bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrated Cementing Hydraulics Design for Massive Salt Zones
Authors: Martins A. L. , Aranha P. E. , Folsta M. G. , Simão C. A. , Batalha N. A. , Pinto G. H. 
Published: April 2012

Abstract
Salt formations are common trap zones for prolific reservoirs. Recent discoveries in the Brazilian coast include light oil carbonate reservoirs below massive salt zones. Well construction challenges in such environments include salt creeping, leaching and proper zonal isolation.
This article presents a comprehensive integrated methodology for cementing design which accounts for the following hydraulic aspects: Adequate fluid substitution design supported by numerical simulation considering two phase flow in eccentric annuli and lubrication theoryDownhole pressures in the operational window considering free fall effects for deepwater environmentsOpen hole volume prediction based on salt leaching phenomena due to the circulation of unsaturated fluids. Flow rate fluctuation as a result of free fall is consideredIncrease in salt concentration due to conduction effects after placement and its impact on slurry properties.
The methodology is exemplified by two typical scenarios for offshore salt cementing in the Brazilian pre-salt cluster. Slurry design, slurry placement schedules and borehole stability considerations are addressed.
Numerical Simulation of Transient Flow for Gas Pipeline and Tank
Authors: Ling K. 
Published: April 2012

Abstract
Gas transient flow in pipeline and gas tank is critical in flow assurance. Not only leak detection requires a delicate model to simulate the complicated yet drastically changed phenomena, but also pipeline and tank design in the metering, gathering, and transportation system demands an accurate analysis of gas transient flow, through which efficient, cost-effective operation can be achieved.
Traditionally there are two types of approaches to investigate gas transient flow: one is treating gas as ideal gas so that ideal gas law can be applied; another is considering gas as real gas thus gas compressibility factor comes into play. Needless to say, the former method can result in an analytical solution to gas transient flow yet with a deviation from the real gas performance, which is very crucial in daily operation. The latter approach needs numerical method to solve the governing equation, thus leads to unstable issue but with more accurate result. Our literature review indicated that no study considered the effect of changing gas viscosity on the transient flow is available. Therefore, this effect was included in our study.
Our investigation showed that viscosity does have significant influence on gas transient flow in pipe and tank leakage evaluation. In this study, a comprehensive evaluation of all variables was done to find out the most important factors in the gas transient flow. Several case studies were used to illustrate the significant of this study. Engineers can do a more reliable evaluation on gas transient flow by following the method we used in our study.
Stepping Forward: An Automated Rock Type Index and a New Predictive Capillary Pressure Function for Better Estimation of Permeability and Water Saturation. Case Study, Urdaneta-01 Heavy Oil Reservoir
Authors: Tillero E. 
Published: April 2012

Abstract
Despite the great effort made to characterize reservoir rock, proper techniques in grouping rock type, in predicting permeability, and also in estimating water saturation from reservoirs that exhibit high variability in permeability-porosity relationship are still debatable today. In addition, core sampling for both routine and special core analysis may be biased in spite of the wide number of existing rock types, mostly in the case of heterogeneous rock reservoirs.
The main objective of this work was to develop a new mathematical expression for water saturation prediction, in the case study Urdaneta-01 heavy oil reservoir, in Maracaibo Lake basin, Venezuela, based on an alternative approach of traditional Leverett J-function. This new equation was developed by introducing two additional power-fit coefficient as function of water saturation (for specific capillary pressure values), Leverett J-function slope (from all values of capillary pressures test), and height above free water level (FWL). In addition, an automatic Rock Type Index was used to accurately estimate reservoir permeability.
A reliable water saturation profile according to rock type was obtained from the new water saturation approach. At least 3 to 5% difference between water saturation from log-based traditional techniques and that of the alternative approach (new expression for Sw) was obtained, mostly in heterogeneous intervals. Also it was determined that the innovative rock type indicator provides a better permeability estimation and rock description because of the high definition of rock type obtained from this new technique.
Qualitative and Quantitative Analysis of Three-Phase Distributions of Oil, Water and Gas in Bentheimer Sandstone Using Micro-CT Imaging
Authors: Feali M. , Pinczewski W. V. , Cinar Y. , Arns C. H. , Arns Ji-Youn , Francois N. , Turner M. , Senden T. , Knackstedt M. 
Published: April 2012

Abstract
It is now widely acknowledged that continuous oil spreading films observed in two-dimensional glass micro-model studies for strongly water wet three-phase oil, water and gas systems are also present in real porous media and result in lower tertiary gas flood residual oil saturations than for corresponding negative spreading systems which do not display oil spreading behavior. However, it has not been possible to directly confirm the presence of spreading films in real porous media in three-dimensions and little is understood of the distribution of the phases within the complex geometry and topology of actual porous media for different spreading conditions. This paper describes a preliminary study using high resolution X-ray microtomography to image the distribution of oil, water and gas after tertiary gas flooding to recover waterflood residual oil for two set of fluids, one positive spreading and the other negative spreading, for strongly water wet conditions in Bentheimer sandstone.
We show that for strongly water-wet conditions and a positive spreading system the oil phase remains connected throughout the pore space and results in a low tertiary gas flood residual oil saturation. The residual oil saturation for the corresponding negative spreading system is significantly higher and this is shown to be related to the absence of oil films in this system. The presence of films for positive spreading systems and the absence of such films for negative spreading systems is further confirmed by the computation of the Eurler characteristic for each phase.
Optimization of Production Allocation under Price Uncertainty: Relating Price Model Assumptions to Decisions
Authors: Bukhari A. A. , Jablonowski C. J. 
Published: April 2012

Abstract
Allocating production volumes across a portfolio of producing assets is a complex optimization problem. Each producing asset possesses different technical attributes (e.g. crude type), facility constraints, and costs; In addition to these field-level specifications, there are corporate objectives and constraints (e.g. contract delivery requirements). While complex, such a problem can be specified and solved using conventional deterministic optimization methods. However, there is often uncertainty in many of the inputs, and in these cases the appropriate approach is neither obvious nor straightforward. One of the major uncertainties is the commodity price assumption(s). This paper tackles this problem in three major sections: (1) We specify an integrated stochastic optimization model that solves for the optimal production allocation for a portfolio of producing assets when there is uncertainty in commodity prices, (2) We then compare the solutions that result when different price models are used, and (3) We perform a value of information analysis to estimate the value of more accurate price models.
Price modeling can affect decision-making, but it is surprising to find so little research that relates the price modeling assumptions (model type and the respective parameters) to the decisions that result from their use (capital investment, production optimization, etc.). Instead, we observe countless papers advocating for more and more complex price models, and an equally large body of work where models are estimated and compared for their accuracy. No one appears to have asked the basic question, "Do any of these models provide any incremental value for decision-making?" Here, we address this question by specifying an integrated stochastic optimization model that simulates decision-maker behavior. Using this model, we compare and contrast the various production allocation decisions that result from different price models. Simple price models are investigated and compared to several currently popular advanced price models with the goal of understanding the impact of price model assumptions (both the model type and its parameters) on decision-making. The results show that the optimum production allocation is a function of the price model assumptions. However, the differences between models are minor, and thus the value of choosing the "correct" price model, or similarly of estimating a more accurate model, is small. This work falls in the emerging research area of decision-oriented assessments of information utility/value. We believe it to be the first paper of its kind on this subject in the upstream literature.
Risk Analysis and Economic Evaluation of Oil and Gas Prospects Offshore Uruguay
Authors: Ferro S. , Tomasini J. , Soto M. , Morales E. , Rodríguez P. , Conti B. , de Santa Ana H. 
Published: April 2012

Abstract
Hydrocarbon exploration offshore Uruguay has been historically very limited. Only two wells were drilled in shallow waters in 1976. Additionally, there are about 30.000Km of 2D reflection seismic, including 6.400Km acquired in 2011. ANCAP, the National Oil Company, offered offshore areas for exploration and exploitation of hydrocarbons to interested international oil companies through Uruguay Round 2009. This bidding round successfully ended with the signature of contracts for two areas. This auspicious result, in addition to the interest shown by the upstream industry, have lead ANCAP to launch the Uruguay Round II.
The most recent 2D seismic survey allowed the definition of several prospects. This article presents the risk analysis and economic evaluation of the potential development of three prospects offshore Uruguay, of different type and depth, considering for each one the possible occurrence of dry natural gas, natural gas with condensate or oil.
The Estimated Ultimate Recovery, Net Present Value, Internal Rate of Return and Payout were determined for each prospect by Monte Carlo simulation. Different development concepts were considered for each case. A sensitivity analysis of the key variables (reservoir parameters, hydrocarbons price, capital and operational expenditures) was carried out showing the impact of each variable on the project. Finally, a decision tree analysis was used to compute the Expected Monetary Value of each case, incorporating the geological chance of success and minimum economic field size as inputs for the assessment.
ANCAP signs the exploration and production contracts with offshore Contractors on behalf of the Uruguayan Government, and is in charge of designing the fiscal regime ruling in Uruguay. Thus, this analysis includes the latest and real terms applied in Uruguay Round II, including ANCAP's participation and actual market considerations; consequently it provides a very good estimation of the oil company's take.
This work constitutes the first evaluation of this kind applied to prospects offshore Uruguay, therefore its results and conclusions are significant for those international oil companies that might be interested in carrying out exploration activities in offshore Uruguayan basins.
A Dynamic Simulation Study of an Extra-Heavy Oil Gathering System in the Orinoco Oil Belt
Authors: Brito F. , Rondon L. 
Published: April 2012

Abstract
The Orinoco Oil Belt (OOB) is the world's largest accumulation of heavy and extra-heavy oil with recoverable reserves of 513 billion barrels. It was divided into four production areas: Carabobo, Ayacucho, Junin and Boyaca. Based on that importance for the country's oil production, the use of dynamic flow simulators is becoming more important for the company when it comes to assess the development of such a huge oil deposit.
Currently, in the Carabobo Area, there is a significant uncertainty about the transient behavior of multiphase fluids in the gathering systems, since all studies have been conducted using steady state models. Because of that, there is no a thorough knowledge where there are slug flow formations, the impact of adding new oil production to the current pipeline networks and the transient hydraulics behavior during start-up/shut-in of wells.
This project aimed to build a dynamic simulation model, where several scenarios were established to study the impact on the current gathering system due to changes in flow patterns, additional oil and gas production, start-up/shut-in of wells.
Results showed that the predominant patterns in the system are slug and stratified flows, being the critical area a 5.7 km pipeline at the end point of the gathering system, where there are considerable slug formations. Moreover, with the oil production growth estimated in the short term (2012-2013), the slug flow formations will be reduced slightly; therefore when wells are shut-in the difficulties to transport the fluids are increased considerably. Even though the dynamic simulator underpredicted pressure values compared to real data in approximately 25%, it is possible to use the program as a reference to conduct transient analysis with oil and gas from Cerro Negro Field. This dynamic simulation proved to be a useful tool to analyzed technical and operational problems in an extra-heavy oil field and for the current and future development of the OOB's vast reserves.
BHA Selection and Parameter Definition Using Vibration Prediction Software Leads to Significant Drilling Performance Improvements
Authors: Amorim D. , Hanley C. , Leite D. J. 
Published: April 2012

Abstract
The understanding and mitigation of downhole vibration has been the subject of intense scientific research in the drilling industry in recent years, as inefficient drilling results in slower and more expensive operations. In order to drill ahead, a sufficient amount of energy must be supplied by the rig to overcome the rock strength, the reactive torque of the drilling system, drag forces, fluid pressure losses, as well as the energy lost by way of downhole vibrations.
It has been well documented that downhole vibrations are a significant drain on the amount of effective drilling energy available to the bit. When the drill string enters resonant modes of vibration, not only does the drilling efficiency decrease, but the likelihood of catastrophic drill string component failures increase. The amount of destructive energy expended in these resonant modes of vibration, when left unchecked, may overcome the material limits of components in the drill string. In this sense, the mitigation of downhole vibrations will result in faster, smoother, and cheaper drilling operations.
Software using Finite Element Analysis (FEA) has been developed to understand these vibration phenomena and to predict which combinations of drilling parameters should result in more efficient drilling. The software graphically presents the results, depicting undesired levels of resonant vibration produced with specific drilling parameter combinations, based on the BHA geometry and wellbore design. Predictions made by this software have produced notable results, including a world record for Rate of Penetration (ROP) in the Gulf of Mexico.
This paper also examines different Bottom Hole Assembly (BHA) designs and the resonant vibration modes that may be initiated while drilling, using the proprietary software package. The combination of proper BHA design and the correct selection of parameters results an overall improvement to drilling efficiency. A variety of case studies from Latin America, incorporating the results of the vibration analysis, will demonstrate solid improvements to drilling operations in terms of time and cost savings, increased penetration rates, and improved dull conditions. The use of field validated software for vibration prediction and mitigation has a potential role in the drilling industry as important as the introduction of PDC bits in the 1980s.
Field Application of New Proppant-Detection Technology—A Case History in the Putumayo Basin of Colombia
Authors: Torres F. , Reinoso W. , Chapman M. , Han X. , Campo P. 
Published: April 2012

Abstract
Traditional fracture-height and/or proppant-placement evaluation following a hydraulic fracture stimulation treatment has relied on the detection of radioactive (R/A) tracers pumped downhole with the proppant. While this technique has proven useful, it raises environmental, safety, and regulatory concerns and issues. In some areas of the world, transport and use of R/A tracers is prohibited.
The proppant placement determination method described in this paper eliminates the downhole placement of R/A materials. A high thermal neutron capture compound (HTNCC) is incorporated into a ceramic proppant during manufacturing in sufficiently low concentration that it does not affect proppant strength or conductivity. Proppant is then detected using standard compensated or pulsed neutron tools, with detection based on the high thermal neutron capture of the compound relative to the surrounding downhole constituents.
Two detection methods use a comparison of before-frac log-count rates and after-frac count rates, with reduced after-frac count rates observed in zones containing proppant. Another detection method, especially useful when formation gas saturations change, involves only the after-frac log.
This paper will describe the methodology and results of an application of the new detectable proppant in the T sand of the Villeta and Caballos formations of Juanambú field in the Putumayo basin of Colombia. The results obtained from this novel technology provided the operator an improved understanding of the geomechanical characteristics of the formations and the achieved fracture dimensions. Additionally, this information will help improve future stimulation treatments. This paper should be beneficial to all completion engineers looking for methods to determine fracture height and/or proppant placement in an environmentally acceptable manner.
Successful Implementation of a Relative-Permeability Modifier Along With Hydrocarbon-Based Ultrafine Cement: Case History from Mexico's Offshore Region
Authors: Castillo M. A. , Chacón W. A. , Cancino V. M. , Palomares A. 
Published: April 2012

Abstract
This paper presents a case history of a well in the Ku Field, Gulf of Mexico (Fig. 1) where, for the first time, a water-control treatment combined the use of a relative-permeability modifier (RPM) and a hydrocarbon (HC)-based ultrafine cement slurry. The challenge was to activate the HC-based ultrafine cement before it was lost into a highly conductive channel in a reservoir with high porosity and natural fractures.
The HC-based ultrafine cement is mixed to form pumpable slurry, which is inactive until contact with water. On contact with water, the slurry remains pumpable for a period of time before forming a dense, hard set. The system is applicable for high temperatures up to 400°F. The RPM additives are basically solutions of polymers that act because of their adsorption on the walls of the pores, achieving a reduction in water permeability without damaging the oil permeability.
This paper documents the pumping technique used in the first well in the offshore Mexico region where the water inlet was controlled with a combination of RPMs and HC-based ultrafine cement. After the treatment was applied, water production was cut from 8 to 0%, which has been maintained for more than 3 years. The benefits to the operator are summarized as follows: Because oil from the Ku field goes directly to sales, quality standards are quite strict and wells with water cuts similar to those presented in this study cannot be produced. Applying the water-control treatments outlined in this study has decreased the water cut and thus allowed the wells to continue production.Production could be maintained at a good pace because the choke had to be reduced to control the flow of water.Application of the documented water-control treatment was a lower cost to the operator than repairs using interventions.
Rock Type Modeling: An Effective Method to Determine Reservoir Quality Rock to Discretize Net Pay in Lower Guadalupe Formation, Abanico Field, Colombia
Authors: Betancourt Jose 
Published: April 2012

Abstract
The quality of a reservoir rock is determined, among other factors by porosity, permeability and the connection between the pores, known as pore throat radii. The determination of the values of this last parameter is important for estimating the flow and storage capacity of the reservoir rock. The aim of this study is the determination of quality rock types in the lower member in Guadalupe Geological Formation in Abanico Field. To achieve this goal were identified pore throats radii in 3 cores taken in the central and north area of the Abanico Field.
Winland, the mid-70's, showed a statistical correlation between the optimal flow through the rocks and the radii of pore throats, when 35% of the pore space of a rock is saturated with a phase that does not wet, during capillary pressure test by mercury injection. For his part, Pittman, achievement extends the study of Winland, which development an empirical set of equations, through the use of a system of multiple regression statistical analysis.
This is job was based on Pittman equations. Pittman calculated the pore thorat radii that correspond to the 35 th percentile, which was extended to a spread of mercury saturations percentiles (between 10 and 75%). Using this methodology it was determined that the dominant pore throat radius in the samples studied for the Lower Guadalupe Formation, corresponds to a mercury saturation of 45% (R45). This result is relevant because from of testing was determined the percentage of pore volume that contributes to the flow capacity of the rock and the percentage of pore volume that provides storage capacity.
Integrating the capillary-pressure data with well log information from the production history, it was determined that the hydraulic unit Lower Guadalupe is primarily Macro-porous type with pre throat radii between 2 and 10 microns, with minor variations Mega-porous rocks (&gt; 10 microns), Meso-Porous (0.5–2 microns), Micro-porous (0.1–0.5μm) and Nano-porous (&lt;0.1), allowing the generation of iso-quality rock maps, which show in an areal way, areas with the best thicknesses which are related directly to the production of hydrocarbons in the Lower Guadalupe Formation, being a key parameter in the characterization of rock-fluid system.