bluuebunny/crossref_metadata_2025_split huggingface dataset:
Breakthrough in 22" Hole Drilling in Kuwait Deep Wells
Authors: Al-Saeedi M. J. , Mahesh V. S. , Al-Ajmi H. S. , Al-Enezi D. , McKinnell D. C. 
Published: August 2008

Abstract
Exploration activities in Kuwait involve drilling of HPHT wells to search for high quality oil from the Jurassic formations. The wells drilled are very challenging with deep horizons (~16,500 ft), over-pressured formations and zones with narrow pore/fracture pressure windows which require the setting of multiple casing strings.
It is imperative that surface/intermediate casing strings are run to the maximum depths possible in order to reach well TD in a workable hole size. This presents the challenge of drilling long sections of large diameter hole in an acceptable time frame while maintaining borehole quality such that the big diameter tubular strings can be successfully run.
This paper will discuss the challenges of drilling 22" hole in such wells from 6,000 to 9,500 ft and the potential to replace established methods with new technology solutions to improve drilling performance.
The conceptual project consisted of an attempt to replace multiple 22" insert bits, rotary driven, with a single PDC bit design run on downhole motor. A partnership approach was initiated with the bit manufacturer and motor provider. Bit designs, downhole motor and rig equipment specs were developed and improved on over the project.
Bit and motor combinations were tested over a number of wells using several drilling rigs. The performance improvements were benchmarked with the original method. Over the trial, the goal was to try and drill the entire section with one bit from shoe to shoe, thus cutting interval costs and drilling times.
This paper will detail key factors in drill bit design, analysis of downhole motor performance, plus the critical role of ‘state of the art’ rig equipment. It will present a case history of this ‘design and development’ process with conclusions which provide the basis for future optimization of the technology.
Optimization of Multiple Bit Runs Based on ROP Models and Cost Equation: A New Methodology Applied for One of the Persian Gulf Carbonate Fields
Authors: Rastegar M. , Hareland G. , Nygaard R. , Bashari A. 
Published: August 2008

Abstract
Improving the rate of penetration (ROP) is one of the key methods to reduce drilling costs. Several ROP models have been developed and modified based on the concept where unconfined compressive strength (UCS) is inversionally proportional with the rate of penetration. These models can predict the rate of penetration of different bit types in an oil or gas field with a reasonable degree of accuracy. The ROP model studied herein relates the rate of penetration to operating conditions and bit parameters in addition to the rock strength. Also, the effects of bit hydraulics and bit wear on rate of penetration are included in the model.
In this paper, the drilling performance was optimized, using the ROP models, for upcoming wells in one of the Persian Gulf carbonate fields. Based on previous drilled wells a rock strength log along the wellbore is created and modified to mach the the new well survey. The rock strength is back calculated from the ROP model which includes bit design and reported field wear in conjunction with meter by meter operating parameters, formation lithologies and pore pressure. By conducting a number of simulations a learning curve was constructed to obtain the optimum bit hydraulics, best combination of operational parameters and the most effective bit design.
Based on the proposed ROP model, a simple and useful simulator was developed. This methodology can be used in pre-planning and post analysis to reduce drilling cost where previously drilled wells exist.
Theory and Application of a New Generalized Model for Torque and Drag
Authors: Aadnoy Bernt S. , Djurhuus Joannes 
Published: August 2008

Abstract
Well friction, or torque and drag play an important role in many well operations. Modelling is performed either with a numerical simulator, or by analytical mathematical models. Although the latter provide better physical insight, they are often cumbersome to use.
A mathematical study was undertaken, analyzing published friction models. Identifying a lot of symmetry in the solutions, we managed to reduce the complexity significantly. The result is a generalized friction model consisting of only two equations, one for rotating friction (torque) and one for pulling friction (drag) that is valid for all well geometries.
The derivation of the generalized friction model will be presented. It covers vertical sections, build-up bends, drop-off bends and straight sections. For all these geometries the new model is valid for tubular both in tension and in compression. The different solutions are obtained by selecting the signs of the coefficient of friction and the well inclination. The new model includes previously unpublished results such as pipe in compression in drop-off bends. Any deviated well geometry can now be analyzed using a spreadsheet with the new model, simply by adding forces starting from bottom of the well.
A field case is presented. An S-shaped well is modelled using the two equations. In addition to provide a worked example, physical effects like friction in bends are shown and discussed.
A General Dynamic Model for Single and Multi-phase Flow Operations during Drilling, Completion, Well Control and Intervention
Authors: Petersen Johnny , Rommetveit Rolv , Bjørkevoll Knut S. , Frøyen Johnny 
Published: August 2008

Abstract
A general dynamic model for any flow-related operation during well construction and interventions has been developed. The model is a basis for a new generation support tools and technologies needed in today's environment with advanced well designs, challenging drilling conditions and need for fast and reliable real-time decision support.
The solution method uses a "divide and conquer" scheme, which computes the flow in each well segment separately, and then solves for the appropriate flow in the junctions.
This simplifies greatly simulating complex flow networks, such as multilateral wells and jet subs. The flexibility allows incorporating additional pumps in the flow loop, as in Dual Gradient Systems.
The model includes dynamic 2-D temperature calculations, covering the radial area affecting the well and assuming radial symmetry in the vicinity of the well.
Other features: Flexible boundary conditions (which includes drilling, tripping)Non-Newtonian frictional pressure lossTransient well-reservoir interaction Slip between phasesAdvanced PVT relationship
The reason for this new approach was to respond constructively to today's challenges (complex and difficult drilling conditions, need for reliable real time decision support). Our approach has been more flexibility, improved accuracy, reduced numerical diffusion and increased computational speed.
The paper will present the basic model assumptions; the model architecture, and solution methods.
Integration of the model into a real time system with links to real time databases and advanced visualization tools is currently ongoing. Thus the model may follow the whole work process through planning, training, execution, and post analysis.
Examples of applications of the model so far will be presented, as well as visions for future applications.
Building a Geomechanical Model for Kotabatak Field with Applications to Sanding Onset and Wellbore Stability Predictions
Authors: Yi X. , Goodman H. E. , Williams R. S. , Hilarides W. K. 
Published: August 2008

Abstract
Kotabatak field, Sumatra, Indonesia is a heavily-faulted field undergoing an aggressive drilling and development campaign. Nine horizontal wells had been drilled with four more planned in 2008. One of the horizontal wells recently experienced well collapse (and sudden productivity decline) after some time on production, with cavings being flushed out during coil tubing workover operations. In addition to horizontal well drilling, feasibility of open horizontal well completions, hydraulic fracturing design and sanding onset prediction also warranted rock mechanics analyses. To make sound decisions on those issues, building a well-calibrated geomechanical model was critical.
In this study, we reviewed the drilling, completion, logging and production information from several wells across the field. We found that (1) The Kotabatak field has a general maximum horizontal stress orientation of NE- SW. However, there could be localized stress orientation variations depending on structure complexity near a specific well. (2) There was no consistent evidence indicating a significant contrast between the maximum and minimum horizontal stresses. Using a maximum/minimum horizontal stress ratio of 1.05 yielded a consistent calibration result for the wells studied. (3) Sand minimum horizontal stress for the Kotabatak field was calibrated against available closure stresses from hydraulic fracturing and mini-frac data. (4) Rock mechanical properties were calculated with openhole logs based on a Rock Mechanics Algorithm that is closely linked to Chevron's worldwide rock mechanical property database. Consequently, even though there were no core test data available from the Kotabatak field to calibrate rock mechanical properties directly, the log data set provided the means to estimate reliable formation mechanical property values that are consistent with Chevron's worldwide database. Furthermore the entire geomechanical model was calibrated against offset drilling performance measures resulting in a high degree of confidence in the predicted values.
Using the calibrated geomechanical model, horizontal well stability predictions were performed and indicated that horizontal sections can be drilled with low mud weight allowing the well to have some yield/failure. Open horizontal well sanding onset prediction indicated that the depth and width of a breakout (or plastic zone if reservoir sand behaves plastically) increase with increasing pressure drawdown. Since water flooding is used in the field to maintain reservoir pressure, sand control may not be needed if an appropriate Bottomhole Flowing Pressure (BHFP) is applied.
Lessons Learned from Highly Deviated Openhole Completions in Two HP/HT Retrograde Gas-Condensate Fields Using Expandable Liner Hangers, External-Sleeve Inflatable Packer Collars, and Swellable Packers for Zonal Isolation
Authors: Lee Seung Kook , Kim Yong Seok , Ou Kwang Kwon , Murugappan Basker , Williford James , Jackson Tance , Nizam Irwan , Lim Derek 
Published: August 2008

Abstract
The Korean National Oil Company (KNOC) has developed seven retrograde gas-producing wells located in offshore Vietnam. The scenarios presented by these wells taught the developers valuable lessons, and the intent of this paper is to share these lessons by presenting the concepts considered for well design, the selection process for the completion equipment and techniques, the preplanning for the installations, and the experiences encountered during the actual installations.
Several completion challenges had to be addressed, including isolation of water production below the casing shoe and control of condensate banking, sand production, and commingling of multiple production zones in the long openhole sections.
A different type of completion that involved an expandable liner hanger (ELH) with an external-sleeve inflatable packer collar (ESIPC) was chosen, and installation and cementing were accomplished in a single trip. The ESIPC was deployed just below the water-producing zone, and cement was pumped up the annulus from the ESIPC to where the expandable liner hanger (ELH) was set above it. It was felt that this design would prevent water from entering the wellbore while enabling optimum production. To prove the concept, a stack-up test was performed at surface before actual deployment on location to ensure that the cement wiper plugs would pass through the expandable-liner-hanger ball seat and that the concept would perform as intended.
Swellable packers were selected from the various proven openhole isolation devices available to the industry to provide the zonal isolation required in the multi-zone intervals.
This was the first openhole completion in Southeast Asia in a high-temperature, commingled gas environment in which isolation would be contained solely by swellable packers.
Evaluation of Water Swelling Elastomers
Authors: Al-Yami A. S. , Nasr-El-Din H. A. , Al-Humaidi A. S. 
Published: August 2008

Abstract
A conventional method of zonal isolation utilizes setting casing in the wellbore using cement. Then, the casing is perforated and a screen is installed. Finally, gravel is placed to control solids production. The shortcoming of this method is that it reduces the inner diameter of the completion, which limits the productivity of the treated well. The best current isolation method is to use either expandable casing or swelling packers. Swelling packers undergo dynamic swelling when in contact with water or oil. The swelling rubbers are bounded to any size of pipe where the thickness of the rubber controls the pressure difference developed across the pipe.1
In this study, water swelling packers from three different vendors were examined at 190ºF using different brines and 15 wt% HCl acid. The effects of 15 wt% HCl acid on the swelled elastomers and exposure to low salinity aquifer water after the acid were examined in detail.
Water swelling packers were able to hold differential pressures of more than 2,000 psi. Coupons obtained from vendors I&II showed acceptable results for 5 and 20 wt% NaCl. Packers soaked in fluids of high pH values (potassium formate with pH 9.5) or low pH values (15 wt% HCl acid with pH nearly 0) did not swell. Water swelling packers obtained from one vendor failed to seal in 20 wt% NaCl. Hydrochloric acid resulted in a significant reduction in the volume of the swelled coupons even after soaking for 15 minutes only. Immersing the coupons after acid exposure in field injection water did not regain their volume prior to soaking in HCl acid solutions.
Based on the above results, it is strongly recommended to perform quality testing for the elastomers before field application. Every effort should be made not to expose water swelled packers with concentrated HCl acids during matrix acidizing.
Effect of Pipe Rotation on Hole Cleaning for Water-Based Drilling Fluids in Horizontal and Deviated Wells
Authors: Ozbayoglu M. E. , Saasen A. , Sorgun M. , Svanes K. 
Published: August 2008

Abstract
One of the major concerns during drilling horizontal and directional wells is proper hole cleaning. If there exists a stationary bed, generally, an increase in the fluid velocity will erode the bed significantly. However, depending on the drilling conditions, very high fluid velocities are needed for bed removal, which may not be applied due to hydraulic and physical limitations. In such cases, pipe rotation may enhance the cuttings transport mechanically, and effective hole cleaning can be achieved even at fluid velocities lower than the critical annular fluid velocities required to prevent stationary bed development. In this study, the effect of pipe rotation on hole cleaning is investigated for horizontal and directional wells. Cuttings transport experiments have been conducted at METU Cuttings Transport Flow Loop using pure water as well as water-based muds consist of different concentrations of xanthan biopolimer, starch, KCl and soda ash, weighted with barite. Effect of pipe rotation have been observed for hole inclinations from horizontal to 50 degrees, for rate of penetrations from 15 to 45 ft/hr, for flow velocities from 2.1 ft/s to 7.2 ft/s, and for pipe rotations from 0 to 120 rpm. Pressure drop within the test section, and stationary and/or moving bed thickness are recorded besides the other test conditions. It has been observed that, pipe rotation has a significant improvement on cuttings transport, especially if the pipe is making an orbital motion. Also, pipe rotation drastically decreases the critical fluid velocity required to remove the stationary cuttings bed totally. However, after a certain rotation speed, no additional contribution of pipe rotation on hole cleaning is observed. When there are no cuttings present, the frictional pressure losses are increasing as the pipe rotation speed is increased. However, as the cuttings are introduced, due to the reduction in the stationary cuttings bed area, frictional pressure losses may decrease. Additionally, the effect of pipe rotation on hole cleaning as a function of fluid viscosity is also examined. It has been observed that, as the fluid viscosity is increased, contribution of pipe rotation on hole cleaning is increasing when compared with no rotation case.
Validation of Blowout Rate Calculations for Subsea Wells
Authors: Oudeman P. 
Published: August 2008

Abstract
Calculating the blowout rate of oil and gas wells is commonly one of the first steps in environmental impact assessment, contingency planning and emergency response. The blowout rate is a direct measure for the economic and environmental damage caused by a blowout and an indicator for the effort required to regain control over the well. Hence a simulator was developed to estimate blowout rates.
This simulator was validated for field cases by comparing calculated blowout rates with estimates based on observable phenomena such as flame length and heat release rates. This limited validation to onshore and platform well blowouts, which are usually governed by critical outflow conditions at surface, i.e. ambient pressure is considerably less than the wellbore pressure just upstream of the outflow. For subsea wells, blowing out against the substantially higher pressures at seabed, this does not apply. The blowout rate is determined by the total system performance from inflow at sand face to outflow at seabed. To validate the blowout rate calculations under these conditions, data were collected on high rate well flow through an annulus against elevated surface pressures, resembling subsea blowout conditions. A comparison of the measured rates with the calculated rates demonstrated that the rates could be predicted with a high accuracy, provided the mechanical condition of the tubulars is properly taken into account. Default assumptions for the hydraulic roughness of the tubulars lead to over-estimates of the blowout rates and consequently worst case estimates for the environmental and economical damage caused by a blowout.
New Techniques Accurately Model and Plan 3D Well Paths Based on Formation's Deflecting Behaviors
Authors: Liu Xiushan 
Published: August 2008

Abstract
Accurate well-path planning is the prerequisite for operators to drill directional or horizontal wells successfully. During directional drilling operations, bit walk objectively exists along an actual drilled well trajectory. Drilling experience shows that it is an effective measure to control a well trajectory by taking the physical bit walk into account if the rate of bit walk can be accurately estimated. As the planned results of bit-walk path can evidently reduce the frequency of azimuth correction and drilling-string trips, and lessen the difficulty and workload of trajectory control, it will undoubtedly improve the rate of penetration and the quality of well trajectory, and cut down the cost of drilling.
The author has published some related methods to plan 3D bit-walk paths, in which the bit-walk rate must maintain constant over each well-path section (build-up, hold-up or drop-off). In some cases, the bit-walk rates are given on the basis of rock characteristics. In addition, it is also an effective measure to determine an appropriate wellhead location, if there is no limitation of surface condition, for the desired profile of a horizontal well. This paper makes further researches on the mathematical model of bit-walk path and gives more concise formulas, analyzes the compositive relation of inclination units and azimuth units, and yields a method to divide them into shorter intervals for calculation. The author discusses the characteristics of planning bit-walk paths and presents the constraint equations and solutions for directional wells. For the desired profile of a horizontal well, this paper also describes the idea and techniques to accurately determine the surface location and a key parameter of the profile, such as KOP, accounting for bit-walk effects. The model and methods provided employs exact mathematical solution and results, and the planned paths are smooth from the wellhead to the given target.
The methods proposed represent significant improvements over the traditional well-path planning techniques, and were programmed into computer software. Several examples are given, and the results proved satisfactory for various directional and horizontal wells.
Field Implementation of Sub-Surface Waste Injection: An Integrated Approach for Field Disposal Perspective
Authors: Ovalle A. , Shokanov T. , Simmons S. , Ronderos J. 
Published: August 2008

Abstract
As the world faces new challenges to protect the environment from all human-generated wastes, self-imposed industry policies as well as governmental regulations support new green policies towards implementing best, not necessarily least costly, practices to prevent any environmental damage due to spillage during operations. Waste Injection (WI) has been selected as the preferred methodology of final disposal of oilfield wastes, including cuttings, produced water, drilling fluids and tank bottoms, etc., by many operators and legislators because it achieves zero discharge in a safe and efficient manner at a lesser operating cost than comparable proven technologies. This may be particularly true for large-scale projects. Mexico, Argentina, Azerbaijan, USA, UK, Norway, Russia and other countries have strategically implemented WI operations in field developments because they comply with local laws and they avoid future liabilities as wastes are permanently isolated and stored below surface.
The development and implementation of such technology in large-scale projects is carefully designed using a risk-based analysis that is comprised of fracturing studies of the area of injection, technologies integration, logistics, equipment specification and process monitoring, all with the aim of performing a seamless and risk-free operation. The following paper addresses planning and implementation methodology for WI operations with real examples that demonstrate the value of proper preparation and integration of various technologies to attain maximum efficiency under QHSE standards.
Well Productivity and Oil Recovery Enhancement in East and West Siberian Fields as a Result of Inflow Control Technology and Application
Authors: Zaikin Igor , Kempf Konstantin Victor , Voll Benn , Budlov Sergey , Laidlaw Duncan 
Published: August 2008

Abstract
A major Russian operator has encountered operational risks and challenges in oil production due to the highly diverse reservoir properties of Siberian fields. The majority of the operator's east and west Siberian fields include heterogeneous sandstones with low to high permeability, complicated geological and stratigraphic cross-sections and an active bottom water aquifer. In some areas, a gas cap is one of the drive mechanisms.
Horizontal wells tend to become more popular in both green and brown fields because of improved recovery efficiency due to increased reservoir drainage area. However, unbalanced inflow profiles along horizontal sections can result in early water/gas breakthrough which shortens well life and decreases overall profitability.
This paper will describe the application of inflow control technology in two Siberian fields (one with a sand control issue), addressing early water and gas breakthrough caused by intensive water injection and a massive gas cap. Production is optimized by ensuring uniform inflow profile along lateral sections and minimizing annular flow. The setting selection process for inflow control devices and the integration of reservoir analysis with well completion are detailed. The resulting delay of water/gas breakthrough in these horizontal wells leads to enhanced recovery efficiency and improved productivity.