water Injector
Authors: Jassem Hasan , Salman Naji K. , Said Rifat , Ahmed Danish , Al Hamwi Kaisar 
Published: November 2018

Abstract
In Middle East carbonate reservoirs, power water injector (PWI) wells are typically completed with long openhole laterals. The reservoir contact provides pressure support and enhances sweep efficiency in the low-transmissibility reservoirs. Due to the wells deviation and length, coiled tubing (CT) interventions are required to successfully enter and identify each lateral, as well as to remove formation damage by pumping the matrix stimulation treatment across entire laterals.
During such CT interventions, laterals are accessed thanks to a hydraulically operated lateral identification tool (LIT), while the stimulation treatment is pumped through a ball-drop-activated high-pressure jetting nozzle (HPJN). LIT and HPJN are efficiently operated by monitoring downhole pressure values both inside and outside of the bottomhole assembly, in real time thanks to CT fiber-optic telemetry. Those downhole pressure readings further assist in optimizing the pumping rate during the job, while keeping it below the fracturing pressure. Finally, the telemetry provides support for gamma ray (GR) logging, which facilitates depth control and lateral identification.
This study features a case history during which the matrix stimulation treatment was conducted in two separate CT runs for both laterals of the well. For the first run, the CT initially entered L-0 following the natural path of the well, whereas L-1 was accessed by activating the LIT. Correct lateral entry was confirmed by matching the acquired GR readings with reference logs. After successfully accessing L-1 and reaching its maximum depth, a ¾-in. ball was dropped to isolate the LIT and activate the HPJN for stimulation.
During the second run, as the CT entered L-0, GR monitoring was used to confirm lateral accessibility. The stimulation treatment was pumped after reaching maximum depth and isolating the HPJN. During the stimulation of each lateral, 20% viscoelastic diverting acid was utilized for diverting from high-intake zones and 20% HCl to stimulate damaged/tight zones.
This operation illustrates how downhole pressure gauge readings are used to sequentially operate the LIT efficiently and activate the HPJN, as well as to pump the matrix stimulation treatment below the fracturing pressure. Real-time GR readings, meanwhile, are used for depth control and to correctly identify laterals.
Use of Legacy and Real Time Data to Overcome Anti Collision Challenges in Highly Congested Fields, Onshore Abu Dhabi
Authors: Dutta Ashim , Stefan Aillud Gary , Bermudez Martinez Rafael , Al Hosani Mariam , Jaiyeola Abiodun , Alejandro Aranda Jose , Al Mansouri Ibrahim , Ahmed Baslaib Mohamed , Al Bairaq Ahmed 
Published: November 2018

Abstract
Decades of field development in onshore Abu Dhabi fields has resulted in significant operational challenges in planning and drilling new wells. These highly congested fields pose a high risk of well collision due to inherent range errors in the accuracy of well survey measurements obtained during the life of individual fields and reservoirs. The study discusses a methodology for improving and normalizing the accuracy of legacy wellbore survey data to aid successful planning of recent multilateral drain hole strategy and how real time data corrections can aid in accurate wellbore placement.
Multilateral wells are risked by higher collision issues for having target areas in separate azimuths from single surface location (SL). Proposed wells were subjected to lower Separation Factor (SF) due to high density of wells. In the study area, survey data of existing vertical and horizontal wells in upper and lower reservoirs in the proposed well path were studies and plotted in well sections and maps in Geological model. Well anti-collision runs of proposed lateral holes with offset wells were done in drilling planning softwares. A notional model study carried out with one of the proposed triple lateral wells in ADNOC Onshore with nearest offset wells with MSA and SAG correction resulted in collision risks being reduced by 52% and hence qualifying with the minimum SF required for safe drilling.
Recent reservoir development strategy in an Abu Dhabi Onshore field is to drill trilateral wells targeting multilayered reservoirs to maximize production while optimizing sweeping efficiency. Well survey quality management with In-Field Referencing (IFR), Multi Station Analysis (MSA) and SAG Correction are the primary steps to be applied to MWD survey measurements to reduce the well collision risk. The normal well anti-collision study with nearest offset wells is mandatory as per standard drilling practices and with densely populated wells in one of the giant Abu Dhabi Onshore fields, it is becoming challenging to meet the minimum separation factor (SF&gt;2) required by the company policy.
A survey correction in all legacy wells followed by real time survey correction in triple lateral wells will add a significant value concerning collision issue in the proposed triple lateral campaign. With growing number of wells in highly congested fields, Pad drilling coupled with advance survey management technique will result in high value addition for future drilling campaigns without having collision risks and hence pave the way for future infill development strategy without subsurface space constraint.
Human Factors in HSE Performance: Using Brain Science to Guide Behavioural Developmental, Pro-Active Talent, Capabilities and Potential for the Long Term
Authors: Jahne Peter 
Published: November 2018

Abstract
We strive for excellence. Such excellence continuously moves to higher standards and to cover more scope. Using another terminology, it is about continuous improvement built upon the realization from learning through experiences. With this as our guiding concept, the long-term value is about developing a framework that drives itself towards enhancement, towards self-governance.
The HSE preparedness standards are guided by the capability to predict scenarios of the future. Specifically, context-shaped scenarios based on very focused activities that include the environmental (nature), material (equipment & tools), procedural (operating processes) and the human (mindFLEX) dimensions. The core element towards superior HSE standards remains at the human level - the core. It is the individual / group mental and behavioural capabilities that become the blueprint, the engine, the calibrator and enhancer of HSE.
If operational excellence is the objective, the people behind it are to sculpture its shape, define its course and develop a behavioural internalization programme. Their behavior then becomes the expression of what their brain is made of. It is therefore the objective to assess, develop and guide brains to have what it takes towards HSE excellence.
Step Change in Reservoir Monitoring in Complex Borehole Environments
Authors: Bin Noordin Firdaus , Mosse Laurent , Albuali Abdullah , Dasgupta Suvodip , Raina Ishan , Zhou Tong 
Published: November 2018

Abstract
Reservoir monitoring carried out using previous-generation pulsed neutron logging tools worked well in ideal borehole conditions. However, evaluations were complicated in non-ideal borehole environments, such as gas in the borehole, which affects capture cross section, sigma, and thermal neutron porosity measurements, changing borehole fluid holdup, which confuses carbon-oxygen interpretation, and identifying hydrocarbon type using only neutron porosity when oil density and hydrogen index are very low or open hole (OH) data are unavailable.
A new-generation pulsed neutron logging tool has been introduced that benefits from a high output neutron generator, two LaBr3 detectors, one yttrium aluminum perovskite (YAP) detector, one neutron source monitor, and an improved acquisition sequence. It provides self-compensated measurements of sigma and thermal neutron porosity, along with full capture and inelastic spectroscopy, including total organic carbon (TOC) and carbon-oxygen ratios. This tool also measures a new formation property called the fast neutron cross section (FNXS), which provides a gas saturation estimate independent of conventional methods. All measurements are recorded in the same logging pass, thus reducing overall logging operation time.
Pulsed neutron measurements were acquired in lateral wells using the new generation tool in the A field, onshore Abu Dhabi. Through lateral sections with changing oil, water, and gas holdups in the borehole, and in changing completion environments, robust sigma and neutron porosity measurements were acquired with the help of the automatic self-compensation algorithm. Neutron porosity helped quantify gas saturations where the OH data are available and of good quality. However, in zones where it is not possible to use the neutron porosity by itself (for example, in zones with missing or uncertain OH results), the FNXS measurement provided an independent estimate of gas presence and saturation. FNXS of brine (7.5 1/m), calcite (7.5), and oil (6.0 to 7.0), are similar and strongly contrast with the FNXS of gas (1.5 to 2.5). Thus, the measurement is insensitive to porosity by itself but highly sensitive to gas presence. A crossplot of thermal neutron porosity (TPHI) and FNXS provides a robust estimate of gas saturation in wells where OH results are uncertain or not available.
This paper presents, through multiple examples, a first comprehensive look at the various challenges faced while logging lateral wells in a light oil environment and showcases how a combination of self-compensated measurements coupled with the new measurement of FNXS can make data interpretation more robust in complex borehole and completion environments.
Application of Interwell Partitioning Tracers for Evaluating the Effectiveness of Chemical EOR in Field A in Southern Sultanate of Oman: A Case Study
Authors: Guntupalli Suryanarayana , Chatterjee Monalisa , Svec Yi , Al-Shuaili Khalfan , Amri Mohsin , Pugla Sarika , Hewitt Paul 
Published: November 2018

Abstract
This paper discusses a case study including the design, implementation and results of an Interwell Partitioning Tracer Test (IPTT) to measure incremental oil recovery from an ASP flood in a major sandstone reservoir in a field (Field A) in Southern Oman operated by Petroleum Development Oman (PDO).
Conservative tracers have been used over decades to evaluate conformance of a flood in reservoirs. Chemical tracer research and development as well as enhanced interpretation capabilities lead to the availability of a number of unique chemicals that allow remaining oil measurement to be routinely measured at the pattern and field level.
An inverted five spot pattern pilot area was chosen in Field A to apply interwell partitioning tracers with three time lapsed IPTT surveys between February 2014 and January 2017 to quantify desaturation by ASP. First, one unique passive tracer was injected in a central injector of an inverted 5 spot pattern flood to study the conformance of waterflood within the pilot area prior to an ASP application. The second stage was carried out during the pre-ASP water flush where one passive and two unique partitioning tracers were employed to estimate the remaining oil saturation after waterflood within the pilot immediately prior to the ASP flood. The third phase was initiated post the ASP flood where one passive and two unique partitioning tracers were added along with chase water. This final step was aimed at evaluating the effectiveness of the ASP flood through estimation of residual oil saturation within the water contacted pore volume between wells.
The resulting passive and partitioning tracer curves were assessed for their difference in retention times related to the amount of remaining oil saturation and tracer solubility in oil and water. The partition coefficient values were measured at reservoir conditions in a specialist laboratory that was used to estimate the average pre-and post-ASP flood oil saturation within the flooded pilot area of Field A. The results of the study showed an excellent reduction in oil saturation by about 30% within the pilot area. Desaturation level in the pilot determined by IPTT was consistent with other methods.
Performance Evaluation and Field Trial of Self-Adaptive Microgel Flooding Technology
Authors: Sun Zhe , Kang Xiaodong , Tang Xiaoxu , Wu Xingcai , Li Qiang , Wang Yu , Wang Tianhui , Zhang Hong 
Published: November 2018

Abstract
Bohai offshore oilfield in China is characterized by high oil viscosity, strong reservoir heterogeneity and big inter-well distances, which leads to the breakthrough of injection water in deep reservoirs with poor sweep efficiency and development effect. To solve this problem, this paper evaluated the performance of self-adaptive microgel system (SMG), and introduced its application in field trial.
The self-adaptive microgel is a kind of microsphere in various sizes with strong deformation ability. In this paper, the physical and chemical properties of the self-adaptive microgel are studied by means of metallographic microscope and the statistical principle. Also, the extreme permeability value of the self-adaptive microgel which allows it to flow though the core is determined through core flow experiments and the evaluation method of resistance factor and residual resistance factor. Furthermore, a long core is used to evaluate the fluid diversion ability of the self-adaptive microgel under the condition of constant speed and constant pressure flooding. Finally, a field trial case study of the self-adaptive microgel is analyzed.
Experiment results suggest that the self-adaptive microgel has good water swelling properties, narrow particle size distribution, huge inaccessible pore volume and large accessible pore volume of its carrier fluid. When the self-adaptive microgel with micron and submillimeter particle size flow through the core and the injection pressure stays stable, the permeability limit is 237×10−3μm2 and 712×10−3μm2, respectively. Since the self-adaptive microgel enters larger pores and generates plugging effect, while its carrier liquid enters smaller pores and displaces oil. So it obtains combined effects of "plugging" and "flooding". Moreover, the oil increment of the self-adaptive microgel under constant pressure flooding is higher than that under constant speed flooding. The case study shows that self-adaptive microgel flooding can increase oil production and reduce water cut obviously, which obtains technical and economic success.
Also, this paper preliminarily establishes a property evaluation method for the self-adaptive microgel, analyzes its mechanism and displacement effect. Furthermore, the field trial effect of self-adaptive microgel flooding is explored. In summary, the research results provide a theoretical basis and technical support for the application of self-adaptive microgel flooding technology.
Considerations of Pipeline Crossing Design
Authors: El-Chayeb Abdul Rahman , Wang Don , Kamal Faris , Takieddine Oussama 
Published: November 2018

Abstract
Pipeline crossings are an integral part of brown field developments and their design for shallow water conditions poses a number of challenges which require special considerations. Hydrodynamic stability and Vortex Induced Vibration (VIV) are typical examples. For both of these design aspects, there is no specific design criteria and methodologies dealing with crossings as is the case for pipelines resting of the seabed which, among other codes and standards, are covered by DNVGL RP F109 and DNVGL RP F105 for stability and VIV respectively. In the absence of specific design criteria, the industry have relied on interpretations of existing codes leading to crossing designs with varying failure probabilities and safety levels for different projects and different operators.
This paper discusses the main aspects of pipeline crossing design in shallow water conditions as is the case for the Arabian Gulf Region. In this region, the water depths could be close to the limits of applicability of the conventional design codes which were established based on experiences and considerations for other geographical regions. As a result, the design of crossings poses an engineering challenge as the calculated allowable span lengths tends to be short and the number of supports greater than what can be reasonably constructed for the pipeline to sit on all supports. The viability of using design criteria adapted from these codes for VIV is assessed using full dynamic simulations taking into account the compressive axial loads in the crossing. It is shown that for the short crossing spans, which are typical in the shallow water of the gulf region, the onset of any VIV will result in phenomenon which is called here "crosswalking". This crosswalking will result in a lateral displacement of the pipeline over the crossing sleepers resulting in an increase in the first natural frequency due to the reduction in axial compressive loads and the change in behavior from beam to shallow arch.
Implementing the analysis procedure discussed in this paper and taking into account the potential for crosswalking will help increase the length of the crossing spans. This increase can be to a level where the hyperstatic conditions can be eliminated and the crossings can be designed to be construction friendly. This will have direct cost and schedule impact on the execution of brown field developments where crossings constitute a major element of the project. It is hoped that further work will be done on studying the VIV of pipeline spans and crossings under axial compression as this area of pipeline engineering has not been fully explored and the focus of VIV research has been directed to risers which are always under axial tension.