bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-Phase Flow through Wellhead Chokes
Authors: Fortunati F. 
Published: December 2007

Abstract
It is possible to find in the literature, some papers concerning the two phase flow through the wellhead chokes, but nearly all these contributions concern only the critical flow.
The critical flow, when only the gas is concerned, happens around a choke downstream - upstream pressure ratio of about 0,5, but this condition is no more valid as the flow is two phase (gas and liquid). The velocity of a two phase flow, both critical and subcritical, is greatly depending from the gas concentration in respect to the mixture, and the downstream - upstream pressure ratio can be also lower than 0.225. pressure ratio can be also lower than 0.225.The practical cases, as experienced during several years, are nearly all in the subcritical flow field, and in the present paper, a simple formula is given for calculating the rates through the wellhead chokes, covering both the critical and subcritical flow fields.
The equation below reported, can be easily also developed through a computer program.
In the text, the number between square brackets, refer to the literature, and the numbers between round brackets, refer to the equations.
This paper is mainly intended for practical purposes, some unavoidable calculation developments were confined in the Appendixes.
A full relief was given to the illustrative numerical examples and through all the paper the metric system of units is used.

Introduction
Since recently two phase flow is receiving more and more attention by the researchers working in the oil industry. It can be said that no one month passes without appearing in the literature, scattered over the world, a contribution concerning this item. The impulse to these researches came from the observation that the pressure drop through a pipe, when flowing a gas/oil mixture, can be also ten times more than that due to a single phase flow.
Calculating Accurate Gas-Lift Flow Rate Incorporating Temperature Effects
Authors: Bertovic D. , Doty D. , Blais R. , Schmidt Z. 
Published: December 2007

Abstract
Gas lift is a common, widely used method of oil production. Efficient design requires knowing the performance of each component of the system. Theoretical analysis supported by experiments is needed to determine a practical model for gas-lift valve performance.
Two sets of experiments are described:to obtain standard flow performance data, andto investigate the influence of temperature distributions on the bellows temperature of a nitrogen-charged gas-lift valve.
The new, empirically based calculation procedure presented is superior to existing procedures by:being independent of whether the constant injection pressure or constant production pressure method is used,reducing the number of empirical model parameters to five,addressing all three gas-lift valve flow regimes: (orifice, transition and throttling), andpredicting gas-lift valve performance more accurately than existing models.

Introduction
For gas-lift operations, reliability and efficiency depend on accurately predicting the performance of the gas-lift valve. Valve performance is defined as the standard volumetric flow rate of gas through the valve as a function of the injection pressure and production pressure for a given port size, and bellows set pressure. Temperature sensitivity, corrosion and erosion resistance, and vibration suppression also affect valve performance.
The degree of temperature sensitivity has been ignored in earlier models under the assumption that the bellows temperature equals reservoir temperature. The large drop in temperature on the production end of the valve where expanding gas exits is familiar to anyone who tests valves. This indicates the lack of a single well defined equilibrium temperature in the vicinity of the valve. An experiment is reported here that assesses the sensitivity of valve performance to this temperature distribution.
Furthermore, experimental studies have identified three flow regimes in the valve with transition flow separating orifice flow from throttling flow. Existing models predict performance for orifice and throttling flow, but not for transition. They also apply subjective supplementary criteria to determine the flow regime and then select a distinct model for that regime. The new model described here applies to all three regimes and objectively predicts which flow regime applies under the design conditions. Finally, this procedure illustrates the sensitivity of the gas-lift valve to temperature.
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Performance Of Oil Muds At High Temperatures
Authors: Methven N.E. , Baumann R. 
Published: December 2007

Abstract
This paper presents data on the performance of oil muds at high temperatures and high pressures. Included are data and discussions regarding static densities, circulating densities, thermal stability and stability in corrosive environments.
The information on static and circulating densities combines PVT data, recently published methods of computing downhole transient and pseudo-steady state temperature data as functions pseudo-steady state temperature data as functions of circulating rates and geothermal gradients, and recently available rheological properties of oil muds at high temperatures and pressures.
Thermal stability of various oil muds are discussed on the basis of theoretical physiochemical behavior of the constituents physiochemical behavior of the constituents as well as on the basis of laboratory aging and rheology data. In addition, data on oil base mud in the presence of hydrogen sulfide and carbon dioxide are presented.
The data and analyses indicate that the two basic oil mud types, oil base and invert emulsion, have several distinct differences in performance characteristics at high temperature. It appears that the invert emulsion muds have temperature limits (at least economic) because of thermal degradation of their synthetic organophilic colloids and organic surfactants. Critical degradation may occur in a matter of hours at 500 degrees F.
Oil base muds that use certain asphalts for the colloidal material have a higher temperature stability. This is because the asphalt does not degrade, at least up to 540 degrees F. and, because the asphalt is a hydrocarbon, does not need synthetic oil wetting and is in itself an emulsifier, and oil wetting agent and surfactant.
ESP Motor Voltage Adjustment for Maximum Profits
Authors: Lea James F. , Liu Joe 
Published: December 2007

Abstract
Oil production with lift requires a lot of energy. It is not uncommon for a major oil company to have energy costs for total lift approaching $100,000,000/year. Because of this, any easily practice that can save even a fraction of these costs can be advantageous. This paper addresses what is the best voltage for ESP motors (systems) that are running at load conditions other than 100%. Reference 1 shows advantages to lowering the voltage on and ESP installation when the motor is less than 100% loaded. One ESP manufacturer has literature suggesting that if an ESP motor is 20% under-loaded, then the voltage to the motor should be lowered by 10%. Also it is known that increasing the voltage over name plate will speed up the unit and you can get more production. Some total system examples are presented to illustrate these effects for some particular equipment.
This paper should apply to any operator that finds a new or old installation where the load is not near 100% on the motor and consideration is made to whether or not to change the applied voltage.
There are many of recommendations from the ESP manufacturers to the end users about how to maximize system efficiency. Sometime these instructions are confusing or difficult to follow by the end users, especially when the motor is operating under "off full load" situation.
Horizontal Well Completion With Stinger for Reducing Water Coning Problems
Authors: Permadi P. , Wibowo W. , Alamsyah Y. , Pratomo S. W. 
Published: December 2007

Abstract
A laboratory experiment has been conducted to study the behavior of water coning under a horizontal wellbore having a stinger inserted. A large Hele-Shaw cell was used to perform the experiment. The length of the stinger employed, oil viscosity, and initial thickness of oil column were varied to investigate their effects on the optimal length of the stinger.
Results obtained show that systems without stinger yield better early recovery performance. Installing a stinger flattens the cone of water and reduces the rate of increase in water cut, leading to an improved recovery significantly. It is found here that the optimal stinger length is about 0.3 of the length of the horizontal wellbore section, regardless of the initial thickness of oil column and water/oil mobility ratio.
Synthesizing of Dispersant for MTC Design and Its Effect on Slurry Rheology
Authors: Jirul Hou , Zhongchun Liu 
Published: December 2007

Abstract
A new method of obtaining improved zonal isolation using drilling fluid solidification technology has been developed. A water-base drilling fluid is converted into a cementitious slurry by the special method, is called simply MTC(Mud To Cement).The MTC technology used for cementing operation can improve the quality of cementing and reduce the disadvantageous effect resulting from flocculation in the mixture of drilling mud-cement and cracking of solidified cement as the filter cake and drilling fluid in washed out sections thereby contain a hydraulic material.The dispersant's synthesizing and its effect on slurry rheology are the base of MTC technique application.This paper provides two methods of which the dispersant is synthesized by using fractions of C9 which are the by-product of Daqing ethene unit. The dispersant is cheaper, and it can be used for MTC design by experiment's verification. The effects of amounts of dispersant and mud on the rheology of MTC slurry are studied and discussed. The results show that the thickening time of MTC slurry is extended clearly with mixing of dispersant, and the mobility of slurry is improved. We find that there is a low mobility or high consistency region, when MTC slurry is making up. The appropriate measures for improving quality of MTC are provided in this paper. Moreover, the rheological model of MTC slurry is studied. Through lots of calculation, the H-B model is the most accurate for describing MTC slurry.Last, the application of MTC technology in Changqing field is introduced.
Overbalanced Perforating Field Study in the Tubb Sand, Bravo Dome Field
Authors: Grieser Bill , Smith Craig C. , Bertrand Bert 
Published: December 2007

Abstract
This paper provides results of a study comparing several parameters from 40 wells that were fracture-stimulated with conventional perforating techniques to 30 wells fracture-stimulated with overbalanced perforating (OBP). All wells are in the Bravo Dome Field and are producing from the same formation. The parameters used for comparison are (1) interval length and depth, (2) number of perforations and phasing, (3) perforating technique, (4) average and maximum bottomhole calculated treating pressure (BHTP), (5) proppant volume to job volume ratio, and (6) production results. There were two opinions on the benefit/risk of using OBP as an initial step in completing wells that may require fracture stimulation. One opinion suggests that OBP reduces near-wellbore tortuosity and creates a dominant fracture geometry, resulting in lower injection pressures and reduced chance of early screenouts. The other opinion suggests that OBP increases tortuosity and creates multiple fractures that could lead to high injection pressures and early screenouts.
Borate-Crosslinked Fluid Rheology Under Various pH, Temperature, and Shear History Conditions
Authors: Shah S. N. , Lord D. L. , Rao B. N. 
Published: December 2007

Abstract
The oil and gas industry has now long been aware of the fact that the rheological characterization of crosslinked fluids under field simulated conditions is very difficult. Particularly, the testing of borate-crosslinked fluids under realistic conditions for better understanding of their rheological behavior, is very complex. For this purpose, the Gas Research Institute (GRI), the U. S. Department of Energy (DOE), and the University of Oklahoma jointly established the Fracturing Fluid Characterization Facility (FFCF) which includes a pilot-plant scale, high temperature, high-pressure simulator (HPS) coupled with a fluid pre-conditioning system. Employing the field-size equipment of the FFCF and field-simulated procedure, various borate-crosslinked fluid formulations are tested and evaluated for their rheological responses.
This paper presents the results of pre-conditioned fluid rheology tests conducted with borate-crosslinked Guar and HPG gels employing the HPS over a range of pH from 9 through 11, subjected to varying levels of shear history and temperature. The network structure of these crosslinked fluids at any time is dependent on the current shear state, past shear history, and borate ion concentration which in turn depends on pH and temperature. Even though the effect of pH and temperature on the borate ion concentration is relatively well understood, the characterization of the shear state of the gel at field conditions is still in its infancy. In this investigation, test fluids are subjected to all conditions, to the maximum degree practical, experienced by a fracturing fluid in the field, including its formulation in surface equipment, its injection through tubular goods and perforations, and its flow and heatup in the fracture. Besides the effects of polymer type, temperature, and fluid pH, the effects of shear history on the rheology of borate-crosslinked fluids are also investigated. The presented results show dramatic effects of shear history on the rheology of borate-crosslinked gels which have been ignored in previous investigations. Certain gel formulations corresponding to specific pH and temperature conditions, were found to be shear history insensitive. Furthermore, these shear history insensitive formulations were also found to exhibit an optimum viscosity which was independent of temperature over the range of ambient to 185 °F.
Drilling Short Radius Dual Lateral Wells in Oklahoma: An Operator's Experience
Authors: Ellis Charles A. , Samuel G. Robello 
Published: December 2007

ABSTRACT
Drilling lateral wells from the same vertical well to improve hydrocarbon production has been successfully applied in many fields. This paper discusses the operator's experience in drilling short radius dual laterals from the same vertical wellbore in the Burbank Sand of the Burbank Field of Osage County, Oklahoma. The laterals were sloped to intersect the many stratified sands and allow gravity drainage to act later in the life of the well.
The completion and difficulty in removal of formation damage from use of xanthan gum from polymer sweeps are discussed.
Something Different In Down Hole Pumping
Authors: Anderson Howard C. , Watson Brock , Earnest Dale , Walla Andrew , Folmar Eddie 
Published: December 2007

Abstract
This paper describes a new and different approach to conventional beam pumping with a subsurface pump and sucker rod string. The beam pumping cycle takes the rod string from tension on the up stroke to compression on the down stroke. Minimizing the compressive forces on the down stroke, creating a higher minimum load aids in extending the service life of tubing, rods and pump. This can be done by the lower portion of the rod string being larger sucker rods or sinker bars or by proper sizing of the pump plunger or a combination of both along with proper stroke length and strokes per minute.
Data presented in this paper shows another means of keeping the rod string in tension by use of a different type of subsurface pump. The fluid load on the areas of the pump act to increase the down stroke load. This down stroke load tends to keep the lower end of the sucker rod string in tension rather than allowing it to go into compression. This paper presents the theory of a different kind of subsurface pump backed up by field data showing the benefits of this pump.
Biotechnological Treatment Removes Xanthan-Based Skin Damage
Authors: TjonJoePin Robert M. , Brannon Harold D. , Beall Brian B. 
Published: December 2007

Abstract
Conventional reservoir drilling fluids typically consist of xanthan-based polymers to optimize recovery of drill cuttings and reduce friction or torque during the drilling operations. Previously conducted laboratory studies have indicated that the damage produced by these types of xanthan-based drilling fluids can be easily removed. Field data, on the other hand, has indicated that substantial amounts of polymeric damage remain in the formation. Even though these psuedoplastic, non-thixotropic, xanthan-based drilling fluids exhibit low shear rheologies during the operations, they can contribute to tremendous amounts of skin damage. This insufficient degradation of filter cake may impede flow and dramatically reduce formation permeability hence well productivity.
Recent extensive research was conducted to develop a treatment which could effectively reduce this type of polymeric damage. A novel biotechnological treatment has been developed, which effectively removes xanthan-based filter cakes or skin damage at temperatures from 70°F to well over 250°F.
Core flow evaluations have shown that multi-fold improvements are achieved with this optimized biotechnological removal treatment. A detailed study of the laboratory and field case histories are presented. Average incremental production rates of the treated wells were significantly improved, clearly demonstrating the effectiveness of this removal system.
New design of a floating storage and production unit
Authors: de Werk E.J. 
Published: December 2007

Abstract
Where a pipeline cannot be employed for technical or economic reasons, the existence of facilities for temporary storage is a prerequisite for the exploitation of an oil well. The choice of an offshore storage system, of which a number of types exist, is largely governed by environmental factors at the field. The advantages and disadvantages of existing storage systems are reviewed and the design of a new "spar" type storage unit discussed. This unit is mobile, yet is well suited to use in adverse weather conditions.
In addition to its role as a storage tank and a single point mooring buoy, the unit also serves for production. The design criteria, the oil system and the single point mooring section are dealt with, and also aspects of the fabrication of the unit and the methods employed to position and recover it.

Introduction
It is envisaged that energy requirements in the next few decades will be met from undersea sources and that the exploitation of oil wells will increasingly involve operations in deeper water and at greater distances from coasts.
Although not new, the storage of oil at sea is a new aspect of offshore technology and one which is in the course of development. Various storage facilities have been developed in recent years, each with its specific advantages and shortcomings. In most cases, such facilities are designed for a particular location and are more or less rigidly attached to the seabed, or resemble a ship's hull and are anchored by means of a number of chains or are moored to a single point mooring system.
Where large-volume storage units are involved, surface vessels can be used for the purpose only if the environmental factors at the location are such that no violent motions occur which impose heavy stresses on the anchorage system.
Field Applications of ERD Hole Cleaning Modeling
Authors: Hemphill Terry , Pogue Tom 
Published: December 2007

SPE/IADC Members

Abstract
With the ever-increasing measured depths and horizontal displacements in extended-reach (ERD) wells, good hole cleaning remains a major challenge. Recently a hole cleaning model for fluids in laminar flow was presented to the industry. Since its introduction, the model has been used on many occasions to characterize hole cleaning efficiency in post-well analysis, evaluate fluid performance during the drilling of ERD wells, and to predict fluid rheological properties and pump output levels for optimum cleaning in pre-well planning. In this paper, four field applications of the hole cleaning modeling in ERD and deviated wells are discussed. In these cases, the hole cleaning model was used to predict intervals of hole cleaning problems and identify certain ranges of fluid rheological properties that promoted good cleaning.

Introduction
The hole cleaning model (hereinafter referred to as "the model") utilizes the following to mathematically describe the ability of a drilling fluid in laminar flow to clean drilled cuttings out of a wellbore:–Herschel-Bulkley rheological modeling of drilling fluids - Annular velocity modeling valid for concentric and eccentric drill pipe cases–Particle settling velocity modeling for static and dynamic cases–Lift factors calculated in a vertical plane under the eccentric drill pipe.
This hole cleaning model is different from other published models in that it exclusively deals with the area lying immediately below the eccentric drill pipe. This specific annular cross-sectional area is chosen because this is where cuttings bed accumulation begins to occur.
In this model, the position of the drill pipe while rotating in the eccentric annulus is the greatest unknown. A particular level of drill pipe eccentricity () is input to cover those situations when the rotating drill string is lifted off bottom. Further complicating things, in a skewed annulus, there are an infinite number of eccentricities at a given angle of deviation. For the high angle situations where the drill string is being rotated, a drill pipe eccentricity level 0.5 is often used.
In this model, operational activities that can promote increased hole cleaning on a temporary basis are not taken into account. These activities can include:–Frequency and duration of trips–Application of backreaming–Application of viscous/non-viscous or weighted sweeps–Increased circulation times–Limits on penetration rates
This model is purposely constructed to characterize hole cleaning efficiency on a steady-state basis where the hole is being drilled in a rotary (eg, non-sliding) mode.
After its development, the model was tested in a number of drilling situations to ensure it was a valid working tool. As part of the validation process, data from Statoil's well Statfjord C-02, a previous world-record ERD well for horizontal displacement, was analyzed according to this model. Concepts learned from this in-depth investigation were then later applied on another Statoil ERD well, Sleipner A-2.
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The Dual Density Riser Solution
Authors: Lopes Clovis A. , Bourgoyne Adam T. 
Published: December 2007

Abstract
The objectives of this project are to determine the advantages, disadvantages, technical feasibility and economic feasibility of the use of gas lift in a marine riser to maintain the pressure in a subsea wellhead equal to the hydrostatic pressure of the seawater outside of the wellhead. Such a dual density system for drilling in deep water would have one effective fluid gradient between the surface and the seafloor and another fluid gradient within the subsea well. This would in effect reduce the casing design problem to that of an equivalent on-shore well. This paper gives a summary of our progress to date.