bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simple Engineering Applications Recycled as Effective Training Aids
Authors: Sawaryn S. J. 
Published: October 2011

Abstract
Technical advances have led to both the expansion and increased specialisation in the engineering skills employed in our industry. In many cases these specialisations involve the use of complex engineering calculations involving a bewildering number of inputs and outputs to match real-world situations. A further problem with high-end applications is that they are costly and their logic is often presented as a "black box" and disclosure may be hampered by intellectual property concerns. Whilst such high fidelity applications may be essential for operations, simpler models with few inputs are better for scoping exercises or training.
The rapid and effective transfer of knowledge and experience to new hires with diverse backgrounds remains a key challenge. Though information technology and richer media have helped standardise delivery methods, accessing appropriate engineering applications for training purposes remains a challenge.
The important requirements are to communicate the fundamentals and build on knowledge gained at University. At the same time, the teaching methods and modules should instill curiosity and encourage critical assessment of the models and methods used. The models should not therefore be too far from reality.
Technical progress and refinement of a broad range of topics is inherent in the content and structure of the SPE paper library. The application to training is illustrated using examples including the simple 2D-BHA algorithm presented by Walker (1973). This paper shows how key refinements have been included using simple geometrical constructs and how the model has been effectively used in spreadsheet form to develop an understanding of BHA behaviour, directional survey sag correction and to identify and correct programmatic errors.
It is suggested that greater use can be made of the SPE library as a ready source of cost effective training material and that the descriptions of the simpler engineering applications it contains can be recycled as valuable training aids.
A Flow Assurance Study on Elemental Sulfur Deposition in Sour Gas Wells
Authors: Tang Yula , Voelker Joe , Keskin Cengizhan , Xu Zhenggang , Hu Bin , Jia Changqing 
Published: October 2011

Abstract
This paper summarizes a flow assurance study for elemental sulfur deposition in the tubing for the Chuandongbei Gas Project (CDB), a greenfield sour dry gas development project in Sichuan, China. The project is a co-venture of Chevron and China National Petroleum Company (CNPC). The development contains several fields, all containing dry gas with 8-17% H2S, and 8-10% CO2
Elemental Sulfur (S8) dissolved in the gas may precipitate in both the near-well reservoir region, and tubing, within the pressure and temperature range predicted for gas well flow in the fields. The precipitate may form gas flow restrictions. An offset operator producing gas from the same reservoir interval and having similar composition has reported flow problems attributed to S8. This study focused on the prediction of S8 deposition in the tubing, during both production and shut-in periods.
Numerical transient well pressure and temperature modeling with the OLGA wax deposition module was used to predict precipitation and deposition of S8 in the tubing. Presently, no other S8 deposition model is available. The model estimates the pressure and temperature gradient between the bulk fluid and tubing wall, and molecular diffusion rates through the laminar sub-layer of the fluid velocity profile. An S8 phase equilibruium model calibrated by measured phase behavior from a laboratory synthetic gas having the composition of CDB field measured surface gases was used to generate the S8 phase diagram.
The study indicates that shut-in periods present the greatest S8 deposition risk: suspended sulfur precipitate accumulates at bottomhole during shut-in periods, possibly forming a flow restriction. Mitigation through solvent treatment applied after shut-in periods is therefore planned. S8 deposition on tubing walls during flow periods was found to present relatively low flow assurance risk.
This study also provides operational design recommendations for well start up, sustained flow, and shut-in periods, as well as flow assurance mitigation design.
A Novel Approach Based on Dielectric Dispersion Measurements to Evaluate the Quality of Complex Shaly-sand Reservoirs
Authors: Pirrone Marco , Han Mei , Bona Nicola , Borghi Massimiliano , Galli Maria Teresa , Pampuri Ferdinanda , Faivre Ollivier , Hizem Mehdi , Kherroubi Josselin , Mossé Laurent 
Published: October 2011

Abstract
This paper presents a novel approach for the formation evaluation of shaly-sand thin layered reservoirs using dielectric dispersion wireline logging provided by a new generation tool. The study is focused on gas fields in the Mediterranean basin characterized by the presence of very thin inter-laminations (centimeter-scale or even less). In these complex reservoirs, the conventional petrophysical analysis is very challenging due to standard logging tools’ vertical resolution limits which prevent the quantitative estimation of the clay content, of a detailed water saturation profile and of the reservoir quality.
The new-generation, cm-scale vertical resolution tool overcomes these limitations thanks to the continuous measurement of dielectric dispersion from the MHz to the GHz frequency range and to a fit-for-purpose inversion based interpretation model. The outcome is a high resolution estimate of the main petrophysical parameters including water volume fraction for determining hydrocarbon saturation, formation water salinity and an additional textural parameter of the rock matrix that is correlated to clay volume.
The model has been developed and calibrated using a statistically representative database of core measurements (including porosity, mineralogy, granulometry, Cation Exchange Capacity as well as dielectric spectra measurements) from several wells drilled in shaly-sand reservoirs representing different geological environments. In all the analyzed wells a full wireline log data set was also available.
The application of the new approach to the examined case histories provided satisfactory, high resolution results in terms of:
lithological description of the formation with the added value of a quantitative estimation of the clay content; reservoir quality evaluation; gas saturation indicator thus reducing the uncertainty in the petrophysical characterization of complex shaly-sand reservoirs.
Successful Discovery of Light Oil from an Unsuccessful Paleozoic Well through Re-entry - A Case Study of HPHT Well
Authors: Al-Bader Haifa , Al-Salali Yousef Zaid , Duggirala Vidya Sagar , Manimaran A. , Packirisamy S. 
Published: October 2011

Abstract
This paper describes the challenges addressed during testing, completion and subsequent re-entry for Jurassic prospects in an ultra-deep HPHT exploratory well in highly sour environments. The approach and methodology adopted to address the problems related to perforation, Coiled Tubing, stimulation and well testing operations are also discussed in this paper.
The exploration activities for gas in North Kuwait are in progress at high pace. An exploratory well, second deepest in the State of Kuwait, drilled in Mutriba field to a depth of 22, 094 feet to cover Triassic and Paleozoic sections. All these deeper formations have very low porosity and permeability. Two formations, Kra-Almaru and Khuff were perforated and tested, which showed the presence of feeble gas. Based on the study, later it was decided to test and complete this well in Jurassic formation through re-entry.
The re-entry in this ultra-deep well was full of challenges due to HPHT conditions, high surface pressure and well killing issues. The re-entry was planned under the supervision of highly skilled task team. A snubbing unit was utilized to isolate the open perforations of the Triassic zone with cement. Subsequently a workover rig was deployed to test the prospect of Jurassic reservoir. Several severe mechanical problems like fishing, isolation and retrieving the tubing were encountered prior to well testing, which were efficiently addressed. Testing the Jurassic reservoir behind two heavy walled casings(7" 46.4 ppf and 8-5/8" 40 ppf), combined with extreme sour and HPHT environment warranted high HSE and technical precautions. Special software was run to simulate the depth of penetration in two walled casings. The targeted Jurassic interval was perforated with suitable TCP guns at a depth of around 16, 260 feet.
During testing, the formation fluid showed presence of unexpectedly high concentration of 20% H2S and 2% CO2.In this extreme sour environment, Coiled tubing operations, stimulation, flowing the well, and fluid disposal were of utmost challenge. By overcoming all the challenges, this well was successfully perforated, stimulated and tested, which led to the first commercial discovery of Oil & Gas within the Jurassic Reservoir in Mutriba field.
Revisiting Microfrac In-situ Stress Measurement via Flow Back - A New Protocol
Authors: Savitski Alexei A. , Dudley John W. 
Published: October 2011

Abstract
The minimum in-situ stress is an important parameter for many applications including cap rock integrity, hydraulic fracturing design and well bore stability. Microfrac testing is the most reliable and direct technique for measuring it and involves creating a hydraulic fracture. The pressure at which the created fracture closes is commonly associated with the minimum in-situ stress. The pump-in/flow back test is one of several procedures that can be done during microfrac testing, and it produces a very characteristic pressure signature at closure.
In this paper we demonstrate the pitfalls of the traditional interpretation of the flow back data based on data acquired during shallow microfrac tests in a shale formation. The importance of identifying the transient flow regime and the significance of the pressure rebound are discussed. To circumvent the drawbacks of the conventional flow back test a new protocol using an incremental flow back/shut-in procedure is proposed. The excellent results demonstrate the merits of the new procedure.
Shale Gas Water Treatment Value Chain - A Review of Technologies, including Case Studies
Authors: Horner Patrick , Halldorson Brent , Slutz James 
Published: October 2011

Abstract
North American shale gas plays discovered over the past ten years contain an abundant tcf of natural gas, providing a long term, low carbon domestic energy source. Drilling and completing techniques developed in the Texas Barnett Shale over the past ten years have unleashed an unprecedented new shale gas industry across North America. The most effective completion technique is known as hydraulic fracturing (or "fraccing"), a process that involves injecting a large volume (60, 000 to 140, 000+ bbls) of fresh water underground to fracture the formation, increasing permeability and thus gas flow. After a frac is completed, a large portion of the frac fluid returns to the surface as "flowback" water which contains high concentrations of dissolved salts, frac chemicals, and formation minerals.
The costs and logistics of managing both fresh and flowback water in shale gas plays are problematic. Development of North America's shale gas resources will require well developed water management strategies that include the effective implementation of water recycling technologies. Treating flowback for re-use as frac fluid reduces the impact of key issues associated with shale gas water management including cost, truck traffic, water availability, and disposal availability.
Factors including salinity, residual frac chemicals (polymers), H2S, NORM, carbonate scales, iron scales, and sulphate scales make the treatment and handling of flowback complex. The overall water management strategy is a function of water sourcing and disposal cost and availability, formation geology and how that impacts both flowback water chemistry and frac fluid compatibility, the regulatory environment, and the availability of commercialized and cost-effective technology.
This paper explores the challenges associated with treating shale gas flowback for re-use and evaluates the role and cost of available commercial technology. Cases studies of technology applications that have been used during the past seven years in major shale basins will be included.
An Examination of Clay Stabilization and Flow Stability in Various North American Gas Shales
Authors: Conway Michael , Venditto James , Reilly Phil , Smith Kevin 
Published: October 2011

Abstract
There is a general uncertainty regarding the issues affecting shale stability in gas shale reservoirs. True swellable smectite is not present in most of the reservoirs currently being exploited. Illite and illite/smectite are the principal clay components, and they do have a distinct fixed water of hydration which is salinity and cation dependent. Historically, two factors had a major impact on the choices made for clay stability in clay rich reservoirs. Today, many hydraulic fracturing treatments are conducted with virtually fresh water, so this comprehensive study was undertaken to identify the role of salinity on the stability of various gas productive shales. Evaluated were various inorganic salts, temporary clay stabilizers and permanent clay/shale stabilizers, and the results of the comparisons will be presented.
The petrophysical properties of the samples studied have been extensively characterized and the swelling and erosional characteristics have been examined with capillary suction time (CST), roller oven (RO) and unpropped fracture flow capacity tests. Some shale samples are inherently unstable, regardless of the fluid used in the measurement, while the majority responds positively to more compatible fluids. A few samples are extremely stable in all fluids. The native state of the clay in the shales has been characterized by a variety of tests, including specialized cation exchange and wettability studies, to help understand the fluid/rock interactions.
The results of this study have identified the relationship between clay stabilizer type and concentration on the stability of the shale and the impact on flow capacity in the "stimulated reservoir volume". This is a compelling story of rock/fluid interaction studies on actual cores, fit for purpose product development, and supporting field production results.
Field Demonstration of a New Method for Making Drillpipe Connections During Managed Pressure Drilling Operations
Authors: Johnson Rachel , Montilva Julio , Sati Mohamed , Grable Jeff , Saeed Saad , Billa Richard , Derise William 
Published: October 2011

Abstract
The use of managed pressure drilling (MPD) during drilling operations has proven to be an effective solution for controlling equivalent circulation density (ECD); however, making a drillpipe connection with MPD is more challenging than with conventional drilling. The current methods for making a connection during MPD rely on large, high-maintenance equipment to provide a sufficient fluid supply to maintain the MPD equipment within an operable range. This equipment is both expensive and difficult to use to control ECD efficiently.
A new method of smoothly diverting rig pump flow during connections from the stand pipe to the MPD pressure control equipment at the annulus uses a valve manifold with an on-board choke. In addition to eliminating more expensive solutions, this method will improve pressure control and increase the operating range of MPD to provide higher pressures during connections and greater drilling flow rates. Reliability is increased by a reduction in complexity when using this method, because most rigs have multiple pumps available for redundancy.
Field trials using a fully automated MPD solution were performed by a major operator in South Texas between late 2010 and early 2011. This paper uses real data based on flow testing and actual field experience to demonstrate that implementing the rig pump diverter method with standard MPD operations effectively controlled the desired annulus pressure during connections. By replacing current methods of making a drillpipe connection, this solution will reduce the overall cost of MPD, making the total MPD solution more feasible for small wells.
GFREE Research Program
Authors: Aguilera Roberto , Harding Thomas G. 
Published: October 2011

Abstract
GFREE stands for a multi-disciplinary target-oriented research program into unconventional gas technology that includes geoscience (G), formation evaluation (F), reservoir drilling, completion and stimulation (R), reservoir engineering (RE), and economics and externalities (EE). The program has concentrated on unconventional gas formations in Canada but the results are widely applicable to worldwide resources. The principles developed can be beneficially applied to other research programs related to the oil and gas industry. The multidisciplinary approach has meant that graduate students are not supervised, in general, by only one professor. Rather, the students have been mostly co-supervised by 2 professors with different backgrounds and/or by professionals working in industry. The program has been supported by industry, government and the university and cooperation amongst GFREE and these organizations has proven to be of utmost importance.
A decision made at the beginning, which has proved valuable for this program, was that the team would concentrate on issues with potential to generate positive cash flows. GFREE students generally share in the same study areas promoting discussion and collaboration. Bi-weekly meetings of the team members allow for exchange of ideas and dry runs that help students prepare for their thesis defenses and/or presentation of papers in local and international conferences. Undergraduate and graduate courses that concentrate on unconventional gas exploitation and naturally fractured reservoirs have proven valuable to train students that join this program and to disseminate results of the research.
Flexibility has proven also to be of importance. As GFREE was developed as a 5-year program it was impossible to anticipate all the hurdles and bridges that would have to be crossed. For example, the anticipation of core availability for the study areas did not always materialize. Consequently it was necessary to switch to the study of drill cuttings for qualitative and quantitative evaluation with limited support of core data.
The multi-disciplinary nature of the GFREE program has led to valuable insights. It is concluded that the integration of many disciplines and the involvement of government, industry and academia has provided significant positive results that could be extended to other disciplines.
Autonomous Perforating System for Multizone Completions
Authors: Entchev Pavlin B. , Angeles Renzo , Kumaran Krishnan , Subrahmanya Niranjan , Tolman Randy 
Published: October 2011

Abstract
Autonomous downhole tools offer a range of advantages over conventional tools controlled manually via umbilicals. For instance, perforating guns or bridge plugs could be dropped or pumped downhole without the use of wireline (slick or electric line), coiled tubing or tractors. Because umbilical intervention is no longer required, the tools may automatically perform an action (e.g., perforate a desired interval) with substantial cost reduction and enhanced safety. The elimination of wireline lubricators, lifting equipment, wires, additional personnel and vehicles minimizes the potential for accidents in this already confined space. This is particularly important during hydraulic fracturing operations where this method may enable faster pumping rates and increased fracture volumes during daylight hours. Use of this technology will also reduce air emissions from support equipment that would no longer be required.
This paper describes an autonomous perforating tool currently being developed by ExxonMobil Upstream Research Company. This patent pending technology is based on using a self-destructing disposable perforating tool which is run without a wireline. To accomplish this objective, the custom designed tool has three frangible components: 1) a logging device; 2) an on-board navigation system; and 3) friable perforating guns. The on-board navigation system reads the log signals and performs real-time processing of the depth data. Upon matching of the desired depth, the system issues a firing command to the friable perforating gun assembly. The latter simultaneously initiates the self-destruction of the tool. Thus, the tool is completely destroyed after perforating and the remaining debris fall to the bottom of the hole, where they could be left, flowed back to surface or removed during cleanup prior to tubing installation. The volume of debris is small and does not require drilling additional rat hole.
The delivery of the tool is achieved by either gravity free-falling in low-angle wells or by pumping it downhole during hydraulic fracturing or any other pumping operation in high-angle or horizontal wells. An important part of the overall design is the safety system built into the tool to make the system as safe as, or safer than currently used perforating practices.
Borehole and Invasion Effects of Formate-Based Mud Systems on LWD Density, Neutron, PE, and Gamma-ray Logs
Authors: Cooper P. , Galford J. , Goodyear G. , Moake G. L. , Truax J. 
Published: October 2011

Abstract
The popularity of formate-brine drilling muds continues to increase as a result of the benefits in the drilling and completion stages of well construction, as well as the lessened environmental impact when compared to some other muds. Growth in use of these muds has caused operators and service companies to re-examine environmental correction algorithms because of the substantial effects these mud systems can have on nuclear logs. In addition, because formate muds generally contain lower solids than conventional muds, they can be strongly invasive. Thus, the influence of formate muds on LWD logging measurements includes both borehole environmental effects to be corrected and formation invasion effects that affect log interpretation.
A combination of laboratory experiments and Monte Carlo simulations have been used to develop a better understanding of the influences formate muds have on LWD gamma-ray, density, PE, and neutron porosity logs. Several hundred lab experiments and numerical simulations have been conducted in this investigation to fully characterize LWD responses to formate muds for families of sensors comprising two collar sizes used in a large range of hole sizes. The results were used to develop borehole corrections for the nuclear logs.
Formate brines are formulated to achieve a desired fluid density by using a mixture of dissolved compounds: sodium, potassium, and cesium formate. In some instances, the mixture results in a fluid with a substantially lower-than-normal hydrogen index. The mud may also have a larger-than-normal potassium concentration. Because invasion consists of nearly the whole formate mud, correct log evaluation in porous, permeable formations requires interpretation techniques that are beyond the scope of customary borehole corrections. We have taken lab measurements to attempt to quantify the effect of this invasion on LWD tool responses.