bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of Test Method and Inhibitors for Lead Sulfide
Authors: Chen Tao , Chen Ping , Montgomerie Harry , Hagen Thomas , Jeffrey Catharine 
Published: July 2010

AbstractLead sulphide (PbS) is one of ‘exotic’ scales deposited in the oil and gas industry. The inhibition of lead sulfide scale deposition is notoriously difficult compared to calcium carbonate and barium sulphate. In addition, it is extremely difficult to test lead sulfide formation and inhibition in laboratory with the conventional static jar and dynamic loop tests and very little is still understood about its mechanism of formation and inhibition.In this paper, a novel stress test method has been developed and applied to test the performance and understand mechanisms of lead sulphide inhibition. Compared with the traditional static jar and dynamic loop tests, this test method shows good reproducibility and provides a quick and effective way to evaluate the performance of lead sulphide scale inhibitors.Typical commercial scale inhibitors, including six phosphonate based scale inhibitors, PPCA, polymaleic acid, polyacrylic acid, polyaspartate, PVS and patented environmentally friendly polyacrylic copolymers have been tested based on this newly developed method. The performance of scale inhibitors on PbS inhibition can be classified as three types:Type 1: Dispersion inhibitors. These scale inhibitors showed a dispersion effect on PbS formation. The turbidity in stress curve in the presence of these inhibitors is slightly higher than that in the absence of scale inhibitors.Type 2: Nucleation/growth dominated scale inhibitors. These scale inhibitors inhibit nucleation and growth of PbS formation, where the test can be stressed further in the presence of these inhibitors.Type 3: Scale inhibitors with poor performance on PbS inhibition. These inhibitors showed less PbS inhibition performance. The turbidity in stress curve did not change obviously in the presence of these scale inhibitors.This paper will give the comprehensive study of lead sulfide formation and inhibition, which includes development of the test method and scale inhibitors for lead sulphide inhibition.
Investigation of Various ROP Models and Optimization of Drilling Parameters for PDC and Roller-cone Bits in Shadegan Oil Field
Authors: Bataee Mahmood , Kamyab Mohammadreza , Ashena Rahman 
Published: July 2010

Abstract
According to the field data, there are several methods to reduce the drilling cost of future wells. One of these methods is the optimization of drilling parameters to obtain the maximum rate of penetration (ROP) in each bit run. Many parameters affect ROP like hole cleaning (including drillstring rotation speed (N), weight on bit (WOB), floundering phenomena, mud rheology), tooth wear, formation hardness (including depth and kind of formation), differential pressure (including mud weight (MW)), etc. Considering the geology and rock mechanical parameters, each part of well has different recommended parameters from the other parts. To optimize the drilling parameters, it is required that an appropriate ROP model to be selected until acceptable results are obtained. In literature, there are various applicable models to predict the ROP such as Bourgoyne and Young model, Bingham model and modified Warren model. It is desired to calculate and predict the proper model of ROP for roller-cone and PDC bits in each well by using the mentioned models and then verify the validity of each model by comparing with field data. Analyzing the drilling parameters by computer optimizationyields recommended range of parameters for each bit. The applications of present study are predicting the proper penetration rate, optimizing the drilling parameters, estimating the drilling time of well and eventually reducing the drilling cost for future wells.
Research into Steam Overlay Pattern and Countermeasures for Block Du84 in Liaohe Oilfield
Authors: Aiwu Yuan , Hong Ma , Xianyong Yang , Xiaosong Zheng 
Published: July 2010

Abstract
Numerical simulation method is applied to study the effects of some parameters on steam overriding, including oil layer thickness, crude viscosity, vertical/horizontal permeability ratio, perforation method, etc. Therefore, the change pattern of steam overriding is obtained and the technical conditions for steam overriding are pointed out. Field test results indicate that by taking some measures, such as adopting the "uphole" perforation, profile control, separate or selective steam injection, vertical and horizontal well combined SAGD, etc., the uneven producing of the reservoir vertically due to steam overriding can be further decreased. Moreover, these measures play an important role in increasing oil recovery ration during the later production period of CSS. The successful application of these techniques will provide theoretical support and technical guarantee for the production of similar super heavy oil reservoirs in the world during the later production period of CSS.
Investigation of Steam Injection at Critical Condition and a Pilot Test in 119-52, Chao-601
Authors: Xin Zhao , Yongbin Wu , Baofeng Wu , Panqing Gao , Huiying Zhong , Bateer Hasi , Yu Qian 
Published: July 2010

Abstract
The Chao-601 is a typical low-permeability naturally fractured reservoir of Daqing. Without a primary depletion, the secondary water flood was employed at the beginning of the development. Because of both the complexity of fracture distribution and relatively high oil viscosity, the water flooding could not meet the demand of stable output; the water broke through only a few years after injection. The predicted waterflooding recovery is only 13.4%. In order to improve the recovery, the investigations of steam injection in the Chao-601 field were performed. Correspondingly, a pilot test was conducted in the 119-52.
By combining plenty of geological study and multidisciplinary investigation, a simulation model describing pilot area was established. The simulation study focused on the flow characteristics of injected steam at critical condition and the effects of fractures on sweep efficiency. Furthermore, the injection system was optimized on the basis of the recognition of steam flow behavior. Important factors included the selection of well pattern, well spacing, and injection rate. Based on the optimization of injection system, the pilot test carried out in the 119-52 block.
Smart and Multi-Functional Coatings Based on Micro/Nano Sized Additives and Their Implementation
Authors: Boura S. Hatami , Samadzadeh M. , Peikari M. , Ashrafi A. 
Published: July 2010

Abstract
Coatings and especially organic ones application is the commonest and in many cases, cheapest and easiest method to protect the structures and equipment from corrosion and sometimes provide decorative appearance. There are many aggressive agents which can make disorder in coating performance. In the today's generation of protective coatings, it is important to provide several functionalities with the essential possibility to react on external impact, such as distortion of the coating integrity, surface pollution and bacterial attack, intelligently. Providing smartness for coating is a young novel to mitigate/solve many of these problems, thus the coating shows an adequate response against mechanical/chemical damages or even environmental changes to neutralize the negative results. Self-healing, self-cleaning, pH sensitive, temperature sensitive, selective absorption of gaseous pollutants and corrosion sensing coatings are a small group of large family of smart ones. These properties have been achieved through organic or inorganic additives in micro or nano size. Creation and manipulating these additives in order to achieve smart coatings with new functionality has been extensively described in literature and patents over the last 10 years.
This extensive study describes the principles of this novel multifunctional/smart coating background, concept and advantages and discusses the smartness and performance on the basis of laboratory results which have been presented by different authors up to now (self-healing, anti-bacterial, high temperature resistance and self-cleaning coatings). Also various approaches for achieving smart and multi-functionality are mentioned. The effects of different parameters on their performance and serviceability are also explained.
Application of Horizontal Wells to Reduce Condensate Blockage in Gas Condensate Reservoirs
Authors: Miller Nathan , Nasrabadi Hadi , Zhu Ding 
Published: July 2010

Abstract
Natural gas is an important source for global energy. It will play a more important role in the future due to increasing energy demands, existing constraints in oil production, and environmental concerns for other fossil fuel types. Much of the current gas reserves can be found in gas-condensate reservoirs. These reservoirs, from a recovery and deliverability standpoint, can have significant differences from oil reservoirs. When the pressure, either in the wellbore or in the reservoir, drops below the dew point pressure, a liquid condensate phase appears and reduces gas production significantly. Several methods have been suggested to handle the condensate blockage problem: hydraulic fracturing, wettability alteration, Huff ‘n’ Puff gas injection, and nonconventional wells. In this work, we study the application of horizontal wells in a giant gas-condensate reservoir (North Field-Qatar) to reduce the condensate blockage. We try to address a critical question of what fraction of increased gas production in a horizontal well is due to increased formation contact and what fraction results from condensate blockage reduction. Horizontal wells have smaller drawdown pressures than vertical wells, which leads to a delay in reaching the dew point pressure compared to vertical wells. Our results indicate that once the dew point pressure is reached and oil saturation is formed in the reservoir, the magnitude of oil saturation buildup in the near wellbore is lower in a horizontal well than a vertical well. The ratio of horizontal well PI to vertical well PI increases after the dew point. The fact that the PI increased after reaching the dew point indicates that this increase in productivity index is directly due to the ability of the horizontal well to reduce condensate blockage in the near wellbore. The PI in the vertical well case is decreasing significantly once the dew point pressure is reached, while the PI in the horizontal well seems to remain steady even after the dew point pressure is reached.
Using Genetic Algorithm to Optimize Well Placement in Gas Condensate Reservoirs
Authors: Morales A. , Gibbs T. , Nasrabadi H. , Zhu D. 
Published: July 2010

Abstract
Well placement within a reservoir is a significant and difficult step in the reservoir development process. Determining the optimal well location is a complex problem involving many factors including geological considerations, reservoir and fluid properties, economic costs, and technical ability. The most thorough approach to this problem is that of an exhaustive search, in which a simulation is run for every conceivable well position in the reservoir. Although thorough and accurate, this approach is typically not used in real world applications due to the time constraints from the excessive number of simulations. This paper suggests the use of a genetic algorithm applied to the horizontal well placement problem in a gas reservoir to reduce the required number of simulations. The objectives are to identify the optimized well placement and then to determine the benefit of optimization. Performance of the genetic algorithm was analyzed through different case scenarios. The genetic algorithm approach is used to evaluate the effect of well placement in heterogeneous and anisotropic reservoirs on reservoir recovery. The wells are constrained by surface gas rate and bottom-hole pressure for each case.
We apply this technique to find the optimal horizontal well location in a gas condensate reservoir in Qatar’s North field. The research provides evidence that well placement optimization is an important criterion during the reservoir development phase for horizontal wells in gas reservoirs, but it is less significant to vertical wells in a homogeneous reservoir. It is also shown that genetic algorithms are an extremely efficient and robust tool to find the optimal location.
Application of Multi-rate Well Tests to Scale Management
Authors: Tjomsland Tore , Sandøy Bernt , Fadnes Finn Hallstein 
Published: July 2010

Abstract
Veslefrikk is a mature oil field in the Norwegian sector of the North Sea. It has a layered structure with several pressure-independent layers and three main fluid systems: the Statfjord Formation, Intra Dunlin Group and Brent Group. Each fluid system has distinct formation water compositions but similar oil compositions. Seawater injection has been used for pressure support and many wells have commingled production. The principal scale control challenges are scaling potential and placement of scale inhibitor into zones with different pressure. Although production logging is performed regularly to aid scale squeeze designs and production allocation, this is costly, involves well intervention risks and it cannot always be undertaken when required.
In this study an innovative approach to obtain ‘production logging type’ information from wells producing from two zones has been evaluated. It involves undertaking multi-rate well tests where produced water samples are collected at each rate. Depending on the conditions for each test, either qualitative or quantitative integrated analysis of the well test results and produced water compositions can be performed. Information obtained from the tests for each zone includes: Pressure, productivity index, water cut, produced water composition and seawater fraction.
The methodologies adopted for the multi-rate tests and the analysis of their results are described, and the results for four multi-rate tests are presented. The multi-rate tests were undertaken under different conditions and the influence of these conditions on the type and quality of results obtained are discussed, and assumptions and associated uncertainties are identified.
The case studies demonstrate that information useful to scale, well and reservoir management can be obtained from multirate tests. In addition, produced water compositions can be obtained from these tests without the need for downhole sampling. However, in each case it is important to assess uncertainties associated with the results.
Wettability Index of Carbonatic Reservoirs and EOR: Laboratory Study to Optimize Alkali and Surfactant Flooding
Authors: Bortolotti V. , Macini P. , Srisuriyachai F. 
Published: July 2010

Abstract
Rock wettability is one of the most important factors driving oil recovery mechanisms, as it controls the location, flow and distribution of reservoir fluids. Wettability affects most of the petrophysical properties of reservoir rocks including capillary pressure, relative permeability, waterflood behavior, electrical properties, and enhanced oil recovery (EOR). Most reservoir rocks are water-wet since they were originally formed in marine or lacustrine sedimentary environments. During hydrocarbons migration, reservoir rocks can be reversed to oil-wet conditions because of surface electrical charges of the grains that attract the oppositely charged components contained in the migrating hydrocarbon phase. Carbonatic reservoir rocks normally show a moderate to strong oil-wet condition. Alkaline substances and some surfactants have the capability to reverse the oil-wet reservoir rocks into a more favorable condition for enhancing oil production. In particular, such mechanism is normally deployed to increase the oil recovery factor of chemical flooding EOR projects. Laboratory testing at reservoir conditions is always required before implementing any field application and the wettability reversal measurement is a key factor for the success of the above EOR application. The present study was performed at the Petroleum Engineering laboratory of the University of Bologna (Italy). Here, it has been clarified that the displacement-by-oil ratio significantly affects the Amott-Harvey wettability index, which affects the final oil recovery expected by the application of alkali and alkali-surfactant flooding EOR technique. On the other hand, only a small change of displacement-by-water ratio can be observed throughout the experiments. This observation can be interpreted as the improvement of oil recovery factor induced by alkali and alkali-surfactant flooding is caused primarily by a lesser preference to oil more than by the complete reversal of previously oil-wet into full water-wet condition. In particular, the maximum relative oil recovery of the strong oil-wet carbonatic rock is obtained when the Amott-Harvey wettability index is close to zero or when the reservoir rock turns into a neutral-wet condition.
Microbial Enhanced Oil Recovery: 3D Simulation with Gravity Effects
Authors: Nielsen S. M. , Jessen K. , Shapiro A. A. , Michelsen M. L. , Stenby E. H. 
Published: July 2010

AbstractMicrobial enhanced oil recovery (MEOR) utilizes the activity of microorganisms, where microorganisms simultaneously grow in a reservoir and convert substrate into recovery enhancing products (usually, surfactants). In order to predict the performance of a MEOR process, a simulation tool is required, with all the relevant physical processes included.We have developed a mathematical model describing the process of MEOR, where reactive transport is combined with a simple compositional approach. The model describes the displacement of oil by water containing bacteria, substrate, and the produced metabolite, surfactant. The metabolite is allowed to partition between the oil and water phases according to a distribution coefficient. Production of surfactant decreases the oil/water interfacial tension, reduces the residual oil saturation, and provides additional oil recovery.In this work, we have implemented our MEOR model into a compositional streamline simulator based on the standard IMPEC framework (implicit pressure, explicit composition) to decouple flow and reactive transport. The reaction and transport processes are solved simultaneously along each streamline. Gravity effects are implemented using an operator splitting technique. To the best of our knowledge, this has resulted in the first full 3D MEOR streamline simulator. For verification purposes, we compare results from our streamline MEOR simulator to those of a conventional finite difference approach for 1D and 2D displacement calculations. We investigate the benefit of MEOR relative to water flooding, comparing the processes in multiple dimensions.The results of our simulations demonstrate that the oil recovery from MEOR processes in relation to water flooding is markedly increased, and the high recovery is achieved much faster. In addition, the compositional streamline simulator is applied to study both microscopic and macroscopic displacement efficiency of MEOR.
Thief Zones and Effectiveness of Water-Shut-Off Treatments under Variable Levels of Gravity and Reservoir Heterogeneity in Carbonate Reservoirs
Authors: Ghedan Shawket , Boloushi Younes , Saleh Moutaz 
Published: July 2010

Abstract
Progressive percentage of total fluids produced in the oil industry is formation brine. Ever, increasing water cut will reduce oil recovery, diminish wells' productivity and increase the cost of eventual artificial lift and produced water handling. In addition to mobility ratio, the predominant factors that cause and aggravate irregular movement of injected water resulting in early water breakthrough and high water cut wells is gravity and reservoir heterogeneity.
Through very comprehensive simulation study, performed on a sector model extracted from a layered and heterogeneous carbonate oil reservoir, this paper investigated the evolution of injected water front and the level at which high permeability layers will act as a thief zone causing early water breakthrough. The paper determined the effect of different reservoir heterogeneity parameters on the behavior thief zones, including thief zone's horizontal permeability, kv/kh ratio, and thickness. The threshold of these parameters and their various combinations that cause a higher permeability layers to act as thief zones were established and for different levels of reservoir permeability (very low, low, medium, high, and very high). Moreover, the paper investigated the effect of gravity on the process by comparing the behavior of top versus bottom thief zones. The difference in the combination of reservoir parameters that cause their different behavior is reported. In order to generalize the outcomes of this paper, all results are presented in terms of dimensionless variables.
Water-shut-off, WSO, treatments were then simulated to determine their effectiveness in delaying the water breakthrough time, and reducing high water cuts, under different thief zones' conditions. Extreme thief zone cases were selected from the first part of the study for this purpose. The paper finally summarizes the applicability of these WSO treatment methods and at which conditions of reservoir heterogeneity and gravity, they are or are not effective.