bluuebunny/crossref_metadata_2025 huggingface dataset:
Laying a 17.2 km Pipeline Using The Dynamically Positioned Reel Ship "Apache"
Authors: Blacoe D. F. , Hagstrom G. H.
Published: December 2007

During the construction of the Ninian Field, Chevron Petroleum (UK)Ltd. was faced with developing a cost effective method for exporting surplus gas in order to satisfy the Department of Energy's increasing requirement to reduce offshore flaring. Agreement was finally reached to connect a spur line from Ninian Central Platform into a seabed tee piece which had previously been laid in the Western Leg of the Shell Expro FLAGS gas gathering and transmission system. This pipeline would also provide fuel gas to the Ninian Northern Platform. Figure 1. shows a schematic of the seabed system. A decision was reached in August 1979 to proceed with the installation of this pipeline during the 1980 construction season. Figure 2. shows the actual cost and schedule for this pipeline.
Marine Operations Handling Large Floating Structures
Authors: Gray Captain J. M.
Published: December 2007

The development of Marine Operations over the past ten years or so has been spectacular and awe inspiring.

The Royal Sovereign Light Tower has been chosen as a start since many of the principles developed for this structure were carried through on subsequent gravity structures. It seems almost irrelevant to mention this structure in the same paper as the Ninian Central Platform, so great is the difference of scale, but among the marine operations for the light tower were an air cushion float out, offshore moorings and deck mating as well as seabed preparation. A great deal of experience was gained on this structure which was applied to later platforms.

The gravity structure development leapt forward with the Ekofisk Storage Tank. As a gravity structure and storage tank it was preceded by the Khasan Tanks at Dubai of completely different design and material. However, as a gravity structure capable of supporting a deck load it started a new trend. This was the first structure requiring a deep water towing route to open sea and the first large enough to stretch the capacity of the towing industry at that time. The tank is 99 metres diameter and towed at 66 metres draft.
A High Quality Water Base Fracturing Fluid
Authors: Dian Chen Li , Ying Chen Gui , Xia Zi Xiao
Published: December 2007

A new type of fracturing fluid containing partially hydrolyzed methylene polyacrylamide crosslinked by multivalent metal ions is investigated as thickening agent and friction reducer, while persulfate, H2O2, perborate or hydrazine are used as breaking agent.

In comparison with conventional fracturing fluid, this fluid, possesses a number of advantages, such as no residue, better thickening ability, lower friction loss, better shear stability, good resistance to high salinity, better temperature-viscosity property etc. This fracturing fluid has been used successfully in hydrulic fracturing treatments in low permeabl formation and excellent results have been obtained in fracturing treatments for deep well (140°C) and injection well. In addition, this fracturing fluid can easily be prepared on-site and the operation is simple.
The Acid Fracturing of Carbonate Gas Reservoirs in Sichuan
Authors: Muyao Meng
Published: December 2007

The discovered sinian-Jurassic producing formations in Sichuan basin are essentially fractured carbonate resevoirs. Based on the geological Characteristics of the resevoirs, this paper presents briefly the mechanism of acid fracturing, the Condition of progress in the research on acid fracturing fluids, the field operation conditions of matrix acidizing and acid fracturing respectively, the influence of formation selection and accumulation conditions on the results of acidization. The paper shows that the acid fracturing method is an effective stimulation measure for the carbonate strata in Sichuan.

The acid fracturing procedure exhibits poor effect on the low-permeable area. many technical problems remain to be solved. The technical experiments being made on the scene, such as padfluid acid fracturing and acid fracturing with refarded fluids would open up a new way for the modification of low-permeable area.
In-Situ Combustion Test on Outcrops in Kramai Oil Field
Authors: Shun-zong Lang
Published: December 2007

The purpose of this in-situ comeustion test is to perform such a test on outcrops of a heterogeneous reservoir, so that characteristics of the reservoir rocks after combustion, oil displacement efficiency, flow of oil., gas and water within this reservoir were inspected directly by cutting out a section profile in a test pit.

Reservoir geology, petrophysical properties of the reservoir rock, fluid properties, are described in this paper, A. brief description of the test procedure, including the well pattern, the test pit, operations in different stage in this test, and inspection made through the test pit and cores \ill\ ken from the reservoir ete. is given, and a general discussion of the results obtained is presented.
Daqing Crude Oil Dehydration
Authors: Jiachao Feng , Xiqing Zhou , Qingkui He , Renpu Wang
Published: December 2007

Due to the process of water injection applied in Daqing Oil Field development the water content in the wet oil increases gradually year by year. It is considered an important technical subject to dehydrate the wet crude so as to achieve the oil quality required for outward transport and refining.

Daqing crude oil is paraffin-based, with wax content of 28.7%, pour point of 26°C, viscosity of 23.79C. P at 50°C and specific gravity of 0.86, and also contains natural emulsifiers such as gels, asphaltines and naphthenic acids, etc. With these properties, a more stable water-in-oil emulsion has been formed during the crude exploition, thus caussing certain difficulties in the crude dehydration.

This paper, based on the practice in Daqing crude oil dehydration, mainly deals with the process of thermo-chemical and D.C electro-chemical dehydration, on the following subjects, such as the optimum selection and application of demulsifiers, the technology of determining electrode space of each individual layer in the electric dehydratύr, automatic control of electric field and requlation for oil-water interface etc. After dehydration by D.C electro-chemical process, the crude contains less than 0.3% of water, and oil content in the effluent water is controlled to below 0.3%, completely satisfying the requirement specified for the crude oil export abroad and refining in the country.
The Unsteady Radial Flow of Compressible Liquids Through a Medium With Multiple Porosity
Authors: Cigun Liu
Published: December 2007

This paper studies the unsteady radial flow of slightly compressible liquids through a medium with multiple- porosity. In the first part of this paper, the exact solution of differential equations of unsteady radial flow through a medium with triple-porosity are obtained by using the method of integral transforms. This solution not only reveals the essential characters of the unsteady flow of oil through finite fractured reservoirs, but also comprises the primary results published /ill/

In the second part a systematic study on the unsteady radial flow of slightly compressible liquids through a medium with multiple- porosity by using the method of numerical simulation is made on the CJ-709 computer. It may reveal the behaviors of unsteady flow through fractured reservoir by calculating dimensionless pressure drop and flow rate vs dimensionless time in the case of constant production rnte at the well-bore and no flow at the outer boundary for different geological parameters.
Application of Modified Non-Ionic Surface Active Agents in Enhanced Oil Recovery
Authors: Capelle Anthony , Littman Wolfgang
Published: December 2007

As early as 1954 a study into the efficiency of nonionic detergents to displace crude oil from sandstone reservoirs was published by Dunning. In this study different exethylated alkylphenols were investigated and it was concluded that this calss of surfactants was among the most promising, provided the solubility in the injected waters at reservoir temperatures is sufficient. Since then hardly any investigation into these chemicals were carried out. Practically all work on chemical flooding, both in the laboratory and in the field has been focussed on petroleum sulfonates. Why this investigation into modified nonionics? The main reason is the excellent stability against electrolytes, a feature petroleum sulfonates do not have.

By combining the favourable properties of both the nonionics and anionics the so called modified nonionics were introduced for chemical flooding. The products show an excellent stability against electrolytes, especially divalent ions, and no temperature dependence of their solubility.

Illustrated by a practical example: sandstone reservoir, average salinity and medium temperature, the development of a flooding recipe based on modified nonionics will be discussed.

Attention will be focussed on the laboratory investigation and the optimization of the flooding recipe. It has been shown that a 50% pv slug containing about 0.5% surfactant will give about 35% incremental oil.
Mechanisms of Retention in Silicate Enhanced Dilute Surfactant Low Tension Floods
Authors: Krumrine Paul Henry
Published: December 2007

Earlier work has shown that the addition of sodium silicates to dilute surfactant systems reduces surfactant retention in Berea cores better than Na2CO3, NaOH or STPP. This paper addresses the fact that in solution the sodium silicate molecule is a complex mixture of species which can exhibit a variety of properties, depending on the concentration and ratio of SiO2 to NaO2. By selecting the specific form in which the sodium silicate is added, it is possible to optimize the recovery of oil under a broad range of reservoir conditions. Specific variables which may be affected by silicate chemistry are IFT, rock wettability, surfactant retention and specific permeability reduction, leading to improved three-dimensional sweep.

A series of dilute surfactant core flooding tests were carried out, both with and without oil present, to determine the concentrations of the injected chemicals in the effluents. These tests covered a range of silicate ratios, brine salinity and hardness levels, and temperature conditions. The results show that each of these variables has specific effects on the retention of the injected chemicals by the sandstone substrate. Specifically, hardness increases retention of both silicate anion and surfactant, even with a large, soft water preflush. However, the silicate anion is preferentially retained, thereby leaving more surfactant in solution. Higher temperatures decrease retention of the surfactant and silicate anions. These results relate to observations of changes in recovery efficiency and permeability.

While few people consider carrying out low-tension floods at surfactant levels of 0.1 to 0.5% by weight, the results of these studies are generally applicable to both alkaline flooding and micellar flooding at much higher surfactant levels. In fact, this technology may have advantages as a low cost and technically less complex enhanced waterflood as compared to a micellar/polymer technique. Such a system would be best applied in the secondary waterflood stage. In either case, these same reactions and mechanisms control the surfactant concentrations in solution, and how well the injected fluid contacts the major part of the reservoir.
Standard Approach To Sampling And Chemical Analysis
Authors: Angwin Meredith Joan
Published: December 2007

Measurements of the chemical constituents of geothermal fluids are frequently not reproducible from sample to sample. Some of this instability derives from changes in the well with time, but a considerable portion of the lack of reproducibility is due to the sampling and analytical methods. Geothermal fluids, at wellhead, are at elevated temperatures and pressures, but chemical analysis methods require samples at ambient temperature and pressure. In much geothermal sampling, the transition between the two conditions is uncontrolled; gases are lost, solids precipitate, and the constituents of the liquid portion of the sample change. This can result in data that are inconsistent and difficult to interpret.

The Electric Power Research Institute has made considerable progress in solving this problem by standardizing the sampling and analysis procedure. This was done by: Building a mobile chemistry laboratory, containing chemical equipment suited for on-site geothermal analysisBuilding a fluid sampling system (FSS) to carefully control the change in temperature and pressure between well-head and ambient.Designing a "chemical signature test" procedure for analyzing geothermal fluids at a variety of sites.

The mobile laboratory travels to the geothermal site to perform the chemical analysis. This makes it possible for samples to be analyzed very rapidly after they are taken, with no delays, since delays can cause chemical changes in the sample.

The FSS is a small, portable flash-condenser system which reduces the fluid's temperature and pressure in a controlled manner.

The signature test procedure defines how the FSS will be used, how the constituents will be analyzed, and what quality control methods will be used. It also outlines expected detection limits for the various constituents.

This paper describes the mobile laboratory, fluid sampling system and signature test. It also describes the laboratory's recent visit to a geopressured site, with results from that site.
Polymer Performance in Low Permeability Reservoirs
Authors: Danri Michael W. , Burnett David B. , Hall Larry M.
Published: December 2007

Polymer performance was evaluated in core material from four low permeability (9.1 to 45 md) reservoirs. Injectivity impairment was noted in the higher permeability cores. Rock properties were examined by a variety of techniques in order to explain the apparently anomalous injectivity behavior. Results show that reservoir core characteristics other than permeability can dominate polymer performance, and that special core analysis techniques can be used to screen and characterize reservoir porous media.
A Study of the Application of Polymeric Gels in Porous Media
Authors: Batycky J. P. , Maini B. B. , Milosz G.
Published: December 2007

Crosslinking experiments with polyacrylamide and cellulosic polymers using chromium and aluminum as crosslinking cations have been performed in glass tubes as well as in Berea sandstone plugs. The dependence of gel strength on salinity, polymer concentration and concentration of the crosslinking agents was investigated to determine optimum conditions. For a given polymer concentration the gel strength was found to peak at optimum concentrations of the crosslinking agents and declined at higher concentrations. Comparisons of gel strengths between the tube and porous media measurements show that the concentrations of crosslinking agents required for maximum gel strength are considerably higher in Berea sandstone plugs than those in glass tube experiments. Further experiments in which the Berea plugs were preequilibrated with the crosslinking agents show that the requirement of higher concentration could not be attributed to adsorption or ion exchange. It is suggested that the differences may be due to the necessity of creating a much finer gel structure in the porous medium and the corresponding requirement of a more prolific nucleation.

It was found that, at low polyacrylamide concentrations, gels did not form, yet mobility reduction still occurred. The basis for the reduction was determined to be due to the precipitation of the polymer from solution, which then plugged the porous medium.
Diverting Agents for Sweep Improvements in Flooding Operations—Laboratory Studies
Authors: Navratil Martin , Sovak Mojmir , Mitchell Mark Stephen
Published: December 2007

Sweep efficiency in oil bearing reservoirs having high permeability zones, streaks or fractures can be improved by injecting gel-forming solutions which have the following attractive features: Prior to gelation, these solutions are low viscosity fluids which can be pumped as easily as water.Gel times from 10 seconds to 100 hours can be obtained at temperatures below 65°C.These gels can withstand temperatures typically employed in steam recovery of heavy oils.Partial removal of gels from high permeability zones and partial restoration of the initial permeability are also possible.
Acid Corrosion Inhibitor Adsorption and its Effect on Matrix Stimulation Results
Authors: Crowe Curtis W. , Minor Stephen S.
Published: December 2007

Acid corrosion inhibitors provide protection by adsorbing on metal surfaces, thus forming a barrier against acid attack. Upon entering the formation, the inhibitor is strongly adsorbed on clays and other minerals present within the matrix of the rock. In some cases, inhibitors contain acid-insoluble residues which can cause surface plugging of the formation face. Inhibitor adsorption and formation plugging by inhibitor residues can have a major influence on cleanup rate and the ultimate effective permeability of the treated zone. Consequently, acid corrosion inhibitors should be evaluated both for their ability to protect metal and for their potentially damaging effect on stimulation results.

Laboratory tests, using a computerized core test permeameter, demonstrate the strong influence of acid inhibitors upon acid injectivity, cleanup rate and stabilized long-term effective permeability. The adsorption characteristics of the inhibitor were shown to strongly influence test results. The beneficial effect of mutual solvent upon injection rate and, in some cases, well cleanup was also demonstrated.

Data are presented showing the influence of temperature, differential pressure and mutual solvent upon injectivity, cleanup rate and apparent stabilized oil permeability. Various types of inhibitors were evaluated under a variety of test conditions.

In general, it was found that damage resulting from the corrosion inhibitors was more pronounced at the lower temperatures and that mutual solvents reduced the magnitude of the problem.
New Acid Systems for Sandstone Stimulation
Authors: Clark Greig J. , Wong Tony C. T. , Mungan N.
Published: December 2007

A new series of prepackaged acid systems have been developed for stimulation of sandstone formations. The original system, containing phosphoric acid and other additives (labelled P.P.A.S.* throughout this article) was specifically formulated to overcome several limitations of existing acid systems. The scope of applications for P.P.A.S. has since been expanded by combining HCl (Hydrochloric acid) or HF (Hydrofluoric acid) with the P.P.A.S. to form hybrid systems that have unique properties. These new systems have been successfully used for stimulating sandstone formations that have been difficult to treat with existing acid systems. The problems associated with currently used acids and their limitations are compared to the P.P.A.S to illustrate the advantages of these new systems.
Clay Protection Chemicals: A Practical Evaluation and Application Technique for their Use in Stimulation Fluids
Authors: Callaway Ralph Edward , Ortiz Joseph , Holcomb David Lee
Published: December 2007

The emphasis on providing protection to sensitive clays in a variety of reservoir types has led to the development and application of specific chemistries. These range from monovalent to polyvalent salts and more recently, to polymer based systems. In numerous published cases exotic interaction studies have been performed to evaluate the potential effectiveness of these clay protection additives.

The need for a simple standard screening technique to allow comparative testing and ultimately specific designs for clay additive usage is obvious. This technique will illustrate the significance of clay species interaction with clay stabilizing fluids and point to any harmful side effects on reservoir permeability that may be caused by the clay stabilizer.

The study presents a simple procedure for indexing clay stabilizing additives in order to insure that the most effective one is chosen and implemented as a "specific" agent to control a "specific" clay situation. Use of a packed column in addition to berea core allows the designer to vary the type and amount of clay in the column in order to simulate the clay content of the formation in question.

Factors affecting the performance of clay stabilizers will be prioritized. They include compatibility with other additives, permeability damage, and ability to prevent clay migration in a packed column.

An attempt will be made to document results with respect to clay chemical/clay species interaction. This will be done before and after permeability flow tests using scanning electron microscopy.

The evaluation of stabilizers examined in this study will be documented by indexing each chemical. This index will be shown to be a useful tool in differentiating among the numerous clay stabilizers available in the market today.
Reservoir Performance Changes Due to Inelastic Deformation
Authors: Schatz John F. , Ahmed Usman , Carroll Michael
Published: December 2007

Long-term prediction of reservoir performance can be strongly influenced by stress sensitivity. As the effective stress in a reservoir increases due to production, the porosity and permeability decreases. Inelastic rock deformation mechanisms play a significant role in bringing about these changes in porosity and permeability. This paper shows that inelastic pore collapse can be the dominant mechanism in reducing pore space and permeability even when reservoir conditions are hydrostatic. The presence of a shear component in the in-situ stress can increase these effects. A numerical simulated reservoir study has shown that well work-over and stimulation projects could be warranted earlier than currently practiced.
Viscous Heavy Brine Completion Fluids
Authors: Darlington R. Keith , House Roy F. , Hunter Daniel V.
Published: December 2007

An activated hydroxyethyl cellulose has been developed which will viscosify brines of any density up to 19.2 lb/gal containing calcuim chloride, calcium bromide and/or zinc bromide. The use of activated hydroxyethyl cellulose allows preparation of viscosified brines at ambient temperature and without undissolved polymer solids. The time required to prepare a viscosified brine is greatly reduced. In addition, the rheology of brines viscosified with activated HEC can be accurately predicted allowing brines with equivalent solution rheology properties to be prepared batch after batch.
A Simplified Predictive Model for Micellar-Polymer Flooding
Authors: Paul George W. , Lake Larry W. , Pope Gary A. , Young Genevieve B.
Published: December 2007

The purpose of this paper is to present a simple, reliable and inexpensive predictive model which allows the economic assessment of micellar-polymer flooding. An oil recovery algorithm is developed from theory and the results of numerical simulation. The model contains correlations which relate factors impacting oil recovery to reservoir and process data: capillary number (permeability, depth, spacing), heterogeneity (Dykstra-Parsons coefficient), crossflow (kv/kh), surfactant sorption (clay fraction) and wettability (relative permeability). Oil breakthrough, peak oil rate and project life are estimated from oil-water fractional flow theory, augmented with an effective mobility ratio to represent heterogeneity. The model is validated against the results of numerical simulation and is compared with the results of several field projects.
Location of Drilling Sites in the Devonian Shales by Aerial Photography
Authors: McIver R. D. , Kyle J. R. , Zielinski R. E.
Published: December 2007

Current estimates of gas in place in the Devonian Shales of the Appalachian Basin range up to 2,500 TCF. For the most part, the majority of this resource is tied up in the shale matrix and the source and reservoir of this gas is the same as the low permeability and porosity of the shale prevents migration of the gas to a more classical reservoir rock. Where there is fracturing of the shales, the fracture network serves as a reservoir and wells drilled in the area of fracturing tend to be good producers.

For exploration purposes, the most probable areas for drilling of the shales are those that have a high density of natural fracturing. Aerial photography has been used to locate potential drilling sites in the Basin. The use of this technique is based upon the premise that fractures evident in surface sediments are often useful indicators of subsurface fracturing favorable for the accumulation of hydrocarbons.

Buried fault traps, anticlines, and salt domes are frequently revealed by surface fault configurations or locally anomalous joint orientations. Moreover, since fractures are frequently conduits and collection sites for hydrocarbons, a concentration of surface fractures may indicate a potential productive reservoir at depth.

Aerial photography allows fractures to be recognized and mapped in almost every type of terrain and soil cover. A photogeological study designed to aid in the location of specific prospects typically begins with a study of LANDSAT photos to spot large scale features. This is followed by a study of stereoscopic photo pairs and photomosaics of larger scale. For pinpointing drilling sites in such cases, the greatest weight is placed on the interpretations from stereoscopic photo pairs.

The current paper reviews the premise of photogeology, the techniques used in applying aerial photography as an exploration tool and finally the application of photogeology in identifying specific well sites in the Devonian Shales of the Appalachian Basin.
Relationship of Methane Content of Coal Rank and Depth: Theoretical vs. Observed
Authors: Eddy Greg E. , Rightmire Craig T. , Byrer Charles W.
Published: December 2007

Prediction of gas content of coalbeds, and therefore potential producibility, has relied primarily on its observed relationship to coal rank, pressure, and the methane adsorption capacity of a given coal. This relationship has been illustrated by the construction of adsorption isotherms for various coals from experimental data. These adsorption isotherms were developed for sized, clean coal particles. The value and limitations of these adsorption isotherms are addressed by relating them to observed coalbed methane gas content data.

Coalbed gas content determined by the "Direct Method" includes three separate figures: lost gas, desorbed gas, and residual gas. The residual gas and its relationship to the total gas content is discussed. The ratio of lost and desorbed gas to residual gas has been determined for some ranks of coal.

The ratio is very dependent on rank. Residual gas increases as rank increases, reaches a maximum at the rank of high-volatile A bituminous and decreases rapidly as rank increases to medium-volatile.

The general conclusion is made that the cause of the pattern of correlation of residual gas to rank is a change in the internal structure of the coal and the moisture content of the coal.
Coalbed Methane Potential of the Appalachians
Authors: Adams Margaret A. , Hewitt Jeanne L. , Malone Rodney D.
Published: December 2007

Coal mines in the Appalachian Basin emit approximately 180 million cubic feet (MMcf) of high-quality methane into the atmosphere daily. The existence of mines in West Virginia, southwest Virginia, eastern Kentucky, Ohio, Pennsylvania, Tennessee, and Alabama with high gas emissions of over 100 thousand cubic feet per day (Mcf/d) suggests that further investigation into the economic development of this unconventional energy source is warranted. Appalachian coals occur as multiple beds, individually up to 14 feet thick (Pittsburgh coalbed in Pennsylvania and West Virginia). The gas content of these bituminous coal seams has been measured at 93 cubic feet per ton (cu ft/t) from a depth of 149 feet (Waynesburg coalbed, Pennsylvania) to over 560 cu ft/t at 1,764 feet (Pocahontas No. 3 coalbed in West Virginia); in the anthracite region, 690 cu ft/t have been measured where the overburden is 685 feet thick (Peach Mountain coalbed).

Detailed studies in the southern Warrior Basin indicate the presence of up to 20 trillion cubic feet (Tcf) of gas, and preliminary work in the Central and Northern Appalachian Basins suggests a resource of 50 and 80 Tcf, respectively. Many coal operators are realizing the production potential of coalbed methane. In Buchanan County, Virginia, the Island Creek Coal Company produced up to 434 Mcf/d from 12 horizontal boreholes drilled into the mine face. Waynesburg College in Pennsylvania will realize a savings of $25,000 toward their annual energy bill from a 1,450-foot vertical well drilled on campus. In Alabama, U.S. Steel's mines just began commercial production, and sold 25 Mmcf to a gas pipeline company in December 1981; and Jim Walters Resources has begun an ambitious program to drill up to 700 wells with a predicted total production of 60 billion cubic feet (Bcf).

These examples of the successful exploitation of a resource formerly considered only a hazard to coal mining indicate a promising future for coalbed methane.
A Successful Stimulation Research Program for a Tight Sand Reservoir
Authors: Greenfield Harvey S. , Ahmed Usman , Schatz John F. , Jones Arfon H.
Published: December 2007

Two research wells were drilled and completed in a known, yet heretofore unproductive tight sand gas reservoir in the Green River Basin. Although previous wells were drilled in the area and hydraulically fractured, there has been no commercial production. The consideration of advanced methods of stimulation design and changing gas prices caused recent renewed interest. A systematic approach led to successful fractures of one zone in each of the two wells. Initial production rose from 107 to 4150 MCFD in one well and from 35 to 1450 MCFD in the second well after stimulation treatments.
Field Study — Steinle Ranch, an Intermediate Depth Oil Field, Shows Significant Benefit from Bauxite Proppants
Authors: Kohlhaas Charles A.
Published: December 2007

The Steinle Ranch Field was initially developed in the mid-1970's. Wells were drilled, cased, perforated, and treated by chemical injection with lease-crude or condensate carriers to restore oil saturation to the formation, which is suspected to be hydrophobic. Stimulation by hydraulic fracturing of four wells was attempted from 1975 through 1977 with mixed results and no particular success. These treatments used sand and glass beads for proppant.

A fifth hydraulic fracture treatment, in which sintered bauxite was used as the proppant was very successful. As a result, all wells in the field have been fractured. This program, in a mature field in late stages of depletion, at intermediate depth (10,600 ft.), has been very successful; approximately 940,000 barrels of additional reserves have resulted for a total cost of approximately $2,000,000, a return on investment of 9.4:1. Comparing these reserves to estimated reserves if the wells had been propped with sand shows a 23:1 return by the incremental reserves on the incremental cost of the bauxite.
Performance of Crosslinked Hydrochloric Acid in the Rocky Mountain Region
Authors: Pabley Avtar S. , Ewing Bob C. , Callaway Ralph E.
Published: December 2007

The crosslinked high strength hydrochloric acid system1 has led to significant production increases in Rocky Mountain wells. A total of sixty five wells have been stimulated with this system utilizing a total of over 470,000 gallons of crosslinked hydrochloric acid in concentrations ranging from 3% to 28%. Old producers as well as the newly drilled wells completed in the various formations such as, Dakota, Mission Canyon, Phosphoria, Minnelusa, Green River, Uintah, Nesson Midale, Red River etc. were treated. The bottom hole temperatures of these wells ranged between 110°F and 260°F (43°C to 126.7°C). The cumulative oil production from the sixty five wells prior to the crosslinked acid jobs has totaled to over 2,300 BOPD. After the crosslinked acid jobs the cumulative oil production has increased to over 8,400 BOPD, which is more than three fold increase in oil production. In a few individual wells oil production has increased by as low as 1–5 BOPD, whereas in some individual wells the production has increased by as high as 1,300 BOPD. One of the old oil producers in the Green River Formation, Utah, was producing 40 BOPD but after a treatment, the production increased to 200 BOPD and a sustained oil production after 90 days was 150 BOPD. Similarly, Production has increased from 16 BOPD to 216 BOPD in one of the new completions in the Dakota Formation in Wyoming.

The treatments have been successful in old and new oil wells as well as in a water injection well. Wells have been successfully treated using sand as proppant, and carbon dioxide or nitrogen in the system. The crosslinked acid system has shown success in wells where conventional acid treatments have provided marginal success or failed. Several case histories of the crosslinked acid system have been presented in recent presentations.2
Introduction to Plunger Lift: Applications, Advantages and Limitations
Authors: Beauregard E. , Ferguson Paul L.
Published: December 2007

This paper discusses the principle of plunger lift and its possible applications.

Typical applications are: Removal of Liquids from Gas WellsHi-Ratio Oil Well ProductionParaffin and Hydrate ControlIncreased Efficiency of Intermittent Gas Lift Wells

Some advantages of this system are low initial cost, very little maintenance and that there is no external source of energy required in most cases. Limitations such as mechanical conditions, gas and liquid volumes and depths are also discussed. There will be a brief section concerning the various types of equipment available.
Calculation and Significance of Water Saturations in Low Porosity Shaly Gas Sands
Authors: Rosepiler M. J.
Published: December 2007

The identification of pay in low porosity shaly gas sands is made difficult by the inaccuracy of calculating and interpreting water saturations. Outlined below are techniques that have been used to calculate water saturations in this type of reservoir.

Laboratory tests have been performed to measure saturation exponent and to define the formation factor-porosity and cation exchange capacity-clay relationships. The tests indicate that saturation exponent, n, is 1.36, and that formation factor, F, is given by .9/øe2.17. Formation factor tests and empirical calculations imply that m may be a function of porosity in porosities less than five percent.

The cation exchange capacity of the rock is due to illite. As the illite contains radioactive potassium, gamma ray activity can be used to calculate cation exchange capacity. Laboratory spectral gamma ray analysis indicates that the potassium component is a good indicator of cation exchange capacity.

Water saturations are calculated using the Waxman-Smits technique. Errors induced by not accounting for clay conductivities are presented as functions of porosity, water saturation, and illite content. The induced errors are greatest in low porosity zones.

Error analysis indicates that the major source of error in calculating water saturations (excluding the effects of exchangeable cations) is the inaccuracy of determining porosity. At porosities less than five percent, the possible error in water saturations approaches one hundred percent.

Data are presented relating the error in water saturations to errors in porosity and resistivity.

The significance of water saturations in low porosity, low permeability sandstones is unclear. Drainage relative permeability data predict that except at extremely high water saturations the flowing phase should be predominantly gas.
The Effect of Weight Material Type on Rate of Penetration Using Dispersed and Non-Dispersed Water-Base Muds
Authors: Blattel Steve R. , Rupert J. Paul
Published: December 2007

The penetration rates of dispersed and non-dispersed water-base muds were studied using Mancos Shale. The full-scale wellbore simulator at Drilling Research Laboratory was utilized. Previous studies1 have indicated that in invert oil muds higher penetration rates can be achieved when the weighting agent is ilmenite rather than barite. This study compares barite and ilmenite in water-base systems. Two grind sizes of ilmenite (fine and standard) were used in order to determine the effects of particle size on penetration rate.

In addition to these tests, hematite, fine-grind ilmenite and barite were tested in a low colloid invert oil mud system as a supplement to the original study. An additional test was conducted with a conventional diamond bit and the low colloid oil mud for comparison.

Highest penetration rates were observed with the standard particle size distribution ilmenite for the water-base muds. For the invert oil mud, similar penetration rates were observed for the fine-grind ilmenite and the hematite; the barite weighted mud resulted in relatively lower rates of penetration. The fine grind ilmenite/low colloid oil mud/diamond bit combination provided penetration rates equal to or greater than the barite/low colloid oil mud/roller cone bit combination.
The Influence Of Project Profitability On Company Growth
Authors: Brons F. , Silbergh M.
Published: December 2007

The financial structure of a large company is quite complex. We are able, however, to follow the trend of such elements as the annual net cash income I (which is the income after paying all costs, including overhead and taxes), the annual net profit P (which is the annual net cash income minus writeoffs) and the dividend paid out. Other characteristics of a company, such as the average annual earning power i and the market value V, are not readily detectable but are related in some manner to the aforementioned elements.

In an attempt to establish mathematical relationships between the various elements a simple model of a company (Figure 1) was studied. This model starts with an investment of $1000 in a project which yields $400 annually for three years. (It is assumed in the model that the incomes are received at the end of each year.) From the definition of earning power, present value income discounted at earning power i equals investment, or Di (1200) 1000, the deferment factor Di is found to be 0.83. Using deferment factor tables, the value of the earning power i of this project is found to be 10 percent. All incomes derived from the first investment are reinvested in projects with the same characteristics as the first (i = 10 percent, three year constant income). The annual cash income first shows an irregular trend but, as shown in the top curve of Figure 2, after some time this trend stabilizes and the growth rate of I becomes constant. For complete reinvestment of cash incomes the following important relation is true:growth rate g earning power i. (1) If, however, as shown in the lower curve of Figure 2, seven percent of I is paid then the reinvestment ratio b is 0.93 and, although the cash income after stabilization obtains a constant growth rate g, this rate is less than the earning power i.
Foam Gravel Packing
Authors: Elson T. D. , Anderson G. W.
Published: December 2007

Foam gravel packing experiments run in a full-scale model wellbore demonstrated that foam is a viable alternative to conventional carrier fluids such as water and viscous polymer solutions in select instances. Because of its special characteristics, foam may have advantages over these fluids in completions where low pressure or sensitive formations are encountered.

Results from experiments were used to design and implement gravel pack completions in nine shallow, low pressure wells in California. Other wells in the area had a history of lost circulation and washouts during drilling and completion operations using conventional fluids. The foam gravel packs suffered no loss of circulation during placement and proved to be less costly than the conventional slurry packs used in the past.
Numerical Simulation of a Production-Well-Ceritered Five-Spot in a Large Scale Micellar/Polymer Project
Authors: Roszelle Wayne O.
Published: December 2007

The numerical SURfactant Flooding Simulator (SURFS) can be used to predict micellar/polymer field test results. In order to develop a set of data inputs, the simulator was used to match the oil and surfactant production histories of a specific well in Marathon Oil Company's 219-R micellar/polymer project and the post-flood oil saturation distributions in the vicinity of the well. The study area was the producer-centered 5-spot surrounding a single producing well and the north half of the 5-spot to the south of this well. This area was chosen for the study because this 5-spot had an oil recovery history, reservoir parameters, and operating history comparable to the total project average. Reservoir properties for the area were taken from the best available sources and well injection and production rates closely simulated actual field rates.

The final simulator run produced a very good match of oil and surfactant production from the well in both cumulative production and production rate as a function of time. Post flood saturation data from seven core tests taken in the vicinity of the well were also closely matched by SURFS.

The paper includes a discussion of the input parameters to the simulator including residual oil saturation as a function of concentration of sulfonate, relative permeability of oil and water in the presence of surfactants and sulfonate absorption.

A brief description of the mathematics of SURFS is reported elsewhere.1
Analysis of Production Tests of Hydraulically Fractured Wells in a Tight Solution Gas-Drive Reservoir
Authors: Verbeek Christiaan M. J.
Published: December 2007

A simulation study has been carried out to investigate how accurate existing techniques are to evaluate tests of non-ideal hydraulically fractured wells in tight solution gas drive reservoirs. Especially in case fracture height is less than layer height the use of existing analytical methods can lead to erroneous interpretation of formation and fracture characteristics. Moreover a second radial flow period preceding the. real formation radial flow, can occur. Formation radial flow starts at a constant dimensionless time, independent of the height ratio, whereas formation linear flow ends at a time linearly related to fracture height. In the reservoir under investigation some frac-jobs have been carried out in stages. Wells, deviating up to 45 degrees, can intersect several parallel vertical fractures. In that case a correct analysis of tests is almost impossible. In practice conclusive results can only be obtained if a prefrac test is available or when a postfrac test formation radial flow is evidently reached.

Existing superposition methods were tested for constant pressure, constant rate and multirate cases to compare their applicabilities. In case radial flow superposition is applied in the time scale and if linear flow is significant results of multirate cases can show too optimistic kh values.

Published pseudopressure techniques to find formation kh values for solution gas drive reservoirs are improved by using average fluid properties instead of those at wellbore conditions. To accurately define fracture and formation characteristics a pseudo time factor was needed to correct for drastic changes in viscosity and total compressibility.
Conditions for the Development of Smaller Discoveries in the North Sea
Authors: Bayly C. H. , Cox T. F.
Published: December 2007

Development options for North Sea fields are discussed and a reference scheme for marginal fields is costed. Against this reference, feasible cost reductions are discussed by broad cost categories with the aim of identifying key areas for cost control and technological innovation.

The impact of the current tax system on smaller fields is reviewed and possible changes to provide incentives for marginal fields are developed.
Sizing Separators for CO2 Flood Operations
Authors: Roye J. E.
Published: December 2007

The design of field separation equipment under CO2 flood operations requires that many variables be addressed. During a CO2 flood, separators will be required to effectively separate large volumes of multi-component gas streams from produced oil and water. Many design assumptions which served well in non CO2 hydrocarbon service cannot be successfully applied to the design of field separation equipment in CO2 flood operations. To adequately size separators for CO2 service, specific attention must be given to design parameters such as K factors, gas density, liquid density, retention time for gas-liquid separation, CO2 and produced gas rates, and the type of vessel best suited for CO2 flood conditions.

After a detailed study of the parameters involved in the design of field separation equipment for CO2 floods, several conclusions were reached. Conventional sizing charts are not applicable in CO2 operations.One to two minute retention time is not sufficient for gas-liquid separation in CO2 operations.K factors normally used for sizing separators should be derated for CO2 operations.Horizontal separators are better suited for CO2 flood operations than spherical or vertical separators.Computer sizing of separators is necessary to determine the optimum operating settings.
New Low-Speed High-Torque Motor Experience in Europe
Authors: Beswick Andrew John , Forrest John
Published: December 2007

A new generation of multi-lobe positive displacement mud motors designed in the USSR has been used in Europe since early 1981. A comprehensive range of experience has already demonstrated the importance and potential of this development for a wide variety of drilling applications. This paper describes the design concept of the motor which operates on the Moineau principle and discusses the performance with reference to a number of recent applications including straight hole drilling, directional drilling and coring. The slow-speed, high-torque characteristics, which permit sustained high bit weights, give near rotary conditions at the bit for the first time with a downhole motor, offering many advantages in drilling.

The references to case histories include a summary of the comprehensive use of the motors for directional drilling in two 7000 ft deep wells in granite for a hot dry rock geothermal energy research project in Cornwall, UK. In addition comments on the use of the motors with polycrystalline diamond and tricone bits for straight hole drilling are presented, together with a number of references to coring applications.

The results so far demonstrate that longer runs, faster drilling, and more successful coring are possible and that the power-speed characteristics offer new important operational options including bottom hole configurations with drilling assemblies below the motor. The walk tendency of the motors in directional drilling is opposite to that of turbines and, therefore, complements turbines for long progressive corrections in drilling tangent sections.

The technical improvements to the original design based on early operational experience are outlined and future potential applications discussed.