bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation and Removal of Hydrates inside Wellhead Connectors
Authors: Akers T. J. 
Published: October 2009

Abstract
Natural gas hydrates have long plagued drilling operations in deepwater environments. Professional papers to date have focused on hydrate formation inside the wellbore. This paper discusses the problem of hydrates that form within the BOP-wellhead connector. A case history is presented of a blowout preventer (BOP) stack stuck on a subsea wellhead due to the formation of methane gas hydrates external to the wellbore but inside of the BOP-wellhead connector. Efforts to release the connector are discussed as well as the thermal modeling undertaken of the hydrate melting attempts. Alternative release methods considered during the event are given along with the final resolution to the event. A discussion of the effectiveness of both thermal and chemical methods of removing hydrates from inside the connector is presented along with expectations of strategy effectiveness. Providences to prevent and mitigate future occurrences of hydrated BOP connectors are offered.
Plunger Lift Modeling Towards Efficient Liquid Unloading in Gas Wells
Authors: Chava G. , Falcone G. , Teodoriu C. 
Published: October 2009

Abstract
This paper is a follow up to SPE 115934, which introduced a preliminary plunger lift model built around the availability of Smart Plunger(**) data. These devices are equipped with internal gauges to record pressure and temperature with time, which can be downloaded whenever the plunger is at surface.
We present an updated model that accounts for pressure drop only due to gravitation, but satisfactorily reproduces the dynamics of a field installation in East Texas, USA.
We also present a comparison of the predictions from the new model and the corresponding results from some earlier plunger lift models available in the public domain.
Simulation of Two Phase Flow in Reservoir Rocks Using a Lattice Boltzmann Method
Authors: Ramstad Thomas , Øren Pål-Eric , Bakke Stig 
Published: October 2009

Abstract
We present results from simulations of two-phase flow directly on digitized rock microstructure images of porous media using a lattice Boltzmann method. The implemented method is done on a D3Q19 lattice with fluid-fluid and fluid-solid interaction rules to handle interfacial tension and wetting properties. We demonstrate that the model accurately reproduces capillary and wetting effects in pores with non-circular shape. The model is applied to study viscous coupling effects for two-phase cocurrent annular flow in circular tubes. Simulated relative permeabilities for this case agree with analytical predictions and show that the non-wetting phase relative permeability might greatly exceed unity when the wetting phase is less viscous than the non-wetting phase.
Two-phase lattice Boltzmann simulations are performed on microstructure images derived from X-ray microtomography and process based reconstructions of Bentheimer sandstone. By imposing a flow regulator to control the capillary number of the flow, the lattice Boltzmann model can closely mimic typical experimental setups, such as centrifuge capillary pressure and un-steady and steady-state relative permeability measurements. Computed drainage capillary pressure curves are found to be in excellent agreement with experimental data. Simulated steady-state relative permeabilities at typical capillary numbers in the vicinity of 10−5 are in fair agreement with measured data. The simulations accurately reproduce the wetting phase relative permeability, but tend to under-predict the non-wetting phase relative permeability at high wetting phase saturations. For higher capillary numbers, we correctly observe increased relative permeability for the non-wetting phase due to mobilization and flow of trapped fluid. It is concluded that the lattice Boltzmann model is a powerful and promising tool for deriving physically meaningful constitutive relations directly from rock microstructure images.
Joint Radial Inversion of Resistivity and Sonic Logs to Estimate In-Situ Petrophysical and Elastic Properties of Formations
Authors: Mallan Robert K. , Ma Jun , Torres-Verdín Carlos , Wang Gong Li 
Published: October 2009

Abstract
Presence of near-wellbore damage, resulting from drilling and mud-filtrate invasion, can substantially affect sonic and resistivity borehole logging measurements. Therefore, unbiased log interpretation must account for presence of invasion in order to procure accurate estimates of formation properties. Our objective is to estimate the formation's dry bulk and shear moduli, porosity, and water saturation from the joint inversion of borehole array-induction resistivity and sonic measurements.
We assume a radial one-dimensional (1D) model in the inversion, with the formation model described by a radial variation of water and hydrocarbon saturations representative of mud-filtrate invasion. The inversion is guided by the data misfit of both array-induction apparent resistivities and sonic-log flexural and Stoneley wave velocity-frequency dispersion curves. Radial distributions of fluids are converted to distributions of resistivity, density, and bulk modulus, which are input to the simulations of apparent resistivity and sonic logs. We make use of fluid-substitution models to relate bulk density, dry bulk modulus, and dry shear modulus to porosity and fluid saturation. Apparent resistivities are simulated based on a commercially available array-induction logging tool. Sonic measurements are analyzed in the frequency domain via flexural and Stoneley wave mode dispersions, which are calculated directly in the frequency domain.
Synthetic cases consider water-base mud filtrate invading a hydrocarbon-bearing sand and oil-base mud filtrate invading a water-bearing sand. Porosities and elastic properties consistent with a soft formation are considered in the models. Sensitivity analysis indicates that sonic flexural and Stoneley mode dispersions naturally complement apparent resistivity measurements in the presence of mud-filtrate invasion. Inversions of synthetic cases produce reliable estimates of dry-rock bulk and shear moduli, porosity, and initial water saturation. Furthermore, these cases show that combining resistivity and sonic measurements reduces ambiguity in the inversion.
Wellbore Stability: A Critical Review and Introduction to DEM
Authors: Kang Yongfeng , Yu Mengjiao , Miska Stefan , Takach Nicholas E. 
Published: October 2009

Abstract
Borehole stability issues are always a spotlight in drilling activities because of their costly consequences, including borehole collapse, lost circulation, stuck pipe etc.
Wellbore instability is primarily a function of how rocks respond to the induced stress concentration around the wellbore during various drilling activities. By considering different failure mechanisms between the formation and drilling fluid interaction, several major wellbore models have been presented over the last seventy years. Those models take into account the mechanical, chemical, hydraulic, or thermal effects between the drilling fluid and the formation, or couple two or more effects in a model. The time effect is also taken into account in some of the models. In most of the models, 1) the rock is treated as a continuous material 2) borehole failure is normally based on single initial failure point. However, rocks are discontinuous materials formed under an environment of complex stresses. Also, it is likely an overstatement to say that instability occurs when only one point fails. Even if a small group of grains disconnects from wellbore, the well can still be stable. While somewhat irregular (noncircular) the wellbore can still accommodate casing and installation of down-hole equipment. Therefore, this paper also introduces a new approach based on grain-scale discrete element modeling (DEM) to mimic the realistic rock condition. The rock is modeled as an assembly of numerous grains bonded by cement-like materials, and pore spaces are formed between the small grains. The dynamics of rock grains is simulated and tracked on a computer. Micro cracks (because of tensile or shear failure) occurring at stress-concentrated zones and their coalescence to form macro fractures are tracked. The borehole shape and size are tracked with time.
This paper is useful to those who wish to understand the main limitations of the conventional models and the potential usefulness of a new approach based on a discrete element method (DEM). The approach presented in this paper can also help engineers understand how wellbore instability (post-initial failure) develops with time.
Development and Implementation of a Slimhole Very-High-Dogleg Through-Tubing Rotary-Steerable Drilling System
Authors: Andersen Stein Kristian , Winterstø Knut Morten , Eidem Morten , Robson Ian 
Published: October 2009

Abstract
The maturing of many of the major oil fields around the world, combined with the drive to extend the life of assets and improve recovery rates, has led to significant interest in technology able to access bypassed oil and multiple small targets by achieving complex 3D well paths using Through Tubing Rotary Steerable Drilling (TTRSD) practices. The technology allows for reentry of existing wells and the enhancement of recovery by the drilling of one or more laterals from the existing well bore, while the completion and Xmas tree remain in place. Since the lateral is created deep in the existing well, the necessary distance, and drilling time, to the target are short and of comparatively low cost. Furthermore, since the existing completion remains in place, a costly re-completion is avoided. Assets will thus have production enhanced and utilization increased by quickly and efficiently getting access to additional reserves.
In June 2006, Statoil (before the merge between Statoil and Hydro) and Schlumberger entered into a joint development program to build the systems suitable for TTRSD. The primary motivation for the program was to make a system that would enable drilling very high curvature well sections. This is important in TTRSD since the laterals are deep, and often in depleted reservoirs, making high doglegs quite critical in order to quickly steer away from water and other problem-zones. The new Very High Dogleg series of rotary steerable tools were developed in a size suitable to pass through existing completions in the North Sea, and communication technology was developed to allow transmission of near bit inclination and azimuthal information.
During the period August-September 2008 the tool was successfully tested out in a Through Tubing Rotary Drilling (TTRD) operation in a well on the Gullfaks field on the Norwegian Continental Shelf, operated by StatoilHydro. The system provided, among other things, an average buildrate of 12,25°/30 m in the build section of the well. For the dimensions in question this is a significant improvement compared to existing Rotary Steerable Systems (RSS) systems.
Incremental Reserves and Production Potential from Horizontal Wells in Chuchupa Field, Colombia
Authors: Rivera Nestor , Meza Nestor , Munoz Jaime , Joya Pedro , Mora Carlos 
Published: October 2009

Abstract
During 2006 we drilled 3 horizontal wells in Chuchupa field, a large gas offshore reservoir in the Colombian Caribbean Sea. The drilling campaign included drilling, logging, pressure testing, and coring a pilot vertical hole, which was key in improving our reservoir characterization. The reservoir thickness and petrophysical parameters found were better than expected and the new information reduced the uncertainty on the Original Gas In Place (OGIP). These wells increased the production potential for this field significantly. Current cumulative gas in Chuchupa is 2.5 Tscf, equivalent to 400 Million barrels of oil. The field has 7 horizontal, 7 slanted and 1 vertical production wells located on 2 production platforms.
We formed a multidisciplinary team to design the optimal development plan for Chuchupa. The team included geoscientists; reservoir, production, drilling, completion, and facilities engineers; decision analysts; and commercial and planning professionals. We performed seismic re-interpretation, petrophyscial evaluation, geologic modeling, and integrated-reservoir-to-surface simulation. The study resulted in a set of static and dynamic models that were used to generate a phased development that consisted of 3 new horizontal wells and installation of a compression system.
The 3 proposed horizontal wells were successfully drilled and completed and field production capacity increased by 250 MMscf/D. We have produced 203 Bscf from these wells after three years. We acquired 330 ft of core in the vertical pilot hole with 100% recovery. We found 60 ft of additional gas column, with average porosity and permeability of 30% and 6 Darcies respectively. Rigorous production- and pressure-history match supported the revaluation of OGIP range from 4.1-5.3 Tscf to 5.0-5.6 Tscf.
Integration of various disciplines, detailed planning, good execution, and use of robust coupled reservoir-surface tools resulted in a successful development project that increased reserves and production potential significantly. The added capacity and additional reserves supported the implementation of compression installed in 2009. The obtained results allow Chuchupa to continue being an important player in supplying the gas demand in this north corner of South America.
Understanding the Roles of Inflow-Control Devices in Optimizing Horizontal-Well Performance
Authors: Fernandes Preston , Li Zhuoyi , Zhu D. 
Published: October 2009

Abstract
Inflow Control Device, often referred to as equalizer, is a completion hardware that is deployed as a part of well completions aimed at distributing the inflow evenly. Even though the detail structures vary from one design to another, the principle for different inflow control devices is the same - restrict flow by creating additional pressure drop, and therefore balancing or equalizing wellbore pressure drop to achieve an evenly distributed flow profile along a horizontal well. With a more evenly distributed flow profile, one can reduce water or gas coning, sand production and solve other drawdown related production problems. In general, inflow control devices are not adjustable; once installed in the well, the location of the device and the relationship between rate and pressure drop are fixed. This makes the design of a well completion and inflow control devices extremely critical for production. Inflow control devices can be either beneficial or detrimental to production, strongly depending on the reservoir condition, well structure and completion design. Realizing that reservoir conditions will change during the life of a well, the impact of an inflow control device is a function of time. The inflow control devices sometimes can be overlooked if the design is only based on reservoir flow simulation.
In this paper, we will investigate how and when an inflow control device should be used. An integrated analysis method of inflow (reservoir) and outflow (wellbore) is used to generate the flow profile of a horizontal well, and additional frictional pressure drop created by inflow control devices will be considered. Two conditions that result in production problems, wellbore pressure drop and breakthrough of unwanted fluids, will be addressed. The focus will be on when and how an inflow control device can optimize production. Examples at field conditions will be used to illustrate that it is critical to understand the reservoir conditions and wellbore dynamics together when designing a well completion with inflow control devices. Since uncertainty of reservoir condition always exists, backup plans and conservative designs are desirable. The observations from this study show that overdesigned inflow control devices will not just increase the cost of well completion, but also impact the well performance negatively.
Coupling Capillarity-Controlled Fluid Displacement with Unconsolidated Sediment Mechanics: Grain Scale Fracture Opening
Authors: Prodanovic Maša , Holder Jon , Bryant Steven L. 
Published: October 2009

Abstract
We rigorously model immiscible displacements in unconsolidated sediments subject to confining stress. Fluid-fluid interfaces are assumed controlled by capillary forces, and the progressive quasi-static (PQS) algorithm based on the level set method determines the pore level geometry of those interfaces. From the pore-level fluid configuration we compute the net force exerted on each sediment grain by capillary pressure, including cohesion at grain contacts supporting pendular rings. We combine those forces with mechanical stress and elastic properties of grains to determine the resultant movement of grains using a discrete element method code (Itasca's PFC3D). To our knowledge this is the first rigorous coupling of capillarity and grain solid mechanics in 3D. When grains can move in response to net force exerted by the nonwetting phase, small variations in the distribution of pore throat sizes lead to self-reinforcing, focused channels of nonwetting phase during drainage. When forces exerted by capillary pressure are the same magnitude as the force required to displace grains, this channeling prevents the emergence of a recognizable fracture.
Determining Acid Distribution Using Distributed Temperature Measurements
Authors: Tan X. , Zhu D. , Hill A. D. 
Published: October 2009

Abstract
Placement of a sufficient volume of acid in all desired zones is critical for a successful acid stimulation treatment. Particularly in thick, highly heterogeneous carbonate formations, the acid distribution is crucial for optimal stimulation results. A variety of diversion methods are applied in acidizing treatments to evenly place acid along the well, but the effectiveness of these diversion methods is generally only inferred from the rate and pressure behavior during the treatment, and is not known with any certainty. It would be extremely helpful if the acid distribution could be measured.
We developed a model to simulate the temperature behavior along the wellbore during acid injection and during the flow back period following an acid stimulation. An important phenomenon in this process is the heat generated by reaction, the key factor enabling the interpretation of the acid distribution from the temperature profile. We have developed a mathematical model that describes the coupled flow and heat transfer process. The flow system consists of a near wellbore formation with a wormhole region and a spent acid region. Wormhole propagation and the spent acid front are simulated as a function of acid injection volume (time). The thermal model includes conduction, convection, and reaction heating to seek the connection between acid volume distribution and temperature profile. The result of the thermal model showed significant temperature effects caused by reaction. During flow back, the zone that took more acid volume would have created more heating because of reaction, providing a mechanism to quantitatively determine the acid flow profile.
Research of Gas Separator with Disperser Influence of ESP Work and Increase of Well Operation Efficiency by the Use of ESP
Authors: Mokhov Mikhail , Tsunevskiy Andrey 
Published: October 2009

Abstract
In recent years there is a tendency of standing increase of ESP share in performance stock of oil recover companies. At the same time there is an increase of oil production from water-producing wells observed in consequence of universal application of water flooding and depletion of the most large deposits. An average watercut of recovered products at pump operation system is at the present time 8085%. As you know, one of the complicating factors of steady operation of ESP is free gas inflow into the pump. For the protection of ESP against free gas deleterious effect on the oil-fields, gas separators are widely used because they allow separate some part of the gas into annular space. When watercut increases, the quantity of free gas in the flow stream falls, and it becomes possible to apply disperser which is required for the generation of fine liquid-gas mixture, which reaching the inlet of ESP decreases free gas effect on the pump operation. Application of the dispersers is also effectually for zero water-cut oil fields with moderate-size gas oil ratio.
Expanding Knowledge to Young Engineers in our Industry
Authors: Jabaley Sally 
Published: October 2009

Abstract
It is a well-established fact in the oil and gas industry that the workforce is aging and there are fewer people in the 10-15 year experience range each year. The solution to this dilemma has been to hire university graduates and quickly train them to succeed the existing aging workforce. Unfortunately, the very people who need to train these new graduates are the experienced employees who are stretched to keep up with the unprecedented workload in the recent environment of asset development and projects. They simply do not have the time to train and supervise new hires. Additionally, current projects and assets are so large and complex, that companies cannot afford the opportunities to allow these new hires to learn by doing, as a mistake can have huge heath, safety, environmental or economic consequences.
In order to help train these new graduates adequately, the Society of Petroleum Engineer's Projects, Facilities, and Construction Committee developed the Expanding Facilities Knowledge Workshop, which consisted of five cafeteria-style presentations. These presentations covered a range of Facility Engineering basic competencies and were held at various locations around Houston throughout the summer. The sessions were heavily attended and there are current plans to continue the workshop in the future. This workshop can also be considered a model for other disciplines within SPE to help train new graduates in their field.