bluuebunny/crossref_metadata_2025_split huggingface dataset:
Engineering Analysis of Coiled Tubing Failure in a Gas Well with Hydrate Plugging
Authors: Hamid Saad 
Published: June 2014

Abstract
Failures provide an opportunity to revisit the existing practices and make necessary improvements in the way operations are designed and executed. Hydrate plug formation in certain operating conditions pose a well-recognized operational hazard. Water can form solid crystalline structure around gas molecules when favorable conditions exist. Very few hydrate formation incidents have been reported in open literature hence limiting the understanding of this subject.
One such incident occurred in Northern Alberta where a coiled tubing string became stuck due to hydrate plug formation in the well bore. Although the coiled tubing operations have become increasingly safer yet the challenging production environment results in greater intervention risks than ever. Coiled tubing failures occurring as a result of operating in these conditions enable us to learn valuable lessons which must be shared with the industry to raise general awareness and reduce industry-wide failures. During this operation, coiled tubing was run for retrieving bridge plug in a 3400m (11155ft) gas well. Restrictions were encountered during the operation, however; coiled tubing safely reached the desired depth. The plug was retrieved successfully but the coiled tubing became stuck close to surface. The pipe was freed up after several attempts and pulled inside the riser section. It was discovered that the pipe had been catastrophically buckled after the risers were opened on surface.
The paper evaluates different failure scenarios in an attempt to analyze the factors that may have been responsible for pipe failure in the given operating conditions while describing the engineering analysis, investigation conducted and lessons learned from it. The paper gives an insight into hydrate prevention techniques in order to avoid stuck pipe conditions hence preventing failures during intervention operations.
The Long Gestation of a Small, Stranded Gas Discovery in the Dutch Sector, North Sea
Authors: Coghlan G. , Westera D. , Ritzema K. 
Published: June 2014

Abstract
F3-FA field is a small offshore gas field in the Dutch sector of the Southern North Sea. The discovery well drilled in 1971 located rich gas in the Jurassic Scruff Greensand Formation. Its constrained size meant field appraisal did not take place for a further decade with two wells drilled in 1982.
Following appraisal, the field struggled to compete for investment capital against other development opportunities and also for pipeline access. Ultimately the original operator exited the field in 2008 - Centrica Energy purchased its equity and field operatorship.
A different opportunity set allowed Centrica and its partner EBN to advance the field development. Uncertainty regarding the dynamic performance of the field and a recognition of limited volumes and therefore producing field life led to the adoption of a Self-Installing Platform (SIP). The platform is a first of its kind at this scale, being the largest mobile production gas platform, 133 meters high and slightly heavier than the Eiffel Tower and designed for re-use on another location to produce some other small accumulation.
The platform was installed in 2010 with full processing and compression facilities in place, tied into the NOGAT pipeline system. Production is from a single, near-horizontal production well. The reliance on a single development well reflected the marginal nature of the development with a range of reserves that reflected uncertainty about the dynamic behaviour of the reservoir that did not have the luxury of any analogues to draw on.
First production was achieved in 2011 and to date the field has performed strongly with no indication of aquifer influx which was an uncertainty going into development. Condensate yield proved much higher than anticipated.
The prolonged time between exploration and first production is a familiar trait for many small developments of recent years in the Southern North Sea, often executed by a new breed of operator. It is also typical of the choices needed to bring such fields to production given modest reserves and unresolvable subsurface uncertainties.
New Insights into Drilling Dynamics through High-Frequency Vibration Measurement and Modeling
Authors: Oueslati Hatem , Jain Jayesh R. , Reckmann Hanno , Ledgerwood L. W. , Pessier Rolf , Chandrasekaran Sridharan 
Published: June 2014

Abstract
Dynamic instabilities of the bottomhole assembly (BHA) such as whirl, stick/slip, and bit bounce have been the focus of the majority of research studies in drilling vibrations. Recently, elevated levels of high-frequency rotational vibrations were recorded in the field with a high-bandwidth downhole vibration monitoring device. New experimental and numerical insights into this relatively unexplored phenomenon of high-frequency torsional oscillations are presented and discussed in this paper.
A suite of laboratory and field tests were conducted to understand and characterize the phenomenon. Computer modeling with in-house drillstring dynamics software corroborated well with the field measurements and validated the research team approach.
The investigation concluded that the drilling process excites BHA torsional vibrations. These vibrations occur at much higher frequencies than drill collar resonance and are significantly dependent on the drilled formation. New insights are gained into drilling dynamics in general and high-frequency torsional oscillations in particular.
The paper presents worldwide field case studies to illustrate the phenomenon. Details are provided of testing where the drilling environment is strategically controlled to characterize the dependence of these high-frequency torsional oscillations on bit design, operating parameters, and formation properties. The implications on drilling performance are also discussed in an attempt to satisfy the quest for efficient and reliable drilling.
Quantification of Low Levels of Mercury in Gas Reservoirs Using Advanced Sampling and Analysis Techniques
Authors: Harfoushian Jack H. 
Published: June 2014

Abstract
In addition to health, safety, and environmental issues, the presence of mercury can potentially have a huge impact on the economics of a gas development project. A mercury removal unit (MRU) must be designed in order to reduce mercury concentrations to below detectable levels to prevent such issues as liquid metal embrittlement (LME) which could lead to catastrophic events. It is therefore imperative to accurately quantify levels of mercury in a gas reservoir to design gas processing and mercury removal equipment accordingly.
Without consistent and precise procedures, accurate quantification is challenging with current technologies used in laboratory apparatus, especially when concentrations of mercury are very low. The conventional method of mercury content quantification is by analysis of samples captured either with wireline formation testers or while drillstem testing (DST) a well. However, these measurements are rarely in line with what is observed once a field is put on production. Loss of mercury due to adsorption by a DST string or by the metal surfaces of sample chambers and sampling tools is significant, especially when the sampling point is thousands of feet away from the producing reservoir. In addition to reaction with metals, test results have also shown how mercury can go undetected if reservoir fluid samples are compromised by small amounts of drilling fluids or mud filtrate. There have been a number of catastrophic failures in gas processing plants attributed to liquid metal embrittlement, such as the explosion at the Skikda LNG plant in Algeria in 1973, or the more recent 2004 New Year's Day Moomba gas plant fire which was confirmed to be due to LME in an aluminum vessel.
Workflows detailing procedures for capturing, storing, if required, and analyzing representative gas samples for the quantification of low levels of mercury have been developed, tested, and proven. Results of recent experiments conducted simulating downhole sampling conditions reveal the reasons why there have been numerous cases in which false negative results were obtained from laboratory analyses. Advanced focused sampling methods together with accurate downhole fluid analysis with wireline formation testers have been applied in the field to provide representative reservoir fluid samples for quantification of mercury levels.
Pressure and Temperature Transient Analysis: Hydraulic Fractured Well Application
Authors: Ribeiro Priscila M. , Horne Roland N. 
Published: June 2014

Abstract
Recent developments in bottomhole data acquisition techniques, such as distributed temperature sensing systems (DTS), have brought attention to the potential increase of information that can be obtained from temperature data. Studies have shown the application of temperature surveys to estimate flowrate profiles, resolve the kind of damage around the well, improve the robustness of the history matching, among others. Nonetheless, Temperature Transient Analysis (TTA) is not a mature technique and its capabilities have not been explored fully yet.
In order to investigate the application of temperature analysis to the hydraulic fracturing problem, in addition to pressure analysis, a numerical model was developed to calculate pressure and temperature responses. Regarding the fracture and reservoir fluid flow, a general approach can be adopted, where the formation permeability and fracture characteristics dictate how the fluids flow during and after fracture growth. We developed a comprehensive model, which accounts for the pressure effect on the temperature response, as well as a dynamic fracture that grows and eventually is allowed to close during falloff.
In this research we analyzed the temperature and pressure responses during and immediately after hydraulic fracturing in order to improve our knowledge of this complicated physical problem. Based on this study, we can better understand not only the fracture properties, but also the reservoir itself. In addition, sensitivity analysis shows how reservoir permeability can impact final fracturing performance, as well as pressure and temperature responses. The developed model is also applied to simulate minifrac analysis, and a field example is presented that shows a good agreement with the simulated behavior during fracture closure.
This paper highlights the potential of Temperature Transient Analysis, expanding the application of temperature in addition to pressure transient analysis to improve the characterization of fractured wells:
TTA has potential to reduce uncertainty related to fracture length and reservoir permeability. TTA also adds value to DTS information, which is commonly measured but often not fully used. Temperature analysis has the potential to give reliable information about the flow dynamics of the reservoir and especially about near well zone.
Optimum Perforation and Changed Stimulation Treatment for Improving Zonal Productivity: Key Enablers for Strategic Reservoir Management of Deep HP-HT Sour Carbonates in North Kuwait
Authors: Pradhan San P. , Acharya Mihira N. , Fidan Erkan , Rao Narhari S. , Al-Awadhi Mansour , Singh J. R. , Dashti Qasem M. 
Published: June 2014

Abstract
Deep HP-HT sour carbonate reservoirs in Northern Kuwait have varied matrix properties and fracture intensities. The wells are drilled with barite laden OBM with 1,000-2,000 psi overbalance. The intervals suffer substantial formation damage during drilling as is evident from the fact that the wells normally do not get activated, in spite of creating an underbalance of 5,000-6,000 psi by displacing mud with a lighter fluid.
During the early exploration phase of these reservoirs, long and/or multiple intervals were perforated and treated with conventional matrix stimulation using 28% retarded/ emulsified acid in stages with chemical diverter (gel based and visco-elastic surfactant based). Post stimulation PLT survey in these wells indicated, that only about 5-10% of the total perforated interval contributed to the production; concluding that the diverters were found to be ineffective leading to sub-optimal reservoir management due to poor zonal contribution.
As part of strategic reservoir management process selective bottom up approach in perforation with higher concentrations of HCl treatment and without diverter has been adopted in these reservoirs. To obtain a degree of diversion over the perforated interval, the acid was pumped at higher rate and with higher pressure. Adoption of this changed perforation and stimulation treatment has been proved to be the key enablers for improving zonal productivity.
Around 30 wells have been completed with this changed perforation strategy and treated with this new recipe and technique. Post stimulation test results are comparable to those wells treated with regular matrix stimulation. The PLT survey post acid wash treatment by this technique showed that zonal contribution has improved. This process in addition to being simpler is faster and cost effective. This paper presents the comparison between the two types of perforation and stimulation strategies vis-à-vis test results and also the QA/QC followed prior to pumping the acid.
Analyzing Completion Efficiency Using Modified Heterogeneity Index
Authors: Salman Ahmad , Chen Jiansheng , Rasdi Faisal 
Published: June 2014

Abstract
Completion techniques in the unconventional reservoirs are continuously evolving. Yet a method to evaluate completion efficiency is still lacking. This study proposes a method employing the conventional Modified Heterogeneity Index (MHI) to evaluate completion competency and reservoir quality.
Hydraulic fracturing is designed to maximize reservoir contact. The hydraulic fractures may grow beyond the target or landed geologic zones due to an improperly planned or executed stimulation. This paper first shows the vertical water saturation profile and the observed correlation between water saturation and water cut. These results help to understand reservoir communication between multiple stacked reservoirs and hence help to quantify completion effectiveness.
Modified Heterogeneity Index is traditionally used in conventional reservoirs to monitor water breakthrough and normalize producer well performance in a water-flood field. This paper proposes a method to exploit the HI analyses and understand the correlation between water production and well productivity. The analysis is also tied to completion techniques to understand completion efficiency and its relation to reservoir properties.
This paper demonstrates that (a) correlation between water saturation, water cuts and production indicates that water saturation is one of the key reservoir properties governing production, (b) modified Heterogeneity Index can be utilized to scrutinize the completion effectiveness and reservoir quality, (c) the new method can be used pro-actively to screen for re-frac candidates and to forecast or estimate the possibility of pressure communication between offset wells.
ASP Flood of a Viscous Oil in a Carbonate Rock
Authors: Panthi Krishna , Sharma Himanshu , Mohanty Kishore K. 
Published: June 2014

Abstract
The goal of this work is to develop an alkaline-surfactant-polymer (ASP) formulation for a viscous oil carbonate reservoir. A large number of phase behavior studies were performed to find a low interfacial tension (IFT) ASP formulation for the viscous oil. The reservoir dead oil was diluted with decalin to get a viscosity equal to that of the live oil (105 cP). The surfactant formulation was tested with an outcrop vuggy dolomite core in both tertiary and secondary modes. Waterflood recovered about 47.8% of the oil in place and reduced the oil saturation to 43.8%. The tertiary surfactant flood increased the cumulative oil recovery to 92.7% whereby the oil saturation was reduced to 7.3%. During secondary surfactant flood, the oil saturation was reduced to 3.1% and the oil recovery was 95.6%. The ASP core floods were modeled by the UTCHEM simulator. The modeling showed a reasonable match between the experimental and simulation results. Experimental data for surfactant phase behavior, polymer viscosity, and surfactant adsorption were useful in matching the experimental results. The effect of divalent ions in the connate water was negligible because the injection brines were softened and the core consisted only of dolomite which has little solubility in water at the experimental conditions.
Experimental Investigation of Water Saturation Effects on Barnett Shale's Geomechanical Behaviors
Authors: Lin S. , Lai B. 
Published: June 2014

Abstract
Shale gas is one of the most rapidly expanding trends in onshore domestic oil and gas exploration and production today. Improving the performance of shale gas wells typically requires the improvements of fracturing technologies. One of the most important factors that affect hydraulic fracture propagation is the geomechanical property of rocks (Young's modulus, E and Poisson's ratio, ν and so on). In reservoir conditions, most reservoir rocks contain a certain amount of connate water, which indicates geomechanical properties measured by using dry samples suffer substantial flaws.
This paper is to experimentally investigate the impact of water saturation effects on Barnett shale's geomechanical properties (Young's modulus, E and Poisson's ratio, ν and uniaxial compressive strength (UCS)). Nineteen Barnett shale cores (satisfied with ASTM standard) were first partially saturated with KCL water to various water saturation degree. A Material Testing System (MTS-810) was then employed to test the elastic properties and UCS of those partially saturated Barnett shale's samples under uniaxial conditions.
Experimental results show that 1) water saturation has a significant impact on Young's modulus and UCS. Young's modulus decreases 6.1‰ with an increase of a water saturation (1%) of Barnett shale core corresponding to the value of dry shale's Young's modulus. 2) Young's’ modulus and UCS decrease linearly with increasing water saturation. And 3) the relationship between water saturation and Poisson's ratio is not obvious. In another word, the water saturation does little impact on Poisson's ratio. Correlations predicting elastic properties and UCS under reservoir water saturation conditions from dry core samples are proposed based on experimental findings in this paper. The improvement of accuracy of predicting geomechanical properties of Barnett shale can better understand hydraulic fracture propagations, improve wellbore stability and optimize hydraulic fracture design in Barnett shale reservoirs.
In-situ Disintegrating Completion Tools by Means of Controlled Microgalvanic Cells
Authors: Zhang Zhihui , Xu Zhiyue , Salinas Bobby J. 
Published: June 2014

Abstract
The technology advancement in horizontal drilling and hydraulic fracturing makes it economically viable in exploration of unconventional oil and natural gas resources where conventional drilling is ineffective. In fact, more than 90% of the wells drilled today are hydraulically fractured. Despite the efforts, there exists demanding challenges to reducing the cost of non-productive time during well drilling and completion. Traditionally, many downhole disposable tools such as frac-balls, disks or plugs that are used for sleeve actuation and isolation of different production zones during fracturing, or control valve actuation for production, are disposed artificially through either a re-entry such as drilling out or flowing back that is limited by the available lightweight materials subject to early yielding or severe shape change.
The concept of in-situ disintegrable tools made of materials that are lightweight, high-strength and have a controllable corrosion rate simplifies operations and represents an obvious advantage. In this work, the integration of light weight and a high corrosion rate is realized in the dissimilar metal composites forming micro-galvanic cells. Simultaneously, an ultra-high strength is achieved through engineering the micro/nano-matrix and secondary nanoscale metallic and/or ceramic additions. The corrosion tests were conducted in 3% potassium chloride (KCl) at 200 °F. The results show the nano-engineered composite materials exhibit a disintegration rate that can be controlled between 10 and 400 mg/cm2/h with ultra-high strength up to 80 ksi. The interaction mechanism between the matrix and nanoscale secondary phases was studied using scanning and transmission electron microscopy. The improved mechanical properties were analyzed in the framework of micromechanical models and the perspective to further increase the material strength was discussed. Field application tests show the completion tools made with the composites reliably eliminated artificial intervention and opened a flow path within controlled time in the natural downhole fluid.
Lessons Learned from 27 Years' Experience of Stimulation Vessel Design and Operation - a Case Study
Authors: Martin A. N. , Austin S. , Glennie A. , Martinez J. , Bradford S. 
Published: June 2014

Abstract
The operating envelope and environmental demands for hydraulic fracturing and stimulation treatments in the North Sea are increasingly larger and more complex. As a result, a generation of vessels designed and built in the 1980s are increasingly unable to achieve operational, economic and/or environmental goals. Thus, a new generation of vessels must be designed specifically to meet these European requirements.
The design characteristics of a new vessel can be split into five categories: (i) stimulation plant (ii) marine systems (iii) environmental protection (iv) welfare of the crew and (v) regulatory compliance. All five categories are critically important to achieving the stated goals for the new generation of European vessels, and all require careful integration of current cutting-edge technology with forward-thinking design concepts that will enable technical evolution over the expected 30-year lifetime of the new vessels.
This paper will outline the most significant problems faced by the current generation of stimulation vessels, compare current technological solutions to those problems, and demonstrate that integrating those technologies in a new vessel can achieve performance and flexibility far beyond what is possible by retrofitting them on an older vessel or in a modular system on the deck of a supply boat.
Tail-end production will have an increased importance in the North Sea and in all offshore production as a large number of producing fields near the end of their life. The effective deployment of production enhancement with stimulation vessels has a major part to play in extending field life.