bluuebunny/crossref_metadata_2025_split huggingface dataset:
Permeability Prediction Considering Surface Diffusion for Gas Shales by Lattice Boltzmann Simulations on Multi-Scale Reconstructed Digital Rocks
Authors: Ning Yang , He Shuai , Liu Honglin , Wang Hongyan , Qin Guan 
Published: November 2016

Abstract
The apparent permeability function in kerogen is developed by combining effects of viscous flow, Knudsen diffusion, and surface diffusion, in which the surface diffusion is defined as the transport of adsorbed gas due to the difference of adsorbed gas concentrations. The concentration of the adsorbed gas is quantified by the monolayer adsorption coverage and the specific surface area in shale. Weighting coefficients of viscous flow and Knudsen diffusion are determined based on the probabilities of collisions frequency between gas molecules and between gas molecules and pore walls. Analyzing the effect of surface diffusion, we found that the mass flux contribution of surface diffusion was dependent on many parameters that include pressure, temperature, pore size, specific surface area, etc. The apparent permeability function is further incorporated into the generalized lattice Boltzmann method (LBM) for porous media. A 3D nanometer-scale kerogen digital rock including macro-pores and larger-scale digital rocks including mineralogical components are reconstructed based on the focused ion beam-scanning electron microscopy (FIB-SEM) and Nano-CT experiments, respectively. The kerogen structures (1.53μm3) from FIB-SEM experiments distinguish macro-pores (&gt;10nm) and kerogen solids. Kerogen solid is permeable as micro/meso-pores (1-10nm) exist in nature but are lost by the FIB-SEM experiment. The apparent permeability function is assigned locally on permeable kerogen solids. In Nano-CT digital rocks (413μm3), 4 different mineralogical components have been differentiated. Rock/fluid properties of shales in nanometer scale and micrometer scale are obtained by performing LBM simulations on digital rocks. The relations of methane permeability in kerogen with pressure, temperature, average pore diameter, and specific surface area have been investigated for the FIB-SEM digital rock. In addition, we have investigated the effects of organic contents on methane permeability in shale by comparing the simulation results of 3 different Nano-CT digital rocks.
ICD Design Optimisation with Single-Well Dynamic 3D Modelling and Real-Time Operation Support
Authors: van der Bol Linda , McCarty Andrew , Pritchett James , Sripornprasert Yurawoot , Goh G. , Ridho M. , Natapak R. , Sowmyanarayanan N. M. 
Published: November 2016

Abstract
Horizontal wells are well-recognized as one of the most effective innovations in exposing the wellbore to maximum reservoir contact and drainage area to improve recovery economics. It creates lower pressure drop to achieve better productivity compared to vertical/deviated wells. In order to enhance sweep efficiency, horizontal wells can be completed with Inflow Control Devices (ICD). ICD completion creates a more uniform inflow distribution along the production interval of the horizontal well. It aims to delay water breakthrough at high permeability zones and to provide better well clean up at initial production. In general, the performance evaluation shows that horizontal wells with ICD's have better sustained productivity than horizontal wells completed open hole or with screens.
ICD completion design was previously done based on near-wellbore data only. A new methodology has been applied by tailoring the ICD completion design with fine-grid dynamic 3D simulation that is fast enough to be used for real-time model optimisation while drilling. 3D simulation enables the optimisation for the number and placement of nozzles and packers by maximising the utilisation of reservoir information. The improvement on delivering ICD completion design also includes torque and drag analysis on every horizontal well candidate.
The new ICD completion design workflow has been applied since 2015. The real-time single-well dynamic 3D simulation-based design results in a better understanding of the completion options and their performance predictions. Various ICD completion scenarios, from constant nozzle sizes to varying nozzle sizes, and different packer numbers and placements are simulated. The new 3D simulation tool is able to provide time-lapse effects of cumulative fluid (oil and water) production for different flow rates. Additional pressure drop across the completion is modelled for different nozzle configurations. Based on these simulation results better informed decisions can be made regarding the nozzle sizes and numbers. In addition, the proposed ICD completion run-in-hole tally is evaluated in the torque and drag simulator to ensure the proposed ICD completions can be run to total depth (TD). The results of these two simulation steps are combined to optimize the final ICD completion design.
Advanced NMR and MRI Methodologies for Wettability Characterization in Carbonate Reservoirs
Authors: Matenoglou G. , Kelessidis V. C. , Garcia A. P. , Heidari Z. , Fardis M. , Anastasiou A. , Papavassiliou G. 
Published: November 2016

Abstract
The heterogeneity of carbonate reservoirs strongly influences their petrophysical properties and oil recovery procedures. Among many reservoir characterization techniques, NMR stands as a unique tool for oil reservoir exploration. The basic advantage of the NMR method is that oil, gas, and water possess different NMR properties. Therefore, they can be distinguished quantitatively. In this work we have combined NMR Laboratory methods and pore-scale numerical simulations, with MRI techniques in order to elucidate the oil/water-rock interactions of mixed-wet carbonates at molecular scale and on the basis of this information to acquire a quantitative measure of wettability. T2, D and D-T2 NMR measurements were performed on limestone core. Water and two types of oil, with different viscosities, were used in the experiments. Pore-scale numerical simulations of magnetization decay on samples taken from both rock types in the presence of different spatial distribution of fluid saturations and wettability assumptions were performed using a random walk algorithm. A sensitivity analysis were performed on the impact of wettability on T2 distribution in the two rock types. The T2 and D distributions were extracted from measured magnetization decay by implementing a new non-negative Tikhonov regularization algorithm, while for the D-T2 experiments a 2-D version of this algorithm was developed and implemented. For the MRI experiments CPMG trains were implemented for calculated T2 Images, and Diffusion Tensor Imaging methods, in order to acquire spatially resolved T2 and D values. The results of numerical simulations were compared against laboratory experiments.
Transport Properties of Natural Gas in Shale Organic and Inorganic Nanopores Using Non-Equilibrium Molecular Dynamics Simulation
Authors: He Shuai , Ning Yang , Chen Tianluo , Liu Honglin , Wang Hongyan , Qin Guan 
Published: November 2016

Abstract
One of the most important characteristics of shale gas formation is that the majority of the natural gas in both organic and inorganic nanopores exists as adsorbed gas and, due to the pressure draw down, the desorbed gas flows into the adjacent fracture network from the shale matrix. Therefore, numerical investigations on the transport behavior of natural gas in the nanopores become increasingly crucial for better understanding the shale gas production performance due to the limitations of current experimental measurements.
In this paper, we applied boundary-driven non-equilibrium molecular dynamics (BD-NEMD) simulation to estimate natural gas transport diffusivity coefficients in both organic and inorganic nanopores. Type II kerogen molecules and montmorillonite clay molecules are used to model the nano-channel with various sizes and methane is used to model natural gas. Driven by an external force, high- and low-density gas regions have been formed and constant flow rate has been established as the system reaches steady-state. Pressure-dependent transport diffusivity coefficients of methane can be then determined based on 1st-order Fick's law. Due to the work done by the external force, the temperature of fluid will inevitably increase and introduce certain artifacts to the diffusivity coefficients. Therefore, fluid temperature must be carefully controlled during the simulation to mimic real isothermal flow experiments. Both convection and diffusion contribute to the gas transport in nano-channel. Results indicate that the molecular mean free path is smaller than the free gas region due to the nano-scale confinement effect. Transport diffusivity coefficients depend on Knudsen number as well as pore geometry. In the continuum regime (Kn &lt; 0.1), transport diffusivity coefficients are mainly dominated by convection and independent on pore size. In the transition regime (0.1 &lt; Kn &lt; 10), gas transport can be estimated by Knudsen diffusion that transport diffusivity coefficients are size-dependent. Meanwhile, in the organic nanopore, similar correlation is observed with smaller characteristic Knudsen number. Deviations may be caused by the surface roughness.
Novel Abrasive Perforating with Acid Soluble Material and Subsequent Coil Tubing Jetting Assisted Stimulation Provides Outstanding Results in Carbonate Gas Well
Authors: Buenrostro Adrian , Abulhamayel Nahr , Malik Usman , Suwaileh Mohammad Bu , Driweesh Saad , Chacon Alejandro , Jimenez Fadul Jose Camilo , Noguera Jose 
Published: November 2016

Abstract
Abrasive perforating with coiled tubing (CT) is a technique that has been in the market for several decades and that has been proven as a very valuable alternative to conventional perforating with e-line. The application is even more valuable whenever a high rate or fracture stimulation treatment is to follow due to the significant reduction in tortuosity and pumping friction losses across perforations. One of the main drawbacks of this type of perforations is that it is a much lengthier process compared to conventional perforating, and it requires a large amount of fluids as well as additional CT runs in the well to complete. These drawbacks discourage the wide use of the technique for more conventional applications.
This paper discusses a novel approach to abrasive perforating with the first ever use of an acid soluble abrasive material and ending with coil tubing jetting assisted nitrified stimulation. The main advantage of the use of this abrasive material is that there is no need for additional clean out runs and changeover of tools, thereby significantly reducing operational time and fluid volumes. Just as well, the benefits of combining the enhanced connectivity to the reservoir and the coil tubing jetting assisted stimulation were reflected in outstanding gas production results, which exceeded all expectations. Finally, as an added benefit, given the nature of the focused stimulation, this type of treatment in specific cases can replace plug-and-perf or multistage fracturing completions, thereby eliminating operational risks and added completion costs.
Subsea Insulation Resistance Monitoring
Authors: Wisselink Martijn , Somboonpakdeekun Kittipong , Kiertkul Suphawat 
Published: November 2016

Abstract
The subsea control system plays an essential role in subsea production. The integrity of the supporting subsea cables is therefore vital. To assess integrity of these cables the conventional method uses 500VDC test in accordance with ISO-13628-5/API 17E. This test is typically performed by connecting a downline from a support vessel to the subsea cable. The test set-up has issues associated with Humidity, Downline Cable Performance, Schedule, and subjective Interpretation. In addition, there is a risk of operator error and very low levels of insulation resistance are difficult to measure.
A new low voltage measurement technology, has been trialed during a 2015 campaign as an alternative to the conventional method. This new method was expected to address at least some of the identified issues.
The low voltage meter uses just 3.3VDC with the insulation resistance measuring range of 1kΩ to 10GΩ. The unit can be deployed by the ROV or diver without a downline cable. An offshore trial was performed on four standard subsea cables within an existing umbilical. The umbilical length of was 18 km and two conductors with sizes of 10mm2 and 6mm2 were tested.
The test results were compared with a measurement by a conventional 500VDC meter with a downline, and a similar test from the far end of the cable at the host facility with the same 500VDC meter. The results of the conventional 500VDC offshore test showed a wide range of sometimes illogical readings, whereas the Low Voltage test at 3.3VDC appears to show more consistent and rational results. As such, it is concluded that the Low Voltage test is actually more reliable than the conventional method.
The added benefit of the Low Voltage meter is that it can pick up low insulation values under 2MΩ comfortably, where the 500VDC meter struggled and failed to register a result.
These low Insulation Resistance values are still well above the operating threshold of the subsea control system, and as such, being able to quantify values between 500KΩ and 5 MΩ is an added benefit to confirm the integrity of the poor insulation subsea cables.
A test on a similar cable of 20km under factory conditions showed a good correlation between 500VDC conventional testing and the 3.3VDC testing with the Subsea Low Voltage meter.
Offshore testing can be significantly simplified with this metet, and overall schedule reduced. This in turn would save substantial costs during offshore inspection and fault finding campaigns. The result of the test by the new technique is more reliable, consistent and cost effective method to confirm Insulation Resistance in a Subsea Cable System.
Integrating Wireline Measurements to Provide Geomechanical Solutions: A Case Study for Optimizing Drilling by Improving Wellbore Stability in a Complex and Tectonically Active Region
Authors: Roy Sunit , Roy G. K. S , Chauhan R. S. , Bahuguna Somesh , Zacharia Joseph , Chatterjee Chandreyi , Basu Jayanta , Bhuyan Priyanuz , Talreja Rahul 
Published: November 2016

Abstract
In recent years, exploration in northeast India has focused mainly in the area south of the Naga fault. This area is tectonically active with complex folding and faulting. Target formations are in excess of 3,000m through these complex structures. ONGC has drilled several wells in the Tripura region of northeast India. Although results were encouraging, the main challenges faced during drilling were various well control and instability events: kicks, tight hole, stuck pipe, lost in hole, etc. The causes of this instability were difficult to isolate. Experience from past wells also indicated the existence of overpressure in the Middle Bhuban Formation, which could not be accurately predicted by surface seismic data. Hence, drilling through these highly stressed and overpressured formations led to excessive NPT and cost. In addition, severe hole enlargement and rugosity through eventual reservoir sections resulted in poor logging conditions and uncertain reservoir evaluation. As a result, access and interpretation of the reservoirs, to prove and produce reserves, is a major challenge in this region. In this paper, two case studies are presented to show how a geomechanics-based approach has significantly improved drilling rates by reducing the drilling-related problems. New wells were drilled within 40% of the planned number of days. Better hole conditions not only improved drilling performance but also led to huge improvements in reservoir evaluation and the identification of unloading mechanisms, probably caused by uplift due to thrusting, in the Middle Bhuban Formation. Integrated study provided valuable information about overpressure and stresses acting in this field/structure for future drilling.
The Performance of an ACROSS Permanent Seismic Source for Time Lapse Seismic at the Aquistore CO2 Storage Site
Authors: Nakatsukasa Masashi , Kurosawa Isao , Kato Ayato , Takanashi Mamoru , White Don J , Worth Kyle 
Published: November 2016

Abstract
Repeatability is one of the most important factors for time-lapse seismic surveys. Several types of permanent seismic sources have been developed previously to improve repeatability but monitoring of deep targets is still challenging because of the small power of such sources. We operated an ACROSS (Accurately Controlled, Routinely Operated Signal System) permanent seismic source at the Aquistore CO2 storage field in Saskatchewan, Canada. This source is known to excite continuous highly repeatable seismic signals by rotating an eccentric mass and to generate large force that is comparable to Vibroseis. This study analysed the quality and repeatability of ACROSS data (before massive CO2 injection) acquired in 4 periods (December 2014, and March, June, and October of 2015). Target reflections from 3300m depth can be observed on the ACROSS shot gather. After stacking over several hours, the S/N ratio of a raw shot gather from ACROSS is found to be comparable with a Vibroseis gather. Although low frequency and high amplitude noise is not negligible at near offset, the quality and repeatability of far offset data are excellent as the time shift calculated by cross correlation between different data is basically less than 1 milisecond. Data in March show a few milisecond time shift on all traces which is presumably caused by near surface changes locally around ACROSS but a global matching filter successfully corrected the time shifts and reduces its median to 0.74 ms which is less than expected time shifts by a previous study. This study indicates the high potential of an ACROSS survey to detect small changes for deep targets.
Investigation of Naphthenates Crude Oil Types and Behaviour to Induce Soaps-Microemulsion and Soap-Fines Foam in Malaysian EOR Fields
Authors: Borhan N. , Salleh I. , Ibrahim J. M. B. M. , Farrell A. R. , Nichols D. A. , Graham G. M. 
Published: November 2016

Abstract
The studies involves several unique case for EOR fields in which crude oil samples were collected from from peninsular Malaysia and Borneo. These fields has different reservoir characteristic in pressure, temperature and gas composition. Five Crude Oil from EOR field were undergone Naphthenate acid extraction using acid IER techniques for further instrument analysis to classification of Naphthenate acid type's component. Comparison of soaps-microemulsion generated was then analyse using static bottle test and Naphthenates/Emulsions Flow Rig Tests. The findings shows the Malaysian crude oil is able to be classified by type of naphthenate acid which are mono-protic acid generating sodium carboxylate soap and tetraprotic acid known as ARN which leads to calcium naphthenate deposit. There are fields that located nearby each other has different characterization of crude and types of acids which leads to different type and severities of soaps-microemulsion and soaps-fines foams formation from apllied EOR chemical. Statics bottle test at higher water cuts shows significant differences with observation from Naphthenates/Emulsions Flow Rig Tests. From this paper classification of Naphthenate acid for Malaysian crude oil has been established with its behavior to induce Soaps-Microemulsion and Soap-Fines Foam in Malaysian EOR Fields using more representive method by Naphthenates/Emulsions Flow Rig Tests.
An Extensive Study of the Thermal Stability of Anionic Chemical EOR Surfactants - Part 1 Stability in Aqueous Solutions
Authors: Hocine S. , Cuenca A. , Magnan A. , Tay A. , Moreau P. 
Published: November 2016

Abstract
If chemical stability of EOR polymers has been extensively studied over the past decades, surfactants have attracted less attention except for a few reference papers. This article presents existing and new data on the chemical stability of a variety of surfactants classically used for EOR applications in aqueous solutions. The aim is to clarify under which reservoir/operational conditions each surfactant types and combinations can be safely used regarding chemical stability.
Anionic surfactants, including alkyl benzene sulfonates, internal olefin sulfonates, alkyl ether sulfates and alkyl glyceryl ether sulfonates are investigated. Their thermal stability is monitored in a wide range of conditions: temperature from 25 to 120°C, pH, oxygen level… Their performance in terms of solubility and interfacial tension reduction is monitored through classical bulk aqueous tests over several months. In addition, liquid chromatography and two phase titration are used to identify any loss of integrity of the studied products.
Results indicate that both hydrolysis and oxidation mechanisms should be considered to guarantee long term stability of EOR surfactants. Hydrolysis sensitive surfactants, e.g. alkyl ether sulfates, undergo hydrolysis with associated loss of performances at high temperatures. This is shown to be true even in alkaline conditions as pH essentially impacts degradation kinetics and not inner stability. This study also shows that properly selected EOR surfactants and blends can withstand very harsh conditions (up to 120°C) for several months allowing high confidence in EOR process performance along with time in a reservoir. Oxygen management is however critical to achieve such performance.
This paper initiates a series of articles giving a clear framework for safe use of surfactants in oil reservoirs regarding their chemical integrity. It is intended to provide reliable guidelines for products selection, lab evaluation and field application. These aspects, often underestimated or simply by-passed in some EOR studies, are critical to ensure field trial success in challenging conditions.
Multistage Stimulation of Sidetrack Wellbores Utilizing Fiber-Enhanced Plugs Proves Efficient for Brown Oil Fields Development
Authors: Serdyuk A. N. , Frolenkov A. N. , Valeev S. V. , Sitdikov S. S. , Shchekaleva T. , Roukhlov V. , Yudin A. V. , Gromovenko A. V. 
Published: November 2016

Abstract
The effective alternative method of multi stage fracturing stimulation of horizontal section of sidetracks completed with cemented liner and utilization of abrasive perforating technique started to be implemented in West Siberia for Priobskoe and Prirazlomnoe oil fields. The goal was to analyze all associated risks, make clear statistics and adjust it for specific oil fields for further implementation on a massive scale.
Abrasive perforating is done through coiled tubing (CT) special downhole perforator that creates holes inside casing and caverns in nearwellbore zone by pumping sand slurry down CT string. After perforation has been done and the well has been stimulated with fracturing treatment, fiber-enhanced proppant plug is placed in order to isolate treated intervals. Adding degradable fibers to proppant plugs helps to achieve successful and efficient isolation between stages, while conventional proppant plugs are non-applicable due to gravity effects that cause settling of proppant and resulting in non-uniform proppant distribution and poor isolation efficiency.
Extensive campaign was conducted in 2015 at Priobskoe and Prirazlomnoe oil fields, located in Khanti-Mansijsk region. The main challenge during all operations was to perform a successful bridging of wide hydraulic fractures. Different approaches to get isolation were used and the most effective variant is narrowly described. Also spacing and number of perforating stations were identified as critical parameter. First operational and wells productivity results look very promising and the technique was proven as a best option of multistage stimulation in short and slim sidetrack wellbores. Such sidetracks have been shown as efficient method to improve hydrocarbons recovery from mature fields.
A comprehensive review of trial campaign with utilization of special technique is presented. Slim sidetracks can be stimulated with several stages in reliable, efficient and economical manner. Technology can be utilized for other brown fields in the region and outside Russia.