bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solution for a Long-Standing Cementing Challenge—Engineered Cement Set Control Additive
Authors: Sorgard Eirik , Viali Rodrigo 
Published: December 2007

Abstract
Solution for a Long-Standing Cementing Challenge— Intelligent Cement Set Control Additive Industry has always found it challenging to cement long zones with a single slurry system. A huge temperature differential exists between the bottom and the top of a long cement column. Cement slurry designed for the circulating temperature at the bottom of the long column will sometimes fail to set at the low temperatures at the top of the cement column. These results in rig nonproductive time and in certain cases can lead to well integrity problems.
While setting unplanned kickoff plugs or plugging and abandoning wells, the bottom hole temperature may not be very well known. The slurry setting is sensitive to temperature, and the setting time can change substantially if the actual bottom hole temperature is different from that used for design. This leads to failure of the cement plugs. This issue is more pronounced around 200°F.
A new generation of engineered cement set control (ECSC) additive has been developed to successfully cement wells in the scenarios mentioned above. The additive works intelligently and not only provides sufficient placement time for bottom of long cement columns where temperature is higher, but at the same time allows for fast compressive strength development even at the top, where temperatures are lower.
A single slurry design incorporating the additive has been used successfully in setting multiple plugs at different depths, with varying bottom hole circulating temperatures, demonstrating the relative insensitivity of the retarder to temperature variation.
This paper discusses successful use of the additive in the field for setting multiple plugs at varying depths and temperatures using the same slurry design. Field cases with results related to the various applications will be provided.
A Simple Productivity Equation for a Horizontal Well in Pseudosteady State in a Closed Anisotropic Box-Shaped Reservoir
Authors: Lu Jing , Tiab Djebbar 
Published: December 2007

Abstract
This paper presents a simple productivity equation for a horizontal well in pseudo-steady state in a closed anisotropic box-shaped reservoir, using a uniform line sink model. A new equation for calculating pseudo skin factor due to partial penetration is also proposed. Compared with the equations for horizontal wells in pseudo-steady state in the literature, the new equations are more practical and easy to use in the field practice. They are derived by solving analytically the involved three-dimensional partial differential equations and are extracted from a very complex general solution,
The effects of the following parameters on productivity have been investigated: well location, pay zone thickness, well producing length, principal permeability, and dimensions of drainage volume. It is concluded that, though each of these parameters has an effect on productivity, the well length and the permeability perpendicular to the well in the horizontal plane have the strongest influence.
First Installation of an Openhole Expandable Sand-Screen Completion in the Iranian Oil Fields Leads to Operational Success and Production Enhancement—A Case History
Authors: Hooshmandkoochi A. , Ghorbani F. 
Published: December 2007

Abstract
Expandable sand screens were developed to overcome the shortcomings of both existing sand control techniques, while also providing some unique benefits. The first commercial application of this technology took place in January 1999. Since then, their use has spread quickly to all parts of the world and in many diverse applications. As of June 2005, over 340 installation of expandable sand screen (ESS) had been run in over 700 years of combined production.
The productivity performance of the ESS has been shown to be very good, with an average skin of 0.3 being achieved in recent openhole applications. ESS completions generally perform better than the baseline models. Where field comparisons were possible, they also performed better than alternative sand control completions.
However, its introduction and acceptance into the Iran has been slower in coming. It was not until in 2005 that National Iranian Oil Company (NIOC) decided to complete its Mansuri oilfield, well MI–34 sidetrack, using openhole expandable sand screen for sand control, thus making it the first such completion in the Iranian oilfields. This paper will provide a brief overview of expandable sand screen, its construction and advantages and will describe some of the issues addressed in this well completion. It will provide details of the installation procedure, the fluids employed and well production results achieved. It will conclude that the use of expandable sand screen as an alternative to conventional sand control methods in the Iranian Oilfields is viable.
Microbial Enhanced-Oil-Recovery Technologies: A Review of the Past, Present, and Future
Authors: Maudgalya Saikrishna , Knapp Roy M. , McInerney Michael J. 
Published: December 2007

Abstract
One form of tertiary oil recovery that does not require exceptional investments is microbial enhanced oil recovery (MEOR). With abundant and easily producible oil supplies dwindling, MEOR could be an uncomplicated aliment to conventional water flooding. Unfortunately it has not gained credibility in the oil industry due to technical and economic reasons. To better understand this problem, a survey of reported MEOR field trials from across the world was conducted here. The survey shows some widely prevalent practices in most of the trials. Few tests could explain the mechanics of oil recovery or presented any post treatment analysis and explanation of to how results were calculated. And some showed improvements that appeared disproportionate to the treatment size. Based on trends observed in the survey results, recommendations are made to overcome barriers to widespread use of MEOR and gain credibility with more users. One recommendation is to standardize test procedures and reporting of results and analysis. This would be the best way to avoid contradictory interpretations of MEOR results. The initial few trials will be expensive if all the pre-treatment and post-treatment recommendations are followed. But the benefits of conducting a few systematic and well designed tests to fully evaluate the potential of MEOR and bring credibility outweigh the expense.
Prediction of Slurry Permeability, k, Using Static Gel Strength (SGS), Fluid Loss Value, and Particle Size Distribution
Authors: Bahramian Y. , Movahedinia A. , Rasaei M. R. 
Published: December 2007

Abstract
Gas migration through the cement column is considered as one of the most sever encountered phenomena during drilling or completion procedures, and has been recognized as one of the most troublesome damaging effects of the petroleum industry on the environment. There are many theories explaining the migration of gas through the cement which mainly considered the following as major factors contributing to gas migration: fluid density, mud removal strategy, cement slurry design, cement hydration processes, cement-formation-casing bonding and cement mechanical properties. Considering cement slurry design, the permeability of the slurry during transition state is explained as one of the main controlling parameters. Therefore low permeability is defined as one criterion for good cement formulation.
In this paper, an approach has been presented which relates permeability, k, to SGS, fluid loss value and pore size distribution of the cement. Modeling k goes through the consideration of the cement as a two-phase porous-elastic material with a changing structure represented by variation of SGS and fluid loss value with time.
The pore sizes of the particles are introduced in the model by using Carman-Kozeny equation, in which the permeability at the beginning of transition state (t = 0) is calculated. The Sabins et al. equation, 1982, which is originally developed to compute pressure drop due to gelation, is used as the basic equation to relate SGS and fluid loss value to k (along with Darcy flow equation). Maximum Darcy flow rate, qmax , which is, according to Sabins et al, simply measurable by using static gel strength and slurry permeability tester, is used to reflect the effect of fluid loss values on k values. Finally the predicted k-values by the equation is compared with measured data.
The approach can be used to optimize cement formulation and simulate gas migration through the cement column.
Finite Element Studies of Near-Wellbore Region During Cementing Operations: Part I
Authors: Gray K. E. , Podnos E. , Becker E. 
Published: December 2007

Abstract
A wellbore cement sheath is expected to provide zonal isolation and borehole integrity during well construction and well life. Cement sheaths mechanically interact with other elements in the wellbore region to stresses from geological processes and operational activities. Quantifying these interacting physical components and processes has technical, economic, and environmental implications of great, and growing, significance.
Staged finite element procedures during well construction sequentially consider the stress states and displacements at and near the wellbore. The model replicates complicated stress states arising from simultaneous action of far-field stresses, overburden pressure, cement hardening and shrinkage, debonding at the interfaces, and plastic flow of cement sheath and rock formation. Presently, temperature and flow are not included. The technique tracks the time-dependent behavior of cement slurry, curing (with or without shrinkage), and hardened cement during the critical period after slurry placement.
Material models for casing, cement and rock formation, failure criteria for cement, formation and interface bonds were calibrated using published information and experimental data. Calculations were conducted for various loading and unloading scenarios, geometric configurations, properties of rock formations, and cement slurry formulations. Results are discussed in terms of field implications, for example: (1) interface micro-channels may or may not develop, depending upon shrinkage magnitudes; (2) simplifying modeling assumptions that are often used, such as 2-D stresses and/or deformations, may obscure critical casing, cement, and formation behavior in the wellbore region, and in the producing horizon.
This paper, part of a series quantifying the interacting physical components and processes at and near the wellbore region, initiates useful comparisons of analytical results and field realities. The series illustrates and compares results and practical implications for simple to increasingly complex, but more realistic assumptions, such as isotropic/directional stress states, and isotropic/anisotropic casing, cement, and formation material parameters.
An Approach To Apply the Gas in the Annulus To Assist Pumping Oil in High-GOR Wells
Authors: Yonghui Liu , Yingchuan Li , Xiaoqi Li , Guilin Tang 
Published: December 2007

Abstract
Gas lift is a good artificial lift for those high gas/oil ratio (GOR) wells. But the positive displacement pump is used on many special conditions such as the limitation of high pressure gas, large equipment investment and low remaining recoverable reserve. To decrease the gas into the pump, the gas would generally be separated at bottom hole, then enter the annulus between the tubing and the casing (tubing-casing annulus), eventually flow in air or enter oil pipeline by many control valves at wellhead. In this system, the gas is a potential damage factor to the pump. So the pump efficiency is low and the frequency of pump checkout is high.
In this paper, a new approach is presented. One or two gas lift valves are installed on the tubing near the wellhead. The other equipments are same as the conventional system. While the casing pressure reaches the aimed value, high pressure gas in the annulus automatically enter the tubing. This lightens the weight of the fluid in the tubing above the working valve, which assists pumping the liquid.
This approach is applied in sucker rod pump system in Wendong oilfield. Dynamometer cards from 2 typical wells indicate that the pump efficiency is improved and the daily fluid production rate is enhanced. Then a similar approach is applied in Electric Submersible Pump system (ESP) and the same good result is obtained. This paper presents the description of this new approach and reports the results obtained in those field trials. The energy-saving theory is analyzed and the design procedure is given.
Liquid Unloading of Depleted Gas Wells in the North Sea and Continental Europe, Using Coiled Tubing, Jointed Pipe Velocity/Insert Strings, and Microstrings
Authors: De Jonge R. M. , Tousis U. 
Published: December 2007

Abstract
Flow from gas wells is often hindered due to water loading problems as fields mature, which often require remedial completions for maintenance of well flow. Velocity and insert string completions, using coiled tubing, jointed tubular and continuous foam injection via micro strings are techniques used to prolong production from these depleted gas wells.
A wide variety of velocity and insert string operations have been performed. To date the authors' in-house experience includes a total of 32 insert/velocity strings deployments in wells offshore in the UK, and 40 in the Netherlands and the rest of Continental Europe, both offshore and on land. Nearly 20 micro strings (0.25″) have been deployed in Continental Europe during the last 3 years. The sizes of the deployed coiled tubing velocity strings range from 1.5″ OD to 3.5″ OD, and 13Cr ‘Flush Joint Liner' strings for gas wells with high CO2 content, range from 2.875″ to 3.5″.
In this paper the aforementioned technologies are summarized, based on an extensive list of case histories of jobs performed in the North Sea and Continental Europe. It describes the equipment, engineering and technologies used for installation of these strings by hanging off either below the SSSV or at surface, as well as the offshore operational challenges experienced, due to small footprint installations, the installations being NUI's (Normally Unattended Installations) and low crane lifting capacities.
The number of engineered and deployed insert/velocity strings represent a vast array of lessons learned, optimizations, and successful operations. The comparison between the different techniques offers a base for preparation and optimization of liquid unloading techniques. A decision tree has been prepared to assist in choosing the suitable installation type.
Development of Unconventional Gas Resources: Stimulation Perspective
Authors: Zahid S. , Bhatti A. A. , Khan H. A. , Ahmad T. 
Published: December 2007

Abstract
Natural gas is an important global energy resource. In the last few years its consumption has increased significantly and being a cleaner fuel it is certain that in future it will play an ever increasing role in satisfying the increasing energy demand across the world. In order to meet the growing energy demand, exploration and production has increased across the world. However, due to the higher depletion rates of oil & gas reserves as compared to their discoveries, today the international energy sector is seriously thinking of developing unconventional energy resources, especially gas, so that the future energy needs can be met not only from an economic but also from reduced environmental impact point of view.
Three such Unconventional gas resources are tight gas reservoirs, coalbed methane and shale gas. These resources hold great potential as a source of natural gas (e.g. USA has the potential of recoverable gas of about 350, 100 & 45 Tcf from tight gas resources, CBM and shale gas respectively) and at the moment extensive work is being done for the development of these resources across the world. But, to produce these resources (gases) economically and efficiently well stimulation plays a major role in achieving the optimal target production from these reservoirs. Unconventional gas reservoirs require the formation to be fractured by hydraulic means to improve the formation productivity by providing a conductive path and joining the existing fractures and cleats in the reservoir.
The purpose of this paper is to discuss the role and effectiveness of different stimulation techniques in the development of unconventional gas resources. The improved stimulation has made a positive impact on the development of these resources which were considered uneconomical to produce due to lack of properly developed stimulation methods. Due to improved stimulation treatments, recovery from these resources has been enhanced greatly and producing gas from these unconventional gas reservoirs is far more economical and feasible than it was in the past. This paper presents a complete overview of the current scenario of unconventional gas resources and focuses on the fracturing stimulation techniques for the development of Unconventional gas resources.
The Important Second Fracture and Its Optimal Placement for Maximizing Production
Authors: Surjaatmadja Jim B. 
Published: December 2007

Abstract
Placement of a fracture in a formation has become a well-understood process in the industry. Recently, this practice was improved by the introduction of a method to properly initiate the fracture into a specific direction using super-high-energy jetting. A drawback of this jetting method though is not knowing exactly where the far-field fracture has gone. Although we know that the fracture will extend in the local minimum-stress direction, it is not known where that direction might be. In all probability, the fracture has gone into a less-than-desired area in the formation, and will result in only an "acceptable" improvement of production.
It was once thought that refracturing merely reopened existing fractures. Recently, however, it has been shown that refracturing can actually create new fractures. In addition, when refracturing causes older fractures to reopen, the results generally show that some new area has been reached by the fracture. It is the opinion of this paper that these new areas are not substantially different from the one reached by the first fracture because local depletion enhances the effects of the original stress regime.
This paper discusses a process whereby fractures are generated in a formation using at least two different fracturing techniques to reach formations in a manner not reached by conventional fracturing alone. In this process, the first fracture may achieve "acceptable" production goals, although the cost may be high. A second fracture is then quickly created to take advantage of the stress modification resulting from the first fracture. This rapid followup fracture is thus able to reach more productive rock not accessible to the initial fracture. Field data supporting the feasibility of this concept will be presented. Various situations where this approach could reap substantial benefits are also described.
Downhole Leak Determination Using Fiber-Optic Distributed-Temperature Surveys at Prudhoe Bay, Alaska
Authors: Julian J. Y. , King G. E. , Cismoski D. A. , Younger R. O. , Brown D. L. , Brown G. A. , Richards K. M. , Meyer C. A. , Sierra J. R. , Leckband W. T. , Sack J. K. , Julian F. C. 
Published: December 2007

Abstract
Distributed Temperature Sensing (DTS) is an emerging technology which allows temperature measurement and transmittal along the entire length of the well. An enclosed fiber-optic cable is deployed into the well to allow a continuous, real-time snapshot of the well's temperature profile. Since its introduction in 1995, DTS has had an increasing number of applications including determining production and injection profiles, monitoring stimulation operations, and performing gaslift surveys. This paper discusses DTS as a method for downhole leak detection based on a North Slope field trial conducted between 2004-2006. Twelve operations were performed using two different vendors’ retrievable DTS systems, successfully identifying tubing, production casing, sand plug, and packer leaks. Theory, case histories, and future improvements are summarized in this paper. Additionally, a comparison between conventional leak detection logs is presented along with the advantages and disadvantages of DTS surveys.
Two-Phase Fluid Flow Through Fully Eccentric Horizontal Annuli: A Mechanistic Approach
Authors: Metin C. Omurlu , Ozbayoglu M. E. 
Published: December 2007

Abstract
The number of wells drilled using underbalanced technique is increasing rapidly due to the advantages of this technology, i.e., increased penetration rate, minimized lost circulation and differential sticking, reduced formation damage and many environmental benefits. During Coiled Tubing (CT) underbalanced operations, gas-liquid mixtures are commonly used. In order to accomplish a successful drilling program, hydraulic calculations concerning two-phase fluid system should be carried out carefully. Since the flow geometry is mostly fully eccentric annuli in horizontal section of the wellbore, a realistic mechanistic model is essential. Although there are numerous studies available for two-phase flow through circular pipes, less is known about the flow of two-phase fluids though annular geometries. Commonly used methodology is using hydraulic diameter for representing the annular geometry, and using the circular pipe correlations by replacing the circular diameter with hydraulic diameter. It is observed that a better methodology is needed for basic hydraulic calculations. Therefore, in this study, horizontal flow of gas-liquid mixtures through fully-eccentric annuli is investigated. A mechanistic model is proposed for estimating frictional pressure losses, which can be used for both circular pipes and annular geometries by introducing a representative diameter term. Flow pattern identification is developed inheriting basic concepts proposed by Taitel-Dukler1. The model results are compared with experimental data obtained from two different annular geometries (4.5in × 2.25in and 3.672in × 1.92in) at Middle East Technical University – Petroleum & Natural Gas Engineering Department – Cuttings Transport and Multiphase Flow Loop. It is observed that, for representing the annular geometries, introduced representative diameter works significantly more accurately than hydraulic diameter. Additionally, flow patterns can be estimated better if representative diameter term is used. It is concluded that, the proposed mechanistic model can identify the flow patterns correctly and estimate frictional pressure losses with an accuracy of less than 20% when compared with the experimental data.