bluuebunny/crossref_metadata_2025_split huggingface dataset:
Technical and Economic Evaluation of Hydrocarbon Prospects Offshore Uruguay and the Challenge of Maximizing Rent from Exploration to Production Phases through Local Content
Authors: Gristo P. , Tomasini J. , Ferro S. , Fennema J. , McLeroy P. 
Published: June 2014

Abstract
From 2009, when the first offshore bidding round took place in Uruguay, and in particular from the second bidding round that constituted a enormous step in the exploratory history of Uruguay, our country faces a new and nontraditional hydrocarbons upstream activity. Government take, including the National Oil Company association in the case of a discovery, is already fixed under the Production Sharing Contracts in force and do not vary much with the field size. Therefore, a possible strategy to maximize the local revenues (income from Uruguayan services, products and human resources), which constitutes a key part for a sound distribution of petroleum revenues within the country, would be to increase the local content in the supply chain.
Taking into consideration analogous geological basins, and the geological and technical probability of success for offshore Uruguay as a frontier basin, the field size and hydrocarbon potential was evaluated from a stochastic point of view. The cash flow analysis of a hypothetic oil development was carried out, incorporating the actual economic variables of the contracts in force offshore Uruguay, as well as the current fiscal regime. The standard project parameters, investments yardsticks and the government and contractor takes were calculated with the aim to obtain the Uruguayan rent and the relative impact of the local content.
This work constitutes the first approach to the analysis of expenditures and investment during the current stage of exploration, and the eventual phases of appraisal, development and production offshore Uruguay. The technical and economic evaluation applied to a portfolio of offshore prospects models the level of expenditures and investment from exploration to production.
The assessment of the potential impact of the activity on macroeconomic variables is carried out considering the local services and products that would be necessary for each stage, in order to identify the areas where increasing local content will provide the larger impact in the country economy.
The use of Constructed Wetlands in Produce Water Treatment; an Option for the Oil and Gas Industry
Authors: Korsah P. E , Ambrose I. S. , Korsah W. 
Published: June 2014

Abstract
Produce water treatment and discharge is a critical public health issue in most oil producing countries, where efficient and economical treatment options are being sought after. The main focus is centred on the removal of heavy metals and hydrocarbon residues. Phytoremediation, the technique that utilizes a plant's inherent ability to accumulate metals, is fast emerging as a relatively cheap and environmentally friendly alternative to conventional wastewater treatment methods. A corollary of this is an urgent need to identify plant species with the appropriate suite of characteristics for phytoremediation. The purpose of this study was to evaluate and compare the phytoremediation potentials of Limnocharis flava, Thalia geniculata and Typha latifolia using three serially connected horizontal sub-surface flow (HSF) constructed wetlands. Each wetland had only one of the three plant species but all were supplied with wastewater from a common source. From October 2010 to March 2011, the growth performance of the candidate plants was measured, and their accumulation and translocation rates of heavy metals (Fe, Cu, Zn, Pb, Hg) determined using atomic absorption spectrophotometer. Mean removal efficiencies ranged from 40-80%, 48-54%, 44-54%, 18-32% and 8-38% respectively for Fe, Hg, Zn, Pb and Cu. The removal efficiencies of the species differed depending on the metal. L. Flava was most efficient (p&lt;0.001) at removing Fe, Cu mostly removed by T. latifolia (p&lt; 0.001) whilst T. geniculate appeared to be the best remover of lead (p&lt; 0.021). Both T. geniculata and T. latifolia appeared to remove zinc better than L. flava (p&lt;0.021), but there was no statistical difference in the removal rates of mercury by the plants. Similar trends were observed for the bioaccumulation factor, which increased substantially with time. The plants accumulated most of the metals in their roots. The findings demonstrate the capabilities of the three phytoremediants for improving the quality of heavy metal contaminated water.
Use of Reservoir Simulation to Estimate Drainage Area and Recovery Factor of an In-Situ Combustion Project in a Complex Water-Drive Heavy Oil Reservoir
Authors: Gonzalez Laureano , Ferrer Jose , Fuenmayor Mac , Castillo Nerio , Gil Edison , Farouq Ali S. M. 
Published: June 2014

Abstract
In-situ combustion (ISC) is being carried out in the Quifa heavy oil reservoir in Colombia, employing four vertical inner wells and four deviated outer wells (inverted nine-spot pattern). Additionally there are four horizontal wells surrounding the pattern, which started producing one year before the combustion project was initiated.
In order to evaluate the project performance key parameters, such as volumetric sweep efficiency and recovery factor must be estimated. Therefore, it is important to have reliable values of drainage area and oil in-place volumes since they are basics for the calculations. Given the complex nature of this reservoir, with a strong water drive, the estimation of the drainage area, oil in place and the recovery factor posed a major challenge. The reservoir is characterized by abrupt permeability and oil saturation changes, resulting in water channeling and well interference.
This paper presents the methodology used to obtain the drainage area and current recovery factor of the ISC pilot project by using numerical reservoir simulation. It comprises the generation of oil drainage maps and cross-plots of what we called "Oil Displaced by Neighboring Wells, ODNW" as a function of time. This approach is more accurate than analytical methods for such complex reservoirs since those methods are based on ideal homogeneous reservoir conditions that assume uniform fluid displacement and a symmetrical advance of the combustion front.
Results are presented for the oil in place, the drainage area, and the recovery factor at one year of air injection. These results are compared with those derived from analytical methods. The methodology was designed to be readily applicable to similar heavy oil reservoirs worldwide.
Testing Results of an Economical Mesh Screen for Thermal Applications
Authors: Smith Kevin , Bowen Eddie 
Published: June 2014

Abstract
Slotted liners have predominantly been selected to provide a low cost control of sand/solids production in heavy oil applications where the need for steam injection is required to reduce the oil's viscosity in place making it mobile. The biggest challenge with slotted liners is the inflow area. Typically, this can range from 2-3% depending on the width, length, and number of slots per foot. This leads to plugging tendency over time.
The advent of wire wrap screen jackets was an improvement to slotted liner technology. Using a longitudinal wire rib and a shaped wrap wire, a series of openings representing a specific gauge can be manufactured into a wire jacket. This wire jacket is then slipped onto a perforated base pipe, creating a screen product. Although wire jackets improved the area to flow, it was still limited to inflow areas of 6-12% depending on the slot opening. Albeit an improvement to plugging resistance, it still provides a less than desirable flow area to accommodate plugging over time without restricting flow. Typically, the least amount of flow area can be found in the perforated base pipe.
Both slotted liners and wire jacket screens have vast experiences in thermal applications but very limited experiences using a mesh filter type media in these applications. As premium mesh filtering screens have become recognized and accepted during the past few decades there has not been much in the form of thermal testing to qualify these products for cycling temperature environments. The design of a premium mesh can deliver inflow areas in the range of 30-55% depending on the nature of the design, woven v. stacked layers bonded or sintered in place. This improvement in inflow area increases the time to plug exponentially.
The intent here is to show the results of thermal testing conducted with an economical mesh screen, supporting its use in the high temperature cycling that occurs during cyclic steam and SAGD applications. Using a myriad of designs, with and without welds, tests of multiple thermal cycles ranging from ambient to 950°F were conducted in the following modes: 1) free floating, 2) both ends fixed, 3) a single end fixed, and 4) gravel packed in place. Based off these results an optimal design prevailed.
Bitumen Extraction by Expanding Solvent-Steam Assisted Gravity Drainage (ES-SAGD) with Asphaltene Solvents and Non-Solvents
Authors: Mukhametshina A.. , Hascakir B.. 
Published: June 2014

Abstract
Steam Assisted Gravity Drainage (SAGD) is a proven enhanced oil recovery technique for oil sand extraction. However, the environmental and economic challenges associated with steam generation limit the application of this technology. To address these issues, we investigated the effectiveness of Expanding Solvent SAGD (ES-SAGD) over base SAGD on a bitumen sample (8.8 °API). Experimental studies are conducted with a two-dimensional physical model. Different strategies for solvent injection are tested (co-injection and cyclic injection) to examine the deposition of polar fractions of the bitumen on porous media or producing polar fractions with non-polar ones. To investigate the level of oil upgrading while toluene is used as asphaltene soluble solvent, n-hexane was selected as asphaltene insoluble. Steam chamber development is monitored with temperature profiles from 47 separate positions. Steam oil ratios, solvent oil ratios, and the level of oil upgrading in terms of viscosity reduction and API gravity improvement are evaluated together. Environmental footprints of SAGD with ES-SAGD are discussed in terms of solvent toxicity, total produced greenhouse gases, and asphaltene precipitation with FTIR analysis on postmortem samples. Furthermore, the energy intensity of the processes is assessed by considering steam generation and solvent costs. This study reveals that co-injection of hydrocarbon solvents with steam enhances the steam chamber development with higher oil production rate. Moreover, ES-SAGD results in recovery of more upgraded oil and has less environment impact. We observe that the selection of the solvent type and injection strategy are the most crucial parameters for the design of hybrid SAGD process and solvent cost can be minimized by using the recycled solvent for continuous injection of solvents. High energy consumption for steam generation during SAGD process can be reduced by co-injection with steam proper solvent type at proper injection strategy. This experimental study reveals that ES-SAGD process has environmental and economic benefits over base SAGD. However, some solvents can cause undesirable effects due to the asphaltene destabilization and precipitation in production or transportation lines. Results of this work can be used to better address solvent interaction with polar components during SAGD.
Identification of Winsor Type III Micro-emulsion for Chemical EOR of Heavy Oil
Authors: Sim Steve S. , Wassmuth Fred R. , Bai Jiang 
Published: June 2014

Abstract
Application of phase behavior studies to optimize chemical formulation for heavy oil EOR is not very common due to difficulties in identifying micro-emulsion in the presence of highly viscous and opaque crude oil. Currently, selection of ASP system for heavy oil EOR is mostly based on IFT value when other selection criteria such as surfactant adsorption, and chemical compatibility, are met. This omission of phase behavior study in the evaluation process can often lead to poor choice of chemical system since the quality of the micro-emulsion generated by the system is unknown and may not exhibit the critical properties (viscosity, stability) required to mobilize capillary trapped heavy oil.
This paper presents laboratory procedures for the optimization of ASP system for EOR of a viscous (&gt;10,000 mPa.s) and high TAN (&gt; 2 mg KOH/g) heavy oil using both phase behavior studies and IFT measurements. The resulting optimized ASP system, when mixed with the candidate heavy oil, displays Winsor type phase behaviors comparable to light oil/ASP system. These Winsor type III heavy oil micro-emulsions are stable and have much lower viscosity (150 - 350 mPa.s) than their parent crude oil. During the phase behavior study, it was observed that the natural petroleum soap from the crude oil plays an important role in the formation of the micro-emulsion and lowering of IFT. Effective utilization of petroleum soap presents in the crude oil during chemical EOR will dramatically reduce chemical cost and improve surfactant propagation within the reservoir. Recovery of the viscous heavy oil from Berea core with this optimized ASP system was excellent (~80%). The ability of this ASP solution to recover capillary trapped oil was demonstrated from the amount of incremental oil produced from a Berea core sample which had been extensively flooded with polymers. To our knowledge, identification of well characterized and thermodynamically stable Winsor type III micro-emulsion from heavy oil/ASP system has not been reported previously. Results from this study can lead to development of improved procedure for optimization of chemical system for heavy oil recovery.
Selection of Optimal Solvent Type for High Temperature Solvent Applications in Heavy-Oil and Bitumen Recovery
Authors: Marciales A.. , Babadagli T.. 
Published: June 2014

AbstractThe selection of most suitable solvent for an efficient heavy-oil recovery process is a critical task. Low carbon number solvents yield faster diffusion but the mixing quality may not be high. Also, high carbon number solvents yield a better qulity mixing (much less asphaltene precipitation) but the mixing process is rather slow. Hence, the understanding of solvent selection criteria for solvent-aided recovery processes has established two main aspects of oil-solvent interaction: (1) Oil-solvent mixture quality and (2) rate of mixture formation.Oil-solvent mixture quality is determined by two parameters: (1) Viscosity and (2) asphaltene precipitation. The rate of mixture formation is quantified by the diffusion rate. These two parameters need to be quantitatively and qualitatively determined to select the suitable solvent for heavy-oil recovery also supported by static experiments that measure solvent diffusion (and oil recovery) from a rock saturated with heavy-oil and exposed to solvent diffusion at static conditions.This paper focuses on these tests and uses three oil samples with a wide range of viscosities (250-153, 000 cp), and three liquid solvents with different carbon numbers varying between C7 and C13. The methodologies applied for diffusion rate measurement were optical applying image analysis under UV light (for processed -mineral- oil) and CT scanning (for heavy-oil obtained from fields). Next, viscosity and asphaltene precipitation measurements were conducted after mixing the crude oil and solvents to quantify the mixing quality.Then, core experiments were performed on Berea sandstone samples using the same solvent-heavy oil pairs to obtain the optimum carbon size (solvent type)-heavy oil combination that yields the highest recovery factor and the least asphaltene precipitation. Based on the fluid-fluid (solvent-heavy oil) interaction experiments and heavy-oil saturated rock-solvent interaction tests, the optimal solvent type was determined considering the fastest diffusion and best mixing quality for different oil-solvent combinations.
The research and application of Hydraulic Jet Drilling Technology In CSS
Authors: An Jiuquan 
Published: June 2014

Abstract
Liaohe Oilfield is the largest heavy-oil production base in china, and Circulate Steam Stimulation (CSS) is one of most important thermal development modes in heavy oil production. Utilizing the advantages of Hydraulic Jetting Drilling Technology, such as the deep penetration, more fractures connection, larger drainage radius and environment-friendly, as well as improve the heating effect in CSS wells, to increase the development performance of the remaining oil. This paper introduce the basic principle of Hydraulic Jet Drilling, and according to the reservoir characteristic of Block Gao-3624 in Liaohe Oilfield, optimize the design parameters, and meanwhile, analyze the feasibility for the application of Hydraulic Jet Drilling in combination with CSS measures, and finally accomplish the first domestic field application in the glutenite reservoir. From the field data, the increase extent of production rate could reach 200%, showing a great promising future for this technology.
Equilibrium or Nonequilibrium Models: A Critical Issue in Determination of Gas Diffusivity in Oil
Authors: Saboorian-Jooybari H. , Dejam M. , Chen Z. 
Published: June 2014

Abstract
Accurate simulation, design and implementation of any gas injection and solvent-based oil recovery processes requires a thorough understanding of a gas diffusion coefficient. This parameter is usually determined by monitoring gas pressure in a PVT cell during a pressure-decline test and analyzing the data by developing mathematical models that are different in imposed boundary conditions at a gas-liquid interface (the so-called equilibrium or nonequilibrium boundary conditions). Classically, the equilibrium boundary condition was applied at the gas-oil interface with the assumption of saturated interface at all times. But, recently in a number of researches it has been claimed that some time is required before establishment of the equilibrium state at the interface. These researchers considered existence of the non-equilibrium state and used a Robin-type boundary condition to account for the effect of resistance at the gas-oil interface on gas diffusion into oil. This paper considers these boundary conditions and investigates the effects of taking into account nonequilibrium nature of a diffusion process on estimation of mass transfer parameters using a lot of literature pressure-decay data of CH4, C2H6, CO2 and N2 dissolution in Athabasca bitumen at two different temperatures (50 and 90 °C) and an initial pressure of 8 MPa. Mass transfer parameters (a diffusion coefficient and a mass-transfer coefficient) are individually determined for each test by means of the equilibrium and non-equilibrium models and compared with each other. It is concluded that the values of the diffusion coefficient calculated by the equilibrium and non-equilibrium models are in an excellent agreement, indicating sufficiency of the classical mass transfer models to estimate the diffusion coefficient. On the other hand, although the non-equilibrium effects exist during gas dissolution in oil, applying a Robin-type boundary condition at the two-phase interface is not significant enough to affect the gas diffusion process.
A New Semi-analytical Model for Predicting Steam Pressure and Temperature in Annuli
Authors: Gu Hao , Cheng Linsong , Huang Shijun , Zhang Huideng , Lin Menglu , Hu Changhao 
Published: June 2014

Abstract
An excellent design of steam injection projects requires accurate prediction of bottomhole steam pressure, temperature and quality. However, it is not always easy to meet the requirement when we design concentric dual-tubing steam injection schemes due to the complexity of downward steam/water flow in annuli. Also, previous methods for estimating pressure gradient in annuli, such as mechanistic models and empirical correlations, are either time-consuming or inaccurate.
In this study, we present a new semi-analytical model to predict steam pressure and temperature in annuli. It is based on Coulter-Bardon equation and on mass and energy balances in the wellbore. A more rigorous thermodynamic behavior of steam/water mixture is taken into account. More importantly, one-to-one correspondence between pressure gradient and temperature gradient of saturated steam is reasonably developed and applied in our further derivation and simplification. It is because of the simplification that we do not have to use mechanistic models or empirical correlations to separately calculate the pressure drop in annuli, which is significantly different from previous work, including Sagar et al. (1991), Alves et al. (1992) and Hasan et al. (1994) models. Our solution procedure is straightforward, the equations of steam pressure, temperature, quality, steady-state heat transfer in the wellbore and transient heat transfer in the formation just need to be coupled and solved iteratively for each segment.
Our model is validated by comparison with measured field data from Liaohe Oilfield, Petro China. The results indicate that the direction of heat transfer between inner and outer tubing depends on wellhead conditions and temperature drop in each tubing. We also show that the equivalent hydraulic diameter is not always a suitable characteristic dimension for steam/water flow in annuli. Moreover, the paper shows that our method can also be applied to single-tubing steam injection design. The predicted results from our modified model are also compared with those from CMG simulator and previous work in our study.
Novel Steam-Resilient Cement System for Long-Term Steam Injection Well Integrity: Case Study of a Steamflooded Field in Indonesia
Authors: Salehpour A. G. , Pershikova E.. , Chougnet-Sirapian A.. , Taoutaou S.. , Adiningtyas D. A. 
Published: June 2014

Abstract
A major challenge of a steamflooded field in Indonesia, one of the world's largest thermal recovery projects, is the short life of the well from the well integrity aspect. The outcome of a joint study group between the operator and the cementing service provider reveals that 77% of the injector wells drilled in a recent period of 5 years required remedial squeeze cementing operations. The operating expenditure of workover operations and the costs of the deferred production to the operator are significant; hence, a cementing solution is needed to improve the efficiency in managing the mature heavy oil reserve.
The current cementing practice calls for placing the API class G cement and silica flour blended system across unconsolidated sand bodies and exposing it to large temperature changes. Results of the stress modeling predict the conventional cement system failure under the anticipated conditions of injection and workover operations. An innovative steam-resilient cement system with tailored thermal and mechanical properties up to a temperature of at least 350° C [650° F], beyond the maximum steam injection temperature of the field, is maintaining the integrity.
Field trials in Indonesia confirm that this new system can be easily integrated into standard cementing operations using conventional equipment. Cement evaluation logs after cement operations prove that proper zonal isolation is achieved. All the candidate wells, first one since January 2011, are currently under the steam injection with no sign of wellbore integrity failure.
This novel cement system, by keeping adequate level of flexibility and optimum thermal properties, provides a long term well integrity solution for any well exposed to similar conditions, such as in fields exposed to steam injection. Operators can rely on cement sheath integrity exposed to thermal processes to produce heavy oils.