bluuebunny/crossref_metadata_2025_split huggingface dataset:
Global Application of Coiled-Tubing Acid Tunneling Yields Effective Carbonate Stimulation
Authors: Stanley F. O. , Portman L. N. , Diaz J. D. , Leonard Darmawan R. , Strasburg J. P. , Clark J. S. , Navarro M. S. 
Published: February 2011

Abstract
Since 2005, a stimulation technique termed "coiled tubing acid tunneling" has been successfully applied on limestone and dolomite reservoirs in several regions around the world (South East Asia, USA, South America, Europe and Middle East). The technique is applicable on carbonate wells with barefoot (open hole) completions, with either relatively thick pay zones, or with thinner pay sections, for example with close water contacts. It consists of creating multiple drainage holes (tunnels) out into the reservoir pay zone. The tunnels are created by pumping hydrochloric acid (HCl) through a specially designed jetting bottom assembly (which includes a special kick off tool and procedure) and uses conventional coiled tubing and acid pumping equipment. Typical acid tunneling is performed on complete losses, resulting in a negative skin completion. The purpose of these drainage holes (with its own network of worm holes) is to improve the connectivity between the reservoir and the wellbore and positively impact well production.
The process can create as many drainage holes as required at different depths (production simulators are used to estimate optimum number of tunnels). The depth selections are based on key well information such as available logs (image, resistivity, caliper, drilling), past reservoir knowledge of the zone and observed lost circulation zones while drilling.
Results of this new stimulation technique on carbonate wells have been excellent as compared against conventional acid work (matrix acidizing, conventional acid jetting with coiled tubing and acid fracing). Numerous case histories from each region of the world are included in this paper and will contain comparisons of acid tunneling to conventional stimulation methods, stimulation design criteria, operational procedures, and production results. In one specific Indonesia field the pretotal average production on 12 wells was 955 bopd while the post acid tunneling result was 1,670 bopd, sustained production (the early 5 wells now have between 850 to 950 days post tunneling production history and all wells have at least 300 days post tunneling history).
A New Look at Nonlinear Regression in Well Test Interpretation
Authors: Dastan Aysegul , Horne Roland N. 
Published: February 2011

Abstract
Nonlinear regression is a standard procedure in the oil industry; however, its practical applications can be constrained by issues observed commonly in real data sets. These issues include convergence performance that depends on starting guess, deviations in the time and pressure data, nonideality in the data, and ambiguity in parameter estimation – these issues limit the ability of well testing results to forecast future reservoir performance. We investigated a variety of strategies to improve nonlinear regression and reduce the susceptibility to these issues.
The first strategy we investigated is Cartesian transformation of the parameter space. We developed transform pairs for common reservoir parameters and achieved performance improvement in terms of higher probability of convergence and smaller number of iterations for a random starting guess. In the second strategy, we applied the wavelet transform to the pressure data. We conducted nonlinear regression on a reduced wavelet basis to achieve improved likelihood of convergence and narrower confidence intervals. Wavelet analysis provided robust interpretation of dual-porosity reservoirs and reservoirs with boundary effects. In the third strategy we used total least squares for accurate estimation of reservoir parameters in the presence of deviations in the time data as well as deviations in the pressure data. We developed a robust approximation for total least squares (orthogonal distance regression) for the nonlinear pressure transient function.
We tested the techniques rigorously by using a large matrix of test cases made up of real and generated well test data sets. The data sets include a selection of reservoir models and test scenarios, including dual-porosity and fractured reservoirs, reservoirs with rectangular boundaries, cyclic buildup-drawdown tests, and general multirate data. We determined the methods or combinations of methods that work best with a particular reservoir model or type of test. We have shown that these novel nonlinear regression algorithms greatly reduce the ambiguity (narrower confidence intervals) and provide robust parameter estimation even for large noise levels or data uncertainty. We demonstrated that our techniques provide faster convergence and are more robust to poor initial guesses. The techniques provide compression and automatic denoising of massive data sets from permanent downhole gauges. We expect that our techniques and analyses will allow for better forecasting of reservoir performance.
Role of Vapor Phase in Oxidation/Combustion Kinetics of High-Pressure Air Injection (HPAI)
Authors: Barzin Y. , Moore R. G. , Mehta S. A. , Mallory D. G. , Ursenbach M. G. , Tabasinejad F. 
Published: February 2011

Abstract
Oxidation reactions and their kinetics are acknowledged to have a major impact on the success of air injection-based improved recovery processes. Vaporization of oil has been reported in the literature as a mechanism associated with kinetics of air injection processes; however, the parameters which control the vapor phase oxidation/combustion behavior have not been included in the studies of oxidation kinetics.
In order to characterize the vapor phase oxidation/combustion behavior of light oils in high pressure air injection (HPAI) process, an experimental and a follow up numerical study have been conducted on a high pressure ramped temperature oxidation (HPRTO) reactor on a 37 ° crude oil and a pure hydrocarbon.
The results of this study indicate that phase equilibrium between the liquid and vapor hydrocarbon and water components has a definite impact on the "flammability range" for vapor phase combustion at given temperature and pressure conditions. The observations also suggest the potential participation of vapor phase oxygen addition reactions in the supply of triggering energy for spontaneous ignition.
Given the importance of vapor phase behavior on the amount and distribution of hydrocarbons available for reaction with oxygen, a comprehensive phase behavior study on the selected light oil was performed. The developed phase behavior model was then used in a hypothetical model to study the behavior of the vapor phase under conditions of HPRTO tests. The significance of this model is its capability to predict the theoretical injected-air/fuel ratio of the vapor phase assuming thermodynamic equilibrium.
First Application of Alternate Path Technology and Concentric Sandface Completion Improved Operational Efficiency and Saved Significant Rig Time
Authors: Saebi Shahryar , Tyutikov Sergey , Bahri Chahine , Elhusseiny Moustafa , Bela Sunanda Magna , Ibrahim Zahidi 
Published: February 2011

Abstract
In line with the production enhancement program in Malaysia, Petronas Carigali Sdn. Bhd. (PCSB) decided to workover a number of idle wells in an offshore field. The reservoir consists of highly unconsolidated, laminated sandstone formation that requires having solid sand control system in place prior commencing production. There were concerns about the possibility of heavy losses of completion fluids in the depleted reservoir and also complications in gravel packing lower zones by presence of existing perforations in the upper zones. The operator also demanded to have selective production capability from the various zones during the life of the well.
In order to address the challenging requirements of the project, a combination of two completion techniques were proposed. Alternate Path technology provides alternate slurry pathways that bypass the bridges to assure 100% packing efficiency. Concentric Completion system provides fluid loss control post gravel placement and also circulation flow path during gravel placement and selectivity during production.
The customized sand control system was successfully installed, achieving the operational objectives.
Increasing the Reach and Selectivity of Completions in Extended Reach Horizontal Wells
Authors: Ritchie Barry , Pitts Michael , Van De Ven Sebastianus , Abul-hamd Abdel Aziz Ibrahim 
Published: February 2011

Abstract
Over 15 years of production and injection history within the Al Shaheen Field has provided more details on the reservoir heterogeneities and performance of extended reach horizontal wells. This additional data, along with the lateral extent of the reservoirs, has increased the need for longer and more selective horizontal completions. Three primary reservoirs have been developed to date and have different requirements regarding liners and completions. The commonality of all reservoirs is the requirement for long liners and completions in vertically shallow horizontal wells.
As the completion philosophy has changed, new approaches have been developed for both deployment and selective isolation. A number of case histories are discussed to illustrate the evolution of the completion requirements. Modifications to zonal isolation, mud over air floatation, and remote triggered packers are some of the cases discussed.
Two of the three reservoirs require acid stimulation to improve the production and injection performance of producers and injectors. Effective stimulation can not be accomplished through what would be considered typical placement techniques, due to the extreme lateral departure of these wells in shallow vertical reservoirs. Two techniques used are described along with some issues regarding hole-geometry in acid stimulated wellbores.
The paper concludes with some future requirements for the further development of the Al Shaheen Field. Increased selectivity and the need for active zonal control will push the completion requirements beyond where they are today. New completion concepts are being actively researched and developed so that the reservoirs can be optimally managed.
Design and Evaluation of Perforation Performance Using Dynamic Under Balance – North Sea Case Histories
Authors: Tovar J. , Appleby R. , Cooper G. , Hamilton B. 
Published: February 2011

Abstract
Dynamic under balance (DUB) pressure is being used by operators to improve completion efficiency and minimize formation damage. An understanding of the pressures generated when perforating allows the prediction of the level of pressure differential required to overcome the surge pressure generated, leaving a clean connection between the wellbore and the reservoir. Results reported by different operators indicate success with the DUB technique; certain criteria have been developed for the determination of the optimum conditions for its use. From the published information, type of reservoir fluid, interval length and formation mechanical properties are some of the main considerations for a successful design and implementation of the technique. Talisman Energy UK has used DUB for perforating several wells in the North Sea. A detailed job design process was implemented starting with the need to characterize the level of formation damage that existed in the wells. Three (3) main damaging mechanisms were quantified; damage resulting from fluid and solids invasion into the reservoir matrix, mechanical damage generated during drilling operations and actual damage caused during the perforation process. Perforation programs were developed and executed based on a clear understanding of the rock mechanical response to the DUB generated by the gun and taking into consideration perforating debris and fluid inflow required to clean the tunnels. The results from this work indicate that current design criterion for the selection of the optimum DUB pressure is limited and it is not clear about the physics and hydrodynamics of the clean up process.
Developing an Invisible Field in the North Sea
Authors: Berntsen B. A. , Hagen E. , Sørlie R. , Gowers M. , Jones C. 
Published: February 2011

Abstract
What can you do with a small oil discovery where you cannot map the reservoir on the seismic data? With a big field the answer is simple: drill more appraisal wells. But in a small offshore field with marginal economics this approach will be uneconomic. The Hanz field in the Southern Viking Graben of the Norwegian North Sea is such a discovery. It is small relative to North Sea oil fields and the seismic data does not allow direct mapping of the reservoir geometry. The discovery consists of two thin sands, an upper gas-filled sand and a lower oil-filled sand. The uncertainty concerning the relative amounts of oil and gas makes development planning difficult. The geology of the reservoirs indicates a coastal shoreface environment and a nearby well shows that the sands are only locally developed, adding another major uncertainty to the reserves.
However this discovery is unusual in one respect: a full scale DST was conducted in the lower oil sand and proved excellent permeability. A multidisciplinary subsurface team took up this challenge and embarked on a project to use the DST data to investigate the geometry of the trap. Normally an engineer's estimation of boundaries and volumes from a DST takes the form of a rectangular box-like reservoir with specific distances to boundaries. In the case of Hanz, the stratigraphic information from the surrounding geology was used to build a series of reservoir models. These models were used to simulate the DST results. In an iterative process the results of the DST simulation were used to adjust the model and simulate a new case. This work process turned out to be very efficient with a turnaround of two days from start of a new model to DST simulated results. This again enabled modeling of a large range of possible geometries, and the subsequent exclusion of a good many alternatives. This enabled the range of uncertainties for the discovery to be significantly reduced, and a workable development plan constructed. The Hanz discovery would never be developed without the available DST. The discovery is simply too small to justify an appraisal well. The next well on Hanz will have to be a combined producer and appraisal well. Based on this work, a robust subsurface foundation has been established for a future subsea standalone development or a third party tie-in candidate in a mature area with good infrastructure. The paper also illustrates the criticality of being able to perform a full scale DST well test in the first exploration well on a prospect in a mature but high cost offshore environment and where all the large structures and fields have been drilled.
Installation of a Produced Water Treatment System on Raml Field (Western Desert), Egypt
Authors: Surace D. , Broccia P. , Salemi Y. , Lovane M. 
Published: February 2011

Abstract
During hydrocarbons extraction from reservoir a big amount of water is produced. The volume of water does not remain constant over time, but the percentage increase passing the time. The presence of water enlarges the hydrocarbons production costs since it decrease the productivity capacity of the wells, increasing the treatments complexity of hydrocarbons. The water treatment is a delicate issue in the oil industry, both from economical and environmental point of view.
In the last years eni has developed different R&D projects for optimizing the water treatment processes and for improving the quality of the water. The produced water, once treated, can be reinjected into the reservoir or discharged in surface (sea, rivers, desert). The use of innovative technologies both onshore and offshore has allowed the discharge of water into surface bodies with oil in water concentration less than country regulations where the reservoir is placed.
This paper presents an ongoing project concerning the application of a produced water treatment system in the Raml field (Western Desert) in order to improve quality of the produced water, reaching the required target for the reinjection (oil-in-water ≤10 ppm and total suspended solids ≤ 15 ppm) also minimizing operations management and equipments maintenance.
A testing campaign on the deoling system, part of the water treatment system, was done on January 2010. This paper reports the processand scheme developed and the positive results obtained during this trial.
Difference Between Traditional and Risk Based Auditing
Authors: Spadaccini Danny 
Published: February 2011

Abstract
Auditors are trained to make detailed examinations of the internal control systems such as ISO 9001, ISO 29001, ISO 14001, OSHAS 18001, API, accounting systems and various legislative requirements and; focus their audit planning, testing, and reporting on internal controls in the business process.
The Evaluation of controls without first examining the purpose of the business process and its risks provides no context for the results. How can the internal auditor know which control systems are most important, which are out of proportion to their risk, and which are missing?
When controls are the central theme of the internal audit, audit reports and recommendations are generated for improving and strengthening internal controls. Over time, layer upon layer of controls are built up. These excessive layers of control slow down business processes, communication becomes more difficult, and people are employed in non-value-added work.
Auditors are typically looking at control activities designed at some previous time to deal with issues that were relevant when systems were implemented. This means the internal auditor is examining activities that may or may not be relevant to current risks. The controls may be inappropriate because they monitor risks that are no longer important or even in existence.
RBA changes the way internal auditors think and talk about risk. Instead of focusing on history, audit reports address the present and the organization's level of preparedness to deal with the future. Internal audit reports "complete the loop" between assurance of control in current operational plans and input to risk assessment for the strategic plan. RBA places an emphasis on risk-based internal audit reports rather than on traditional controls-based reports.
Three Dimensional FEM Simulation and Parameter Study on Laden Torque of Interference Friction of PCP
Authors: He Liu , He X. D. , Wu H. A. , Wang X. X. , Cao G.. 
Published: February 2011

Abstract
A three-dimensional finite element model for Progressive Cavity Pump (PCP) is constructed. The steel stator is simplified as a rigid body and the deformation of the rubber rotor is considered in the model according to the characteristic of the stator and rotor materials. The laden torque of friction due to the interference between stator and rotor is calculated with the model. The obtained numerical results are consistent well with experimental data. The effect of parameters on laden torque is performed and discussed. The parameters include the amount of interference between stator and rotor, eccentricity of the track of the rotor moving etc. The results demonstrate that the amount of interference between stator and rotor is the major factor of influencing the laden torque and the laden torque reduces as eccentricity decrease.
Gas Content Measurement With and Without the Use of Coring
Authors: Gray Ian 
Published: February 2011

Abstract
This paper examines alternatives to using core for gas content measurement of coal. The measurement of gas content from cuttings is presented in two forms, one involving the recovery of cuttings with air drilling and the second involving the collection of all released gas from the hole during overbalanced drilling. The latter approach is suitable for not only coal but all gas bearing formations such as shales which do not have major open pore space such as vugs.
Core desorption is the standard process for determining the gas content of cores. This process is described by McCulloch and Diamond (1976), and more recently Standards Australia (1999). The process generally involves using wireline coring to cut a core so that the core may be retrieved quickly. Once the core is retrieved to surface the core is placed in a canister and the released gas is monitored with respect to time. This should be undertaken at reservoir temperature. An example of gas release versus time is shown in Fig. 1.
Once the core has been further desorbed the canister is opened and the core is logged and weighed with density determination. Weighed sub sections of the core are then crushed to enable the remaining gas to diffuse out more quickly than from the core.
This process is relatively straight forward but the determination of the gas lost before the core is placed in the canister is not. The usual process adopted is to assume a time when the core begins to release gas and to plot the gas release with respect to the square root of time. An example of such a plot is shown in Fig. 2.
Combustion Assisted Gravity Drainage (CAGD) Appears Promising
Authors: Rahnema H. , Mamora D. 
Published: February 2011

Abstract
In-situ combustion (ISC) is an effective thermal recovery process that provides an important alternative to steam injection. However, the conventional ISC process has many apparent failures, which are mainly related to inappropriate reservoir application and instability of the process. Operational difficulties like gravity segregation, air channeling, unfavorable air to oil ratio and low sweep efficiency affect the performance of ISC. Horizontal well air injection is an interesting concept, which through positioning of horizontal wells attempts to overcome the problems that make ISC challenging.
Combustion Assisted Gravity Drainage (CAGD) is a new EOR process that use dual horizontal wells for injection of air and production of heavy oil. One important feature of this technique is that the properly oriented dual horizontal wells aid the development of combustion chamber and stabilized growth of the combustion front.
In this research, detailed reservoir simulations are conducted to examine the performance of the CAGD process in comparison to other practiced thermal recovery methods like Steam Assistance Gravity Drainage (SAGD) and Toe to Heel air injection (THAI). The results reveal that CAGD process has the lower cumulative energy to oil ratio in comparison to other two methods and its oil production rate is comparable to SAGD. The research identifies CAGD as a potential alternative to ISC method.
Safety and Operating Standards and Practices Used by Saudi Aramco To Conduct Critical Onshore Rigless Well Intervention Operations in Water, Oil, and Gas Wells
Authors: Al Jubran Hasan H. , Al Bu Hassan Shaker A. , Solares J. Ricardo 
Published: February 2011

Abstract
Saudi Aramco’s vision is to be the recognized industry leader in safety, and as such the company has applied high safety standards governing any well intervention work in all types of wells throughout its history. Moreover, detailed Standard Operating Procedures (SOP) and Operating Instruction Manuals (OIM) for all well intervention operations are regularly used to ensure safety and best operating practices are consistently applied. These standards and operating procedures are continuously reviewed and revised as needed.
This paper discusses the most salient safety and operating standards regularly applied in Southern Area well intervention operations, which has helped Saudi Aramco accumulate a stellar record of successfully and safely completing a very large number of well intervention jobs. The paper also provides case histories of challenging procedures in which the strict application of existing procedures and standards resulted in a positive and successful outcome.