Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
OnePetro
Abstract A simple 3-D physical model has been developed to investigate the use of horizontal producer wells in in situ combustion processes. The semi-scaled 3-D model was a rectangular box with 40 cm by 40 cm by 10 cm dimensions. Dry in situ combustion experiments were conducted with three different well configurations a vertical injector and horizontal producer; a vertical injector and two horizontal producers; and injector and producer, both vertical. A matrix of 60 thermocouples was used to obtain temperature profile information, ill the vertical and horizontal mid-planes. Most experiments were conducted with sandpacks containing a high saturation of heavy crude oil SOi โ 0.80. For each horizontal well configuration, the effect of oxygen flux and oxygen enrichment (21% and 35% oxygen) was investigated. Combustion peak temperatures up to 400 ยบC were recorded, with oil recoveries exceeding 66% OOIP for the single horizontal producer well case. The recovery using two horizontal producer wells was 71.5% OOIP, higher than both the vertical producer and horizontal producer well cases. Generally, a much more stable propagation of the combustion front was observed for the single horizontal well vs single vertical well configuration. The vertical sweep especially was noticeably stabilized compared to the progressive tendency for gas override developing along the mid-plane of the vertical well experiment. Both single and double horizontal wells gave an earlier commencement of oil production and at a higher rate subsequently. However, the additional incremental oil recovery achieved by the double horizontal well was proportionately lower than indicated by theperformance of the single horizontal well, owing to interference between wells. At increased injected oxygen flux, the oil recovery reduced due to oxygen channelling through to the production end, causing higher rates of low-temperature oxidation ahead of the combustion from. Significant improvement of the combustion efficiency occurred with enriched air, but the oil recovery was lower due to higher fuel consumption. Overall, there was a very significant improvement in the quality of the produced oil using the horizontal well arrangement, Compared to that achieved with the single vertical well. Introduction The demand for crude oil and the increasing difficulty of discovering new large reservoirs, as well as the decrease in Conventional oil reserves, has generated special interest in heavy oil and tar sands. The high viscosities of heavy oils at reservoir conditions is the predominant factor limiting economic recovery. Any reduction in the oil viscosity will create an increase in oil mobility and therefore improve production. The most effective method of lowering the viscosity is by the application of heat to the reservoir. Heat may be introduced into the reservoir in the form of hot water, gases or steam lt may also be generated in situ by burning part of the oil in the reservoir, This process is known as in situ combustion or ISC. Fireflooding or ISC is a thermal EOR method in which heat is generated within the reservoir by igniting the formation oil and then propagating a combustion front through the oil bearing media.
Abstract An approximate analytical transient time solution has been developed for temperature and stress fields around a circular borehole during constant rate fluid injection into a permeable porous medium. The solution implies that significant reduction or increase of tangential (ฯฮธ) during cold or hot fluid injection may occur, alld this has applications in borehole stability problems or induced fracturing. This solution may also be used in thermal enhanced oil recovery schemes where hot fluids are injected, in cases of cold fluid injection for waste fluid disposal, or in cases of geothermal reservoir circulation for heat extraction. The transient temperature field is solved separately for the fluid and the rock. This solution is achieved from energy conservation by coupling convective heat flow carried by an injected fluid from a borehole, and local heat conduction between a fluid boundary layer and a solid grain. First, temperature is solved in radial coordinates by taking into account radial fluid flow divergence; then, the transient time pressure distribution is calculated from the Theis solution. Once the temperature and fluid pressure distributions have been determined, the stresses around a borehole are calculated taking into account both poroelastic and thermoelastic rock response. It is shown that during fluid injection, ฯฮธ on the borehole wall may change, and shear failure or hydraulic fracture may be triggered. Also, stresses are changed farther from the borehole because of fluid and heat propagation into the porous medium. Introduction As conventional reservoirs are depleted, new oil recovery methods are deployed in oil production management. Thermal methods are among the more popular enhanced oil recovery methods in viscous oils. For instance, in steam-flooding, hot fluid injection is used, and in fire-flooding, combustion heat is employed to lower heavy oil viscosity and increase its mobility. On the other hand, cold fluid injection may occur during waste water disposal, or may be deliberately used to enhance rock fracturing, thus increasing its permeability. Other cases where borehole behaviour may be affected by thermoelastic stresses include:In drilling, the base of the hole may be cooled as much as 10 ยฐC to 20 ยฐC by the mud; As the mud warms going up the annulus, it may heat upper formations by as much as 10 ยฐC to 20 ยฐC; In water floods, waste process water injection, or geothermal projects, major reductions in stress develop after long-term cool water injection, opening joints and facilitating fracture; and, In gas production, the cooling effect because of gas expansion near the borehole may cause significant thermoelastic stress reductions. Temperature changes in the rock induce thermoelastic stresses because of thermal strains, and these stresses may lead to rupture or shear. However, if elastoplastic processes and nonlinear deformation moduli effects are assumed negligible, stresses may be calculated from equations for a fluid-saturated, poroelastic solid by incorporating thermoelastic rock volume changes. The equations for poroelastic theory were developed by Biot . Schiffman extended Biot's theory to include thermal effects.
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.76)
Abstract Many oil reservoirs in Alberta overlay active water zones which provide well maintained high pressure drives for primary oil recovery. However, such high pressure aquifers create water coning which is the entry of the bottom water into the production well during the primary oil production. Thus, a well can produce a substantial amount of water along with oil at the expense of oil production. Cold, non-condensable gas injection into an oil reservoir with bottom water has been observed as an effective method for water coning suppression thereby extending the economic life of a production well. A project was initiated to investigate the effect of gas injection in suppressing water coning during oil production from an oil reservoir overlaying an active aquifer. The research program included partially scaled, high pressure physical model experiments in sand packs supported by numerical simulations to understand the mechanisms by which injection of gases (such as carbon dioxide and methane) suppresses water coning. Tests with different non-condensable gases showed consistent reduction in water production or reduction in water-oil ratio of the produced fluids. This paper indicates a number of possible mechanisms for the anti-coning effect of gas injection. It is inferred that the injected gas migrates toward the production well along the oil-water interface as a blanket thereby increasing the free-gas saturation. The presence of even a small amount of free-gas creates a three-phase region of oil, water and gas which results in reducing both the relative permeability for water flow and the residual oil saturation. Thus, water production is reduced. The injected gas (if soluble) also dissolves in the oil and reduces its viscosity. When the oil is less viscous and more mobile, the injected gas sweeps a greater volume of oil. Any swelling caused by gas dissolution would also help in more oil displacement. The preceding mechanisms based on gas dissolution may not be significant in reservoirs with โliveโ oil containing significant amount of dissolved gas. Another minor mechanism is the plugging of pores by the possible in situ formation of viscous water-in-oil emulsion with acidic gas injection. A key result of this research study is the first time demonstration of the anti-coning effect of cold gas injection under controlled laboratory conditions and the investigation also provided a strong support for the development of Alberta Oil Sands Technology and Research Authority's (AOSTRA) commercial Anti-Water Coning Technology (AWACT). Background Water coning is a term given to the phenomenon of the entry of bottom water into a production well. Under static conditions, water being denser than the formation hydrocarbon fluids, remains below the production well. When oil is produced at high rates however, the interface between the oil zone and the underlying water zone rises and imbibes into the oil depleted region near the production perforations as a โwater coneโ (Fig. 1). The water cone may extend into the wellbore when the upward pressure gradient associated with the flow of formation fluids into the production wellbore balances the hydrostatic head of the resulting elevated water column.
- Overview (0.47)
- Research Report (0.35)
Abstract A complete mathematical model for describing microbial transport, nutrient propagation, and microbial growth in porous media is presented in this paper. Also presented is the scaling up criteria for conducting meaningful experiments in the laboratory. Microbial Enhanced Oil Recovery (MEOR) is one of the fastest growing EOR schemes in the world. This is due to low cost of MEOR as compared to other EOR schemes, such as chemical flooding, thermal methods, etc. Micro-organisms are able to travel relatively easily in an oil reservoir with preferential access into the wafer-bearing channels. In situ bio-generation of chemicals has the unique advantage of minimizing chemical loss by adsorption. If properly designed, microbial species can be used for selective plugging of high permeability water-bearing channels, leading to improved oil recovery. Even though there has been considerable experimental and field work done on MEOR, very little effort has been devoted to mathematical simulation as well as studies of scale-up procedures of MEOR. The lack of reliable numerical prediction techniques or proper scaling criteria often leads to inaccurate evaluation of a field project. This paper presents a new approach for modelling microbial plugging of water channels which are often present in oil reservoirs. Combination of the bacterial and nutrient transport models are coupled with a kinetic model of bacterial growth. A detailed parametric study of the MEOR simulator is presented. This model accurately redicts bacteria entrainment and deposition in a laboratory core. The numerical simulation results compared favourably with published experimental data. This model provides an insight into bacterial transport laboratory and field and may be used to define new targets for bacterial plugging. Based on the numerical model, scaling criteria/or conducting experiments using MEOR arederived. These scaling criteria are essential for scaling up laboratory experimental results to the field. Introduction Many field trials have been conducted using microbes for mainly two applications: selective plugging of undesirable channels(1), and reduction of oil-water interfacial tension and oil viscosity for oil mobilization(2). Only a few field trials have been successful even though most field trials preceeded by laboratory experimentations. In the past, laboratory experiments have been poorly extrapolated to design a field project. This is mainly due to the lack of scaling criteria or a proper mathematical simulator which could be used for modelling field perfomance under realistic field conditions. Even though there have been several studies reporting transport of bacteria through porous media(1โ4), very little has been conductedin the areas of mathematical modelling of microbial transport and metabolism. A simplified model was proposed by Knapp et al.(5). This model used a fundamental conservation laws along with growth and retention kinetics of biomass in order to predict porosity reduction as a function of distance and time. Updesraff(6) used a filtration model in order to express bacteria transport as a function of pore entrance size. A similar model was used by Lang el al.(1) as well. In a recent work, Jenneman el al.(7) modified the filtration theory to relate permeability, with the rate of bacteria penetration.
- North America > United States (0.17)
- North America > Canada > Alberta (0.15)
ABSTRACT A 515-km pipeline in northeastern Australia exhibited 5 V telluric potential fluctuations in the 130 km of its length adjacent to the coast. The rest of the pipeline was relatively unaffected. The potential fluctuations were constrained using a combination of potentiostatic cathodic protection (CP) units, diodes connecting the pipeline to Earths, and insulating joints. There remained a significant rate of corrosion in the telluricaffected area. The CP criterion is to be modified and based on potentials that have been correlated with electricalresistance probe data. This minimizes the effect of the variable soil voltage gradient errors in potential measurement resulting from the telluric effects and also the unknown effects of short duration positive transients. Additional work is required to determine acceptable transient potential frequencies, amplitudes and durations. Introduction The Earth?s magnetic field is essentially a fixed dipole, resulting from rotation of the Earth?s core relative to its mantle. The field from the dipole projects out into space where it is affected by the solar wind, a constant stream of protons emanating from the sun. Variations in the solar wind (or other influences) can perturb the field. Such perturbations fluctuate the field up to one percent of the total field strength.1 These perturbations are caused mainly by such solar emanations as:2 Solar Flares ? Explosive emanations of broad spectrum electromagnetic radiation and charged particles disturb the field, causing geomagnetic storms that typically last one to two days. Coronial Holes ? The long life of these emissions of intense solar winds causes geomagnetic storms that last one to two days and may reoccur for a number of 27-day solar rotational cycles. Solar Filaments ? The collapse of these cool, dense structures above the solar surface results in intense solar winds and geomagnetic storms. Solar activity varies in an 11-y cycle, with the number of energetic solar flares varying between 10 and 600 per year. Solar activity was high in 1990/91. There is also an annual cycle of solar activity. During a period around each of the two equinox (March and September), solar activity that disturbs the magnetic field is two to three times higher than during the rest of the year.3 Major geomagnetic storms resulting from solar flares and solar filaments tend to occur at the peak of the solar cycle and predominately during the night. Intermediate level storms resulting from coronial holes tend to occur on the declining phase of the solar cycle. The two effects combine to provide a 5.5-y cycle for geomagnetic storm activity. Lower level storms? whether resulting from solar flares, coronial holes, or solar filaments?tend to be evenly distributed
- Europe (1.00)
- North America > United States > Texas (0.69)
- Oceania > Australia (0.69)
ABSTRACT Many studies have been devoted to the inhibition of iron corrosion in acidic media by aromatic or acetylenic compounds,1-4 but surfactants have been relatively little studied. The action of primary aliphatic amines on the behavior of iron in 1 M HCl has been investigated.5 It was shown that the inhibitory efficiency increases with the number of carbon atoms in the molecule.5 In another study, non-ionic surfactants were found to have a marked inhibiting effect, but only at low concentrations.6 The best efficiencies appear to be obtained at concentrations around the critical micelle concentration (CMC).6-9 The parameters influencing the inhibitory action of aliphatic amines and quaternary ammonium salts also have been described.10 Schmitt has suggested that the surfactant compounds act by forming a bimolecular layer at the electrode area.11 In this work, the authors present a study of the inhibiting effect of some betaines in the case of iron in 1 M HCl deaerated solution. These products have been examined before12-18 and have been applied in the food and cosmetics industries.19 Loussayre et al.20 found that the N-alkylbetaines were adsorbed strongly on wool fibers. MATERIALS AND METHODS The samples were commercial iron of the following chemical composition: C 0.0100; Si 0.0050; Cu 0.0020; Mg 0.0020; Ni 0.0010; Al 0.0005; Ag 0.0002; Cr 0.0001; and Mn 0.0001.
- Europe > France (0.28)
- Africa > Middle East > Morocco (0.28)
- Materials > Chemicals > Specialty Chemicals (0.77)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.75)
- Energy > Oil & Gas > Downstream (0.75)
- Energy > Oil & Gas > Upstream (0.50)
ABSTRACT At corrosion crack tips, special electrochemical conditions result from the high rate of metal dissolution and very low rate of solution interchange. The metal in the growing crack tip (at KI KISCC) plastically deforms. Our measurements on locally deformed steel 40X13(1) and aluminum alloy 16(1) specimens in 3% NaCl solution showed the electrode potential on plastically deformed specimen surfaces can be more negative by 0.5 to 0.7 V than the potential of nondeformed surfaces.1 As a result, the metal dissolution rate at deformed surfaces is thousands of times higher than it is on nondeformed surfaces. The appearance of the crack (Figure 1) demonstrates the high local dissolution rate of the metal in crack tip. The measurements of the solution pH and of the electrode metal potential in the crack tip on 45.30X CHA(1), 12X18H10T steel(1), 16 aluminum alloy, and AT3 titanium alloy (Table 1) in 3% NaCl solution were made with antimony and silver-chloride micro-electrodes. The measurements were made with glass or fluorine plastic ร0.5 to 1.0 mm capillaries that were introduced into the crack tip through special cavities. The antimony micro-electrode had been calibrated in a series of buffer solutions. Experiments were performed on the 70 by 70 by 10 mm specimens in which a crack of 20 mm had been previously produced under static loading KI = 0.85 KISCC, which does not produce crack growth,2 and also on 10 by 20 by 150 mm specimens with an initial crack of 2 mm length at KI > KISCC, which does produce crack growth.3 All experiments were made immediately after the new surface at the crack tip formed. Experiments on the stable crack (i.e., where crack growth did not occur) were most useful in determining the type of reaction occurring at the crack tip. The solution pH and electrode metal potential in the crack tip were measured over time (Figure 2). All measurements showed initial acidification and subsequent alkalization of the crack tip solution. By converting the electrode potentials to corresponding pH values, a -pH trajectory during the test can be produced (Figure 2). The lines of hydrogen and oxygen electrode equilibrium potentials in Figure 3 show the crack tip metal electro-chemical state and the type of reactions occurring.
ABSTRACT The intergranular stress corrosion cracking (IGSCC) behavior of sensitized type 304 (UNS S30400)(1) stainless steel (SS) in high-temperature aqueous solutions has been extensively investigated1-6 and reviewed7,8 in relation to light water reactors. However, most studies have been conducted above 130ยฐC, especially at the reactor temperature of approximately 288ยฐC. Few studies have been carried out at approximately 100ยฐC.9-14 Ford and Povich9 reported IGSCC of sensitized type 304 SS during slow strain rate testing (SSRT) in pure water containing 1 to 2 ppm of oxygen at temperatures ranging from 50 to 100ยฐC. Ford and Silverman10 identified the potential range of 140 to 240 mV (standard hydrogen electrode [SHE]) over which IGSCC occurred at 100ยฐC, based on SSRT performed in 0.01 M solutions of Na2SO4 and NaCl. Herbsleb11 also observed IGSCC of sensitized type 304 SS in Na2SO4 and NaCl solutions at 100ยฐC in constant load tests (CLT). Cracking was obtained only
- Materials > Metals & Mining > Steel (0.71)
- Energy > Oil & Gas > Upstream (0.61)
- Energy > Power Industry > Utilities > Nuclear (0.54)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (0.98)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (0.98)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (0.87)
ABSTRACT Laboratory exposure tests involving chemicals commonly found in soil and an AC current flow between a tin-coated copper electrode and a surrounding electrolyte were conducted to provide data regarding the mechanism and rate of concentric neutral corrosion encountered in underground rural distribution systems. Experimental data supportive of an AC-induced pit initiation mechanism followed by autocatalytic pit growth are presented. In the absence of AC, the potential of tin-coated wire stabilizes at a more negative potential than that of bare copper wire, thus providing cathodic protection to exposed copper. In the presence of an AC signal, the potential of the tin-coated wire shifts to a more positive potential than that of the bare wire, indicating that AC-induced resistive currents on tin-coated samples passivate the tin coating, rendering it cathodic to the underlying copper. The large cathodic area leads to rapid pitting of the copper substrate at coating imperfections. INTRODUCTION Failure of underground rural distribution (URD) cables due to corrosion of the copper concentric neutral is an ongoing and increasing problem for the utility industry.1,2 The concentric neutral is a helical sheath of copper strands, often coated with tin or a lead/tin alloy, which surrounds a concentric structure consisting of a solid, high-voltage central conductor, a layer of insulating polyethylene, and a layer of semiconducting carbon-filled polyethylene (Figure 1). Corrosion of the concentric neutral is a relatively recent phenomenon. Commercial URD systems have been in service since the mid-1960s, and reports of neutral corrosion started to appear in the early 1970s.3 This was unexpected because of the apparently corrosion-free history of copper as a grounding material in the electrical power industry. Being negative to oxygen in the electromotive series but positive to hydrogen, copper can corrode by oxygen reduction but not by hydrogen evolution4,5 and, therefore, is thermodynamically stable in oxygen-free water. Accordingly, copper has a history of corrosion resistance as shown by archaeological artifacts. Some authors attribute the perception of a recent problem to the fact that, historically, underground copper components were frequently associated with buried steel structures which cathodically polarized the copper and created a less than justified reputation for corrosion resistance.7-9 A comprehensive study by the U.S. National Bureau of Standards found that the anions present, moisture content, pH, and level of aeration determined the corrosiveness of a specific soil type to copper.10 It also found that no specific soil composition is uniquely associated with corrosion and that corrosiveness cannot be predicted solely on the basis of soil
- North America > United States > Texas (0.16)
- North America > United States > New York (0.15)
- Energy > Power Industry (1.00)
- Materials > Metals & Mining > Tin (0.68)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
ABSTRACT During hot working processes for plain carbon and lowalloy steels, significant metal is lost to oxide scale formation. Scale also causes roll wear by abrasion during hot working. Expensive descaling operations can be minimized by restricting the oxidation of iron at high temperatures. Attempts to suppress scale formation by reheating steels in nonoxidizing environments and through rapid cooling have been moderately successful but are not applicable in all instances. There have been several attempts in recent years to apply inorganic compounds containing boron and silicon to steel surfaces to restrict oxidation.1-4 This Trade name.
- Production and Well Operations > Production Chemistry, Metallurgy and Biology (0.54)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (0.32)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (0.32)