bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maintaining Well Integrity in Underground Gas Storage Wells in China Using a Novel Cementing Technology
Authors: Wu L. , Yi L. , Taoutaou S. , Yao K. , Fan Y. , Liu W. , Fan X. , Liu H. , Liu L. 
Published: December 2014

Abstract
Underground gas storage (UGS) wells have become the natonal strategy for natural gas storage and supply throughout China. PetroChina is building UGS facilities throughout the country, with planned construction extending from 2011 to 2015. The Chongqing gas storage well project in Central China is one of the constructed facilities. Because the life expectancy of gas storage wells is at least 50 years, long-term maintenance of well integrity is one of the major challenges faced during the construction and operations phases of UGS wells. The wells must bear the injection pressures, temperature changes, and frequent cycling of injection during production. With conventional cement, the pressure and temperature change during the injection and production phases can result in cement traction, compression, or microannulus failure. This leads to gas migration through the damaged cement sheath, which means the well will fail its mission as a UGS well.
To maintain well integrity, a novel engineered flexible and expanding cement system has been introduced for UGS cementing in the Chongqing project, whereas past service companies have failed to deliver the fit-for-purpose solution. The optimized mechanical properties of this novel cement allow the cement to remain intact under extreme pressure and temperature changes.
To prove the ability of the selected flexible and expanding cement to withstand the pressure change, logging was conducted at various times during the construction and after the casing pressure test cycle. The logs show excellent results.
Since its implementation, the flexible and expanding cementing system has become the standard solution for China's UGS wells, in which long-term well integrity and sustained casing pressure are required. This paper discusses the challenges for cementing UGS wells, which case histories describe the successful implementation of the FEC solutions.
Application of Micro-fine Cement for the Sequential Zonal Abandonment of a Multi-Zone Sand Propped Fractured Horizontal Well With Coiled Tubing - Lab Studies, Field Trial & Computational Fluid Dynamics
Authors: Boekholtz E. A. , Bansal B. D. , Pasturel C. , Madsen M. M. , Tonell D. 
Published: December 2014

Abstract
For the first time in a Danish field, micro-fine cement was used to abandon a multi-zone horizontal well by plugging each sand fractured zone sequentially. Lab testing was performed to investigate the depth of penetration of different conformance systems in a 20/40 sand pack. The micro-fine cement showed the highest penetration and was considered the best option for abandoning sand propped fracs in horizontal wells. The first field application was unsuccessful due to pre-setting of the micro-fine cement in the Coiled Tubing. Extensive lab tests were performed to understand the causes of the pre-mature setting of the cement. A new cement recipe was selected and subjected to modified lab test procedures to successfully abandon the horizontal well.
To economically develop chalk reservoirs in the North Sea, long horizontal wells are drilled, hydraulically fractured and waterflooding is applied to the field. To ensure conformance, flow from each fracture is controlled by a Sliding Side Door (SSD).
Well A suffered injection water breakthrough which could not be controlled by closing the SSDs. To enable the full abandonment of each zone the decision was made to isolate each zone sequentially from the toe of the well up with cement retainers and to use Coiled Tubing to squeeze a pre-determined volume of special micro fine cement into the zone in order to plug the tubing, the tubing-liner annulus, any cement channels and a limited section of the sand propped fracture. In this manner any potential water channeling between zones and with other wells in the pattern would be prevented.
This paper discusses the results of initial lab tests, causes of failure of the first job, testing of new micro-fine cement and the successful application. This paper also discusses the results of computational fluid dynamics simulations which were performed to understand the behavior of cement in a fracture and enable further improvements to similar abandonments in the future.
Chemical Solutions for Improved Waterflooding in Carbonate Reservoirs
Authors: Acevedo-Vélez Claribel , Mukherjee Joydeep , Yu Wanglin , Mounzer Hamza , Buckner Wanda , Falcone-Potts Susan , Hernandez Martha 
Published: December 2014

Abstract
Improving oil recovery in mature carbonate reservoirs is a significant challenge in the petroleum industry. Carbonate reservoirs present several characteristics which lead to low oil production during waterflooding, including reservoir rock heterogeneity and heterogeneous wettability. Several laboratory investigations have shown that changing the rock surface wettability to a more water-wet state can lead to significantly higher oil recovery during the waterflooding process. In particular, the addition of wettability altering surfactants enhance water imbibition into the low permeability matrix and enhance water spreading on the carbonate rock to release trapped oil and hence increase cumulative oil recovery. This paper reports the development of wettability altering surfactant formulations to improve waterflood performance in carbonates under a wide range of reservoir conditions (e.g., temperature, salinity). First, an efficient wettability altering surfactant was developed for application at low salinity (up to 4%) and moderately high temperature (up to 80°C) conditions. Second, a design of experiments was developed and executed to explore formulations consisting of surfactants and additives for application at high salinity (greater than 10%) and high temperature conditions (greater than 100°C). In addition, the effect of divalent cations on the stability of the surfactant formulations was investigated. Finally, laboratory studies were conducted to evaluate the performance of the developed surfactant formulation at relevant reservoir conditions, including core flood experiments. This paper also describes laboratory studies aimed at providing further insights into the wettability alteration mechanism by these surfactant formulations. Overall, the results presented in this paper support the hypothesis that altering the rock surface wettability using the developed surfactant formulation can improve waterflood performance in carbonates under a wide range of reservoir conditions, which may present a significant opportunity for application in the oil field.
Geosciences Understanding as a Breakthrough to Enhancing Borehole Stability Management - Lower Tawilah Sandstone, Central Yemen
Authors: Yasir M. , Neff P. , Zabalza I. A. , Klaa K. , Krusche K. , Kuzmanovic U. 
Published: December 2014

Abstract
Well bore stability management is key to HSSE and cost effectiveness while drilling. This work focuses on the role of Geosciences to understand, explain and better predict the occurrence of well bore stability issues during onshore drilling operations in Block S2, central Yemen.
To reach the primary reservoir target, the fractured Basement, development wells must penetrate a complex stratigraphic column, characterized by ten key formations and approximately 2000 meters thick. Lithologies vary from sandstones to carbonates, including salt layers with clay intercalations. Severe mud losses are often encountered in poorly consolidated sands of the Lower Tawilah formation where well inclinations are vertical or sub-vertical. At their most severe, they can translate to a complete loss of drilling mud returns on surface. Severe mud losses are not only a threat to borehole stability but they can have a serious impact on the drilling budget and timing.
In order to improve drilling efficiency and speed-up the decision-making process associated with mud losses management and well stability, a detailed Geoscience study has been carried out. This work focuses on identifying three critical factors to explain the occurrence of severe losses: –the lithological variability of the Lower Tawilah,–the formation pore pressure–the local stress regime.
Despite the challenging working environment and the interaction of geological heterogeneity, pore pressure and stress across the development area, the prediction and prevention of mud losses has been greatly improved while drilling new wells.
The main objective of this paper is to highlight the role these three major elements play during drilling by illustrating with case study examples. Finally, mitigating actions and strategies implemented to prevent and/or deal with severe drilling mud losses are presented.
G&G Data Integration to Model a Carbonate Giant Field: Predicting & Managing Reservoir Properties in an Underexplored Basin till Production Phase
Authors: Marini A. I. , Spadafora E. 
Published: December 2014

Abstract
The early integration of geological concepts and seismic (qualitative and quantitative) interpretation is a powerful tool to enhance the probability of success of an appraisal campaign. The presented example of an integrated workflow was applied to Perla Field (offshore Gulf of Venezuela), an Early Miocene carbonate reservoir containing gas and condensates. The work was therefore tailored on the integration of geological data and advanced seismic interpretation since exploration project start-up is a key to improve success of appraisal campaign and early production phases.
The presented case refers to an Early Miocene gas-bearing carbonate asset, Giant world-class reservoir. 3D Seismic data shows an isolated bank developed on basement high, thickness decreasing from crest-to-flanks. Wildcat well found 200m high-porous bio-GRST/PKST having moderate diagenetic imprint.
The red algae-dominated system formed low-angle ramps more than classical flat-top platforms. AVO attributes (Gradient) fully supported detailed seismic interpretation, since Carbonate reflections responded to elastic changes rather than subtle acoustic contrasts, negligible on conventional seismic.
A petroelastic model and strict quantitative amplitude reliability were validated.
Acoustic Seismic inversion was performed right after the wildcat well.
Efforts devoted to realistic a-priori model building accounted for overburden trend and carbonate sequences velocity fields. The inversion results permitted seismic to effective porosity calibration (Seismic Pseudo-Porosity Volume), a significant tool for the delineation campaign.
Inversion properties vs depositional facies geometries relationships also allowed facies belts areal definition; jointly with structural attributes they were used to optimize the number, locations and trajectories of delineation wells. Appraisal wells confirmed the porosity predictions at seismic scale, and approach stability. No needs for acoustic inversion or calibration revision were considered, due to the high-quality blind tests results on appraisals. The availability of hard-data from extensive core campaign, re-enforced the geophysical calibration to reservoir facies, via petrophysics and rock-physics lab measures.
Seismic Porosity, Non-Supervised, and Supervised Facies cubes got into reservoir model, driving the areal distribution of Sw and K.
Elastic-Porosity large variability was tentatively correlated with the factor Gamma-K, representing the frame flexibility, hence pore structure of different sed-petro-facies.
Manipulation of Elastic Inversion data and more stable Rock Physics Model would be the next development to capture internal reservoir model microstructure variances.
Complex Phased Development for CO2 EOR in Oil Carbonate Reservoir, Abu Dhabi Onshore
Authors: Figuera Luis , Al-Basry Ali , Al-Hammadi Khaled , Al-Yafei Arafat , Sakaria Dipak , Tanakov Mikhail 
Published: December 2014

Abstract
CO2 injection into oil reservoirs for EOR is well known as one of the most proven and efficient Enhanced Oil Recovery (EOR) processes. The subject study was conducted with the objective of enhancing oil recovery by injecting CO2 into a heterogeneous, low dipping and low permeability carbonate oil reservoir. The required CO2 is captured from a steel plant (Emirates Steel Industry (ESI)) which is part of a large scale carbon capture and injection project. The project entails capturing, dehydrating, compressing, and transporting the CO2 to the oilfields for sequestration and/or EOR processes. The carbon capture from ESI is part of a collaboration (Joint Venture) between ADNOC and MASDAR which will help make CO2 available for potential future EOR operations along with the added benefit of reducing Abu Dhabi's carbon footprint.
As part of this initiative, planning of the CO2 EOR process as part of ADNOC's EOR strategy is essential and includes building a phased development CO2 EOR model. The strategy is to breakdown the overall objective into phased developments/projects in order to gain experience in surface and subsurface aspects of CO2 EOR, operations and mitigate risk. The end goal of the phased development is to enhance oil recovery, improve CO2 utilization, and maximize project profitability by implementing more complex operations such as Continuous/WAG CO2 injection, CO2 recycling, and the development of "difficult oil" from flank areas with higher water saturation (transition zone). This paper discusses the benefits and rationale behind building such a phased development model.
Deployment of New Sonic-While-Drilling Technology in a Large Development Project in the Middle East: A Case Study
Authors: Murray Doug , Belaud Didier , Ogawa Ryoko , Shaban Mohamed , Edwards Ewart , Abbas Nashat , Al Ayadi Kholoud Ghareeb , Boyd Douglas 
Published: December 2014

Abstract
A new logging-while-drilling (LWD) sonic tool was successfully deployed in a large development project in the Middle East. The new LWD sonic tool offers robust compressional and shear measurements, irrespective of mud speed, and Stoneley information for a wide range of applications. The acquisition of LWD sonic measurements can be challenging. The introduction of the new tool with a novel hardware design, extensive tool modeling, and an alternative approach to data handling has significantly improved both overall data quality and the viability of advanced answer products while drilling.
The fundamentals of both wireline and LWD sonic measurements are similar; however, differences in the measurements dictated by the deployment environment need to be considered. LWD tools are deployed on a drillstring and have a large diameter. Wireline tools are much smaller and are deployed on wireline after drilling is completed. Operational frequencies, acquired waveform modes, and transmitter-receiver source spacings are also different. The most fundamental difference is that the new LWD tool uses quadrupole technology to acquire shear slownesses in slow formations (shear formation slowness slower than mud speed), whereas, in the same environment, the wireline tool relies on dipole technology.
Although there is considerable literature that discusses waveform quality, processing, and interpretation of wireline sonic measurements, very few such studies exist for LWD sonic measurements. In addition, no studies compare the measurements. To investigate the interpretation and use of the new LWD tool and to compare it with wireline sonic tool technology, both methods were deployed in the same wellbores in a large development project in the Middle East. Most observed disparities were across washed out boreholes where data quality from both wireline and LWD tools was negatively affected by the borehole environment.
Integrated Simulation Study of a Gas Condensate Field with Nitrogen and Hydrocarbon Recycling
Authors: El Gohary Mohamed , Al Bairaq Ahmed , Al Hashemi Hussain H. , Abed Abdulla , Saeed Yawar , Torrens Richard , Kumar Arun 
Published: December 2014

Abstract
This paper presents a feasibility study for the development of the unexploited outlying area of a gas condensate field operating under gas recycling mode to optimize condensate recovery. Heavier components have migrated to the flanks which is the motivation to exploit this area. To maintain reservoir pressure the voidage replacement ratio must be maintained at 100%. However, due to high demand for natural gas, a certain percentage is replaced with non-hydrocarbon makeup gas. This strategy has the potential to reduce the condensate recovery as well as affect the quality of the produced gas.
A reservoir simulation study was conducted to maximize the condensate and clean gas recovery through development of the flanks. Two major scenarios were created consisting of more than twenty different development strategies based on well location, number of wells and well production rates. Additional sensitivities on blow down time, under-injection, injection stream composition and compression were considered for both scenarios. The influence of the surface infrastructure on production performance has been quantified by the application of Integrated Asset Modeling, which improves the accuracy of the standalone reservoir simulation scenarios.
The study highlighted a significant upside in terms of oil recovery by exploiting the outlying area of the field. Multiple optimization scenarios were performed and a maximum gain of approximately 10% in recovery was observed above the base case. Integrated Asset Modeling led to more optimistic estimates of future recovery and reduced makeup gas production, through the removal of simplifying assumptions related to back pressure and injection composition.
Major Step Change in Sampling While Drilling Technology Combined with Best Practices Delivers Fluid Samples and Pressures in S-Shaped Well Over Challenging Thin Bed Successions
Authors: Tran Huy N. , Tang Binh V. , Nguyen Tuan M. , Tran Dinh V. , Tran Ninh D. , Hardikar Nikhil P. , Pragt Jos S. 
Published: December 2014

Abstract
This case study highlights a major step change in fluid sampling technology while drilling. The decision to deploy a Logging While Drilling (LWD) fluid sampler was made because of the S-profile well, which would have required pipe-conveyed wireline fluid sampling. This would have added rig days to the project and increased the risk of stuck pipe. One run of the LWD fluid sampler, during a wiper trip, was sufficient to acquire the necessary 60 pressure tests, fluid gradients, down hole fluid identification and analysis and PVT samples. Six single phase oil samples (four liters total volume) were acquired. Lessons learnt offer additional best practices and risk mitigation techniques for future LWD sampling projects.
The thin bed succession comprises centimeter to meter scale sandstones, inter-bedded with shales. The sandstones have a variable measured mobility between 1.2- and 296-mD/cP. This type of succession poses significant challenges to obtain a gradient for each sand layer, particularly since each layer may have different fluids. Moreover, inherent depth uncertainties in these measurements, affects the fluid gradient. The excellent repeatability of the pressures allowed adjusting formation tops by reconciliation to pressure profiles. This reconciliation process could only be achieved by taking many pressure tests (upto 60). A consequence of this process was the high-grading and selection of representative locations for sampling. There were zero lost seals during the pressure testing and sampling operation. Laboratory analysis results showed about 15% WBM filtrate contamination, which was comparable to wireline runs in the same formation.
In conclusion, this case study shows that LWD pressure and sampling technology provides high quality results over complex thin bed reservoirs with different fluid types; Operators no longer need to consider a well's deviation or complex geometry to collect fluid samples while drilling; the demonstrated operational efficiency and good sample quality resulted in significant savings in rig costs (USD 2 million) and the LWD sampling application reached the same sample integrity and safety standards as compared to existing wireline methods.
Experimental Study of Plastering Effect During Casing While Drilling
Authors: Naveen Velmurugan , Babu Vinay 
Published: December 2014

Abstract
The objective of this work is to experimentally understand the plastering effect during Casing while Drilling (CwD). CwD can be considered as the process of drilling the well wherein the drill pipes are replaced by the casing and the well is cased as it is being drilled. Literatures have exclusively shown that CwD is practiced with a notion to reduce the Non - Productive Time (NPT) and to tackle problematic zones of fluid loss or unstable formation. One plausible reason that has been claimed is the plastering effect during CwD, in which the drill cuttings are crushed to finer particles between the casing and the wellbore during contact due to limited annular clearance. These finer particles are smeared into the formation by the mechanical contact of casing to the wellbore. Plastering effect leads to formation of a thin layer of mud cake that is strong enough to prevent fluid loss and had been proven in the field trials.
Actual forces acting on the drill cutting in the limited annular space can be majorly divided as centrifugal force and the drag force due to circulation of drilling fluid. Apart from the smearing effect, the acceleration due to the centrifugal force may also be responsible for the cuttings to be adhered to the wellbore. Here, in this study, authors consider the CwD process to be analogous to a large vertical centrifuge and experimentally understand the process.