bluuebunny/crossref_metadata_2025 huggingface dataset:
An Efficient Finite Volume Approach for Modelling Miscible Displacement
Authors: Santos R. L. A. , Pedrosa O. A. , Correa A. C. F.
Published: December 2007

Miscible displacement in two-dimensional reservoirs is simulated using a finite-volume approach that includes a nine-point discretization scheme based on the flux interpolation technique. The approach also incorporates a locally one-dimensional exponential scheme to discretize the convection-diffusion terms. The numerical results showed the effectiveness of the proposed technique in reducing numerical dispersion and grid orientation effect for adverse mobility ratios.
Automatic Fitting of Equations of State for Phase Behavior Matching
Authors: da Silva M. B. , Rodríguez F.
Published: December 2007

Phase behavior modeling of a reservoir hydrocarbon mixture through an equation-of-state, EOS, is preceded by the adjustment of some of the parameters in the equation so as to reproduce measured PVT data of the mixture. In this paper we propose a methodology for the automatic fitting of EOS parameters for phase behavior matching.

Critical properties of the heaviest, C+, fraction are obtained from available correlations and fitting of EOS parameters, Ωa0 and Ωb0, for CH4 and C+ as well as of the binary interaction coefficient, δCH4−C+, are performed according to the following procedure: First, keeping the theoretical values of Ωa0 and Ωb0, we calculate the interaction coefficient δCH4−C+ that matches the saturation pressure of the mixture. In a second step, the parameters Ωa0 and Ωb0 for the CH4 and C+ fractions are fitted through a non-linear least squares regression technique to match PVT experimental data in the one-phase region. Peculiarities of the system of equations produced by the fitting algorithm are discussed; proper solution techniques are discussed as well.

The above procedure was used to adjust the Peng-Robinson EOS to four reservoir hydrocarbon fluid samples, which include gas condensate. Phase behavior in the two-phase region predicted with the EOS was verified to match PVT laboratory data obtained under flash and differential liberation processes. It was verified that the interaction coefficient, δCH4−C+ is the relevant parameter for saturation pressure matching. Analysis of regressed parameters indicate, in all four applications, that relevant parameters in the non-linear regression fitting are Ωa0 and Ωb0 of the CH4, fraction.
In Situ Combustion with Metallic Additives
Authors: Castanier L. M. , Baena C. J. , Holt R. J. , Brigham W. E. , Tavares C.
Published: December 2007

In-situ combustion is the most energy efficient of the thermal recovery methods. In light oil reservoirs, too little fuel may be deposited thus making combustion impossible while in heavy oil reservoirs too much fuel may be deposited thus ruining the economics of the process. A research program has been initiated to try to solve these problems. Water soluble metallic additives were tested to attempt to modify the fuel deposition reactions.

In a previous paper1, results were reported from kinetics experiments run on Huntington Beach, California and Hamaca, Venezuela crude oils in the presence of aqueous solutions of metallic salts. While the presence of copper, nickel and cadmium had little or no effect; iron, tin, zinc and aluminium increased fuel laydown for Huntington Beach oil. The results were similar for the heavier Hamaca oil.

This paper describes thirteen combustion tube runs using four different crudes. In addition to the above two crude oils, a 12° API and a 34° API Californian oil were tested. The metallic additives iron, tin and zinc improved the combustion efficiency in all cases. Fluctuations in the produced gases were observed in all control runs but disappeared with the iron and tin additives. The front velocities were increased by the metallic additives. Changes were also observed in H/C ratio of the fuel, heat of combustion, air requirements and density of the crude produced. The amount of fuel deposited varied between the oils. For Huntington Beach oil, the amount of fuel increased in the order: zinc, control, tin and iron while for the Hamaca crude the order was: control, iron and tin. The most interesting result occured with the light California oil. The control run showed that we were unable to propagate a combustion front while with iron additive a good combustion was achieved.

To date we have not been able to find a suitable additive to reduce fuel deposition. Iron and tin salts seem suitable agents to increase fuel when that is needed.
Steam Foam Studies in the Presence of Residual Oil
Authors: Hutchinson D. A. , Demiral B. D. M. , Castanier L.
Published: December 2007

This paper reports ongoing work at Stanford University aiming at better understanding of steam-foam flow behavior with oil present. Steam foam systems were studied in a one dimensional sandpack at residual oil saturation (about 12 %). The strength of the in-situ generated foam, indicated by pressure gradients, is significantly affected by injection procedure, slug size, steam quality and non condensible gas (nitrogen). In the range studied, surfactant concentration has a minor effect.

In the presence of residual oil, simultaneous injection of steam and surfactant fails to generate foam in the model, while the same procedure generates a strong foam without oil. When surfactant is injected as a liquid slug ahead of the steam, foam is generated, albeit at a lower strength than when no oil is present. The minimum slug size required to generate foam by this procedure is about 5 % of the pore volume at 1.0 % weight concentration. Above this minimum, increases in slug size or in concentration had little effect. The quality of the steam when it is increased, improves the foam strength. One implication of these results is that savings in the amount of surfactant needed for a steam-foam project may be possible by using a large slug of dilute solution. That is, if the slug volume is above some minimum, a dilute concentration may give acceptable foam generation. The reverse procedure, a small slug of high concentration surfactant gives poor foam generation and should probably be avoided in the field. Steam quality effects are consistent with the existing literature.
Steam Distillation and Oil Quality Change During Thermal Oil Recovery
Authors: Lim K. T. , Ramey H. J. , Brigham W. E.
Published: December 2007

A general method has been developed to compute steam distillation yield and to quantify oil quality changes during steam injection. It was found that steam distillation data from the literature can be correlated with the steam distillation yield obtained from the DOE crude oil assays. The common basis for comparison was the equivalent normal boiling point. Blending of distilled components with the initial oil results in API gravity changes similar to those observed in several laboratory and field operations.
A Stochastic Role for Engineering Input to Reservoir History Matching
Authors: Watkins A. J. , Parish R. G. , Modine A. D.
Published: December 2007

This paper is concerned with the role of engineering input to, and interaction with, algorithms used in reservoir history matching. The underlying iterative cycle common to all techniques allows considerable scope for such input; however, for maximum benefit to result, it is important that the information accurately reflects engineering experience, and can be suitably quantified for use in algorithms.

The discussion is illustrated with some salient points of examples based on one technique which uses a stochastic framework to accommodate explicitly the uncertainty in such essentially deterministic problems.
The Heat Efficiency of Thermal Recovery Processes Resulting from Non-Uniform Vertical Temperature Profiles
Authors: Prats M.
Published: December 2007

Original analytical results provide estimates of the heat remaining in a homogeneous and uniform reservoir during injection of steam or hot water, for the practical cases where the temperature is not vertically uniform within the reservoir.

Temperatures quadratic in the vertical position within the reservoir are used to accommodate the boundary conditions for three cases: steam extends to the boundary of both, only one, or none of the formations above and below the reservoir. The first case corresponds to steam extending over the full thickness of the reservoir, already published. The second case approximates steam flooding with gravity override, and the third case approximates hot water flooding.

Two graphs, sufficient to estimate the time dependence of the heat remaining in the reservoir, are provided. Results depend on the thermal properties of the reservoir and its adjacent formations, which may differ. Results also depend on the square of the reservoir thickness and the rate of heat injection.

Heat efficiency is defined as the fraction of the injected heat remaining in the reservoir. Comparison of our hot water heat efficiency with Rubinshtein's formal analytical results1 (for equal thermal properties) shows excellent agreement.

The heat in the reservoir is not a function of the injectant temperature, a result which had been shown previously only for the case that steam extends over the full reservoir thickness. Nor is the heat efficiency dependent on the rate of heat injection when the latter is constant.

Because of low temperatures at the boundaries with the adjacent formations, the heat efficiencies of hot water floods and steam floods with override are higher than those for steam extending over the full reservoir thickness. For hot water floods, the increase is as much as 16%. For steam floods with override the increase is more modest.
Conformance Improvement by Using High Temperature Foams and Gels
Authors: Isaacs E. E. , Green M. K. , Jossy W. E. , Maunder J. D.
Published: December 2007

The use of foams to divert the steam from the swept zone has been extensively tested both in the laboratory and the field. On the other hand, gels for plugging unproductive zones have mostly been considered for conventional or relatively low temperature applications. The objectives of this study were the development of strategies for improving the long-distance propagation of foam in the reservoir and evaluation of gels for near-well applications in thermal recovery operations.

The major limitations to the growth of the foam zone include the inefficiencies in foam generation and poor bubble transport. Flow experiments were carried out in sand packs at steamflood conditions to develop strategies for improving foam generation by a pre-foam reduction of residual saturation in the swept zone. The results showed that the pre-foam concept could be used with small slugs of low interfacial tension chemical or solvents to substantially improve the rate of foam propagation.

Studies to determine the propagation behavior once foam is generated showed that bubble transport is sensitive to oil saturation but relatively insensitive to injected fluid velocities and liquid volume fraction.

Laboratory experiments were also conducted to test gel performance in porous media over the temperature range 100-300°C. Although the gel strength diminished at high temperatures, significant reductions of steam mobility were still observed at 300°C. Gels in porous media were shown to withstand moderate pressure gradients for extended periods of time at elevated temperatures. The advantage and disadvantage of foam and gel applications at elevated temperatures will be discussed.
Design and Application of Sintered Porous Stainless Steel Well Screens in Sand Control Completions
Authors: Cole R. C. , Arterbury B. A. , Pearce J. L.
Published: December 2007

Wire-wrapped screens, in many different design configurations, have been the industry standard for use in gravel pack completions. Lately, some of the advantages of prepack designs, have generated interest and are being used in both cased and operinole completions. Of specific interest have been prepack designs having a thinner aggregate layer which affords more annulus clearance to help assure adequate gravel placement and retreivability.

One recent development in porous sintered stainless steel technology introduces a thin-walled, sintered stainless steel screen that appears to offer improvements over prepack screens. Some advantages to the porous sintered metal screens (PSMS) over thin-wall designed prepack screens (TWPS) have been confirmed by current testing. These include uniformity of the porous metal screen media and resistance to damage due to handling.

In addition to a discussion of the above findings, the paper presente results of comparative testing of the two type screen designs for the effect of bending stresses, flow capacity, scaling tendencies, and cleanout by backflusbing. A study of the effects of brines, acids, and H2S on the porous metal is also included.

The most gravel pack screen-related failures have been traced to. impact damage and erosion cutting. The introduction of this new porous sintered metal technology to reduce screen failures can save money in reducing the number of workoveis and in prevention of production declines.
Waterflood Stimulation for Fractured Limestone of the Austin Chalk
Authors: Rose R. E. , Austin C. E. , Pike J. R.
Published: December 2007

A process for treating older wells completed in the Austin chalk has produced impressive production increases in wells which had previously been fracture stimulated using water-based, sand-laden fracturing fluid. The process utilizes high volumes of water pumped at high rates (more than 25 bbl/min). Termed ‘waterflood stimulation,’ this technique has helped rejuvenate wells which had experienced major production declines since the original fracturing treatment. Incorporated in the treatment fluid are surfactants, diverting agents, weak acids, and friction reducers. Based on analysis of 3 years of treatment results, ‘waterflood stimulation’ appears to provide a waterdrive production mechanism, as evidenced by well response.

Austin Chalk completions have typically been characterized by high initial production followed by rapid production declines. Reservoir characteristics of the Austin Chalk indicate that production is dependent on the fracture system, both natural and created, rather than on the actual rock matrix. Methods have been developed to help determine feasibility of ‘waterflood stimulation’ on an individual well basis. Factors to consider include cumulative production and gas:oil ratio. Guidelines for treatment rates and volumes have also been developed based on well parameters and field experience. Other, similar-type reservoirs may also be receptive to this form of treatment.

Subject paper will present case histories from approximately 20 wells, descriptions of reservoir characteristics, evaluation criteria for candidate wells, and treatment design and operation with production data before and after treatments.
The Mechanisms of Solids Production in Unconsolidated Heavy-Oil Reservoirs
Authors: Chalatumyk R. J. , Wagg B. T. , Dusseault M. B.
Published: December 2007

A research program into the mechanisms and management of solids production is currently underway. The major objective is to develop a comprehensive understanding of solids production mechanisms which will lead to drilling, completion, and operating strategies that can be used to reduce the costs and risks associated with oil and gas production. The research program is comprised of four major components: (1) a Field Study, to conduct a detailed review of past sanding experience by accessing the large body of information that exists within the well records of several companies; (2) a Laboratory Testing program to characterize the hydraulic and constitutive behavior of reservoir materials; (3) a Field Testing program to obtain data for specific reservoir characteristics and to assess products/processes for controlling and exploiting solids production; and (4) a Numerical Modelling program to develop a predictive capability for solids production. At present, the research program is focussing on sand production from heavy oil deposits in Alberta and Saskatchewan. The technical challenges associated with the field study component of the research program are presented and discussed.

This study of solids production is analyzing the entire history of the well, extending from spudding to abandonment This includes the "formation disturbance" effects that accumulate from drilling, cementing, perforating, production and workovers. Data management procedures developed for handling field information are presented. A Reservoir Disturbance Index (RDI) has been developed to quantify the degree of reservoir disturbance created during drilling, completion, production and workover phases. The procedures for computing RDI values and use of this index in comparative statistical analyses are described. Geophysical logs are incorporated in the field study to develop a capability for assessing solids production potential.
An Experimental Investigation of Formation Damage in Heavy Oil Reservoir During Steam Injection
Authors: Okoye C.U. , Onuba N.L. , Ghalambor A. , Hayatdavoudi A.
Published: December 2007

SPE Members

A laboratory study was conducted to evaluate formation damage due to steam injection. The investigation includes the adsorption and desorption of divalent ions and the transportation of scales through the formation. Several displacement tests were made at different elevated temperatures (200 degrees F to 500 degrees F) and steam salanity or alkalinity to determine the rate and nature of formation damage during steamflooding. Other tests conducted in this study include; roller oven tests, SEM EDEX and petrographic studies.

The results from this study show there is decline in the permeability when temperature permeability when temperature and alkaline concentrations are increased. It was also observed that the alkaline solution PH decreased with increase in temperature. SEM, X-Ray, EDX and petrographic analysis show petrographic analysis show pseudo-hexagonal stacks of pseudo-hexagonal stacks of mineral overgrowth which blocked the pore throats. There was dissolution of minerals and precipitation of aluminosilicate such as zeolite. This study provides screening procedure for estimation of potential formation damage due to steam injection. Also, the results obtained in this study relate to actual formation during steam cyclic steam and direct steam injection.

Introduction

In order to understand the theory of reaction kinetics related to this experimental investigation, it is necessary to look at the physio-chemical aspects of reaction kinetics.
Fracture Reorientation in Model Tests
Authors: Weijers Leen , de Pater C. J.
Published: December 2007

An experimental study has been carried out to investigate the influence of the cementing chronology. That is to say, cementing of a perforated casing in a stress-free borehole or a loaded borehole resulted in a difference in near wellbore fracture geometry.

Starter fractures, propagating into multiple fractures, were observed when the casing was set and cemented in a stress-free borehole. Cementing the casing in a stressed borehole resulted in a continuous fracture along the wellbore, which sometimes ignored the perforations. Therefore, hydraulic fracturing experiments with the aim to represent field situations should be carried out when the casing is cemented in a stressed borehole.
Predictability of Formation Damage by Modeling Chemical and Mechanical Processes
Authors: Chang F. F. , Civan Faruk
Published: December 2007

A phenomenological model for formation damage by chemical and mechanical processes in petroleum reservoirs is presented. Geochemical reactions involving dissolution/precipitation and ion exchange are modeled. The precipitates are considered mobile and mixed with formation particles to contribute to the pore throat plugging. Size distribution of both precipitates and clay fines is represented by a bimodal distribution function. A semi-empirical approach is used to estimate the fraction of the plugged pore throats. The model parameters are determined through an optimization method by matching the model predictions to laboratory core test data.

The capability and validity of the model are demonstrated by comparing the predictions obtained from this model with experimental data for four cases. The predicted and the experimental data are shown to be in good agreement in each case. This model can be used for diagnosis, evaluation, and simulation of damage and alteration of reservoir formation during drilling, production, and chemical flooding processes.
Study of Waterfall Effect on Formation While Underbalance Tubing-Conveyed Perforating
Authors: Sampson T. W. , Dunn H. E. , Walton D. S. , Combo J. C.
Published: December 2007

This paper describes the naturally occurring phenomenon of hydrostatic reduction and oscillation about an underbalance pressure when hydrostatic pressure is decompressed by the opening of a ball valve to the underbalance pressure when tubing conveyed perforating is performed. Downhole memory pressure gauges have recorded this event on wells on three separate zones. Laboratory testing was conducted and was successful in recreating and recording this pressure transient. All the data indicates that the magnitude of the hydrostatic reduction to be a function of the differential pressure being decompressed. The continued decrease of pressure below the underbalance pressure occurs at a rate of approximately 20 psi (.14 MPa) per 100 psi (.69 MPa)of differential pressure. The duration of the oscillating pressure wave (i.e., the time from the opening of the ball valve until the pressure wave is damped out) is a function of the volume of fluid being decompressed. Theduration time increases at a rate of one second per400 U.S.gals (1.514m3).

The data has been plotted on pressure vs. time graphs. The curves are characteristic of damped harmonic motion with a single degree of freedom and therefore, can be solved by using a linear second order differential equation.
Chacterization of Carbonate Precipitation and Scale Formation in Solids-Free Clear Brines
Authors: Swartwout R. T. , Ho Tien
Published: December 2007

The following brines, a 11.0 lbm/gal (1.32 g/cm3) NaCl/NaBr, 13.5 lbm/gal (1.62 g/cm3) CaCl2/CaBr2 and 16.0 lbm/gal (1.92 g/cm3) CaCl2/CaBr2/ZnBr2 were studied for carbonate precipitation and scaling tendencies in the presence of CO2 gas. The brines were subjected to CO2 gas pressures ranging from 50 to 500 psi (0.34 to 3.45 MPa) and temperatures between 200 to 400°F (93.3 to 204°C).

The 11.0 lbm/gal (1.32 g/cm3) NaCl/NaBr and 13.5 lbm/gal (1.62 g/cm3) CaCl2/CaBr2 brines formed small amounts of carbonate solids upon exposure to CO2 gas. The 16.0 lbm/gal (1.92 g/cm3) CaCl2/CaBr2/ZnBr2 brine in contact with CO2 gas produced significantly large amounts of carbonate solids. The concentration of precipitated carbonates formed by the 16.0 lbm/gal (1.92 g/cm3) CaCl2/CaBr2/ZnBr2 brine would raise concerns of possible formation damage.

Two commercial scale inhibitors were evaluated and were found to provide very little to no protection towards inhibition of carbonate solids formation.
Wellbore Stimulation Using Microorganisms to Control and Remediate Existing Paraffin Accumulations
Authors: Peiger J. W.
Published: December 2007

This paper will explain and demonstrate a method to increase production in individual wells or fields with skin damage, due to paraffin accumulations, corrosion, emulsion and scale formation, utilizing an individual treatment design from a library of facultative anaerobic microorganisms.

These neutrally charged marine organisms, in a saline solution of nutrients, are naturally occurring, non-pathogenic, non-toxic, non-careinogenic, non-combustible and require no permits from the Environmental Protection Agency for storage, transportation or disposal. Environmentally, these microorganisms are as safe as any product in our industry to control and reduce skin damage.

Paraffin, corrosion, emulsion and scale formation have resulted in significant economic losses, reducing profitability for producers and operators. The resulting skin damage can be controlled and reduced through proper treatment by locating microorganisms in the immediate formation, perforations, and in the case of most problem preventing restrictions in production streams or failures in lifting equipment. Traditional control methods for treatment involve implementing techniques such as hot oiling, paraffin cutting, chemical and condensate treatments. These techniques have been marginally successful, economically prohibitive and temporary at best. Many of these traditional methods are dangerous from a safety standpoint and often have caused serious long term damage to the productive life of the well (especially in the case of hot oiling).
Laboratory Investigations of the Effects of Formation Damage in a High-Permeability Reservoir
Authors: Mehdizadeh A. M. , Hashemi Reza , Caothien Scott
Published: December 2007

A four foot long pipe (ID = 2″) packed with silica sand was used to study the effects of formation damage caused by completion and work-over fluids in a high permeability reservoir. Pressures were recorded at five locations (1 foot apart) across the high permeability sand pack as different fluids at a rate of 5 ft/day were injected into it. Bentonite and salt concentration of the injected fluids were changed and their effects on the single phase permeability of the sand pack at different filtration levels were investigated. Some runs were performed using field water from San Ardo field in California. Finally, effects of formation damage on oil recovery by water-flooding were also studied.

Results show that depending on the composition and the amount of the injected fluids, high permeability sand pack develops irreversible permeability loss which in turn limits the ultimate oil recovery during water-flooding. Results also show that maintaining proper filtration level can minimize the degree of damage to the high permeability sand pack.
Dual-Diameter Drillpipe Offers Advantages in High-Angle Drilling
Authors: McNeely B. M.
Published: December 2007

This paper introduces a unique drill pipe design concept proposed primarily for high angle/horizontal service. The design consists of a pipe joint, the middle two-thirds of which are light-wall and has an outside diameter only slightly smaller than the tool joint. Handling space of nominal diameter is provided at both ends. Tool joints are conventional.

Two principal design effects are tabulated comparing Dual Diameter Pipe with API in four sizes. (1) Mud volume and pressure loss to produce various annular velocities. (2) Load to produce buckling calculated using Dawson Paslay and Euler.
Consideration for Design of Drilling Conductors for the New Generation of Deepwater, Harsh Weather Jackups
Authors: Wetmore S. B. , Halbleib B. L.
Published: December 2007

As the next generation of harsh weather jackups for the North Sea push the operating water depth limits from 300 feet (91m) upwards to 500 feet (150m), the environmental criteria also increase. At these more severe depth and environmental conditions the increased dynamics of both platform and drilling conductor will increasingly affect drilling operations. When drilling in water depths greater than several hundred feet the conductor must be tensioned to resist buckling and increase its stiffness, the amount of tension being proportional to water depth and environmental conditions. The tensioning device is usually placed at the top of the conductor and just below wellhead/BOP stack, thus creating a point of lateral fixity. As currents and waves act on the tensioned but unstayed conductor, the wellhead/BOP stack rotates about the point of support to suit the structural deflection of the conductor below. At some limiting sea state, the top of the BOP stack no longer lines up with the rotary table and drilling must be suspended. If the top of the BOP stack is also laterally fixed (or hydraulically snubbed), a bending momement is induced in the BOP stack, which under severe storm conditions, can exceed the structural limit of the BOP stack connections.

A frequency domain computer program was used to parametrically analyze the dynamics of the system and to calculate the maximum stress levels in the various components. The paper examines over 75 combinations of physical configuration, water depth, environmental criteria, drag coefficient, conductor diameter, vertical tension and joint stiffness. Appropriate graphical representation of the results are presented. Based on the analysis, the authors conclude that the design of the drilling conductor for winter storm conditions in the North Sea and for water depths greater than 300 feet will be significantly more complex than present shallow water designs. An ongoing analytical program is postulated to study composite configurations, fatigue effects, and drilling downtime.
A Critical Examination of Rotary Drilling Hydraulics
Authors: Bourgoyne Ted , Kimbler O.K.
Published: December 2007

A new computer technique has been developed for providing information on rotary drilling hydraulics. The computer program determines the proper bit nozzle size and pump operating conditions for all combinations of depth and mud density for a given hole size. By performing the calculations for all hole sizes used, the program completely defines optimum hydraulics for a given rig, making repetitive calculations for each well unnecessary.

The computer program presented was used to compare various published optimization procedures over a typical range of field conditions. The optimization procedures studied were

establishment of maximum jet impact force, establishment of maximum bit horsepower, establishment of maximum nozzle velocity, establishment of known cleaning needs with the least pump horsepower expenditure, and pump horsepower expenditure, and establishment of optimum bit horsepower using the Economy Method.

The comparison includes differences among the procedures in pump cost as well as the differences in the hydraulic horsepower, jet impact, and nozzle velocity of the bit.

Introduction

The development of the jet bit has been one of the most significant improvements in drilling technology. The main advantage of the jet bit is its higher efficiency in removing rock cuttings from the hole. Cuttings remaining on the bottom of the borehole will impede further penetration by the bit until they are removed. Wasteful regrinding is prevented if the fluid circulating past the bit removes cuttings as rapidly as they are formed.

In order to utilize the full potential of the jet bit, the proper potential of the jet bit, the proper nozzle size and pump pressure must be used. Figure 1, after Kendall and Goins, illustrates the large increase in bit hydraulic horsepower that can be achieved by the selection of a proper hydraulics program of bit nozzle proper hydraulics program of bit nozzle size and pump operating conditions.
Drilling Contractors Long Overdue Focus on Drill Floor and Its Equipment
Authors: Pedersen P. Carsten , Kudsk G. , Lund T.
Published: December 2007

The paper introduces some suggestions as to why development of new equipment/approaches has been slow in the drilling contracting industry and why this situation now appears to have changed. It goes on to describe a systematic development method utilized by Maersk Drilling in improving the drilling process by focusing on safety and efficiency in the layout and in the equipment chosen.

Some of the results such as driller's control, FOXHOLE etc. are explained from the arrangements on board the contractor's two new harsh environment jack-ups presently under construction in Singapore.
New Roller Cone Bits with Unique Nozzle Designs Reduce Drilling Costs
Authors: Moffitt S. R. , Pearce D. E. , Ivie C. R.
Published: December 2007

Selection of the optimum rock bit design to achieve the lowest drilling cost in a given application is often difficult due to a large number of rock bit performance considerations. However, in a majority of applications increased penetration rate is the key consideration in reducing drilling costs. Discovery of a new bit design concept has led to the development of roller cone bits that achieve significant penetration rate increases using superior hydraulic nozzle designs.

Prototype designs have achieved 20 to 40% increases in penetration rate with comparable footage drilled when tested in 6½, 8½, 8-3/4, 9-7/8 and 12¼ IADC 437, 517 and 537 type bits in the U.S., North Sea, Italy, and Oman. Second-generation designs tested in a full-scale drilling laboratory have delivered 70% increases in penetration rates.
Analysis of Buoyancy-Assisted Casings and Liners in Mega-Reach Wells
Authors: Ruddy K. E. , Hill Douglas
Published: December 2007

This paper presents an analysis of the drag in extended- and mega-reach wells. An extended-reach well has been defined as any well with a measured depth to true vertical depth ratio (MD/TVD) greater than 2.0. A mega-reach well has a MD/TVD ratio greater than 3.0.

The drag while running casing in the mega-reach well can be excessive. This paper investigates various applications of selective floatation devices to reduce the drag on the casing.

First, the theoretical foundations of drag analysis for directional wells are reviewed. A methodology for analyzing buoyancy-assisted casing designs is presented. This methodology is used to analyze casing run fully filled with mud, partially filled with mud, and completely floated in mud. In addition, the friction forces during cementing operations are studied.

While previous papers were presented on selectively floated casing designs for extended-reach wells, this study goes further to include an analysis of fully and selectively floated liners. In addition, a liner/tie-back combination is compared with the alternative long string casing design.

The study concludes that completion of some high angle wells, previously thought unattainable due to high drag, can be achieved using buoyancy-assisted casing programs.
Real-Time Downhole Shock Measurements Increase Drilling Efficiency and Improve MWD Reliability
Authors: Rewcastle S. C. , Burgess T. M.
Published: December 2007

Many BHA and MWD failures are the direct result of high shock and vibration produced by the drilling process. Shocks resulting from high lateral vibrations have been shown to contain the most energy and do the most damage to downhole electrical components. High lateral and torsional vibrations can result in tool joint fatigue and twist-offs, and can be shown to reduce roller cone bit bearing life and damage PDC bit cutters.

Many published attempts have been made to model downhole vibrations from surface measurements so that rotary speeds can be selected to minimize vibration. However, downhole data shows that currently these models have limited application in practice. Contact between the drillpipe and wellbore damps outs the transmission of vibrations in directional wells. In vertical wells, most models are highly sensitive to boundary conditions (e.g. BHA/wellbore contact points, hole size, bit/rock interaction) which result in limited predictive value.

A simple, practical and cost-effective solution to the problem has been found. An accelerometer has been installed in MWD systems to count lateral shocks above a programmable "normal" value. A "normal" value of 25 g's has been found to give good field results in offshore environments. The number of shocks is transmitted to the surface every one or two minutes. This enables the driller to modify the rotary speed, and weight-on-bit, to eliminate or significantly reduce the downhole vibration. Eliminating lateral vibrations is expected to minimize axial and some torsional vibrations because there appears to be significant mode coupling.

Examples from the field show that:

– changes in rotary speed can have an enormous effect on the downhole shock environment. – surface measurements of vibration are a poor indicator of the downhole environment. – downhole shocks often correlate well with lithology as indicated by the MWD gamma ray. – PDC bit damage can be avoided by using the shock measurement. – MWD reliability has been improved.

As a result of the improvements, the shock measurement has been made a standard component of all new MWD tools.
Technology and Technique for Scientific Drilling in Crystalline Rocks: Experience and Perspectives
Authors: Mnatsakanov A. V. , Gelfgat M. Y. , Alikin R. S.
Published: December 2007

Continental and offshore scientific drilling is one of the most effective methods of earth investigation. The experience of realization of such wells drilling programs obtained in the last few years points to the fact that there are a number of problems, particularly when drilling crystalline rocks. Simultaneous analysis of deep water and continental drilling results allows to draw up general principles of drilling and coring technology.

In the paper there are given the results of tests and field use of coring technology and technique in crystalline rocks without pulling out the drill string, developed by VNIIBT. Onshore drilling strategy consisted in coring with retrievable tool and research of the pilot slim hole for one drill string running, and then drilling’ the main borehole with minimum vertical deviations.

In offshore drilling without re-entry equipment with retrievable down hole motors and retractable bits it was possible to spud and core the well on the sea floor into bare rocks. On the paper the information about the characteristics of technical means for the technology realization is given. From the onshore and offshore drilling of more than two thousand meters with retrievable down hole motors and core barrels in crystalline rocks there are shown the advantages and perspectives of using drilling technology without pulling out drill string in different conditions.
Economic Environmental Management of Drilling Operations
Authors: Longwell H. J. , Akers T. J.
Published: December 2007

This paper presents significant environmental and regulatory initiatives developed by Exxon's New Orleans Drilling Organization. Specifically, the paper will cover drilling waste minimization techniques and disposal options, recycling of drilling waste streams, and environmentally managed drilling location design considerations. The implementation of some of these initiatives at Exxon's Chalkley field land locations have resulted in a fifty percent reduction in drilling location waste management costs. Some of these same initiatives have been successfully applied to Exxon's barge drilling locations. For operations at the environmentally sensitive Mobile Bay, Exxon contracted with a local company and assisted in the development of an economically and environmentally superior drilling waste disposal and treatment system. In summary, it is possible for drilling operators to pro-actively manage escalating environmental and regulatory challenges through the implementation of economic and practical initiatives.
The Environmental Compliance Audit and Its Cost
Authors: Haffner D. J.
Published: December 2007

The objective of this presentation is to present a decision making flow chart for use in preparing, conducting, evaluating, and responding to an environmental compliance audit. The necessity for an audit emanates from a vast array of federal and state environmental legislation and regulations. Each step of the flow chart is addressed in light of the appropriate legislation. An application model has been constructed to illustrate the use of the flow chart. The model incorporates environmental issues typical of an oil and gas facility used to store and maintain equipment. This information should be sufficient for the uninitiated to be convinced of the need for conducting an audit and made aware of its associated costs.
Minerals Management Service Regulation of Floating Drilling Unit Operations in the Beaufort and Chukchi Outer Continental Shelf
Authors: Regg J. B. , Kuranel R. Y.
Published: December 2007

This paper describes the environmental conditions, exploratory drilling experiences, types of monitoring programs and defense systems, and Minerals Management Service (MMS) regulations for floating drilling systems operating in the Arctic Outer Continental Shelf (OCS) of the Beaufort and Chukchi Seas. The MMS's regulatory requirements for drilling unit and wellbore safety, how the industry has addressed these requirements, and specific information and performance requirements to obtain approval to operate during periods when sea ice and severe weather conditions could be present are emphasized. The effectiveness of contingency plans, including shutdown criteria, and ice monitoring and management programs proposed by operators and previous experience for floating drilling units used in the Beaufort and Chukchi Seas are also discussed.
Rapid and Reliable Gas Influx Detection
Authors: Codazzi Daniel , Till P. K. , Starkey A. A. , Lenamond C. P. , Monaghan B. J.
Published: December 2007

A new and reliable method for early gas influx detection is described. It is based on the increase in sonic propagation time which is observed when gas is present in the annulus. Unlike detection methods based on differential flow or pit gains, the instrumentation required for this technique is simple, reliable and cost effective. Pressure transducers which are mounted on the standpipe and on the annulus a few feet below the flowline monitor the sonic pressure waves generated by the mud pumps. The output from the pressure transducers is used to measure the rate of change of sonic propagation time around the circulating system. This quantity is strongly influenced by the presence of gas. In addition to the theory behind the technique, the paper describes controlled tests and field examples from around the world.
Evaluating Horizontal Well Potential in the Spraberry Trend
Authors: Barba R. E. , Cutia A. S.
Published: December 2007

Eight attempts have been made to drill and complete horizontal wells in the Spraberry trend of West Texas. The results have been disappointing to date. The production history of each attempt will be discussed, along with an economic analysis. By using the drainhole production and results from vertical well completions, a model for predicting the performance of these wells will be proposed. The key input to the model is a modified Coates-Denoo relationship between porosity and permeability that utilizes openhole wireline inputs. The model predictions will then be compared to actual performance and used to help predict the optimum completion strategy for wells in the Spraberry trend.
Jennifer Queen Unit Waterflood – A Textbook Example
Authors: Vanorsdale C. R. , Hickman T. S.
Published: December 2007

The Jennifer (Queen) Unit produces from a northeast extension of the Concho Bluff, North Field of Ector County, Texas within a Queen producing trend containing four separate reservoirs. The three adjacent reservoirs have been successful waterflood projects due to very favorable rock and fluid properties. The Jennifer (Queen) Unit reservoir was an obvious candidate for waterflooding shortly after discovery in 1984 as its areal extent became apparent. Extensive data gathering enabled reservoir modeling to assess the efficiency of a waterflood project. When installed, the project raised production from 120 BOPD to 2500 BOPD in 5 months. Intense waterflood surveillance has identified operational problems at an early stage and provided data for an updated reservoir model. The enhanced simulation will help manage the flood for optimum recovery.
Seismic Imaging of Porosity and Hydrocarbon in Consolidated Formations
Authors: Neidell N.S. , Landwer W.R. , Smith Maggie
Published: December 2007

SPE Members

Consolidated reservoir formations are defined here as those formations of significant thickness having acoustic impedance (density-velocity product) which is consistently greater than or equal to that of similarly aged, normally pressured shales. For such formations, porosity and hydrocarbon presence can be effectively imaged via seismic velocity changes over a presence can be effectively imaged via seismic velocity changes over a substantial range of depths (to 16,000-plus feet). Here we shall note consolidated sand and carbonate reservoirs from East Texas, the North Sea and Oklahoma. Plays of current interest encompassing such reservoirs would included the Austin Chalk, Alaskan formations, Niobrara and Frio-Vicksburg, as well as others. Starting with a brief summary of requirements for definitive seismic imaging of consolidated reservoirs we move on to the technology for interpreting, calibrating, and using such displays. The effectiveness of spatially dense seismic-velocity measurements and color inversion sections scaled in velocity is clearly demonstrated by the variety of successful examples reviewed. These approaches and the positive results obtained suggest that, in the future, seismic techniques will be even more definitive in addressing consolidated reservoirs for both exploration and production applications.

Introduction

Our approach to hydrocarbon exploration and reservoir definition rests principally on sound basic geology and refined seismic methods. There are principally on sound basic geology and refined seismic methods. There are two themes which are applied in parallel to the seismic data. Significantly improved and definitive seismic imaging constitutes one of these directions. Use of a unified framework, an organized sequence of high technology procedures, to identify and qualify key anomalies and subsurface characteristics is the second theme.

Enhanced Seismic Imaging and Display

It was recognized more than 10 years ago that as much as 80% of the stratigraphic information contained in seismic data presented in conventional black and white displays was lost due to inappropriate processing and limitations in visual dynamic range (see references). processing and limitations in visual dynamic range (see references). P. 269
North Riley: Integrated Evaluation of a Heterogeneous Reservoir
Authors: Howell E. P. , Gutberlet S. S. , Glossa J. M.
Published: December 2007

An integrated study of the North Riley Unit has been made in order to quantify engineering parameters needed to justify improvements in a secondary recovery system. Data available included well logs from more than 200 wells, approximately one third with open-hole logs; cores along with special core analysis, depositional facies descriptions, diagenesis evaluation, and standard core measurements; as well as production history and wellbore completions. These data were used to calibrate well logs, first to predict geologic parameters, and then to calculate physical properties for individual reservoir facies. Separate porosity equations were developed for each facies. These were followed by saturation and permeability assessments which were calibrated with field-wide data.

Well logs were used to extrapolate the core and production data to the entire field with resulting geological and engineering parameters mapped on a zone-by-zone basis. Results included oil in place, Rw (which varies systematically across the field), water cut, permeability and an estimate of producibility. Using these maps and summary tables, engineering efforts are now underway to increase sweep efficiency and productivity in a cost effective manner. Specifically, recovery from this very heterogeneous reservoir can be improved by increasing well-to-well continuity with additional wells and by greater selectivity in choosing production or injection intervals within each well.