bluuebunny/crossref_metadata_2025 huggingface dataset:
Results from Using the CSAMT Geophysical Technique to Map Oil Recovery Processes
Authors: Bartel L. C. , Wayland J. R.
Published: December 2007

Use of electromagnetic geophysical prospecting techniques to map EOR processes depends upon electrical resistivity changes of the affected region. Sandia is evaluating the use of the controlled source audio-frequency magnetotelluric (CSAMT) electromagnetic geophysical prospecting technique to map steamflood and fireflood EOR processes. Results are presented of the CSAMT technique mapping of a steamflood, tar sand oil recovery experiment (depth, 500 ft) and of the mapping of a fireflood heavy oil recovery experiment (depth, 360 ft). In both experiments, contours of constant apparent resistivity for measurements taken several months apart show the movement and asymmetry of both processes. The CSAMT shows promise as a technique to map EOR processes.
Drilling with New-Generation Positive Displacement Motors
Authors: Herbert Pat
Published: December 2007

Successful penetxation of harder formations at greater drilling depths will play an important role in the continued exploration program of our nation to meet energy needs of the future. As drilling costs continue to rise, more efficient drilling methods must be developed and implemented if economies are to be realized.

Recent advancements in drilling technology, coupled with significant engineering improvements, have spawned a new generation of positive displacement downhole mud motors designed for long interval straight hole drilling with natural or man-made diamond bits or with conventional three-cone rock bits. Field results of the past 24 months have demonstrated that these motors are now cost-competitive with rotary drilling methods. The advantages of increased penetration, deviation control and reduced casing wear contribute to a lower cost per foot of hole drilled compared to rotary techniques.

To be successful, these new-generation motors must be used effectively and efficiently so that maximum tool life can be realized.
Geopressure-Geothermal Testing of Five "Dry Holes" During 1980 and 1981
Authors: Klauzinski Richard Z.
Published: December 2007

This paper summarizes the testing of five hot, geo-pressured aquifers in different geologic environments in Texas and Louisiana by Eaton Operating Company for the U.S. Department of Energy.

The results were encouraging. Natural gas-to-brine content ranged from 33.0 to 55.0 SCF/bbl. Gas production rates ranged from 93 to 600 MCFD. Sustained water production rates ranged from 1,950 to 15,000 BWPD. Bottom-hole temperatures ranged from 260 to 327°F. Reservoir pressures ranged from 6,627 psia to 13,203 psia. A test near Beaumont resulted in discovery of oil and gas.
The Possible Impact of the Geopressure Resource on Conventional Oil and Gas Exploration
Authors: Quitzau Robert , Bassiouni Zaki
Published: December 2007

Gulf Coast Geopressured aquifers are thought to contain large amounts of dissolved gas. Although the total amount of geopressured water may be considerable, this resource is still considered marginal because of the low solubility of gas in water.

A calculation technique was developed to evaluate the economic potential of a geopressured aquifer for numerous conditions that could allow the exploitation of this unconventional gas resource. This technique allows for the consideration of both wells drilled with the sole intent of producing the geopressured resource and unsuccessful conventional hydrocarbon wells completed in geopressured intervals. The calculation technique allows also for the consideration of different water disposal methods and different taxation schemes.

The net present value of a prospect is used as the parameter to measure economic potential. Net present, value is calculated as a function of gas price. Monte Carlo simulation is used to account for the uncertainty of the many parameters necessary to calculate net present value.

The calculation technique was applied to a typical Gulf Coast geopressured aquifer. From this application it is apparent that for certain likely conditions the conversion of an unsuccessful conventional hydrocarbon well into a geopressured brine well is economically feasible provided that any associated environmental and legal problems are overcome.
Development and Application of a Streamline Micellar/Polymer Simulator
Authors: Wang Ben , Lake Larry W. , Pope Gary A.
Published: December 2007

A large-scale, two-dimensional, muticomponent, multiphase, compositional simulator for micellar/polymer flooding has been developed and applied. It can be used to calculate the areal sweep with any well pattern and any irregular reservoir boundary. This model involves both streamline and finite-difference techniques. Time invarient streamlines without transverse dispersion are assumed. The change in the flow rates into each streamline is accounted for as a function of mobility ratio.

Computation results show that a line drive pattern produces a greater tertiary oil recovery than a 5-spot under the same pressure drop. However, the injection time of the line drive is two-to-three times larger. On the other hand, the oil recoveries of a 5-spot and a 9-spot are very close, but the 9-spot requires a longer project life. The fractional oil recovery for a 5-spot is found to decrease as a function of increasing well spacing. It is also observed that the orientation of an anisotropic reservoir with a 5-spot pattern plays a very important role in the micellar/polymer process. The injection time for a 5-spot may be reduced by a factor of one-half to one-third if the polymer solution is shear thinning. The proper control of the production rate of a single or isolated 5-spot pattern can greatly increase tertiary oil recovery.

In order to demonstrate that this model is capable of handling much larger field problems, a large-scale simulation of the north lease of the El Dorado micellar/polymer pilot test was made. The simulated final oil recovery and the production histories of each producer are illustrated.
Effect of Formation Compaction on Steam Injection Response
Authors: Rattia Aquiles J. , Ali S. M. Farouq
Published: December 2007

Formation compaction, if present, can have an important influence on thermal recovery methods, as observed in Western Venezuela, and elsewhere. This paper discusses the effect of formation compaction on oil production by cyclic steam stimulation and steamflooding, using a fully implicit steam injection simulator. The simulator accounts for three-phase mass and heat transport occurring in steam injection processes, for a wide variety of operating conditions. It employs an implicit formulation together with a Newtonian, direct solution approach, and was shown to be stable for large time steps.

It was found that oil recovery in a compacting reservoir increases with an increase in the uniaxial compaction coefficient. However, whereas cyclic steam stimulation yielded a favorable response in a compacting reservoir, the opposite was true for a continuous steamflood. A delay in implementing a steamflood in a non-compacting reservoir can lead to a considerable loss of recovery, in the range of 10 to 40% of oil-in-place, depending on the value of the uniaxial compaction coefficient. This finding has far-reaching implications for steamflooding subsequent to intensive depletion by cyclic steaming, or primary production.

Although formation compaction can be beneficial from the standpoint of cyclic steam stimulation response, there is strong dependence on the compaction coefficient. Furthermore, it was found that if the oil in question exhibits non-Newtonian flow behavior – reported for some Venezuelan oils – it must be accounted for in numerical simulations, otherwise the oil production rates may be in error by as much as 100%.
The Economics of the Offshore Contract Drilling Industry: Implications for the Operator
Authors: Rankin Mark David
Published: December 2007

This paper represents a general assessment of the primary factors driving the market for mobile offshore drilling rigs and the utility of those factors as choice variables for the offshore drilling program planner.
Recent Experience with Wireline Fracture Detection Logs
Authors: Hirsch J. M. , Cisar M. T. , Glass S. W. , Romanowski D. A.
Published: December 2007

In the last year Shell has extensively cored the fractured Mlssissippian Madison Limestone formation in the Mondak field. The field extends from Richland County, Montana to McKenzie County, North Dakota. In three wells we have recovered over 1500 feet of core which have been analyzed for in situ natural open fractures. In an effort to delineate these fractures using wireline logs, we have run the commercially available logging tools as well as the prototype devices designed to respond to open fractures.

In some or all of the three cored wells (depending on availability), we have analyzed the Schlumberger Circumferential Microsonic Tool, the USGS Borehole Acoustic Televiewer, and the Schlumberger Fracture Identification Log.

The open natural fractures described in the core are predominately vertical, with a length ranging from several inches to several feet, and a width typically less than a fraction of a millimeter, with occasional fractures 2 millimeters wide. The matrix rock is limestone with porosity of order 3% or less and unstressed, uncorrected air permeabilities less than 0.1 millidarcies. Wells in the field produce from 10 to 250 BOPD from this tight rock. It appears that the fractures are important for production.

The paper discusses the mechanism of fracture detection and interpretation for each of the logging tools and compares their response to the core described fractures.

We conclude that the currently available fracture detection tools do not adequately identify the fractures observed in the Mondak cores.
Diver Training
Authors: Sharp Duncan
Published: December 2007

1) When we examine the statistics concerning diving fatalities in the offshore industry in the UK between 1971 and 1975, we find the following:

1971…………1

1972…………1

1973…………2

1974…………5

1975…………6

It was in 1975 that the Government stepped in, and through the Manpower Services Commission established a syllabus to which Air and Mixed Gas divers had to be trained.
Strategy for Environmental Studies in North Sea Oil Development
Authors: Johnston C. S. , Appelbee Jane F.
Published: December 2007

At frequent environmental meetings the importance of close communication between careful planning of environmental strategy associated with any new industrial development has been stressed (Appelbee & Johnston, 1978). Particularly crucial is the inclusion of all key environmental criteria at the initial planning/design phases, involving a close interaction between design engineers and environmental staff. It is equally important that this communication develops into a real understanding, a sympathy, which is maintained throughout the development. Not only will this minimise (and often totally remove) any barriers and conflicts associated with environmental matters, features so common in many US developments, it will lead to improved design and operation of plant.
Mechanism Of Drilling Wells With Air As The Drilling Fluid
Authors: Singh Madan M. , Goodwin Robert J.
Published: December 2007

A microbit apparatus has been used to study how and why field drilling rates are usually higher when air is circulated rather than liquids. Our laboratory results with air are compared with the work of others who have circulated liquids to remove cuttings, and a theory for air drilling has been developed. Chief results of this program are that most of the parameters operative in liquid drilling are also operative in air drilling, but in air drilling many of these factors are much less detrimental to the drilling rate.

Our major conclusions are that drilling rates with air are much greater than with liquids because chip removal is facilitated by:low bottom-hole pressure exerted by the column of air,low viscosity of air which permits it to enter cracks more readily,less restriction to widening crack by highly compressible air, andlow cohesive forces between rock particles in environment of air.

Furthermore, there is far less plugging of widening cracks around chips because of the absence of solids from the drilling fluid and the better hole cleaning afforded by the high-velocity air stream. The greatest reason for high drilling rates with air is that the air is greatly cooled by expansion as it passes through the bit and thereby cools the bottom of the hole to reduce the stresses exerted on the rock by the overburden. Overburden pressure, liquid saturation of the rock and rock ductility have a more adverse effect on gas drilling than drilling with liquids. The effect of overburden pressure is greatest on dry rocks.
Corrosion of Buried Pipeline Under Effect of Electrical Field With Industrial Frequency
Authors: Kohua Yin , Minhua Tang , Chiangjian Hsiong
Published: December 2007

There may be induced AC voltage on the buried pipeline of oil and gas by power line and electrified railway, resulting in "AC corrosion". Although the reseach on AC corrosion has lasted for 74 years, many important problems about this subject are, heretofore, not clear.

In this paper, a new way viz. to investigate the AC corrosion on the basis of the theory of electric field in combination with that of the electrochemistry was proposed. New concept is hereby introduced; that is the electric-field corrossion.

Under the effect of the field which varies swiftly and holds powerful intensity, the reactive process of internal electrochemistry changes essentially, and the intensity of electric field is an important physical quantity. Making measurement and analysis of the interfered voltage, the gradient of potential, the point density of current, the weight-loss and depth of corrosion, we discovered that the weight-loss increases according to average density of current, and the depth of cavity becomes deeper according to the interfered voltage. Based on the results of experiment, prematurely safety limits of voltage of AC corrosion are proposed.
The Use of Laboratory Tests to Evaluate Scaling Problems During Water Injection
Authors: Read Peter Arne , Ringen Jon Knut
Published: December 2007

Seawater and a North Sea formation water has been mixed in glass and in porous media. Core tests showed severe permeability loss due to scaling.

The extent depended on the mixing ratio and the amount injected.

Scanning electron microscopy and X-ray diffraction were used to identify and compare mineralogy of scales formed in cores.
Laboratory Tests of Polymer Fluids at Geothermal Temperatures
Authors: Tyssee Donald A. , Caenn R. , Vetter O. J.
Published: December 2007

This paper describes work done to characterize by chemical methods the temperature/time degradation behavior of polymer based fluids that may be used in stimulating geothermal wells by fracturing. The polymers tested were hydroxypropylguar (HP guar), hydroxyethylcellulose (HEC), carboxymethylcellulose (CMC), and XC Polymer. Also, two commercially available cross-linked HP guar systems were tested.

The paper covers the development of analytical techniques for characterizing the polymers and the results of static and dynamic high temperature aging of the polymers in various salt water environments. The fluids were tested at 150, 200 and 250°C. The paper covers the implications of these results based on the time/temperature degradation of the polymers and the relative ease of removing the degraded polymer from sandpacks.
New Concept — High Density Brine Filtration Utilizing a Diatomaceous Earth Filtration System
Authors: Barron William Cook , Young John A. , Munson Richard E.
Published: December 2007

For several years the chemical industry has used diatomaceous earth systems as a standard in effluent dewatering. Recognizing the similarities in clarity requirements between effluent dewatering and brine completion-fluid filtering, a new diatomaceous earth filtration system has been designed, tested, and is successfully being used in Gulf Coast operations.* The system consistently shows a one-pass solids removal efficiency of greater than 98%, at varying flow rates. Resulting solid concentrations average 74 parts per million (ppm, 0.007% by volume) and have been recorded as low as 10 ppm. This is a 40% improvement in removal efficiency and a filtrate that is 17 times cleaner, after one pass filtration, than the average of several existing cartridge units.

The efficiency of filtering high density brines is dependent upon several factors including the effectiveness of the filtration system, the physical characteristics of the brine and suspended solids, and operator experience.

Filtration removal efficiency and Industry standards for brine cleanliness can be modified to become more realistic and field-oriented. In future filter unit evaluations or comparisons, an absolute term of removal efficiency, which is defined by multivariable correlations through time, should be utilized. And rather than a maximum particle size standard, the Industry standards for brine cleanliness should be field-oriented and can be based on a concept of clarity and degree of contamination.
The Analysis of the Dynamic Filtration and Permeability Impairment Characteristics of Inhibited Water Based Muds
Authors: Peden James M. , Avalos Margarita R. , Arthur Kevin G.
Published: December 2007

The impairment of permeability in the near well bore region is dependent upon fluid loss to the formation. The dynamic filtration properties of KCl-Polymer and Gypsum-lignosulphonate muds have been individually investigated and the role of individual components has been analysed. The associated permeability impairment due to particle invasion and the response of cores to backflushing has also been investigated. The scanning electron microscope has been employed to qualitatively identify particulate plugging.
Factors Affecting Gelling Agent Residue Under Low Temperature Conditions
Authors: Almond Stephen W.
Published: December 2007

The relative reduction in both formation permeability and fracture flow capacity caused by the residue remaining after water based fracturing fluids are broken is often very important in the final selection of a fracturing fluid. Therefore, it is important to understand some of the factors which can affect the amount of residue produced from the gelling agents and the changes in relative flow which may result.

One of the most important factors in determining the amount of residue produced is the type of gelling agent used as a viscosifier. In general, the following order is commonly used as a guideline to determine the relative residue content of a number of gelling agents: guar gum > derivatized guar gum > derivatized cellulose.

Test results have shown that this relative order can be changed by varying the break time, breaker concentration, crosslinker and pH of the fluid system. For example, data has shown that a cellulose fluid can potentially cause more reduction to both fracture flow capacity and formation permeability than commonly used derivatized guar gelling agents.

The information which will be presented in this paper will contain results of an investigation into the effect of breaker concentration, breaker type, break time, crosslinker and pH of a fluid system on the relative flow reduction caused by a variety of water based fracturing systems. Fluids prepared with standard guar and cellulose gelling agents broken at low temperatures in a variety of porous media have been investigated. The importance of evaluating an entire fracturing fluid system and not just the specific gelling agent to determine which fluid should provide the optimum production increase from a hydraulic fracturing treatment will also be presented.
Carbonate Acidizing: A Thermodynamic Analysis
Authors: Hayatdavoudi A. , Chiu C. B. , Kalra S. K. , LeBlanc J. L. , Schluntz E. K.
Published: December 2007

The authors have noted a common problem in deep well acidizing. The problem is that, as the wells become deeper, the quantity of unspent hydrochloric acid increases. This fact in some cases renders the well stimulation useless. In this paper we look at the pressure and temperature effects on the quantity of unspent acid in low permeability - high pressure wells. In the past, only the temperature effect has been critically studied and the effect of pressure has been neglected. By adding the pressure terms of the ideal gas law to the Gibbs free energy equation, the effect of pressure can be seen easily, though it may not be too great.
Weeks Island "S" Sand Reservoir B Gravity Stable Miscible CO2 Displacement, Iberia Parish, Louisiana
Authors: Perry G. E.
Published: December 2007

Shell, in conjunction with the United States of America Department of Energy, is conducting a gravity stable displacement field test of the miscible CO2 process. The test is being conducted in the portion of a fault sealed reservoir lying below a subsea depth of -12,750 feet. Injection of the CO2 slug at the producing gas-oil contact commenced in October 1978. Injection of the 860 MM cubic foot slug was completed in February of 1980. The slug of CO2 was moved downward through the watered out sand by production of downdip water. The leading edge of the displacement has reached the producing perforations and production of the oil column commenced on January 26, 1981.

Conventional cores and the log-inject-log technique were used to determine residual oil saturation in a well drilled as the pilot producer. Pulsed neutron logging devices have been used to detect the CO2 slug and monitor its subsequent movements in the vicinity of the production well. The monitor logs indicate the thickness of the oil column had increased during the displacement to the production perforations located 130 feet below the level of CO2 injection. The 23 foot oil column remaining at initiation of the project had apparently grown to 57 feet.

PVT samples and production data indicate CO2 has penetrated the oil column and free gas is being produced with the oil. However, the qualitative measurements of the logs do not indicate a large gas or CO2 content in the oil column.
Design and Implementation of Four Enhanced Recovery Projects in Bay Fields of South Louisiana
Authors: Boardman Roger S. , Moore Larry J. , Julian Michael H. , Bilbrey Don G. , Moore J. Stephen
Published: December 2007

This paper reviews the design and implementation of four enhanced recovery projects that were initiated in the shallow-water environment of two bay fields located along the coastline of South Louisiana. These four projects are a caustic augmented waterflood, a miscible carbon dioxide waterflood, both in Quarantine Bay Field, and two polymer augmented waterfloods in the West Bay Field. The paper focuses on the design modifications required for the projects due to the hostile overwater environment and the logistics problems associated with the locations of the projects.
Enhanced Oil Recovery in Rumania
Authors: Carcoana Aurel N.
Published: December 2007

The wide oil field experience of the Romanian oil men in producing hydrocarbon reservoirs is based on an old tradition, but only after 1945 reservoir engineering studies were started in Romania.

Beginning with 1950 conventional recovery methods expanded continual.

During the last 10 years, however, the crude oil, as energy resource, has become of tremendous importance. The need for increasing the ultimate oil recovery has been felt in Romania as everywhere else. To attain this goal EOR methods were and are tested and expanded on a commercial scale.

The paper describes the application of the fire-floods to a broad range of Romanian oil reservoirs and crude properties and reviews the field tests of polymer flooding, surfactant flooding and alkaline flooding. A commercial scale project with cyclic steam injection is presented and also the use of the domestic CO2 sources to enhance oil recovery.

The results and the difficulties encountered are briefly discussed and also the potential of EOR methods in Romania are presented.
A Comparative Evaluation of Surface and Downhole Steam Generation Techniques
Authors: Hart Carolyne M.
Published: December 2007

It has long been recognized that the application of heat to reservoirs containing high API gravity oils can substantially improve recovery. Although steam injection is currently the principal thermal recovery method, heat transmission losses associated with delivery of the steam from the surface generators to the oil-bearing formation has limited conventional steam injection to shallow reservoirs.

The objective of the Department of Energy's Project DEEP STEAM is to develop the technology required to economically produce heavy oil from deep reservoirs. The tasks included in this effort are the development and evaluation of thermally efficient delivery systems and downhole steam generation systems. This paper compares the technical and economic performance of conventional surface steam drives, which are strongly influenced by heat losses, with (a) thermally efficient delivery (through insulated strings) of surface generated steam, (b) low pressure combustion downhole steam generation, (c) high pressure combustion downhole steam generation using air as the oxygen source, and (d) high pressure combustion downhole steam generation substituting pure oxygen for air.

The selection of a preferred technology based upon either total efficiency or cost is found to be strongly influenced by reservoir depth, steam mass flow rate, and sandface steam equality. Therefore, a parametric analysis has been performed which examines varying depths, injection rates and steam qualities. Results indicate that the technologies are not readily distinguishable for low injectivity reservoirs in which conventional steam drives are feasible. However, high injection rates produce a notable cost difference between high pressure combustion systems and the other technologies. Issues that must be addressed before gaining further insight into the economic viability of downhole steam generation are discussed.
Analysis of the Early Performance of the M-6 Steam-Drive Project, Venezuela
Authors: Schenk L.
Published: December 2007

Since January 1978 Maraven is conducting the M-6 Steam Drive Project in Tia Juana, one of the Bolivar Coast Heavy Oil Reservoirs near Lake Maracaibo. The project is carried out on a semi-open seven- spot well configuration, using the existing 231-m grid and comprises at present 21 injectors and 130 producers. The project area is 7, 4 Km2, depth 1800 ft ss, and originally contained 525 million bbl of 13 degr. API Crude. The recovery by primary depletion, enhanced by steam soak, was 22 pct. STOIIP at the start of steam drive.

Steam is supplied by a plant with a nominal capacity of 10,000 t/d of saturated, dry steam at 1000 psig. Lake Maracaibo water softened by ion-exchange is used as feed water and natural gas as fuel.

Following a build-up period of 6 months the steam injection rate has ranged between 6000 and 8500 t/d, averaging 7400 t/d up to end 1981, at well head pressures of around 500 psig. The oil production increased from a pre—project level of 8000 b/d to 18,000-23,000 b/d since early 1980, accompanied by an increase in water production from 4000 up to 40,000 b/d. Cumulative performance data for the period Jan. 1978-Dec. 1981 are: steam injected 10.2 million tons, oil produced 23.7 million bbl, extra oil produced 15.9 million bbl and water produced 33.0 million bbl. Corresponding main project parameters are: cumulative oil production 4.5% STOIIP, of which 3% STOIIP is extra, oil/steam ratio 2.3 bbl/ton, extra-oil/steam ratio 1.6 bbl/ton.

Although these figures show that the overall performance has been very satisfactory so far, individual well performances indicate an irregular flow distribution, both areally and vertically, duo to the heterogeneous nature of the reservoir. Corrective measures taken so far are selective recompletion of producers where steam breaks through and adjustments to the well pattern. Results from this policy have been favorable during the second half of 1981, the oil production rate reaching a high of 23,000 b/d in December.

Selective recompletion of the injectors on the lower sands which do not take steam at present is under consideration.

It is expected that by continuous adjustment of the project policy to the performance as it develops under the given conditions, it will be possible to recovery 20% STOIIP of extra oil at an oil/steam ratio of 2 bbl/ton. In later stages when additional information has become available the merits of increasing the recovery by injecting more steam and/or interspacing will be investigated.
Mobilization and Banking of Residual Oil in High Salinity Reservoir Systems with the Use of Aqueous Surfactant Solutions of Ethoxylated Carboxymethylates
Authors: Kraft Harald R. , Pusch Guenter
Published: December 2007

Highly saline reservoir brine and crude oil with ethoxylated carboxymethylates and cosolvents show a complicated phase behavior. Easily obtainable and well defined indicators are therefore required to characterize phase conditions, which prevail in displacement processes.

The phase inversion temperature (PIT) has been investigated with respect to its ability to discern phase transformation in oil-brine- surfactant systems.

PIT proved to be very sensitive to changes in salinity, ionic strength, water-oil ratio and surfactant concentration, which simultaneously are responsible for phase inversion of chemical systems in the porous medium.

Core flood tests using an ethoxylated carboxymethylate as surfactant have shown that a rapid formation and production of a continuous oil phase in form of an oil bank can be achieved by a composition of the system in the boundary region of phase type III and II+ according to the terminology of NELSON and POPE.

However these flood conditions may cause increased pressure gradients during the flood at the trailing end of the oil bank.

Viscosity measurements on the emulsion in a low shear viscosimeter demonstrated that the increase of viscosity of a water-in-oil emulsion can be attributed to the increase of the WOR.

In displacement processes this may be provoked by viscous fingering of the mobility buffer into the mobilized oil bank.

The length and profile of the oil bank is controlled by phase conditions and viscous forces in the transition zone of the mobility buffer.

By addition of a suitable alcohol as a cosolvent to the surfactant slug or to the mobility buffer the temperature range of the stable displacement process could be extended without loss of recovery efficiency and the pressure gradients observed during the flood were in the normal range.
Comparison of Vertical, Slanted, and Horizontal Wells Productivity in Layered Gas-Condensate Reservoirs
Authors: Jamiolahmady M. , Ghahri P. , Victor O. E. , Danesh A.
Published: December 2007

The performance of a horizontal (highly slanted) well (HW) or a slanted well (SW), is generally believed to be better than that of a vertical well (VW) due to its greater exposure to the reservoir. However, the costs of drilling and completion are more and the options for monitoring, control and intervention often limited. Gas-condensate reservoirs are increasingly considered as suitable candidates for drilling SWs or HWs. These reservoirs pose special challenges selecting one type or the other due to the complex nature of fluid flow in porous media exhibited by these low interfacial tension systems, which are different from those of conventional gas-oil systems.

In this study we have investigated the performances of SW, HW and VW in both single-layer homogenous and layered gas-condensate reservoirs. ECLIPSE 300 compositional reservoir simulator, which includes our inhouse relative permeability (kr) correlation accounting for the coupling (increase in kr by an increase in velocity and interfacial tension) and inertial (decrease in kr by an increase in velocity) effects, has been used to conduct a series of sensitivity analysis on a single-well model resulting in some important practical guidelines. The effect of fluid properties and that of reservoir anisotropy (vertical to horizontal permeability ratio, kv/kh) have also been studied.

For homogenous systems, HW and SW have higher productivities. The improvement due to increase in lateral reach is less pronounced at lower kv/kh values especially for SW. In the case of layered reservoirs, the productivity of SW is adversely affected by the extended cross flow from low permeability to high permeability layers. In this case the impact of position of layers and that of kv/kh is more pronounced for SW and both at lower kv/kh. The decrease in velocity around the wellbore of HW decreases the impact of kr velocity dependency on production.
North Burbank Unit 1,440-Acre Polymer Flood Project Design
Authors: Trantham Joseph C. , Moffitt Paul D.
Published: December 2007

Substantial areas of the North Burbank Unit, Osage County, Oklahoma, gave poorer than average response to waterflooding. After studies showed that the performance of these areas could be traced to greater than field average heterogeneity, a pilot polymerflood was conducted during the period from 1970-1979. Good response to polymerflooding, followed by economic evaluation of proposed expanded operations, led to the design and implementation of a 1440 acre commercial scale project.

The project involved injection of fresh water preflush during the period from September, 1980 to late April, 1981. Then a liquid emulsion type polyacrylamide was blended to 500 ppm in fresh water and injected at a total rate of 63,000 BPD until approximately 4.4 percent of the pore volume had been injected. This was followed by a water spacer, and a 0.8 percent (PV) slug of aluminum citrate containing 500 ppm of aluminum was injected as a cross-linking agent into those two-thirds of the injectors which were expected to present no injectivity problems. Following injection of a second water spacer, 500 ppm polymer injection was resumed.

Plans call for injection of polymer at 500 ppm until the total amount reaches 15 percent of pore volume. This will be followed by polymer slugs of 250 ppm (10 percent of pore volume) and 50 ppm (15 percent of pore volume), fresh water (20 percent of pore volume), and finally drive (produced) water. Any localized channeling problems will be handled by treating individual injection wells with crosslinking agents such as aluminum citrate.

Methods of scaling up pilot results to the 1440- acre commercial project, site selection, design of the fresh water preflush, estimation of aluminum citrate requirements, and project costs are discussed.
Investigation of High-Temperature Fluid Loss Control Agents in Geothermal Drilling Fluids
Authors: Carney Leroy L. , Guven Necip , McGrew George T.
Published: December 2007

This paper is a report on research work recently accomplished on examination of various polymers for the purpose of controlling the fluid loss in drilling fluids when subjected to temperatures of up to 371°C (700°F). Investigations have shown that attapulgite and sepiolite will transform to smectite under downhole conditions of temperature and pressure.

While this improves the rheology and fluid loss, to some degree, of a system containing attapulgite or sepiolite when subjected to high temperature, there is a need to further lower the fluid loss.

A series of polymers, copolymers and terpolymers have been evaluated for further control of both rheology and fluid loss.

These systems prove to be superior to conventional water base systems used in oil and gas drilling.

The clay constituents of the fluids have been examined with both x-ray diffraction and electron microscopy. The newly formed smectite has been dehydrated and rehydrated to make up a system for high temperature drilling.

Improvements are noted in the process of dehydrating and rehydrating the newly formed smectite for obtaining viscosity for temperature stable fluids.

The newly formed smectites coupled with high temperature stable polymers have resulted in the formation of a temperature stable drilling fluid for use in geothermal drilling.
The Laboratory Development and Field Testing of Steam/Noncondensible Gas Foams for Mobility Control in Heavy Oil Recovery
Authors: Dilgren Richard E. , Deemer Arthur R. , Owens Kenneth B.
Published: December 2007

Steam foam formulations were developed to reduce steam mobility in the steam drive process. Several commercially available alkylbenzene sodium sulfonates and alpha olefin sodium sulfonates appear promising. Other foam components were nitrogen and sodium chloride. Ottawa sand packs were the primary screening tool used in the laboratory. Reduced steam foam mobility in the field was evidenced by significantly increased flowing bottom-hole pressures for the injectors. An increased rate of oil production was also observed.
The Thermodynamics of Evaporation and Condensation in Porous Media
Authors: Udell Kent S.
Published: December 2007

The thermodynamics of a single component, vapor-liquid system subjected to capillary pressures characteristic of porous rock have been examined. Van der Waal's equation was coupled with the Gibbs-Duhem differential expression for the chemical potential and integrated. The resulting expression for chemical potential as a function of pressure, temperature and specific volume provided the key to the understanding of the thermodynamic equilibrium between the wetting liquid and its vapor across the capillary pressure discontinuity.

Through this analysis it was found that when capillary pressures are present, thermodynamic equilibrium can only exist if both liquid and vapor phases are in a superheated state. This result is consistant with Kelvin's equation for vapor lowering. Furthermore, the superheated liquid phase, which is in a metastable state if no vapor or capillary pressures are present, is in an unconditionally stable state if capillary pressures are imposed. The degree of liquid superheat was found to be a function of contact angle, interfacial tension, effective pore radius and heat of vaporization.

Using water as an example, quantitative values of liquid and vapor pressure lowering are presented for various pressures and pore radii. It was found that for porous media of pore size distribution similar to that of reservoir rock, the vapor thermodynamic equilibrium pressures and temperatures do not differ significantly from the steam table values. Significant liquid pressure lowering does result. Also the transition from capillary condensation to thin film adsorption may be identified from the liquid pressure lowering curves. Applications to other systems in thermodynamic equilibrium with a porous media are discussed.
Loudon Surfactant Flood Pilot Test
Authors: Bragg J. R. , Gale W. W. , McElhannon W. A. , Davenport O. W. , Petrichuk M. D. , Ashcraft T. L.
Published: December 2007

A successful surfactant (microemulsion) flood pilot test has been completed by Exxon in a watered-out portion of the Weiler sand, Loudon Field, Fayette County, Illinois. The microemulsion system tested was designed to be effective in the presence of high-salinity formation water containing 104,000 ppm (mg/1) total dissolved solids (TDS) without use of a preflush. The test was conducted in a single, 0.68-acre 5-spot operated to approximate a confined pattern. Approximately 60 percent of the waterflood residual oil present in the pilot pattern was recovered. Extensive data for determining sweep and displacement efficiencies were obtained from observation well logs and fluid tracers. Although problems were encountered with bacterial degradation of biopolymer and with produced oil-water emulsions, the test is considered to be a technical success and confirms the effectiveness of the high-salinity microemulsion formulation. Additional pilot tests are needed to determine the effects on oil recovery of microemulsion bank size and well spacing.
Overview of Regulating Burdens and their Affect on Various Areas of the Industry
Authors: MacDowell Peter
Published: December 2007

The world of regulatory affairs is in its usual state of disarray and flux, with promises of reform echoing from the electorate while compliance procedures are being enforced in the field at an ever increasing level. The difficulty encountered by industry in planning future operations and expenditures in regard to regulatory affairs is a real problem and no facet of the industry is immune from these concerns. An overview of these burdens and their effect on various areas of the industry will be discussed.
Offshore Operations on Great Salt Lake
Authors: Woodhall Robert J.
Published: December 2007

Amoco recently drilled 15 exploration wells and ran production tests from floating barges on the Great Salt Lake, Utah. To compensate for the lack of critical lake data and the lack of conventional offshore equipment, Amoco embarked on a comprehensive engineering effort to plan for drilling operations.

Engineering studies included: wind and wave measurement; sub-bottom technical data evaluation; design of a drilling barge with the associated anchoring system; and later, performance monitoring and redesign to meet a second drilling phase.

The unique environment and remote location presented some very interesting engineering challenges which require innovative solutions. This paper discusses the overall planning effort, as well as documenting solutions and results for this frontier offshore operation.

Information from this operation has reference value to operations in similar remote frontier areas.
Foam Fracturing in the Uinta Basin — A Field Study of the Dakota and Wasatch Formations
Authors: Goelitz R. , Evertz G. E.
Published: December 2007

The Dakota and Wasatch formations of the Uinta Basin in northeastern Utah and northwestern Colorado have been historically difficult to clean up following a fracturing treatment. Recovery of normal water-based fluids has been averaging 20 to 30%, with much rig time spent in swabbing before the wells were put on production. Because of low recovery and the potential for clay problems, a number of techniques and fluids were tried without any significant improvement. Since these formations were very low in permeability, .05 to .2 md, deeper penetration through fracturing remained a high priority for treatment success. To achieve this penetration, relatively large volumes of treating fluids were needed. Foam fracturing was then instituted as a means of controlling the amount of water put into the formation. The first treatments were relatively small and sand concentrations of two pounds per gallon were the maximum that could be achieved. The results were encouraging enough to warrant the continued use of foam as a fracturing fluid. With the advent of equipment to achieve higher concentrations of sand at the formation and better materials to stabilize the fluid itself, foam fracturing matured into a much more viable means of treating both formations.

The immediate advantages of foam are obvious. There is 65 to 75% less water put into the formation that has to be recovered and the possibility of damage due to swelling or migrating clay is reduced. The reduced damage is the result of smaller volumes of water and easier handling, of clay control agents, KCl and/or chemicals. A very important aspect of this technique is a faster and improved cleanup, which can be attributed to less water, more energy and lower hydrostatic head.
Modern Techniques and thorough Evaluation Yield More Consistent Stimulation Results in Frontier Formation
Authors: Hodges J. E. , Paoli B. F.
Published: December 2007

A study was made of stimulation treatments being conducted in the Frontier Formation, southwestern Wyoming. The purpose of the study was to determine why some treatments were successful while others resulted in inadequate production increases.

The initial step was to gather as much data as possible from treatments previously pumped. Although this information helped to pinpoint trends in the field, it was of little value in determining the cause of stimulation failure. In an effort to get more information, rninifracture treatments were pumped on new wells to determine fracture parameters. Bottom-hole pressures were also monitored during all pumping operations. Applying current technology to these data led to a better understanding of how the fracture was propagating. On previous jobs, post-fracture temperature logs consistently indicated "in-zone" treatments, which could not be supported by the interpretation of bottom-hole treating pressures. The assumption that fractures were confined in the pay zone was also disproved by post-fracture, pressure buildup tests. These tests indicated that effective propped fracture lengths were far shorter than calculated fracture lengths. The key to successful stimulation was found to be controlled fracture height throughout the fracture.

Our goal was to build an artificial barrier the length of the fracture using 100-mesh sand. Other techniques applied included lower pump rates, lowering breakdown pressures to avoid unwanted fracture geometry, and gut shooting the pay zone to predetermine the point of fracture initiation. Production results to date show a definite increase in the percentage of successful stimulation treatments.
Design, Application, and Future of Polycrystalline Diamond Compact Cutters in the Rocky Mountains
Authors: Cerkovnik Jerry
Published: December 2007

The Rocky Mountain Region has proven to be one of the greatest challenges to manufacturers of bits utilizing Polycrystalline Diamond Compacts (PDC) as cutting elements. Constant advancements in bit design, and further exploration of possible drilling applications has proven to the industry that PDC bits have a place in Rocky Mountain Drilling. The knowledge of what makes a PDC bit drill is essential for everyone connected with the application of this bit. An understanding of terms such as back rake, side rake, exposure, and profile, is necessary to correctly select the right style of bit.

The type of chip generated by the cutter is dictated by the characteristics of the rock being drilled. We can control this generation of cuttings by orientation of the cutter face. This orientation is controlled by exposure, side rake, back rake, and cutter density. Differing profiles can enhance directional characteristics and improve the cleaning of the bit. Setting up a proper hydraulics program for the bit, thee rig, and the formation is critical in optimizing bit performance.

Running procedures used with PDC bits are similar to those used in diamond drilling, which includes careful setting of a bottom hole pattern, light weights and low RPM's while reaming. Drilling weights and RPM's are determined by optimum rates of penetration, keeping in mind that the shearing action of the PDC cutter requires considerably less weight than conventional bits to fail the rock. With the increasing performance and success rate achieved in just the last year, the future of PDC drill bits is very promising in the Rocky Mountain Region.