bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of Waxy Crude Oil on Appropriate Crude Conditioning Techniques and Core Flood Testing for the Maari Oilfield
Authors: Kidd Samuel , Stalker Robert , Graham Gordon , Einzinger Christian , Duff Lauchie , Hobbs George 
Published: June 2013

Abstract
The Maari Field is located 50 miles off the coast of South Taranaki, New Zealand. In this paper, we will present details of a laboratory test programme which was conducted to assist in the design of removal and mitigation treatments for flow assurance in the Maari oilfield. Main operating partner OMV initiated laboratory testing of a series of carbonate and sulphate scale dissolver and inhibitor treatments for use in the field, examining formation damage aspects potentially associated with the use of such fluids in the field. The waxy nature of the reservoir crude oil presented challenges for core flood testing, in particular the design of appropriate crude oil conditioning techniques to provide representative samples and core flood protocols to omit potential laboratory artefacts.
The Maari crude oil contains heavy oil fractions, high wax content and a high wax appearance temperature. Standard field sampling, laboratory conditioning and sub-sampling methods can result in loss of light fractions through evaporation and thus a crude oil sample weighted towards the heavier molecular weight oil fractions. Also there is potential for heavy end losses due to insufficient conditioning temperature, filtering and sub-sampling. Appropriate protocols were therefore required to condition the crude oil to a field representative state for use. Heavy oil fractions within the crude oil presented challenges for conducting effective core flood tests. Oil particulates and heavy fractions can induce wax deposits and fines mobilisation effects that can be considered test artefacts obscuring formation damage test results. Alternative test methods were therefore designed to ensure the crude conditioning methods and core flood tests are as representative as possible of the oilfield whilst also providing clear and accurate formation damage assessment.
This paper therefore presents a laboratory strategy designed to account for the aforementioned challenges alongside laboratory test results and subsequent recommendations for crude and core conditioning and core test protocols under similar conditions.
Field Case Histories of a Non-Damaging Guar Alternative for Linear Gel Application in Slickwater Fracturing
Authors: Sun Hong , Zhou Jia , Cutler Jennifer , Royce Tom , Nelson Scott , Qu Qi 
Published: June 2013

Abstract
Slickwater hydraulic fracturing is commonly used to stimulate unconventional formations, including many shale reservoirs. Large volumes of water and additives are pumped downhole at high rates to propagate the fractures and delay proppant settling. At high flow velocities, proppants in friction reducer-based fluids can be very abrasive, leading to reduced service life for fracturing equipment. Slickwater fluids also often lead to poor proppant transport and placement, resulting in reduc ed stimulation efficiency. Traditionally, medium- to high-viscosity guar linear gels are used to mitigate these challenges, which may leave behind polymer damage and can also be affected by periods of guar shortages.
An alternative solution is presented here to deliver the desirable viscosity with a novel synthetic polymer system. The new polymer incorporates easily breakable linkages in its backbone, susceptible to conventional oilfield oxidizer breakers under downhole conditions. The system also shows fast hydration with almost instantaneous viscosity development, and thus allows rapid and easy adjustments of fluid viscosity and rapid switching between polymers when needed. Laboratory testing demonstrated that the polymer solution breaks in the presence of oxidizer breakers at elevated temperatures and leaves no formation or fracture damage. Many successful treatments using this system have been pumped and confirmed the above benefits, and significantly improved production of the trial wells over the offset wells has been observed. The new system greatly simplifies the overall process of hybrid hydraulic fracturing applications, making the new polymer an effective and economical option to address the ongoing guar availability and pricing challenges.
This paper will show the laboratory data, discuss several successful field applications of the new fluid system and present production data to demonstrate its real-world performance and effectiveness.
Impact of Charge Type Used in Perforation on the Outcome of Matrix Acid Treatment in Carbonate Formations: Comparative Study
Authors: Rabie Ahmed I. , Nasr El-Din Hisham A. , Hardesty John T. , Clark Nathan G. , Bell Matthew R. 
Published: June 2013

Abstract
Perforation is the most common way to establish effective communication between the reservoir and the wellbore in wells completed with casing. Although perforation with shaped charges has become the dominant method for completion, conventional shaped charges do not always provide deep and clean-enough tunnels that result in the required productivity and/or facilitate subsequent stimulation treatments.
Therefore, the objectives of this work are to utilize the Perforation Flow Cell (PFC) and the Perforation Treatment Cell (PTC), both developed by GEODynamics, to investigate the impact of using reactive liner shaped charges on the outcome of matrix acidizing treatments and to compare the performance of reactive and conventional charges for different charge types and loads.
Cream Chalk cores with 7 in. diameter × 24 in. length were perforated with two weights of reactive and conventional charges (15 and 23 g) under simulated downhole conditions using two designs of charges; deep penetration (DP) and good hole (GH). All cores were initially saturated in odorless mineral spirit (OMS) and the same fluid was used to flush the core before and after the acidizing step. Porosity and pre-shot (initial) permeability were measured.
After perforation, post-shot permeability was reported and the cores were CT-scanned to visualize and measure the geometry of the perforation tunnels. 15 wt% HCl was used for the acidizing step at 200°F and the effluent samples were periodically collected to measure Ca, Mg, Fe, Al, and metal ions that are present in the core, tubulars, cement, and shaped charge material in the perforation assembly. Cumulative acid pore volume and acid injectivity were reported. CT scans were performed again after acidizing to assess the wormhole morphology obtained with various types of charges.
Experimental results showed that reactive charges create tunnels with more effective (open) length when compared to the equivalent conventional charge, especially at the tip of the tunnel. As a result, stimulation treatments were enhanced and less acid pore volume and time to breakthrough were required. These results were confirmed by chemical analysis that showed higher calcium and metal ion concentration in the effluent samples when the conventional charge was used. CT-scanning after treatment showed a dominant wormhole created from the tip of the perforation tunnel when the reactive charges were used compared to multiple and deviated/branching wormholes with the conventional charges.
Quality Control of Particle Size Distributions
Authors: Kumar Arunesh , Chellappah Kuhan , Aston Mark , Bulgachev Roman 
Published: June 2013

Abstract
Two important aspects often overlooked in the design of bridging solids packages for drilling fluids are: a) obtaining accurate particle size measurements, and b) allowing for the influence of particle attrition. This paper explores both aspects and illustrates, using field data, the challenges and positive impact on productivity (or injectivity) of getting the distribution right.
Commonly-used bridging solids were sized in the laboratory by sieve analysis and laser diffraction techniques and the results compared. The two methods gave similar results for particles in the range ~ 50–500 μm, but there was a significant discrepancy for larger particles. Since sieving best reflects the functional purpose of the particles (to block pores or fractures) it is suggested that sieve analysis should be the preferred method for particles with a d90 above about 500 μm.
Studies of particle grind down (attrition) showed the critical attrition parameters to be the particle type (material), the initial particle size, and the shear rate. Large particles ground down faster and to a greater extent than smaller ones. In the laboratory tests, large 1400 μm particles were found to reduce in size by up to 80% compared with only a 5% reduction in size for 300 μm sized particles over a 30 minute test period. Fluid viscosity also had an influence on attrition but particle concentration appeared to have only a marginal effect.
Two field case studies are presented. These used small bridging particles for pore sealing to minimize formation damage in two drill-in fluid applications. A grind-down effect was observed in case 1 (water based mud) which used 50 μm marble particles, and so steps were taken to restore the size distribution. There was no apparent attrition effect in case 2 (oil mud) which used a mixture of smaller 20 μm marble particles and barite. Careful management of the fluids led to a successful outcome in terms of well performance in both cases.
Evaluating Flowback Proppants for Proppant Diagenesis in Shale
Authors: Raysoni Neelam , Sarda Anjali 
Published: June 2013

Abstract
The concept of proppant diagenesis has been discussed for several years. Detailed studies and analysis have been conducted to better understand hydrothermal degradation of alumina-based proppant, which has sometimes led to a significant loss of fracture conductivity. Also, testing has been performed in laboratories at high temperatures to accelerate the rate of reactions over short durations. Many of these tests have been reported in the literature and have provided significant insight to various geochemical reactions that occur within the fracture and the possibility of the proppant pack being unstable under laboratory conditions.
However, it is equally important to look for evidence of proppant pack instability under reservoir conditions. Attempts were made to evaluate proppants that were flowed back during production from fracture stimulated reservoirs. A sample of a manufactured proppant obtained for evaluation was taken from a well that had a sandstone-dolomite lithology, while natural sand (quartz) proppant samples were obtained from different fracture stimulated wells where shale was the dominant lithology (Barnett shale). Various evaluation techniques were used, such as looking at pH of the fluids, inductively coupled plasma (ICP), X-ray diffraction (XRD), X-ray fluorescence (XRF), and loss on ignition/total organic content (LOI/TOC). Scanning electron microscope coupled with energy dispersive X-ray (SEM-EDX) proved to be beneficial for detailed analysis and helped improve understanding of the structures (growths) on the proppant surface. Extensive efforts were made to finalize best-method testing procedures along with different analytical methods.
Efforts were also made to validate some of the results generated in the laboratory under near-reservoir conditions of temperature and test duration. This paper presents data from the analysis for flowback manufactured proppants and fracturing sands that confirm the phenomena of proppant diagenesis under reservoir conditions, as well as laboratory conditions that replicate pseudo-reservoir conditions as closely as was practical.
New Treatment Method for Enhancing Propped Fracture Conductivity: A Laboratory Study
Authors: Nguyen P. D. , Rickman R. D. , Weaver J. D. , Vonk T. Z. , Loghry R. A. 
Published: June 2013

Abstract
Much effort in hydraulic fracturing technology has focused on fracturing fluid development to maximize its proppant transportability, while keeping potential polymer damage to a minimum. This paper presents the results of a laboratory study that demonstrates and quantifies the effectiveness of a new method for enhancing and sustaining proppant pack conductivity.
The approach uses an aqueous-based surface modification agent (ASMA) as part of the pad fluid stage to treat the fracture faces before placement of proppant into the fractures. ASMA treatment forms a thin film that becomes tacky and hydrophobic on both the fracture face and formation particulates. This coating causes the proppant to adhere to the created fracture faces, which can help to mitigate proppant settling inside a hydraulic fracture, resulting in improved vertical distribution of proppant within the fracture. It was also determined that ASMA treatment helps reduce polymer damage and results in the binding of fines that are generated during the fracturing process.
This study used Berea sandstone and various shale core samples that were split along the core length to create artificial fracture faces. These fracture faces were then treated with an ASMA solution, followed by immersion in proppant fluid slurry, and were then reassembled for core flow testing under closure stress. A permeability comparison of the fractured cores, with and without ASMA treatment and proppant slurry exposure, demonstrated a dramatic increase in the fractures of the treated cores. The results show that ASMA treatments are applicable to most types of formations, including shales, sandstones, and coals. The experimental results are presented by examining the reliability of ASMA treatments on the fracture faces during formation of the fracture and the ASMA's effectiveness at forming a partial monolayer of proppant for enhancing well productivity.
Physics Mechanisms of Enhanced Recovery By Fines-migration-assisted Waterflooding (Laboratory Study)
Authors: Zeinijahromi A. , Bedrikovetsky P. 
Published: June 2013

Abstract
Several different physics mechanisms yield in enhanced oil recovery with low salinity water flooding: reduction in interfacial tension, alteration of wettability, mobilization and size exclusion of fines. In this paper the laboratory study of fines migration and straining during low salinity waterflooding is performed. First, single-phase flood with piece-wise salinity decreasing was carried out to assure the presence of movable fines in the rocks under investigation. The, sequential waterflooding by formation water, restoration of the connate water with oil and waterflooding by fresh water, were undertaken. The laboratory tests have been performed under the conditions of large scale approximation, so Welge-JBN methods for determining relative phase permeability were applicable. The relative permeability curves were obtained from the coreflood data. The obtained curves show that the permeability for water increases at low water saturations while it decreases at high saturations. The non-monotonic behavior of relative permeability for water is the main finding of this paper.
CT Scan Study of the Leak-Off of Oil-Based Drilling Fluids into Saturated Media
Authors: Frequin Dorien , Bedrikovetsky Pavel , Zitha Pacelli L.J. 
Published: June 2013

AbstractLeak-off of oil-based drilling mud into liquid-saturated cores was studied both theoretically and experimentally. First a simple model for the leak-off process was developed extending an earlier analysis of static filtration into unsaturated cores. Then CT scan aided static filtration experiments were performed in dry, brine-saturated and oil-bearing cores, simulating possible reservoir saturation regimes. Formation of external filter cake and internal filtration of solid particles were visualized and leak-off volumes were measured as function of time. At the end of the experiments the formed external filter cake and internal particle deposition were characterized with the aid of an Electron Scanning Microscope. Using drilling fluids containing carbonate particles it was found that leak-off volumes for saturated cores are larger than for unsaturated cores. It was observed further that leak-off volumes increase with particle size, i.e. consistently with a more permeable external filter cake and limited internal filtration. Leak-off volumes decreased when using smaller hematite particles or barite particles having wider particle distribution size.
An Experimental and Simulation Study of Asphaltene-Induced Permeability Impairment under Natural Depletion Condition
Authors: Khalifeh Mahmoud , Kharrat Riyaz , Bagherzadeh Hadi , Izadi Milad 
Published: June 2013

Abstract
Asphaltene deposition is one serious problem in many of Iranian oil reservoirs. So, a deeper understanding of this phenomenon is essential to prevent its related formation damage and increasing ultimate production through selecting a proper planning. The major goals of this study are (a) investigation of asphaltene deposition on rock surfaces under natural depletion condition during dynamic flow tests, and (b) simulation study of asphaltene-induced permeability damage by using commercial software and evaluation of its strengths and weaknesses.
To extend the results of this work, asphaltene deposition and simulation study performed on both carbonate and sandstone rocks. The results of dynamic flow experiments show asphaltene deposition is a continuous process causing permeability impairment and is also partially reversible. Simulation results indicate good matching of the experimental data at final steps of the experiments and it means that software should be modified respect to modeling of asphaltene deposition. In addition, surface deposition and entrainment mechanisms are more important in carbonate rocks than sandstones while pore plugging mechanisms depends on the pore size distribution of the rock and it may play same role in carbonate and sandstone rocks. The simulation model considers constant values for adsorption and plugging coefficient, while these coefficients are changing during experiment. All the tests are performed and simulated in accordance to reservoir condition and oil production rate of wells.
Investigation of Effective Mechanisms in Permeability Reduction Due to Asphaltene Deposition through Porous Media
Authors: Khederzadeh M. , Ostadrezaei S. , Kharrat R. , Bagherzadeh H. , Mahdavi S. , Khalife M. 
Published: June 2013

Abstract
Asphaltene deposition during natural depletion and miscible gas injection is a common problem in matrix and near well-bore region of oil reservoir throughout the world. This problem may lead to formation damage and reduction in production. Understanding the permeability reduction mechanisms during different processes of production is vital in optimizing production and injection processes in order to minimize the formation damage.
In this study, asphaltene deposition during natural depletion and miscible CO2 injection was conducted through core flooding tests at reservoir conditions. The natural depletion was done at several pressure steps while CO2 injection was performed simultaneously with live oil into the core sample. The CO2 mole percent in injected fluid was chosen to be more than the onset value. According to static experiments the onset of asphaltene precipitation due to CO2 injection was equal to 10% mole percent for the desired oil.
The main purpose of this paper is to consider asphaltene deposition mechanisms including surface deposition, plugging and filtration cake formation during primary depletion and CO2 injection. Consequently these mechanisms were investigated using related models. Based on results, plugging became dominant mechanism of permeability impairment, although surface deposition may exist during the tests. The pressure drop diagrams confirm the most pressure reduction was encountered at the entrance of the core; hence permeability reduction at initial part was more severethan the final portion. The results of this work may be helpful for understanding of permeability reduction mechanisms related to asphaltene deposition during natural depletion and CO2 injection in this heavy oil reservoir.
Formation Damage Due To Iron Precipitation In Carbonate Rocks
Authors: Assem A. I. , Nasr-El-Din H. A. , De Wolf C. A. 
Published: June 2013

Abstract
Iron precipitation during matrix acidizing treatments is a well-known problem. However, extensive literature review highlighted that no systematic study was conducted to determine where this iron precipitates, the factors that affect this precipitation and the magnitude of the resulting damage.
In this paper, the effect of iron precipitation in the acidizing operations is studied. HCl solutions (5 – 10 wt%) containing 5,000 to 10,000 ppm of Fe3+ were used for these experiments. The effect of varying acid concentration, initial core permeability, core length, temperature, and flow rate was studied. Coreflood experiments were conducted on 6 and 20 in. long Indiana limestone cores over a wide range of permeabilities and up to 300°F. In these experiments, 0.5 PV of acid solution was injected. The cores were scanned after treatments using a CT scanner and cut to better determine the location of iron deposition. The core effluent samples were analyzed for iron and calcium concentrations using ICP-OES.
Results showed a significant amount of iron precipitated on the injection face of the cores and the sides of wormholes, i.e. where the contact occurs between the acid and the rock, producing a minimal or no gain in the final permeability, which indicated severe formation damage. The damage increased with the increase of the amount of iron in solution. At higher temperatures and flow rates, the damage was significant. Core length didn't affect the degree of damage. This paper will discuss the results obtained and give recommendations on whether to use iron control agents in the field or not.
Integral Completion Technique for Heavy Oil Thermal Recovery
Authors: Yue Hui , Pang Wei , Duan Youzhi , Zhang Tongyi , He Zuqing , Deng Dawei , Hou Qian , Du Juan , Zhao Xu , Feng Xiaoxu 
Published: June 2013

Abstract
Nowadays, the annual heavy oil production is more than 15 million tons in China and more than 60% of which are developed by cyclic steam stimulation (CSS) technology. Vacuum insulated tubing (VIT) with thermal packer is the mostly adopted thermal insulation manner during steam injection progress. This usually leads to two major problems. One is casing integrity issues like casing crack, casing collapse, and cement sheath damage induced by thermal packers's failure or cyclic casing as Well as cement heating. Another problem is frequent injection and production strings transformation, and this leads to operation cost increasing and high temperature production time wasting especially when CSS is of short cycle in super-heavy oil or thin thickness reservoirs.
In order to solve the two problems, the vacuum insulated casing (VIC) and relevant integral completion technique are researched taking well completion, heat insulation and hereafter production into consideration simultaneously rather than separately. This completion technique injects steam by VIC while not by VIT and produces in normal tubing, thus eliminates the thermal packer's failure problems, meanwhile, simplifies the injection and production pipe conversion process and saves production time. VIC's heat loss and steam quality along wellbore are compared with that of VIT. The related techniques like cementing, perforation while adopting VIC are also studied.
Field trials in Henan oilfield in China verify this completion's suitability for CSS in heating insulation, production performance and economics compared with normal method of CSS. The completion provides a long-term Well integrity solution for thermal Well recovery not only by CSS, also by other thermal manners like SAGD. Also, it can play an important role in heat proof exploitation of other resources like gas hydrate and geothermal energy.