bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous Well Stimulation and Scale Squeeze Treatments in Sandstone and Carbonate Reservoirs
Authors: Jordan M. M. 
Published: May 2012

Abstract
In many oilfields the relatively small number of high-cost, highly productive wells, coupled with a carbonate and or sulfate scaling tendency (upon waterflood breakthrough of injected seawater) requires effective scale management along with removal of near-wellbore damage in order to achieve high hydrocarbon recovery.
The nature of the well completion strategy in new fields such as frac packs for sand control and acid stimulation for carbonate reservoirs had resulted in some wells with higher than expected skin values due to drilling fluid losses, residual frac gel, fluid loss agents, and fines mobilization within the frac packs where applied.
The paper will present how the challenges of managing impaired completions and inorganic scale forced innovation in terms of when to apply both stimulation and scale inhibitor packages to sandstone and carbonate reservoirs. This paper will outline a novel process for non-conventional batch chemical applications where bullhead stimulation treatments have been displaced deep into the formation (&gt;20ft) using a scale inhibitor overflush. Not only does this benefit the stimulation by displacing the spent acid and reagents away from the immediate wellbore area, but the combined treatment provides cost savings with a single mobilization for the combined treatment. The paper will describe the laboratory testing that was performed to qualify the treatments for both sandstone and carbonate reservoirs. The four field treatments that were performed demonstrate how these coupled applications have proven very effective at both well stimulation/skin reduction and scale inhibitor placement prior to and after seawater breakthrough in a sandstone reservoir. The lessons learned for the evaluation of the carbonate core via coreflood studies will also be presented.
Many similar fields are currently being developed in the Campos basin, Gulf of Mexico, West Africa and Middle East, and this paper is a good example of best-practice sharing from another oil basin.
Methods of Isolation and Diversion for High Rate Carbonate Acidizing
Authors: Entchev Pavlin B. , Shuchart Chris , Burdette Jason , Rosenbaum Darren 
Published: May 2012

Abstract
Some form of acid treatment is generally required when completing wells in carbonate reservoirs. The treatment objectives range from near well damage removal to true stimulation, using well work techniques that range from acid washes to acid fracturing. All depend on delivering the appropriate acid volumes to the right intervals at the rates needed to achieve the desired results. Because most carbonate reservoirs feature multiple layers, implementation often requires a combination of isolation – separating a particular zone so it alone receives treatment – and diversion, directing the acid from zone to zone as the treatment progresses. Conventional elements of the acidizing toolkit include mechanical plugs, limited entry perforating, ball sealers, and a variety of chemical and particulate diverting agents.
In long deviated completion intervals, a multi-stage perforation / stimulation approach was previously developed and implemented. Successful stimulation and resulting productivity of all target intervals was achieved through a combination of selective perforating, high-rate acid injection, fluid diversion, and linking stimulation results to long-term performance. However, in wells with existing perforations, this approach is not possible. Use of high rate and diverter fluids alone may not provide sufficient diversion to achieve the desired stimulation effectiveness.
This paper describes the initial development of an innovative destructible ceramic plug and seat system as an alternative option for diversion or acid placement during multizone acid treatment. The plug would enable acid diversion in multizone reservoirs with large pressure differentials and/or permeability contrast between the zones. The design and testing of the plug system included Finite Element Analysis (FEA) modeling of the plug, manufacturing of the plug and seat, mechanical strength testing and destruction testing.
The Controlled Freeze Zone Technology™ for the Development of Sour Gas Resources
Authors: Valencia Jaime A. , Mentzer Beverly K. , Denton Robert D. , Mart Charles J. 
Published: May 2012

Abstract
Controlled Freeze Zone™ is an efficient single-step cryogenic distillation process for the removal of carbon dioxide, hydrogen sulfide and other impurities from natural gas. Rather than avoiding the freezing of CO2 at cryogenic temperatures, the solidification is allowed to take place, albeit in a very controlled fashion. The technology has shown the potential to more efficiently and cost-effectively separate carbon dioxide and other impurities from natural gas, and to discharge these contaminants as a high-pressure liquid stream ready for underground injection, either for enhanced oil recovery applications or for acid gas injection disposal.
Towards Next Generation of Smart Fields Using Intelligent Online Multi-Objective Control
Authors: Mikkelsen Lars Lindegaard , Jørgensen Bo Nørregaard 
Published: May 2012

AbstractProduction optimization for offshore oil and gas production is in general a challenging task, even at fields operated "Smart" with continues 24/7 optimization, due to the intrinsic complexity of the domain. In this paper, we present an intelligent multi-objective-control-software approach for the next generation of Smart Fields.At the DONG Energy E&P operated Siri area, which we use as a test case, several optimization studies have shown that an increase in production throughput is possible, if the comfort zone, i.e. the band between the actual and the maximally possible production level, is reduced dynamically. Maximal production will be obtained when the comfort zone meets the minimally required margin that ensures a safe and stable production in all constraining systems of the installation. This can be hard for the control operators to achieve with the present complex dynamic production configurations.In our approach, we focus on intelligent online control to minimize the comfort zone by pushing the production towards the process constraints which always have to be satisfied. The new intelligent online multi-objective control system is implemented as a stratified multi-agent system allowing control concerns to be dynamically introduced, changed or removed without the need to modify or inspect the existing control system. The stratified approach supports multi-objective optimization in all layers, i.e. in contexts of strategy, tactics and operation. Optimization conflicts are dynamically identified and propagated to a higher layer. The "irony of automation" predicts that more advanced automation systems require more tacit knowledge; an essential property of any advanced control system is, therefore, the capability to identify and explain optimization conflicts well in advance.In this paper, we demonstrate that it is possible to continuously minimize the comfort zone and thereby gain higher production throughput by using intelligent online multi-objective control, even at fields with complex configurations.
Examination of Hydraulic Fracture Production Modeling Techniques
Authors: Akuanyionwu Obinna , Elghanduri Khaled , Mokdad Belkhir , Norris Mark 
Published: May 2012

Abstract
Advanced hydraulic fracturing has become a complex and investment intensive operation; hence, predicting its performance has become more important than ever. Robust prediction of production profiles for hydraulically fractured wells is imperative for optimizing the fracture scheme for productivity and determining completion economics. Various methods are currently being applied to modeling production after hydraulic fracturing treatments ranging from traditional analytical methods to semi-analytical and advanced numerical methods. A key requirement for any production modeling approach is the ability and flexibility to cope with uncertainty in fracture, reservoir and well properties to optimize fracture design.
In this study, we applied different modeling techniques to a range of fracture treatment scenarios and compared several real case studies and examples from the North Sea area. A number of factors had to be taken into account during the selection of a particular production modeling technique. These factors included considerations related to well type, fracture design, extent of geological and petrophysical properties, availability of data and ready reservoir models, and turnaround time. Multiple simulations generating multiple production profiles were carried out in most of the cases to support uncertainty bracketing and guide informed decision making even in areas extending to completions optimization.
The results reflect the need to curtail the use of simplified models and approaches when sufficient data is available or where data can be integrated to further reduce uncertainties on a case-by-case basis. On one hand, hydraulic fracturing treatment can be capital intensive while on the other hand, profitability is often a dynamic and changing parameter. Hence, longer term productivity benefits (post fracturing) require explicit and realistic pre-evaluation. Finally, the work highlights robust approaches for uncertainty handling within the production modeling workflow.
Using Advanced Water Treatment Technologies To Treat Produced Water From The Petroleum Industry
Authors: Dores Raul , Hussain Altaf , Katebah Mary , Adham Samer 
Published: May 2012

AbstractProduced Water (PW) is the water trapped in underground formations that is brought to the surface along with oil or gas in extraction operations and it is the highest volume liquid waste stream generated by the petroleum industry. Historically, the treatment of PW has been limited to free oil and suspended solids removal and subsequent discharge into water bodies or deep injection in disposal wells. Only a small fraction of the PW is currently being treated to an extent that allows it to be recycled & reused.However, due to any of a variety of factors including legislation, geological restrictions and local water scarcity, the future will require a greater fraction of the PW to be extensively treated and ultimately recycled & reused. The petroleum industry will have to change how it has historically been managing PW and start to consider PW as a "by-product" of strategic importance and value and not as an operational liability.This paper focuses on the application of Advanced Water Treatment Technologies (AWTTs) for the treatment of PW. The specific technologies presented include direct membrane filtration, biological treatment in membrane-bioreactors (MBRs), thermal evaporators and advanced oxidation processes (AOPs). In addition to describing their respective advantages and disadvantages, this paper also presents examples of case studies where PW is being treated and recycled & reused through the application of AWTTs in full scale facilities.This paper also presents a brief overview of a laboratory investigation carried out by ConocoPhillips GWSC, where various treatment processes (membrane filtration, biological degradation, membrane distillation (MD) and ozonation) were evaluated as PW treatment methods.The case studies reported demonstrate that thermal evaporators and membrane filtration technologies have been proven at various installations to be cost-effective at the full-scale for PW treatment. Data reported in this paper also reveal that PW can be successfully biodegraded or chemically oxidized and hence processes such as MBRs and AOPs, which have been successful in other industries but overlooked by the petroleum industry, will need to be considered. In the long term, hybrid technologies such as MD may also become a cost-effective alternative to treat PW.
Triazine-Based Scavengers: Can They Be a Potential for Formation Damage
Authors: Al-Duailej Yaser K. , Al-Khaldi Mohammed H. , Al-Kulaibi Saleh A. 
Published: May 2012

Abstract
Hydrogen sulfide (H2S) scavengers have been used extensively in different field operations such as drilling and acid stimulation treatments. Typically, H2S scavengers are preliminarily designed to react effectively at different in-situ conditions. For example, Triazine-based scavengers are designed for neutral-high pH conditions, while aldehyde-based scavengers are intended for low pH conditions. However, reaction products of these scavengers with H2S could lead to potential formation damage.
The efficiency of two Triazine-based H2S scavengers were investigated over a wide-range of parameters: solution pH value, temperature and exposure time. Additionally, the effects of both scavenger concentration and its ratio to H2S gas on the scavenging capacity were explored. In this work, the scavenger concentration varied from 1 to 5 vol%, reaction temperatures up to 50°C.
Earlier studies have shown that, at low pH, triazine-based have a very low efficiency in scavenging H2S because the hydrolysis rate of triazine is faster than the reaction rate with H2S. Nonetheless, in this study, it was found that long exposure time between triazine-based scavengers and H2S can result in significant scavenging efficiency even at low pH values. Doubling the exposure time had almost doubled the amount of scavenged H2S in acidic solutions. In addition, this work, for the first time, highlights the possibility of calcium sulfide (CaS) precipitation in spent acid containing H2S scavengers. This precipitation has been observed when low scavenger concentrations were used in spent hydrochloric (HCl) acid. This paper provides optimum design parameters that allow for much effective use of H2S scavengers without causing the formation of calcium sulfide scale.
Design of Sucker Rod Pumping Systems for Effectively Handling Solids and Sand
Authors: Ghareeb Mohamed , Beck Anthony (Tony) 
Published: May 2012

Abstract
Subsurface pumps in sandy wells suffer mostly from abrasion of Sand (quartz). To prevent the pump from being stuck by sand grains and to reduce pump part failures due to sand, it requires understanding of sand problems and how they damage pump parts and cause stuck pumps. This can help with the design of the pump configuration in order to improve pump inherent reliability in sandy well conditions. Usually the common types of sand problems are Plunger sticking in barrelPump sticking in tubing (insert pumps)Sand damage to barrel, plunger and valvesSand packing off in the pumpSticking valves
The subsurface pump equipped with a sand screen and additional modifications worked out over the years with different oil producers have helped it become one of the best solutions for difficult sand laden wells. Where some sucker rod pumps and some exclusion devices are designed to keep solids from entering the pump. Certain pump configurations help in handling sand in terms of moving the sand through the pump with a minimum of wear.
This paper will discusses the main concepts in sand handling with highlighting some exclusion devices, and the most practical solutions for best sand handling pump and completion design as a function of conditions
Acidizing Sandstone Reservoirs Using HF and Organic Acids
Authors: Yang F.. , Nasr-El-Din H. A. , Al-Harbi B.. 
Published: May 2012

Abstract
Mud acid, which is composed of HCl and HF, is commonly used to remove the formation damage in sandstone reservoirs. However, many problems are associated with HCl acid, especially at high temperatures. To overcome many of these drawbacks, organic-HF acids have been used as an alternative to mud acid. However, very limited research has been performed to reveal the reactions between organic-HF acids and minerals in sandstone reservoirs.
In this study, formic-HF and acetic-HF acids were examined to react with various clay minerals (kaolinite, chlorite, and illite), in comparison with mud acid. A series of acid mixtures with different ratios and concentrations were tested. Inductively coupled plasma (ICP), scanning electron microscopy (SEM) and 19F nuclear magnetic resonance (NMR) were employed to follow the reaction kinetics and products. Core flood experiments on sandstone cores featured with different mineralogy, with dimensions of 1.5 in. × 6 in. were also conducted at a flow rate of 5 cm3/min. The core effluent samples were analyzed to determine concentrations of Ca, Mg, Fe, Si, and Al by ICP.
Both formic-HF and acetic-HF acids are much milder than mud acid. The species and amounts of reaction products of different clay minerals in organic-HF acids depend on mineral type, acid composition, and ratio. This conclusion is further confirmed by core flood experiments, in which sandstone cores with different mineral compositions give quite different responses to the same acid mixture. This paper will discuss the detailed chemical reactions that occurred within cores and were followed by chemical analysis of core effluent samples.
Virtual Flow Meter pilot: based on Data Validation and Reconciliation Approach
Authors: Haouche Mohamed , Tessier Adrien , Deffous Younes , Authier Jean-Francois 
Published: May 2012

Abstract
To face the new challenges of production metering and back allocation, TOTAL is making an important effort to develop and test new approaches to improve its current production metering systems particularly for multiphase conditions. New technologies are tested through pilot applications within different subsidiaries worldwide. Thanks to these pilots, the suitability of various approaches to the needs of each asset can be analyzed and tested in detail.
The SPE-149908 (M. Haouche 2012) paper presented a Virtual Flow Meter (VFM) field pilot in Qatar. The approach used on this VFM is the Data Validation and Reconciliation (DVR). The single Well model of the VFM is an assembly of three main units: Reservoir unit, Electrical Submersible Pump (ESP) unit and Production Tubing unit. The conclusion was that the VFM was catching-up the production trends of all the Wells of the pilot. However, the VFM results are not quantitatively comparable to the production measurements, especially when the VFM is running far away from the calibration period. A recommendation was to enhance the ESP model that controls mainly the information on the flow rate.
The present paper describes a new method for modeling the ESP performances in the VFM. This method takes into account the impact of the Gas on the ESP performances. Results are presented for three operational cases to see the benefits of this method and where it is applicable. The ESP operational data have been considered for a long time period in order to get a representative range of operational conditions. Conclusions are made on the capabilities of the new method to assess the impact of Gas on the ESP operational performances.
Core Flood Study of a New Emulsified Acid with Reservoir Cores
Authors: Sayed M. A. , Zakaria A. S. , Nasr-El-Din H. A. , Holt S.. , Al-Malki H.. 
Published: May 2012

Abstract
The main objective of well stimulation has been to create wormholes or fractures in order to bypass the damaged zone and enhance the permeability in the near-wellbore area. Regular HCl was the main stimulation fluid. However, at high temperatures, both reaction and corrosion rates become very high and regular HCl loses its advantages. There are many alternatives for regular HCl; emulsified acid is one of the available alternatives for regular HCl.
In the present work, an emulsified acid system was used formulated using a cationic surfactant. This system was tested using reservoir cores obtained from a carbonate reservoir. The core samples were analyzed using CAT scan to study the presences of vugs or channels, and to determine the presence of anhydrite. Small samples of the cores were analyzed using the SEM technique. A series of core flood tests were conducted using 15 wt% HCl emulsified acid systems formulated using 1.0 vol% emulsifier. The acid volume fraction was 0.7, and all experiments were performed at temperature of 220°F. The acid injection rate ranged from 1.0 to 10 cm3/min. After acid treatment is accomplished, the cores were CAT scanned to study the number and distribution of wormholes. Samples of the effluent fluid were collected during the core flooding experiment. These collected samples were analyzed using the ICP, to determine the calcium and magnesium concentrations.
The CAT scan of the cores obtained from a carbonate reservoir showed a great heterogeneity. The static test for solubility of rocks in regular 15 wt% HCl, indicated that the rocks has a high solubility in acid and the need to use an effective retarded acid system. From the coreflood study, there is an optimum injection rate for an emulsified acid system when it was tested reservoir cores, and it was found to be in the range from 5 to 7 cm3/min. The emulsified acid system can be used effectively, with no face dissolution, at low and high injection rates. For high permeability cores, the final permeability enhancement (ratio of final to initial permeability) increased with increasing the injection rate.
The Effect of Viscoelastic Surfactants and a Mutual Solvent on the Wettability of a Carbonate Rock
Authors: Adejare O. O. , Nasralla R. A. , Nasr-El-Din H. A. 
Published: May 2012

Abstract
Proper acid placement/diversion is required to make matrix acid treatments successful. Viscoelastic surfactants (VES) are used as diverting agents in carbonate matrix acidizing. However, these surfactants can adversely affect wettability around the wellbore.
Spreading droplets may not reflect wettability, if they result from low oil-acid IFT's. Therefore, a procedure was proposed for contact angle measurements when surfactant solutions, such as spent acid with VES and EGMBE,reduce interfacial tensions (IFT's) and cause oil droplets to spread (Adejare et al. 2012).
The effect of two amphoteric amine-oxide VES', designated as "A" and "B", and an EGMBE preflush and postflush on the wettability of Austin cream chalk was studied using the proposed procedure.In addition, the two-phase titration experiment was used to measure VES adsorption.
A treating schedule sequence typical of carbonate matrix acidizing was used. Rocks were centrifuged in fluids representing the preflush, main acid stage, diverting stage, and postflush.The difference in contact angles before and after centrifuging shows the effect of surfactants in the spent acid on wettability.Contact angles were measured in spent acid with HCl only to prevent VES and EGMBE from reducing IFT's.
VES "A" and "B" adsorb on the rock surface at 25 and 80°C.Experiments with acid treatments with 4 vol% VES "A" and "B" diversion stages and a 10 vol% EGMBE preflush and postflush made initially oil-wet rocks water-wet at 25°C, 80°C, and 110°C. Acid treatments with a 4 vol% VES "A" diversion stage only made rocks water-wet at 25°C and 80°C. For the parameters investigated, our results suggest that diversion with VES "A" only, andan EGMBE flush following diversion with VES "A" and "B",can alter wettability to water-wet and increasethe relative permeability to oil.