bluuebunny/crossref_metadata_2025_split huggingface dataset:
Shale Drilling: The Impact of Shale Chemo-Physical Constituents on the Issue of Poor Drilling Performance at Depth
Authors: Hayatdavoudi A. , Nasab Y. Sardooee , Mensa-Wilmot G. , Hover V. , Boukadi F. 
Published: June 2014

Abstract
New energy demands are pushing the petroleum industry to drill more shale formations. At the same time, the shale slow drilling rate at depth convinces us that there is a need for serious attention to this field, namely finding a way first to understand the causality and then to resolve the bit balling issue associated with slow shale drilling. For this reason the industry has always been interested in finding viable solutions to mitigate "bit balling" as a main source of shale slow drilling rate. In this work we try by various means to understand the shale slow drilling issues.
Rosebank is one such field located in the west of Shetland, North Sea. This field encounters slow drilling rate at great depths. The authors studied the aforementioned field to investigate different shale chemo-physical parameters affecting drilling rate and most importantly, those which adversely affect drilling performance. These parameters comprise (1) shale chemo-physical constituents and (2) operational drilling parameters. For finding a cause and effect relationship between (1) and (2) and characterizing the shale we carried out extensive Elemental Oxide analysis using Energy Dispersive Xray (EDX), Xray Diffraction (XRD) to identify and understand relationship between the shale-clays structural formula Non Performance Factor intervals. What guided us to these relationships were the chemical reasons for shale Water Retention which addresses part (1) and devise a theoretically sound model (HDPP) to pinpoint troublesome shale sections and for addressing the shale slow drilling issue in part (2) above.
The results show a clear cause and effect relationship between (1) the shale chemo-physical constituents and (2) poor shale drilling at depth where the bit records indicate inefficient Drilling Performance Parameter. Specifically, we have pinpointed the depth where the increase in the shale Iron and Water content match the onset of poor drilling and the necessary sidetracking the well for the prospect under study. We concluded that shale water retention is due to the hydration property of Iron and Sodium especially when the ratio of Iron / Sodium becomes very high. This high ratio is also found where the ratio of Smectite / Illite and the shale water content is high as well. Obviously these high values do not permit the shale to completely expel water under the Compaction- Consolidation stresses at depth and that shale water retention renders it plastic, bit-balling shale. The benefit our work to industry is imbedded in our trouble shooting methodology for this particular prospect. Specifically, assuming all mud plan and treatments and the choices of selecting drilling parameters are made properly, we recommend the Iron control additives be a part of mud formulation for this prospect to mitigate further activation of shale stickiness and balling effect.
Methodological Approach for Analyzing the Impact of Chemical EOR on Surface Processes
Authors: Argillier J-F. , Dalmazzone C. , Henaut I. , Mouazen M. , Noik C. , Boufarguine M. 
Published: June 2014

Abstract
One important aspect that is generally neglected in chemically-based enhanced recovery technology concerns the impact of the EOR chemicals on the produced water cycle. After the chemical breakthrough, part of the EOR chemicals will be recovered in the produced fluids and may strongly impact oil/water separation and water treatment surface processes.
This paper describes a specific laboratory methodology designed to study the impact of ASP-type chemicals on produced fluids treatment efficiency and will highlight the impact of polymers and sulfonated EOR surfactants on oil/water separation and water treatment efficiency. The methodology consists in a first step in evaluating the risk of stable emulsion formation and assessing the impact of chemical EOR on separation efficiency. Produced fluids are formulated and characterized (different water cuts, type of agitation, EOR chemicals,…). The stability of the different emulsified systems is analyzed over time. Then the efficiency of separation of water-in-oil (w/o) emulsions is determined for the three main types of dehydration processes: gravity separation, chemical demulsification, electrical dehydration. The quality of the separated water is systematically reported. In a second step, impact of chemical EOR on produced water treatment efficiency is studied. Produced waters are formulated and characterized (different oil concentrations, simulated back produced EOR chemicals,…). Behavior of theses systems are then studied using here an induced gas flotation lab column and membrane filtration. Turbidity of the water and concentration of oil in water is monitored as a function of time to quantify the impact of the EOR chemicals on treatment efficiency. This methodology will be illustrated on a heavy oil in presence of EOR chemicals (HPAM, sulfonated surfactants). The results show that these chemicals can have a strong impact on surface processes. This work emphasises that water management is an important challenge for chemical EOR that needs an integrated approach and should be studied upfront.
An Evaluation of the Significance of Permeability Measurements
Authors: Warren J.E. , Skiba F.F. , Price H.S. 
Published: June 2014

Abstract
A technique for comparing core-analysis permeabilities to those determined from pressure build-up tests has been developed. This comparison has been used to obtain a qualitative indication of the spatial permeability distribution within the producing formation. Data from 14 wells, equally divided between the Bromide sands and the McKnight dolomite, have been analyzed; results have indicated that the permeabilities in those particular reservoirs are randomly arranged so that they appear to be homogeneously heterogeneous. It has been emphasized that more accurate core data, improved pressure build-up testing and independent determinations of anisotropy are needed before a more quantitative description of the reservoir is feasible.

Introduction
The purpose of this paper is to compare permeabilities determined by core analysis with those calculated from pressure build-up data. Since a single value for the effective permeability of the drainage area is obtained from a build-up test, it is necessary that the core analysis values be averaged in some manner to allow the comparison to be made. If an averaging method that reconciles the core and build-up permeabilities can be found, it is possible to infer, in a qualitative sense, the spatial distribution of permeabilities that exists in the reservoir. Since the suggested approach gives a gross indication of the type of reservoir heterogeneity that is based on a comparison, the inherent errors in the raw data must be carefully considered.
Recent experimental and theoretical research on the nature of recovery mechanisms, developments in the field of numerical analysis and the evolution of truly high-speed digital computers have made it possible to predict the performance of virtually any reservoir that can be adequately described. Unfortunately, the necessary condition that demands an adequate description of the formation cannot be satisfied in general. As a result, the usefulness of the available numerical models is seriously impaired.
A Visual Journey Into the 3D Chemical Nanostructure of Oilwell Cement
Authors: Torsæter Malin , Opedal Nils , Vrålstad Torbjørn , Vullum Per Erik 
Published: June 2014

Abstract
To enable efficient design of oilwell cements that can be placed with precision and that can withstand the harsh conditions often encountered downhole, it is important to understand how these materials are built up at smaller length scales. Since cement pores and grains can be of micro- or even nano-meter sizes, and since they are connected in space, detailed cement characterization requires advanced experimental techniques of good resolution that can provide three-dimensional (3D) information.
In the present paper we demonstrate how the nano- and micro-structure in the interior of set cement samples can be studied by using a Focused Ion Beam - Scanning Electron Microscope (FIB-SEM). This instrument performs nano-tomography, allowing small 3D cement volumes to be digitalized. In this way, chemical mapping of element distributions within the solid cement phases can be performed, and the 3D pore network can be reconstructed in great detail. This makes FIB-SEM an ideal experimental technique for investigating e.g. cement porosity, chemical attack on cements, cement-formation (de)bonding and structural or chemical effects of additives. The final output of FIB-SEM experiments, being digitalized microstructural features like grains or pores, can be used as input for numerical modeling schemes.
The FIB-SEM experiments presented in this paper demonstrate how this technique can reveal subtle microstructural differences in two Portland G cement samples mixed with water-to-cement ratios varying within the range that is typically used for well cementing. These distinctions are shown to be complementary to the larger-scale differences observed within the same samples when analyzing them with micro computed tomography (μ-CT). It is shown how the spatial extent of the internal pore network and the pore sizes are dependent on the water-to-cement ratio. We also show, through various mechanical testing procedures, how this multi-scale cement porosity affects the macroscopic properties of the material.
Scale Prediction for Iron, Zinc and Lead Sulphides and Its Relation to Scale Test Design
Authors: Okocha C. , Sorbie K. 
Published: June 2014

Abstract
The accurate prediction and management of oilfield sulphide scales, such as iron sulphide, is an important issue in oil production. This has become particularly significant as high temperature high pressure (HTHP) fields are being brought into production, and the life of mature fields is being extended. In such systems, additional scales such zinc and lead sulphide (ZnS and PbS) are often being reported.
This paper presents a detailed description of a sulphide modelling approach, leading to the prediction of saturation ratios (SRs) and masses of the formed sulphide scales, final solution compositions, final pH levels etc. The equilibrium equations for the sulphide system are presented and solved in a manner in which they are compared directly with the experimentally measured quantities. The actual Saturation Ratios (SRs) (e.g. SR = [Fe2+][S2-]/Ksp,FeS) are calculated for the various experiments and the prediction model is used directly to the design the details of the sulphide scaling experiment in the blank solutions.
Some calculated sulphide examples are presented and some key predictions of the sulphide scaling model are tested experimentally for FeS, ZnS and PbS systems. The quantitative agreement between the predictions of the model and the experiments are very good. The resulting sulphide test methodology is thus well underpinned theoretically and it is then applied to evaluate some examples of proposed commercial sulphide inhibitors/dispersants.
Produced Water Chemistry History Matching Using a 1D Reactive Injector Producer Reservoir Model
Authors: Vazquez O. , McCartney R. , Mackay E. 
Published: June 2014

Abstract
Understanding connectivity between injection and production wells is valuable information for reservoir management. Typically, connectivity might be evaluated using downhole pressure information or by injecting tracers into the reservoir. A less established but inexpensive technique is to history-match produced water compositions. For example, previous studies using this method have identified barriers to flow in reservoirs. Information on connectivity is also beneficial to scale management, and particularly where SO4-rich seawater is injected into reservoirs containing formation water rich in divalent cations (i.e. Ba, Sr, Ca) because in these cases the sulphate mineral scaling conditions in production wells are a function of the physical properties of the flow paths connecting the injection and production wells.
In this study, we have considered this latter relationship from a reverse perspective and explored the potential of history-matching produced water compositions to understand the physical properties of flow paths connecting injection and production wells for reservoirs under seawater flood. We have done this using a 1-D reactive transport model connecting an injector and a producer through a number of non-communicating layers characterized by permeability, porosity and height (completion interval). The model simulates the injection of seawater, its mixing with reservoir formation brine and the subsequent deposition of sulphate scales (barium and calcium sulphate among others) in the reservoir under equilibrium and kinetic conditions. The results of interest are the predicted produced water compositions over time from the model.
The model has been used to demonstrate how produced water compositions vary as the physical properties of the layers between the wells are modified and particularly how they vary in the presence of thief zones. Finally, a stochastic method was applied, in particular a Particle Swarm Optimisation algorithm, for the automatic history-matching of actual produced water compositions from individual wells in fields under seawater flooding. The results are promising and show that this technique can provide valuable information about the nature of inter-well connectivity.
Laboratory Characterization of Gel Filter Cake and Development of Non-Oxidizing Gel Breakers for Zirconium Crosslinked Fracturing Fluids
Authors: Reddy B. R. 
Published: June 2014

Abstract
Borate or Group 4 metal-crosslinked biopolymer fluids constitute the bulk of gelled fracturing fluid volumes used in field fracture stimulation operations to date. Oxidizing chemicals remain the primary gel breakers to breakdown the filter cake and establish regained formation or fracture conductivity. These breakers presumably oxidize the polymer backbone, causing chain breakdown, thereby facilitating fluid flowback. Safety hazards associated with using bulk quantities are one of the many potential problems associated with the use of oxidizing agents as gel breakers. Proper timing of gel breakdown is of utmost importance with respect to oxidizing gel breakers. Conversely, premature polymer oxidation can cause premature proppant settling. On the other hand, a long delay between the completion of the fracturing operation and activation of the gel breaker could cause deposition of additional filtercake on fracture faces, which could be difficult to break down. A desirable advancement of designing improved fracturing fluids is to develop non-oxidizing gel breakers that focus on decrosslinking the crosslinked gel structure by reacting with the crosslinking agent, rather than only breaking down the polymer chain. Additionally, by insolubilizing such breakers, they can be embedded in the filter cake and, on activation, they can degrade the filter cake completely without leaving any residues.
This paper begins by examining a study on filter cake characterization using zirconium-crosslinked fracture fluids. The filter cake was formed by flowing, under pressure, crosslinked fluid through synthetic aloxite discs of different porosities. Results from the evaluation of relationships between permeability/porosity of the discs, filter cake thickness, and filter cake polymer concentration are presented. Next, laboratory development and screening of some non-oxidizer type chemical gel breakers that can actively decrosslink zirconium at formation temperatures are discussed. Finally, the paper discusses some insolubilized breakers that become embedded in the filter cake and break it down from within.
Novel High-Efficiency Boron Crosslinkers for Low-Polymer-Loading Fracturing Fluids
Authors: Legemah Magnus U. , Guerin Michael , Sun Hong , Qu Qi 
Published: June 2014

Abstract
Boron based crosslinkers are commonly used to increase viscosity, and improve fluid loss control and proppant transportability of guar and its derivative fluids. Boron crosslinkers are usually preferred because of their ability to reheal after shearing and their favorable environmental properties. More efficient crosslinkers capable of cross-linking fluids with reduced polymer loading have always been of great interest to reduce formation and proppant pack damage from polymer residues, and to reduce overall fluid cost, especially with reduced availability and higher cost of guar.
We recently reported in SPE 140817 the synthesis of poly-aminoboronates, bulky compounds containing multiple boron sites and capable of interacting with multiple polysaccharide strands to form more complex crosslinking networks at lower polymer loadings than conventional guar fluids. However, to improve the marketability and acceptance of the product, a lower-cost combination of raw materials is sought. In addition, a delaying mechanism to improve the control of the fluid viscosity buildup can make the product fit into broader applications.
A readily available polyamine was used as the base scaffold, and boron incorporated via intermediate borate formed in the condensation reaction between boric acid and ethylene glycol to replace volatile and highly flammable trimethylborate. New chemistry was developed to produce more controlled crosslinking. The resulting compound exhibited desired adjustable delay characteristics.
This paper will show effect of a series of new crosslinkers in terms of delay properties. Testing results of fluids with 20% lower polymer loading, crosslinked with the new crosslinker will be reported and compared to conventional fluids. Analysis and discussion of the chemistry, crosslinker performance, and economics will be presented.
Quantitative and Visual Characterization of Asphaltenic Components of Heavy-Oil and Bitumen Samples after Solvent Interaction at Different Temperatures and Pressures
Authors: Moreno L. , Babadagli T. 
Published: June 2014

Abstract
Due to inefficiency of steam injection caused by technical, economic, and operational reasons, solvent methods have received special attention in heavy oil and bitumen recovery recently. A solvent can be injected in the form of vapor extraction process at reservoir temperature. Hot solvent injection can be applied to improve the recovery rate at lower temperatures than steam injection. These solvent driven recovery processes are quite complex on account of their "asphaltene destabilization" that takes place due to changes in temperature, pressure, and solvent dissolved in oil. As a result of this destabilization, the asphaltene precipitates, flocculates, and eventually plugs the pores in the reservoir.
In this research, the de-asphalting of a heavy oil sample was evaluated in a PVT cell with optical visualization. The experiments were undertaken at different temperature ranges (50°C to 80°C) and pressure (30psig to 500psig), which is the suggested range for hot solvent injection. Three light hydrocarbons (propane, n-hexane, and n-decane) were used as solvents. Applying standard SARA analysis (ASTM D2007 and ASTM D2549), the characteristics of the asphaltene precipitated at the bottom of the PVT cell, were determined quantitatively. Moreover, a methodology for "asphaltene precipitation concentration analysis" was developed in order to determine the effect the temperature, pressure, and solvent type had on asphaltene destabilization. This quantitative analysis was complemented through visual observations of asphaltene characteristics on the PVT cell as well as using optical microscopy. In addition, the refractive index measurements at the onset of precipitation were used to evaluate the changes in the oil after interacting with the solvent at different temperatures and pressures.
Finally, a comparative analysis of the esults was provided. Based on the quantitative and qualitative observations, the characteristics of asphaltene were classified in terms of their shape, size, and amount for different oil/solvent types, pressure, and temperature. This study will eventually lead to the identification of the effects of asphaltene characteristics on pore plugging during heavy-oil/bitumen recovery by gravity drainage from oilsands.
Interrelationship of CO2, Weak Acids, Bases, and pH in Scale Prediction and Control
Authors: Kan Amy T. , Zhang Nan , Shi Wei , Wang Kevin , Wang Lu , Yan Chao , Yan Fei , Tomson Mason B. , Tomson Ross C. , Zhu Huiguang , Razavi Syed M. 
Published: June 2014

Abstract
pH is one of the most important parameters for evaluating the scale and corrosion potential of the water during oil and gas production. The effectiveness of chemical treatment can also be influenced by pH in the production tubing and reservoir. Unfortunately, pH is not a conservative parameter that can be determined independently. pH changes from reservoir to surface facilities due to changes in temperature and pressure of the production system and the corresponding G/O/W phase changes. Measured pH value of a produced water sample is often unreliable and influenced by temperature and ionic strength of the solution, degree of degassing and sample preservation. Measuring pH in line or with downhole probe at real field condition can be expensive and difficult. pH can be predicted theoretically from charge balance equations more economically and reliably by assuming a good knowledge of thermodynamic equilibrium constants, activity coefficients, G/O/W flow rates, temperature, pressure, and reliable produced water composition. The author's research group recently developed a new automatic titration method to simultaneously measure total alkalinity and weak organic acids concentrations of brine. The carbonate thermodynamics were evaluated with calcite solubility studies at ultra-high temperature and pressure. The newly developed thermodynamic data and method enable accurate prediction of produced water pH at temperature and pressure typically encountered in deep water production. In this paper, the influences of water chemistry parameters on pH are reviewed. The newly developed automatic alkalinity titration method is discussed. pH calculated by the recently validated thermodynamic constants and activity coefficients are compared with live water pH measurements.