bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of CO2 Injection Considering Multi-Component Transport and Geomechanical Effect in Shale Gas Reservoirs
Authors: Kim T. H. , Park S. S. , Lee K. S. 
Published: October 2015

Abstract
Although several researches have been conducted for CO2 injection in shale gas reservoirs, there is definite lack of study that concentrates on the multi-component transport and geomechanical effect. This paper presents shale gas model for CO2 injection considering dissolution, molecular diffusion and stress-dependent permeability as well as multi-component adsorption. Based on information of Barnett shale reservoir, a simulation model is constructed for CO2 flooding. Extended Langmuir isotherm is used to simulate the competitive sorption among the molecules involved. Gas solubility is represented by Henry's law. Co- and counter-diffusive transportsare depicted by Sigmund correlation. Stress-dependent permeability in shale reservoir is considered by exponential correlation with the linear-elastic constitutive model. In the proposed model, the mechanisms and parameters which could influence on CO2 injection are studied. A series of reservoir simulations based on these effects are performed to study effective injection of CO2.
Mechanisms of CO2 injection in shale gas reservoir contribute to both enhanced CH4 recovery and storage of CO2. Desorption of CH4 in the model with the multi-component adsorption is activated by competitive sorption with the CO2 which is preferentially adsorbed over CH4 with a ratio up to 5:1. Molecular diffusion enables CO2 to displace CH4 in ultra-low matrix permeability condition. The model with molecular diffusion presents wide spread CO2 in the reservoir compared with the model not considering molecular diffusion. Because of ultra-low permeability of shale reservoir, effect of diffusion is higher than conventional reservoirs so that it should be considered in the CO2 injection model of shale reservoir. CO2 injection supports the reservoir pressure so that effect of stress-dependent permeability is mitigated compared with primary recovery model. In this model, CO2 injection improves shale gas recovery about 12%. The CO2 injected in the reservoir exists as a super-critical phase, adsorption trapping, and dissolution trapping of 45.8, 46.5, and 3.6%, respectively. According to reservoir and fracture parameters, amount of each state would be changed. The sensitivity analysis for either enhanced CH4 recovery or CO2 storage is conducted to investigate the critical parameters that control these CO2-EGR process and CO2 storage, respectively.
This work presents study for mechanisms of CO2 injection in shale gas reservoir taking account of multi-component adsorption, dissolution, molecular diffusion, and geomechanical effect and sensitivity analysis for uncertain parameters of the shale reservoir. The investigation is important for better understanding and design of CO2 injection in order to enhance CH4 recovery and CO2 storage.
An Innovative Algorithm to Detect Washout in Wellbore From Large-Scale Measured Caliper Data
Authors: Xie Liangjun , Chaudhary Saleem , Chen Zhongming 
Published: October 2015

Abstract
Detecting washouts (short, enlarged hole segments) is critical for job design computations in drilling and completion. However, the large-scale raw data from a six-arm caliper can have hundreds of thousands of measurements. This means manually determiningwellbore geometry and washouts from the raw data can be time-consuming and inconsistent. The industry needs an algorithm that can detect washouts effectively and consistently, and reduce data pointswhile preserving the fundamental characteristics of the data.
In this paper, we introduce a novel approach to detect washouts with significantly reduced data points from large-scale multi-arm caliper data. The proposed algorithm employs a two-loop data points reduction technique modified from the adaptive piecewise constant algorithm (APCA). In the first loop, the raw data is reduced to an intermediate number of segments by APCA, keeping the main peaks. A new data set is then reconstructed by replacing the values in the raw data with the calculated constants, and the data isthen processed by APCA to the required number of segments. Finally hole-size and washout are calculated with equivalent volume for each segment.
Data from borehole caliper logs have been processed by the proposed algorithm to reduce data points while keeping significant washouts. Comparisons were made by running APCA with both logged field data and simulated data. Our approach detected more washouts from fluctuated data than APCA with the specified number of segments. Applications with abnormal caliper data with unevenly distributed depth intervals also illustrate the effectiveness, androbustnessof the algorithm, while the original APCA fails to determine washouts in those cases. As a data mining method for similarity search for time series, the advantage of the proposed algorithm is that it can preserve peaks while reducing data. This new algorithm could also be applied in realtime monitoring.
The Wellbore Temperature Test and Simulation Analysis for Liquid Carbon Dioxide Fracturing Management
Authors: LV Xinrun , ZHANG Shicheng , YU Baihui , HOU Tengfei , ZHONG Ziyao , MENG Siwei , ZHANG Jin 
Published: October 2015

Abstract
Since physical parameters of CO2 are affected heavily by temperature and pressure, including density, specific heat capacity, thermal conductivity and viscosity, the calculation of wellbore temperature distributions during CO2 fracturing is different from hydraulic fracturing, in which those physical parameters are regarded as constants. In this paper we consider those physical parameters as variables in order to get more precise distributions of wellbore temperature during CO2 fracturing management.
A wellbore temperature distribution model during CO2 fracturing process is established in this paper. The math model is based on the energy balance equation and the momentum balance equation and solved by finite difference method. In the calculating process, we considered the effects of temperature and pressure on physical parameters of CO2. Span-Wagner model and Vesovic model are used to calculate those parameters including density, specific heat capacity, thermal conductivity and viscosity. MATLAB is used here to implement those algorithms.
Data of H79-31-45 well, a liquid CO2 fracturing well in Ji Lin-Field, is used to compare the calculated temperature with the measured data. This well use 0°C liquid CO2 as fracturing fluid to fracture the formation in depth of 1600 meters. The result shows that in the depth of 1000m and 1600m where the detectors are located, the relative errors between calculated data and measured data are less than 2% both at the beginning and the ending of the management. And as the injection time increases, the temperature of the wellbore has a significant decline, which illustrates very good agreement with result of the calculation. It indicates the precision of the simulation satisfies engineering requirement.
In general, since the established model has a high accuracy, sensitivity analysis can be undertaken to analyze the effects of different parameters like the injection rate and injection time on wellbore temperature and the results can provide insights for designing fracturing schemes.
Integration of Pressure Transient Analysis in Reservoir Characterization: A Case Study
Authors: Pinillos Carlos , Rong Yeo Chuo 
Published: October 2015

Abstract
Development of computer processing capability has helped nowadays to develop tools that are not only able to interpret a single Build-up or Drawdown but instead the whole pressure history acquired during welltest or the whole life of the well (when Permanent Down-Hole Gauges, PDHG, are available) by using either analytical solutions or numerical simulation techniques.
The use of recorded bottom-hole pressure during welltests to conduct Pressure Transient Analysis (PTA) should not be limited to classical approach of determining permeability and skin parameters. Moreover, when PTA is used in combination with classic Reservoir Engineering tools such as Material Balance and Rate Transient Analysis (RTA), then it can be very useful in Reservoir Characterization, Reconciliation of Initial in Place Volume obtained from different techniques and Identification of main Drive Reservoir Mechanism.
This paper describes the successful implementation of the aforementioned Pressure Transient Analysis applications in a Gas Field where the main uncertainties identified during the Field Development Plan (FDP) stage were: 1) Initial in Place Volumes, mainly as result of uncertainty of the Gas Water Contact (GWC) depth in the deeper reservoirs, 2) Connectivity between blocks, due to a fault presence and 3) Aquifer pressure support.
A deviation of historical pressure behavior from the Field Development Plan estimates was observed, which resulted in: a) Revisit of the assumptions made in the FDP and b) Re-evaluation of the Gas Initial In-Place Volumes (GIIP). The Integration of PTA, Material Balance and RTA together with the incorporation of 3–4 years of production and pressure history has proved to be a good practice to understand and characterize the reservoir allowing different methods (Volumetric, Material Balance, Rate Transient Analysis) to converge to a similar GIIP estimates.
Numerical Computer Modelling and an Innovative Spacer-Cement Train Results in Successful Zonal Isolation in Critical Well Offshore Australia with Minimal Casing Centralisation
Authors: Higgins M. C. , Nolan T. J. , Brandl A. , Bottiglieri A. , Jha L. K. 
Published: October 2015

Abstract
Challenging wellbore conditions in an offshore well in the Northern Territory, Australia led an Operator and Cementing Service Company to pursue a sophisticated approach to achieve zonal isolation on the critical 9–5/8-in. casing cement job. Some of the specific well challenges prior to and during the cementing operations included high bottomhole temperatures of 135°C at 3,724 m, lost circulation, low fracture gradients, and over-pressured source rock (gas). In particular wellbore instability due to tectonic stresses made it difficult to run casings to bottom, so centralizers were used only on the shoe track. The potentially increased casing eccentricity was a major concern during the cement job, risking channeling and resulting in insufficient zonal isolation.
Consequently, a comprehensive study focused on enhanced mud removal and cement placement to compensate the lack of proper pipe centralization and pipe movement during the job. Mud displacement and slurry placement efficiency were investigated as functions of important spacer and slurry design features as well as the given wellbore parameters (such as fluid density and friction hierarchies, gel strength, pump rates, fluid expansion and buoyancy, eccentricity, and temperatures) using computational modelling. The simulations and findings enabled optimization of fluid designs with the corresponding job execution increasing the success for zonal isolation. Proper pre-job planning, cementing program simulations, fluid lab tests, and reliable job execution were performed to achieve zonal isolation for the overall integrity of sidetracked wellbore section. Post-job analyses of the cement jobs, lab test results, pressure tests, and azimuthal ultrasonic cement bond log results were evaluated concluding sufficient cement coverage along the desired annuli, meeting the operator's requirements to demonstrate zonal isolation. This paper reviews the job performance and lessons-learned from the 9–5/8-in. casing cement job on this well. The findings contain useful cementing guidelines for critical well scenarios where optimum pipe centralization and movement are not feasible.
A Bio-Inspired Vibration Energy Harvester for Downhole Electrical Tools
Authors: Qinghai Yang , Xiaohan Pei , Cheng Hou , Gang Tang , Jingquan Liu 
Published: October 2015

Abstract
At present, most of the downhole electrical devices use disposable batteries or rechargeable batteries as power supplies. When the disposable batteries run out, the downhole devices have to be fished up to replace the batteries. For those tools with rechargeable batteries, chargers should be put into the downhole position close to the tools to recharge the batteries. The operations are very tedious and the normal production is interrupted. Inspired by discharging characteristic of electrophorus electricus, this paper proposes a vibration energy harvester, aiming to provide a long term power supply for downhole tools. The harvester mainly consists of bluff body, piezoelectric energy transducer, the size of designed piezoelectric beam is 52mm * 7mm * 0.82mm (Length * Width * Thickness), and a proof mass. The bluff body is cylinder and installed in front of the harvester, facing the flowing fluid. It destroys the steady flow and makes the piezoelectric energy transducer vibrating. Due to the piezoelectric effect, the vibrating of the energy transducer regularly generates electric energy. The electric energy rectified by voltage conversion circuit can be used to power the controlling system and the driving unit, or to recharge the rechargeable batteries of downhole tools. Under the laboratory condition of water flow velocity of 0.81 m/s and the Reynolds Number Re is 20000, the output peak-peak voltage of the piezoelectric energy harvester is around 44 V, which means it can directly provide the energy for rechargeable battery. This results show that the harvester can potentially offer an intriguing alternative for harvesting ambient energy from flow and provides a new method for long-term energy supply for downhole electrical tools. Futere piezoelectric energy harvester may use more efficient piezoelectric transducer and this device must be optimized to make the piezoelectric energy harvester could have a higher harvesting power.
A Two-Phase flow Model To Predict Liquid Holdup and Pressure Gradient of Horizontal well
Authors: Xu Darong , Li Xiangfang , Li Yuansheng , Teng Sainan 
Published: October 2015

Abstract
Gas-liquid two phase flow occurs extensively in petroleum industry. In gas-liquid two-phase flow, droplet entrainment in the gas phase and dispersed droplet adheres to the tube surface was usually observed in experiments; when gas velocity is larger than the critical velocity for entrainment.
Based on this new information, a new model is prosed to predict the liquid hold up and pressure gradient in stratified and annular flow, which could be considered the correction of Fan's model. The proposed closure relationships include the viscosity and density of the gas mixture weighted by gas and entrained droplet volume; the gas mixture-wall friction factor weighted by gas-wall friction and entrained droplet-wall friction; the increased flow rate of gas mixture and the decreased flow rate of liquid due to droplet entrainment. Then apply these new relationships into the momentum equation of gas mixture and calculation of interfacial-friction Factor, then liquid holdup and pressure gradient are solved through iterative calculation.
Then, the basic parameters of the proposed model were adjusted to agree with the stratified flow laboratory data from Meng and Fan's experiments. And the predictions of holdup and gradient are agreed well with that of laboratory data. What's more, the predictions are more accurately than Fan model when there have existed droplet entrainment.
Real-Time Surface and Downhole Measurements and Analysis for Optimizing Production
Authors: Gonzalez L. E. , Chokshi R. N. , Lane W. C. 
Published: October 2015

Abstract
Permanent surface and downhole measurement technologies have advanced considerably in terms of availability, reliability, performance and costs, and are increasingly deployed for real-time monitoring of wells and equipment. Permanent downhole sensors are used to measure pressure, temperature, flow rates, fluid phases and to reflect operating conditions in wellbores. Surface sensor systems provide real-time measurements of pressure, temperature, fluid phases and flow rates that need to be integrated for analysis. The resulting large volume of data has created challenges in data management, evaluation and analysis. It is important that production analysts have access to workflows and tools that provide real-time efficient and effective visualization and analysis. The optimal approach is to perform the visualization and analysis of data in real time, or near real time, to provide analysts with actionable information for timely and accurate decision making.
Permanent downhole gauges are used for monitoring reservoir drainage, injection efficiency, well-completion hardware performance, and downhole pump performance. Some of the resulting benefits include reduced operational costs, improved safety, and properly monitored well integrity. Several onshore and offshore case studies are discussed to demonstrate application of real-time measurements coupled with visualization and analysis techniques to also achieve improved artificial lift performance, reduced operating costs, and manage production. The value of the information obtained from downhole permanent gauges and surface measurements are justified as evidenced by the growing number of operators relying on real-time permanent gauges.
This paper reviews technologies that are used to monitor and manage equipment and production in oil and gas wells. It explains that the realized value of permanent monitoring depends on an efficient workflow for collection, evaluation, and analysis.
Nanofluid Alternating Gas for Tight Oil Exploitation
Authors: Zhang K. , Li Y. , Hong A. , Wu K. , Jing G. , Torsæter O. , Chen S. , Chen Z. 
Published: October 2015

Abstract
Over past decades, technology innovation in exploiting unconventional resources has become increasingly important. Associated with technologies applied in shale gas development, exploiting tight oil resources comes into a new stage. Primary recovery in tight oil reservoirs remains low even produced with massively hydraulically fractured horizontal wells.
Waterflooding is applicable over a wide range of reservoir conditions but its recovery is not high enough. In addition, gas flooding suffers from channeling problems with existence of highly permeable channels. A water alternating gas (WAG) process seems a good method to recovery tight oil.
Recent breakthrough in nanotechnology provides a promising technique in the oil and gas industry. Nanoparticles have a very high surface-volume ratio, easily moving into tight formation without external forces. Nanoparticles additive does not raise weight of an injection fluid, associated with wettability alteration and interfacial tension reduction, and can be an excellent solution in improving recovery in tight oil reservoirs.
This paper demonstrates the merits of nanofluids; concentration of 0.05wt% nanofluid gives the best performance in a core flooding test. Simulations of nanoparticles additive in a WAG process are run by Eclipse and CMG in various cases. As the degree of wettability alteration and permeability reduction highly depends on concentration of nanoparticles underground, a tracer is applied in the simulations to confirm the locations of nanoparticels underground and its concentration, and it shows that nanoparticles mainly stay around injection wells and high permeable zones. Simulation results show that a nanofluid alternating gas (NAG) process has a great potential in improving WAG performance, and it performs better with existence of natural fractures.
Unconventional Resources: The Next Generation. Assessing Coal to Liquids, Oil Shale, Underground Coal Gasification, Microbial Coal Conversion and Other Technologies within the SPE-PRMS.
Authors: Peacock Douglas , Majid Azlan , Gaffney Gaffney 
Published: October 2015

Abstract
As unconventional resources such as Shale Gas and Coal Bed Methane become mainstream, many companies are looking towards the next generation of resource types. Coal to Liquids, Oil Shale, Underground Coal Gasification and Microbial Coal Conversion are examples of resource types that are being assessed and in the early stages of commercial exploitation within the Asia Pacific region. How can companies looking to exploit such resources assess their projects within a common framework? Such projects run the risk of falling between the cracks of petroleum assessment guidelines such as the SPE-PRMS and mining guidelines such as JORC.
These resources often do not occur naturally as hydrocarbons. They typically involve a mining, or in-situ, extraction process followed by a direct or indirect upgrading process whose end product is a saleable liquid product such as synthetic crude oil. In some cases, in-situ extraction is possible. Whilst such mining and upgrading processes are clearly included within the SPE-PRMS for such deposits as tar sands and bitumen (which are already naturally occurring hydrocarbons), the situation is less clear when the raw material is not naturally occurring hydrocarbons.
Coal to Liquids involves mining the coal/lignite followed by an upgrading process to produce synthetic hydrocarbons. Oil Shale is essentially an immature kerogen-rich source rock which requires artificial maturation to generate hydrocarbons. Various techniques are available, either in-situ or mining followed by an upgrading process at the surface. Underground Coal Gasification is an in-situ process used in non-mined coal seams to generate gases including methane through injection of oxidants and steam to fuel an underground combustion process. Another emerging technology is microbial coal conversion.
Although they do not fully satisfy all of the definitions of the SPE-PRMS, the authors believe that the principles of the SPE-PRMS can be used to assess such resources. The project can be evaluated as a whole i.e. from mined raw material through upgrading process to saleable end product.
Further clarity and definition within the SPE-PRMS would assist such assessments. Overlap and integration with JORC and other mining codes would also aid understanding and transparency. There are also challenges required during the assessment of such projects. Traditional petroleum industry skills must be supplemented with expertise in mining and product upgrading in order to perform a full analysis. With many companies in the Asia-Pacific region, especially Australia and China, assessing such resources and looking to commercialise them, improvements in their understanding and assessment would be beneficial to all stakeholders.