bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Analytical Approach for Evaluating the Capillary Trapping during CO2 Storage in Aquifers
Authors: Zhu Langtao , Liao Xinwei , Chen Zhiming , Mu Lingyu , Wang Tianyi 
Published: October 2017

Abstract
Geological storage of CO2 in saline formations is employed as a key emissions reduction method in the global effort to mitigate against climate change. There has been significantly development of numerical and simple analytical techniques to support screening analysis and performance assessment for potential carbon sequestration sites. However, these techiniques had ignored the capillary trapping mechanism which has been shown as the fastest mode of trapping.
In this work, we focused on the capillary trapping phenomenon occurring during the gas alternating water (GAW) injection and developed a new analytical method to predict the potential of capillary storage. Firstly, based on the fractional theory and considering the effect of mutual solubility between CO2 and aqueous phase, the saturation profile of two-phase flow is acquired. And the drainage and imbibition phenomenon are applied to simulate the capillary trapping mechanism. Then, accoring to the saturation profile, the analytical method for estimating the capillary trapping capacity of GAW is proposed. Finally, this new analytical model is applied in a real case to estimate the capillary trapping capacity, and the sensitivity analysis of some important parameters is also conducted.
The results of this work show that the capillary trapping of subsequent gas injection occupied about 5.77%, which could not be ignored in estimating the capillary trapping potential. In addition, results of sensitive analysis show that higher residual gas saturation would lead to higher capillary trapping capacity. And higher retardation factor would lead to higher capillary trapping capacity of subsequent gas and water injection, which illustrated that the mutual solubility between water and gas is important to the capillary storage potential.
This work further developed and improved the accuracy of our previous method in estimating the capillary trapping capacity. And it also provides a new idea for evaluating the potential of capillary sequestration.
Enhanced History Matching and Prediction Using Integrated Analytical and Numerical Modeling Approach
Authors: Ghadami Nader , Benayad Nourreddine , Motaei Eghbal , Raub M Razib 
Published: October 2017

Abstract
Integrated reservoir modeling with representative data is crucial for an effective reservoir management and depletion plan. Both analytical and numerical approaches benefit from this integrated process. The objective of this study is to incorporate the outcomes of analytical techniques such as rate transient analysis (RTA) and pressure transient analysis (PTA) into numerical reservoir model to have a better understanding of drive mechanisms, reservoir connectivity with minimal time-consuming for history matching efforts but a more reliable production forecast.
In order to demonstrate the methodology, a clastic reservoir from Malay basin was considered. Sedimentology and sequence stratigraphy studies were performed to have a better picture of heterogeneity and zonation of the reservoir. All production and injection data were investigated along with pressure data to filter data inconsistency. Shut-in time should be long enough to take representative reservoir pressure and accordingly material balance study conducted for accessible volume for a given area. However, flowing material balance is able to be applied with no restriction on the production data for evaluation of historical data and prediction cases.
The boundary of the channel sand was constructed based on the well log data and seismic attributes. Amplitude impedance was used as a guide for lithofacies and porosity distribution in the geological model. In addition, stratigraphy definition with further details were incorporated. Lithofacies, petrophysical and SCAL data were incorporated in rock-type classification and accordingly saturation-height-function were modelled. Analytical approaches including PTA, material balance, and RTA were utilized to have a better understanding of fluid flow and drive mechanisms. The well and reservoir properties and also connected volume from analytical approaches were utilized as a tuning tool of static model. This approach considerably reduced the iteration between static and dynamic models for history matching exercise. Afterwards, the production forecast were conducted with two development opportunities identified.
In this study, an integrated methodology was applied to mitigate the complexity of history matching task. Moreover, it is demonstrated that using such analytical methods help to improve the development plan of a given field significantly.
Dynamic Analysis of Surface Casing During Assembling and Installation
Authors: Yamamoto Marcio , Takagi Ken , Wada Ryota , Agostini Cristiano , Malta Edgard B. 
Published: October 2017

Abstract
During the assembling and installation of a surface casing into a subsea well, the casing string is hanged by its top end and free to move at the bottom end. The floating platform motions generates dynamic loads on the whole string. In this article, we assess the dynamic stresses along the surface casing using a commercial software for riser analysis. Three 20" surface casing strings with different lengths (400 m, 731 m, and 1036 m) were used as model for numerical simulation. The results show that, at the top and middle parts of string, the main component of the Von Mises stress is the axial tension; and the lower part of casing has the bending stress as the main component. Further, the effective tension results show that, for the shortest casing, axial compression may occur. Despite, such dynamic stresses are relative low compared yield stress of the material, the prolonged action of such dynamics loads may result in fail of connectors or other components.
Enhancing Well Construction for More Efficient Well Abandonment
Authors: Dahmani L. , Hynes L. 
Published: October 2017

Abstract
The lack of planning for well plug and abandonment (P&A) during the well-construction phase can significantly contribute to the extended operational time and associated high cost of P&A. The impact on time and cost is mainly due to insufficient well data, uncertain casing cement integrity, and lack of information on competent formation for permanent barrier placement. Undocumented pressure and stress evolution, and well events also can contribute to increased time and cost of P&A.
Although new technologies can reduce plug and abandonment cost, another approach is to effectively plan for well abandonment during the front end engineering design (FEED) and well-construction phases and during drilling of new wells.
This paper examines recommendations for improvement and requirements that should be addressed by the industry, regulators, and operators to introduce clear well-abandonment requirements into FEED and well-construction phases for new drilled wells. –Requirement for planning for well integrity for the entire well life cycle of the well from well construction to well abandonment and after well abandonment–Identify number and position of required barriers for abandonments–Requirement to identify and document competent formation during well-construction phase–Requirement to demonstrate there is cement with good bond / isolation between the casing and the formation in the areas where internal cement plugs are to be set.–Qualification of the formation as possible well barrier–Well monitoring: consider introducing sensors or instrument in cement (cement behind casing) to continuously monitor and track any pressure build-up in the casing annulus.–Completion design: Avoid control lines at the intended well-barrier depth(s) and install production packer(s) in a location enables through-tubing well-abandonment methodologies.
Other considerations to be addressed in this paper are the change of regulations between the time the well is constructed, and its final P&A.
The novelty of addressing well abandonment requirements in the FEED and well-construction phases will significantly simplify the abandonment phase reducing risks and cost while improving well barrier integrity.
Redevelopment of Mature Combination Drive Reservoir to Enhance Ultimate Recovery in Asri Basin, Indonesia
Authors: Widiatmo R. , Waskito L. B. , Afi F. N. , Nugroho P. , Gunawan H. 
Published: October 2017

Abstract
The 34-X sand is a solitary sand reservoir and locally sinuous sandstone body. This reservoir is displaced by major normal fault zone known as the Widuri Fault that divided in two contrast areas of 34-X facies and production characteristic. The objective of this paper is to present how the combination drive reservoir redevelopment project was planned, extensive evaluation process has been made, and successful cases in enhancing reservoir ultimate recovery. The solution for this title is multi-disciplinary approach to create sharp analysis. The first step is numerical calculations of material balance to determine oil-in-place in a reservoir and to predict the future performance, this phase is tricky due to multi-driving mechanism reservoir behavior, therefore material balance analysis need to be supported by deep sub-surface analysis in property distribution on second step. This part simultaneous inversion, 4D timelapse seismic and sweep pattern analysis have been done to get comprehensive interpretation of reservoir characterization and reservoir connectivity monitoring. The third phase is supporting analysis by tracer injection, we implement tracer in several wells to ensure connectivity of the reservoir, and to evaluate injection performance. The last phase is technical difficulties in operation area, complex reservoir evidently cause complex operation difficulties, sand problem, formation damage, tubing leak, water out, plug-up injector well, etc. are problems we have to deal with. From reservoir pressure data distribution, surface gas-oil ratio, water production, and well behavior concludes that 34-X is combination drive reservoir (water drive-solution gas drive) and based on fault analysis we divided into two areas east and west, 34-X West area sandstone body is straight, with approximately 100-300m wide and 8m thick. The western part water cut is over 90%, this indicates the conduits for preferential water flow has established. From material balance calculation OOIP estimated 16.3 MMSTB. The eastern part of the 34-X sand appears to be isolated from western portion of the channel by a fault with a throw of 90 feet. The eastern portion of the widuri field is influenced by a partial water drive, indicated by high water cut histories. However the water drive is weak, the average pressure has declined to 520 psi, estimated OOIP 56.2 MMSTP. Before the redevelopment project recovery factor is 22%, and increase significantly to 27.4% simultaneously with oil production rate increase up to 40%. Dominantly pressure-depletion drive during hydrocarbon production in 34-X sand in west area occur since that area provide poor connection to an aquifer and for east area of Widuri Fault condition is limited aquifer. The water cut of production in 34-X sand well varies across the axis of the sandstone body, it caused by controlled by internal heteroginity.
The Integrated Environment for Real-Time Decisions: Delivering Excellence in Brunei Drilling Operations
Authors: Rowe Shawn , Keasberry Shawn , Hunt Jeffrey , Arias Alex 
Published: October 2017

Abstract
Hydrocarbon exploration in Brunei has resulted in sophisticated drilling projects highly dependent on integrated environments, real-time decisions, and top-class drilling engineering. During peak activity in 2011 and 2012, an operator faced a declining performance in well construction projects caused by well-related drilling issues in extended reach drilling (ERD), snake, fishhook wells, leading to an unnecessary increase of total well costs.
Managing the previously mentioned risks to reduce non-productive time (NPT) was the main driver for building an integrated environment for real-time decisions (IERTD), a new concept to optimize drilling operations by facilitating the decision-making process while maximizing the value of historical and real-time data. The pre-existing real-time operation center was integrated into the operator's performance process where all workflows were redesigned to help ensure focus on cross-department value, risk mitigation and real-time interventions, instead of reporting and low-value interventions. Novel and innovative application of monitoring software technology helped align well teams to actual versus plan engineering models, helping ensure faster and reliable data analysis, providing teams better visibility of well status, allowing improved decision making.
Two years after the implementation of the IERTD, the operator experienced a reduction by 10 times in terms of leaving a bottomhole assembly (BHA) in the hole. The number of stuck pipe events was reduced by 67%, by improving the quality of information for decision makers and controlling the risk associated with the well challenges. The last 36 wells (included in this study) were drilled with zero NPT associated with drilling dynamics. The operation significantly benefited from the continuous flow of reliable and accurate processed information that allowed every final user to dispose the adequate tools to respond on time.
This paper illustrates the techniques, technologies, and fundamentals behind the successful operation of the IERTD and how the interaction of these innovative concepts may contribute to operational excellence in future drilling projects.
Economic Comparison of Hydrocarbon Recovery under Injection of Different Polymers
Authors: Cenk Temizel , Dike Putra , Henny Anggraini , Raul Moreno 
Published: October 2017

Abstract
Injection of water in waterflooding operations provides pressure support and displaces oil in the reservoir, thereby improving the recovery factor. A factor of significant importance in this process is mobility ratio; a higher mobility ratio allows for better displacement of oil by the injected water. For further increasing the volume of reservoir swept, gelling agents are used to improve the mobility ratio of injected water. It is imperative to identify the right type and amount of viscosity reducer to be used since shear stress and high temperatures cause polymer degradation, due to which polymer macromolecules may be forced into narrow channels.
Performance of xanthan and synthetic polymers in a polymer injection process were compared. The model is assumption is that reduced gel kinetics forms a microgel without redox catalysis. For modeling purposes, a commercial reservoir simulator coupled with an optimization tool was used. The reservoir was modelled having 6 layers for injection, where first 4 layers have high horizontal permeabilities and the bottom 2 layers have a high permeability streak. For the first 450 days, injection water was continuously pumpedinto all layers andin the next 150 daysgel systems were injected only into the bottom 2 layers followed by which water was continuously injected for a period of 4 years. The optimization tool was used for sensitivity analysis investigation of variables to reduce variable uncertainty.
Per modelling results, gel penetrated deep in reservoir but in bottom layers there was blocking. In terms of viscosity effects, the relative benefits of biopolymers and xanthan polymer were highlighted in the sensitivity analysis. Also, this investigation indicated merits of synthetic PAM in terms of resistance factor, insitu gelation treatments and their crossflow dependence. Retention of polymer-gel and their adsorption were shown to be dependent on permeability.
In this study, for comparative purposes, different viscosity reduction treatments were modelled in the same model reservoir to highlight their relative advantages. Also, investigation of control variables through sensitivity analysis outlined the significance of each towards displacement efficiency. Keeping in mind the wide spectrum of areas around the globe where gel solutions can be applied, this study highlights factors that are critical to optimal reservoir management.
Using Business Intelligent Tool to Gain Insight into Well Integrity, Surveillance and Production Data
Authors: Haris Hamzah M , Hui Nicholas Foo , Ismail W Rokiah , Zulkifli Shahrul Anwar , Redzuan Sdn Bhd. , Zahid Ahmad Syafiq 
Published: October 2017

Abstract
The main goal in well integrity management is to ensure integrity of the well is designed, achieved, monitored and maintained throughout the life cycle of the well. In PETRONAS, the status of the well integrity is closely monitored by Subsurface Team. One of the important aspects of monitoring and maintenance of the well integrity is to have a reliable data management system that able to automate all the processes from data storage until data utilization stage. The system should be developed in such a way it follows the organization business workflows hence it will be fitted to increase the efficiency in managing well integrity. The process of transforming operational data into a form best suited visuals for analysis and reporting is essential to extract valuable insight from various datasets.
Since most of the well data are resided in various sources such as different type of database, servers, local workstations etc., it will generate another level of complexity if traditional way of data mining is being practices, i.e. using excel spreadsheet to analyse large and varied data sets. Thus, Business Intelligent (BI) concept is adapted to simplify the automation of data mining and transformation of the data to knowledge.
Web-Based Application, "Well Workbench of Asset Repository (WellWAR)" has been developed for SKG (SKG) Subsurface Team with the above intention. In general, WellWAR will automate some part of data lifecycle processes, that include but not limited to; data entry, data mining, interactive visualization, analytic and reporting. At the current stage, there are well construction parameters, well integrity, idle well, well's budget, surveillance data, technical potential and general reservoir parameters which are all have been integrated into the application. This significantly enhanced existing well data and well integrity management as WellWAR has centralized most of well data information at one place.
This paper will demonstrate on how BI concept can be utilized to produce the more insightful report in making business or operational decision by integrating various dataset that related to well integrity. In terms of functionality, the flexibility to filter with the feature of a responsive visual gives another level of experience while exploring the data, especially when investigating the impact of well's technical potential in relation to unhealthy, idle well status and condition of the wells.
The Reversible Emulsion Controlled by Inorganic Salt at High Temperature or Low Permeability Reservoir
Authors: Ren Jinheng , Wang Yanling , Jin Jiafeng , Wang Kun , Guo Baoyu , Wang Xudong 
Published: October 2017

Abstract
Due to the significant difference of water-in-oil emulsion and oil-in-water emulsion in viscosity, conductivity, rheology, thermal resistance, emulsion system has been widely used in the development of oil fields. The reversible phase inversion technique can enhance the performance of emulsified working liquids during the transportation of fluids in porous media. The objective of this study is to study the preparation and the application of the reversible emulsion controlled by inorganic salts.
SDBS, SDS, and SPS were used as emulsifiers in this study. The white oil and deionized water were emulsified into anoil-in-water emulsion by high-speed stirring. Multivalent metal cations were added to the emulsion to control the inversion of the emulsion to water-in-oil type. Then, the multivalent metal cations were removed by anions, leading to the emulsion reversed from water-in-oil to oil-in-water type. The stability of emulsions was evaluated by the stratification time, thermal resistance, conductivity, emulsion-breaking voltage and microstructure.
The results showed that emulsion's dehydration rate was 8.1% at 25°C, which increased to 14.3% as the temperature reached 90°C after 5 hours. The average diameter of droplets was about 6 μm and conductivity was about 619 μs·cm−1. The emulsion processed by CrCl3·6H2O solution inverted to water-in-oil type, and its oil separation rate was 11.9% at 25°C and 18.2% at 90°C after 5 hours. The emulsion-breaking voltage and average diameter of droplets were 153 V and 13 μm, respectively. After Cr3+ was removed by Na2CO3 solution, the type of emulsion became oil-in-water againand the dehydration rate of this emulsion increased from 3.2% to 5.8% when the temperature reached up to 90°C. Under this circumstance, the average diameter of droplets was 5 μm and conductivity was 1907 μs·cm−1. The emulsion was of high stability before and after inversion.
The emulsion controlled by inorganic salts can be reversed between oil-in-water and water-in-oil type efficiently, which can be used as emulsifier within drilling fluid in the low-permeability reservoir. The characteristics of reversible emulsion drilling fluid include inhibition for shale rock, good lubricity, thermal stability, and excellent cementing quality.
A Workflow from Seismic to Forecast for Tight-Oil Reservoir Development Using a Semianalytical Well-Testing Model with Boundary Element Method
Authors: Chen Zhiming , Liao Xinwei , Zang Jiali , Zhao Xiaoliang , Peng Kewen , Wang Shaoping , Yu Wei 
Published: October 2017

Abstract
Treatments of stimulated reservoir volume (SRV) have been the most effective techniques to enhance well productivity in unconventional plays, like tight-oil reservoirs. Unlike conventional reservoirs, the work in unconventional plays needs to focus on the SRV scale rather than field scale, which requires an integration of many techniques to properly evaluate the SRV properties. Unfortunately, there still lacks of a comprehensive integration of seismic, models, and data for SRV, although much work has been done for fracturing estimations and performance predictions of wells with SRV. To narrow the gap, this paper presents a comprehensive seismic-forecast workflow for tight-oil reservoir development on the SRV scale. The workflow is an integration of microseismic data, well testing interpretation, rate normalized pressure (RNP) interpretation, and numerical production history match. Its contents are described as the following steps: (1) introducing the technique of microseismic monitoring (MSM) and proposing a corresponding simplified SRV model, (2) developing and verifying its well-testing model with boundary element method (BEM), integral method, and superposition principle, (3) discussing the rate normalized pressure (RNP) model of SRV, (4) building a numerical SRV model, and (5) demonstrating the workflow by a field case from Junggar Basin. This paper paves a good way to evaluate well performance and improve future completions in tight-oil reservoirs.