Condensate Accumulation Research Articles

Water And Hydrocarbon Phase Trapping In Porous Media-Diagnosis, Prevention And Treatment

Abstract The entrapment of extraneous phases within porous media can occur in a number of different situations during drilling, completion, workover and production operations. The introduction of an additional immiscible phase, or an increase in an existing phase saturation within porous media can cause deleterious relative permeability effects which can substantially impact the permeability and relative permeability to oil or gas. This phenomenon is commonly described as aqueous phase trapping or hydrocarbon phase trapping, depending on the situation under consideration. This paper describes specific conditions required for the establishment of aqueous and hydrocarbon phase traps and provides diagnostic equations to evaluate the potential severity of an aqueous phase trap in a given reservoir situation. Specific procedures are recommended for the prevention of aqueous phase traps during drilling, completion and production operations and, in a situation where phase traps are determined to exist in a reservoir, a variety of treatment techniques are presented to attempt to remove or reduce the severity of the aqueous or hydrocarbon phase trapping phenomenon. Introduction Aqueous phase trapping and hydrocarbon phase trapping represent a significant mechanism of impaired productivity in many oil and gas reservoirs in various locations throughout the world. Bennion et al. (1994)(1) have provided a detailed discussion of the basic mechanisms of aqueous and hydrocarbon phase trapping and associated reductions in permeability. Aqueous phase trapping can occur in both oil and gas reservoirs and may be associated with reservoir situations where the reservoir exhibits a sub-irreducible initial water saturation. Specific additional documentation on subirreducible water saturation reservoirs is documented by Katz et al. (1982)(2) and Masters et al. (1984)(3). Hydrocarbon phase traps may be established in gas reservoir applications where extraneous immiscible hydrocarbon phases are introduced into the reservoir, or in retrograde condensate reservoir applications where the reservoir is produced at some pressure below the dewpoint resulting in the accumulation of liquid retrograde condensate within the pore space. This paper discusses various types of phase trapping and provides criteria for the diagnosis of the potential severity of a reservoir to be susceptible to aqueous phase traps. Additional discussion is then presented with respect to the prevention of aqueous and hydrocarbon phase traps in different reservoir operational situations and potential remediation of oil and gas reservoirs where aqueous or hydrocarbon phase traps have already been established. Mechanisms of Aqueous Phase Trapping Figure 1 provides a schematic illustration of the establishment of an aqueous phase trap within a low permeability gas reservoir application. The initial basis for the establishment of an aqueous phase trap is a reservoir which exists at what is classified as a subirreducible saturation, where the initial water saturation in the reservoir is less than what would be typically quantified as the irreducible water saturation which would exist in the porous media under the prevailing capillary conditions. Sub-irreducible saturations are postulated to be established by a combination of dehydration, desiccation, compaction and diagenetic effects which occur over the life of certain reservoirs.

Petroleum geochemistry of the Midyan and Jaizan basins of the Red Sea, Saudi Arabia

During the 1960s, petroleum exploration activities in the offshore Red Sea areas of Saudi Arabia tested gas and condensate reservoired in the Miocene sands immediately below the Mansiyah evaporites in the offshore Midyan basin. Recent onshore exploration activity in the Red Sea has resulted in the discovery of accumulations of oil, gas and condensate in the Lower Miocene Maqna Group in the Midyan and Jaizan basins. As a result of this exploration success, an effort to understand the origin of these hydrocarbons was initiated. The two basins were assessed geochemically by addressing: (1) the potential source rocks; (2) the extent of the hydrocarbon kitchens; and (3) characterization of the hydrocarbons. The potential source rocks for the reservoired hydrocarbons are: (1) the organic-rich, oil-prone shales of the predominantly evaporitic Mansiyah Formation; (2) the variable quality shales and carbonates of the Magna Group; and (3) the moderately organic-rich shales of the Burqan and Tayran Groups. The reservoired hydrocarbons were characterized by carbon isotopes, gas chromatography-mass spectrometry and gas chromatography and compared with the potential source rocks. The results showed an acceptable match to the Maqna and Burqan organic-rich units. Detailed burial history/thermal modelling projects were undertaken to assess the hydrocarbon kitchens of both basins. Results for the Midyan basin indicated that over large areas Tayran and Burqan sediments are oil to gas mature and may be sources for the gas and/or condensate accumulations, whereas the limited area of mature Maqna sediments may be responsible for sourcing the black oil accumulations. In the Jaizan basin, the Maqna and Burqan sediments range from high oil maturity to thermally spent due to high geothermal conditions and excessive burial. The burial of the source rocks increases fairly rapidly from east to west in the Jaizan basin.

Depositional Processes and Predictive Modelling of Deep Water Turbidite Sands of the Britannia Formation, Britannia Field, U.K. North Sea: ABSTRACT

The Britannia Field is a large gas condensate accumulation located 125 miles northeast of Aberdeen in the U.K. North Sea. The reservoir formation is Lower Cretaceous in age, and is composed of a wide variety of {open_quotes}deep{close_quotes} water turbidite sands. These were shed off surrounding highs and temporarily stored in a shelfal setting before being fed axially into the asymmetrical Wytch Ground Graben. Depositional compartmentalization resulted from sand input from both the east and west. The sands represent a localized regression associated with the Austrian Orogeny, set in an overall transgressive regime. Detailed core examination has resulted in the recognition of an unusual variety of facies types arising from sediment gravity flow processes that span the spectrum between turbidity current and debris flow. Sandy high density turbidity (HDT) flows give rise to {open_quote}conventional{close_quotes} HDT deposits. With the addition of mud, cohesion becomes an important factor, and its amount, nature, and distribution governs the behavior of the flow. The resulting flows are termed {open_quotes}Slurry flows,{close_quotes} and their deposits exhibit a spectrum of internal structures and properties that reflect the changing dynamics of clay/sand interactions. Understanding the depositional processes, within the framework of a chronostratigraphically sub-divided reservoir, has enabled predictive mapping ofmore » the facies distribution across the Field. Depositional pattern models are being tested by predrilling producing wells. Since there is an intimate link between lithotype, permeability, and gas saturation, the development of a predictive model has greatly increased the confidence in OGIP estimation.« less

Controls on the Distribution of Oil, Gas, and Gas-Condensate Pools in the Timan-Pechora Basin

The distribution of hydrocarbon pool in the Timan Pechora basin is controlled by various aspects of the geological structure and stratigraphy. Oil pools are confined to tectonically stable areas, and there are often stratigraphically trapped (Omra-Lizha saddle in the Izhma Pechora basin, Khoreyyer depression). Structures in more active tectonic areas (Pechora-Kolva aulacogen and Ukhta-Izhma swell) usually contain complex accumulations of oil, gas, and condensate. The mixed character of these pools proves their multistaged origin involving further gas charge during stages of increased subsidence in the kitchen areas and degassing of oil during later stages of uplift. However, active tectonics led not only to gas-cap development but also, in places, to complete loss of hydrocarbons at the surface. The Varandey Adzhva zone is an example, with its considerable volume of heavy and medium-heavy oils. In the Ural foredeep basins, older oil and gas accumulations at the outer edge and on transverse uplifts were enriched later by gas generated from deeply buried formation the axial part of the orogenic trough and its eastern border. Younger fold structures contain gas and gas-condensate pools charged by gas generated in both orogenic and preorogenic formations and by residual oils re-migrated from preorogenic accumulations that oncemore » existed in the pericratonic region.« less

The Bruce Field

The Bruce Field is a giant gas condensate accumulation which lies on the western side of the Viking Graben at the northern end of the Beryl Embayment. Although discovered in 1974, the Annex B was not approved until 1990 by which time the field had been shown to extend across three exploration licence blocks (9/8a, 9/9b and 9/9a) and to be extremely complex. There are three main elements to the complexity: structure, reservoir distribution and hydrocarbon charge. The major structural elements are the Western Flank (a rotated fault block) and the Eastern High with a central low between, the Central Panel; however, relatively poor seismic data quality makes detailed structural interpretation difficult. Each of these structural elements has a different hydrocarbon–water contact, with a proven range of nearly 500 m. The shallowest contact is found on the Eastern High and though the contact in the central low is nearly 350 m deeper, pressure data indicate that the gas leg is in communication with that in the Eastern High. The distribution of the main reservoir, the Middle Jurassic Beryl Group, and the magnitude of the unconformity that underlies it, appear to be controlled by earlier faults which are cross-cut by the present structure. The result of these complexities is that long hydrocarbon columns can be found in the structural lows, and thick reservoir successions can occur on the structural highs.

Facies analysis of the Kopervik sand interval, Kilda Field, Block 16/26, UK North Sea

Abstract The Kilda Field is a large gas condensate accumulation located in UK Block 16/26. The reservoir sands, informally termed Kopervik, are Lower Cretaceous in age and are developed on the southern dip slope of the Fladen Ground Spur. They represent a localized sandy development within the lower Sola and upper Valhall formations, associated with the Austrian orogeny. Sands were carried out into the basin by a variety of sediment gravity flow processes, and were deposited as an apron near the foot of the slope. Their distribution is controlled largely by the nature of the flow and by pre-existing topography. Six main sand facies have been recognized, three of which are high-density turbidite (HDT) types and contain virtually all reservoir quality rock. HDT S 3 sands resulted from suspension collapse. They exhibit porosities around 15%, and permeabilities around 40 md. HDT Laminated sands probably formed from traction sedimentation. They have similar average porosities but reduced permeabilities between 10 and 15 md. Sands of the Marginal facies are of an inferior reservoir quality. The remaining three facies consist of non-reservoir quality sands deposited by liquefaction, debris or low-density turbidite flow. Post-depositional disturbance suggests that deposition took place on an unstable palaeoslope. Subsequent porosity loss within clean sand intervals has been dominantly through compaction.

Regional Jurassic geologic framework of Alabama coastal waters area and adjacent Federal waters area

To date, numerous Jurassic hydrocarbon fields and pools have been discovered in the Cotton Valley Group, Haynesville Formation, Smackover Formation and Norphlet Formation in the tri-state area of Mississippi, Alabama and Florida, and in Alabama State coastal waters and adjacent Federal waters area. Petroleum traps are basement highs, salt anticlines, faulted salt anticlines and extensional faults associated with salt movement. Reservoirs include continental and marine sandstones, limestones and dolostones. Hydrocarbon types are oil, condensate and natural gas. The onshore stratigraphic and structural information can be used to establish a regional geologic framework for the Jurassic for the State coastal waters and adjacent Federal waters areas. Evaluation of the geologic information along with the hydrocarbon data from the tri-state area indicates that at least three Jurassic hydrocarbon trends (oil, oil and gas condensate, and deep natural gas) can be identified onshore. These onshore hydrocarbon trends can be projected into the Mobile area in the Central Gulf of Mexico and into the Pensacola, Destin Dome and Apalachicola areas in the Eastern Gulf of Mexico. Substantial reserves of natural gas are expected to be present in Alabama State waters and the northern portion of the Mobile area. Significant accumulations of oil and gas condensate may be encountered in the Pensacola, Destin Dome, and Apalachicola areas.

238U decay series systematics of young lavas from Batur volcano, Sunda Arc

Abstract Activities of 238U decay series radioisotopes have been determined for both postcaldera basalts erupted between 1849 and 1974 and genetically related young precaldera dacites from Batur volcano, Bali, Sunda arc. All rocks possess (230Th/238U) = 1 within 2 sigma error indicating that little, if any, fractionation between Th and U occurred during their genesis, or in their source regions, within approximately the last 350 ka. Both the basaltic and the dacitic rocks possess (230Th/232U) ∼ 0.71, consistent with both having a common mantle source with an unusually high Th/U weight ratio of 4.4 and with the dacitic magma having formed by closed-system convective fractionation of the same basaltic magma from which the postcaldera lavas were derived. The historical basalts possess ( 226 Ra / 230 Th ) > 1 , indicating a significant Ra enrichment relative to Th and U within approximately the last 8 ka. The highest degree of 226Ra enrichment occurs in the most mafic basaltic lavas, which form a cycle of mafic volcanism between 1888 and 1926. If Ra enrichments were produced during mantle-melting as a result of its greater incompatibility relative to Th then variations in (236Ra/230Th) may reflect the presence at Batur of a periodically replenished, but poorly mixed, open-system magma chamber. In addition, this result implies that the primitive Batur basaltic magmas take considerably less than about 8 ka to travel from their mantle source through the Batur magma chamber to the surface. Whole rock ( 210 Pb / 226 Ra ) > 1 in the youngest historical basalts indicates that Pb has been enriched relative to Ra within about 100 years of their eruption. Because Pb is expected to be less incompatible then Ra during mantle melting, the enrichments are probably due to late stage processes, such as accumulation of 210Pb-rich plagioclase phenocrysts or post-eruptive condensation of volatile Pb salts in vesicles.

Experimental study of the viscosity of lithium vapor at high temperatures

The viscosity of lithium vapor was measured at temperatures from 1600 to 2000 K and pressures from 0.02 to 0.1 MPa with an experimental setup consisting of a closed circuit with a short annular channel used as a measuring element. The accuracy of the data obtained was estimated to be 3–4%. The characteristic features of the designed apparatus are the following: a high stability of the pressure difference within the viscometer during experiment, the absence of condensate accumulation out of the flowmeter, and a sufficiently large flowmeter volume. Since the length of the measuring section is short, the hydrodynamics of the gas flow through an annular channel were studied carefully. This enabled us to introduce the necesary corrections in the working equation. The results obtained are compared with available experimental data and the results of theoretical calculations.

The effects of zinc chloride on the RNP structures in HEp-2 cells: Accumulation of perichromatin granules

The effects of zinc on the ribonucleoprotein (RNP) constituents of HEp-2 cells have been analyzed. Pulse-chase autoradiographic experiments show a preferential inhibition of nucleolar RNA synthesis and a block in the transport of nucleolar and extranucleolar RNA in zinc-treated cells. Concomitantly with the disturbance in RNA metabolism and in protein synthesis, nucleolar condensation, accumulation of perichromatin granules and fibrils, condensation of interchromatin fibrils, and appearance of dense granular bodies occur. Accumulation of perichromatin fibrils and condensation of interchromatin fibrils appear to be related to the block in the transport of heterogeneous nuclear RNA. Depletion of certain proteins required for the assembly of RNP particles could share in the abnormal behavior of RNA and lead to the accumulation of perichromatin granules and the appearance of dense granular bodies.

Condensing Heat Transfer Enhancement on Vertical Spiral Double Fin Tubes With Drainage Gutters

Spiral double-fin tubes with drainage gutters are proposed for a vertical condenser to achieve high-condensing heat transfer performance for ocean thermal energy conversion application. There aluminum tubes have 5 or 10 spiral primary fins per pitch of spiral drainage fin. The condensation occurs mainly on the 0.8-mm-high primary fins; the 2-mm-high drainage fin collects the condensate from the primary fins, and a vertical drainage gutter removes the condensate from the drainage fin. Thus performance degradation due to accumulation of condensate in the vertical direction is avoided. Experiments were carried out using R-22 (chlorodifluromethane) as the working fluid in a shell using seven aluminum tubes (900 mm in effective length and 20 mm in nominal diameter). The drainage fin pitch, the primary fin pitch, shape of primary fin, and number of drainage gutters per tube were selected as parameters. One of the tubes had a 0.2-mm-thick titanium cladding on the inside (water side). The measured working-fluid-side condensing heat transfer coefficients for these tubes were four to six times those for a smooth tube based on the outer surface area.

Ventilation of Timber Flat Roofs

Reviewed here is a major co-operative investigation in Denmark into the effect of ventilation of timber flat (cold) roofs to combat condensation and moisture accumulation. Field measurements of moisture content in a number of test roofs over long periods and under different conditions are evaluated and conclusions drawn. They include the advice that, where moisture accumulation is a problem, it can be aggravated if roof vents are installed.

Recovery of Retrograde Condensate from Naturally Fractured Gas-Condensate Reservoirs

Abstract This paper considers the flow behavior of retrograde condensate in naturally fractured gas-condensate reservoirs and the possibility of recovering part of the condensate by gravity drainage. The analysis is applied to calculate the potential for retrograde condensate recovery in the Waterton reservoir in Alberta. The calculated results are in agreement with field observations: for fracture density, matrix permeability, and reservoir-layer thickness typical of the Waterton reservoir, a small part of the retrograde liquid will accumulate within a practical time span. Condensate accumulation and recovery will significantly increase if the reservoir pressure is restored—e.g., by lean gas or nitrogen injection.

Geologic Factors Affecting Reservoir Analysis, Anschutz Ranch East Field, Utah and Wyoming

Introduction The Anschutz Ranch East field, a retrograde condensate accumulation discovered in late 1979, was soon recognized as the jewel of the U.S. Western Over thrust Belt and as one of the most significant recent discoveries in the entire U.S. At this early stage of development, many questions are not vet answered, including the extent of the structures and the magnitude of reserves. Recent interpretations shown in this study are in some ways speculative and are expected to change as new data become available. Regionally, as shown in Fig. 1, the field is within the Absaroka thrust sheet, one of four major northeast/ southwest-striking, rock, packages believed to have been thrust eastward during Cretaceous and early Tertiary time. Total crustal shortening across these major thrust faults is estimated to be nearly 60 miles (96.6 km). The field lies along the narrow northeast/southwest-striking Mesozoic liquids trend that presently extends northward from Pine view field to Painter reservoirs and Ryckman Creek fields. This Mesozoic trend is parallel to and east of the Paleozoic sour gas trend producing from fields such as the Whitney Canyon-Carter Creek field. The source for Nugget hydrocarbons in the liquids trend is believed to be sub thrust Cretaceous. Migration may have coincided with the structural evolution of the overriding thrust sheet and probably continued after cessation of movement. This paper presents an overview of geologic factors that influence initial reservoir analysis and performance prediction at Anschutz Ranch East. A more detailed prediction at Anschutz Ranch East. A more detailed geologic discussion is presented in Ref. 5. In early stages of development, gross structural interpretation and the prediction of reservoir size and orientation is paramount. prediction of reservoir size and orientation is paramount. As development proceeds, geologic input becomes more specialized to include small-scale structural, stratigraphic, and diagenetic factors. At Anschutz Ranch East, pressure maintenance must be instituted before any pressure maintenance must be instituted before any retrograde condensate is produced. Therefore, geologic data normally associated with secondary recovery studies are in this case needed for initial reservoir development. Because reservoir pressure is so close to the dew point pressure, the field is essentially shut-in until pressure pressure, the field is essentially shut-in until pressure maintenance in the form of hydrocarbon gas and nitrogen injection is begun. Currently, the working interest owners, including Amoco Production Co., The Anschutz Corp., Champlin Petroleum, BWAB Inc., Tom Brown Inc., Mesa Petroleum, BWAB Inc., Tom Brown Inc., Mesa Petroleum Co., and Gulf Oil Exploration and Production Petroleum Co., and Gulf Oil Exploration and Production Co., are collaborating to form a development unit. Amoco Production Co. will be the major interest holder and the field operator. Evolution of Structural Interpretation The size and orientation of the reservoir is of major importance in evaluating a hydrocarbon accumulation. At this time, more than 2 years after the discovery, and with more than 20 additional pay penetrations, delineation of the field remains a critical and dynamic issue. To illustrate the importance of gross structure mapping, several historic interpretations are presented. These interpretations were made from the best subsurface well-control and seismic data available at the time. At the surface, Tertiary terrestrial sediments overlie the field. These surface beds are structurally detached from underlying rock units and therefore provide little information on deeper structures. JPT P. 1539

Vapour condensation and corrosive attack in exhaust systems

The service life of mild steel exhaust systems is limited mainly by corrosion. A useful life of two or three years is typical. Design changes can be made to extend this period, but because the process of corrosive attack is poorly understood, the changes are not necessarily as cost effective as possible. To address this problem, the way exhaust vapours condense and accumulate in a standard system has been studied. Dew point temperatures have been measured to be 48°C, and the time dependent accumulation of condensate in the rear muffler box has been recorded. The relationship between system temperature, condensate accumulation, and corrosion is discussed. The use of thermal insulation to reduce problems of condensate accumulation has been investigated. Experiments show that the increase in system temperature results in a substantial reducton in liquid accumulation at points prone to corrosive attack.

Hoadley--A Potential Supergiant Gas Field in South-Central Alberta, Canada: ABSTRACT

The Hoadley gas field is a potential supergiant gas condensate accumulation, discovered in November 1977 by Sundance Oil. The discovery well, Sundance et al Hoadley 6-2, has an AOF of 26 mmcf of gas per day with 60 bbl of natural gas liquids per mcf of gas. The field covers approximately 1,500 mi2 (3,885 km2) in south-central Alberta. The producing zone is in the Lower Cretaceous Glauconitic formation consisting of 25 to 80 ft (7.6 to 14.4 m) of sandstone pay. The sand was deposited as a gigantic marine barrier bar with an approximate width of 15 mi (24 km) and a length of more than 130 mi (209 km), trending southwest-northeast across south-central Alberta. The central and southwestern part of the barrier bar (approximately 100 mi [161 km] long) is e tirely saturated with gas and natural gas liquids. Of more than 100 Glauconitic gas wells completed within this section of the barrier bar since discovery, none has tested or produced salt water. The field is estimated to contain a potential recoverable reserve of 6 to 7 tcf of gas, and a potential recoverable reserve of 350 to 400 million bbl of natural gas liquids. End_Page 961------------------------------ The geology of the Hoadley gas field is a classic example of a modern barrier-bar complex. Principal facies recognized in the studied area include marine shale, bay, barrier sand bar, eolian sand ridge, tidal channel, levee, inter-bar lagoon, and back-bar washed sands. A deltaic complex, found immediately to the southeast of the barrier bar, includes deltaic distributary channel and abandoned channel sand facies. Each of these facies can be recognized from diagnostic electric-log characteristics. End_of_Article - Last_Page 962------------

Procedures and Modifications for Reliable Use of the Unidirectional Microflow Respirator in the Investigation of the Carotid Body of Gallus domesticus

An artificial respirator was used to ensure successful and precise artificial respiration in short and long term experiments during radical exposure of the caudal cervical region and thoracic cavity to investigate cytological changes in the carotid body of mature chickens (Gallus domesticus). Modification of the respirator to stabilize gas flow, temperature and humidity consisted of replacing the ball check valve in the heating and humidifying cylinder with a fine regulating stopcock in the water outlet of the cylinder and inserting eight glass rods in a circle inside the cylinder. Accumulation of water condensate in the trachea and lungs during long term experiments was prevented by inserting a cotton filter moisture trap in the tracheal cannula.

Compositional Simulation to Develop an Optimnum Gas Cycling Scheme At The Kaybob Beaverhill Lak C Pool, Alberta

Abstract This paper discusses the application of a compositional model to develop an optimum exploitation scheme for the C Pool gas condensate reservoir. Performance predictions of a straight blowdown and three cycling schemes involving different replacement ratios have been obtained. Considerable emphasis was placed on predicting the reservoir rock properties in a highly heterogeneous reservoir such as the Kaybob Beaverhill Lake C Pool, and on the phase-behaviour matching of data derived from laboratory studies. Also, a productivity loss factor which results from condensate accumulation in the vicinity of the wellbore was incorporated in the model. These special features were necessary to increase the reliability of model predictions while cycling. During the development of the compositional model, a good match of phase behaviour of the reservoir fluid was obtained and so ensured a reliable prediction of gas cycling. Predictions indicated that cycling was technically feasible and that recovery of an additional two million barrels of hydrocarbon liquids will occur when compared to a straight blowdown scheme. This simulation study formed the basis of an application filed with the Energy Resources Conservation Board of Alberta requesting approval to implement a gas cycling scheme in the Kaybob Beaverhill Lake C Pool. Introduction The Kaybob Beaverhill Lake C Pool, discovered in 1961, is approximately 180 miles northwest of Edmonton, Alberta (Map 1) It is a gas condensate or dew-point reservoir having a hydrocarbon liquid content of approximately 190 bbl/MMcf. The volumetric original raw gas-in-place is estimated at 82 Bcf. Exploitation of the pool is expected to commence early in 1979 through five wells located in Townships 63 and 64, Range 18 west of the Fifth Meridian. Originally, it was believed that this gas condensate reservoir was in communication with an oil reservoir toward the northwest of the Kaybob Beaverhill Lake area. However, reservoir fluid analyses from wells 12-24-63-18 and 10-4-64-18 as well as pressure surveys in wells 2-4, 10-4 and 4-10-64-18 led to the conclusion that [he East Kaybob Beaverhill Lake area consisted of a saturated volatile oil reservoir and a gas condensate reservoir which do not communicate(1). This was further confirmed with the drilling of 11-3-64-18 well, which encountered the early postulated permeability barrier. The well was then subsequently abandoned. Because production from this gas condensate reservoir under a straight blowdown could be detrimental to hydrocarbon liquids recovery due to retrograde liquid loss during depletion, gas cycling can be carried out to maintain the reservoir pressure and minimize retrograde loss by simultaneously changing the reservoir fluid composition. Data for the Model Study Reservoir Description & Fluid Properties The Kaybob Beaverhill Lake C Pool is part of the Swan Hills reef limestone development. The reservoir dips toward the south and west, as indicated by the structure contour map of the bottom of the pool (Map 2). Maximum net pay thickness, based on the reef section encountered in the 12–24 well, is 195 feet (6875–7070 ft subsea). The hydrocarhon-porosity-foot.ge distribution is shown in Map 3.

Migration of Fluids in Sedimentary Basins

The basic mechanisms governing the migration of water and hydrocarbons in sedimentary basins are related ultimately to basinal structural history, rock properties, compaction, and temperature regime, which themselves are interdependent. Compaction of the sedimentary rocks promotes the expulsion of water during the progressive burial of the sediments. The physical-chemical properties of the rocks are responsible for the migration of the expelled water toward the surface and for the distribution in the basin of various parameters such as hydraulic potential, salinity, heat flow, temperature, and cementation. Primary migration is used herein to refer to migration of hydrocarbons soon after their generation; secondary migration refers to their delayed movement. Oil has difficulty migrating in shaly rocks. A possible way of removing oil from a source rock, in addition to the colloidal or true solubilization in water or the flow in a three-dimensional oil-wet kerogen network, is through its solubilization in high-pressure gas generated in the deeper part of the basin and coming up through preferential paths such as faults and fractures. Molecular distillation of the oil occurs because its vapor pressure in the liquid phase is higher than the vapor pressure in the gaseous phase. In the upper part of a lithologic column, retrograde condensation occurs and gas and condensate accumulations start to form below little compacted plastic caprocks. Owing to the high displacement pressures of the gaseous column, gas can pass through the caprock and disperse to the surface while the condensate remains in place. The pore-size distribution of the little compacted shaly caprock is responsible for the chemical and isotopic fractionation of the rising gas; almost pure and isotopically light methane thus is found in the upper layers of a stratigraphic column. High-volatile oil can be easily degraded by circulating water, especially in the presence of sulfate ions, hydrogen sulfide, and bacteria, and transformed progressively to heavy oil. Geochemical tools which can be used by explorationists in prospecting for new oil and gas fields include isotope analysis, hydraulic potential, salinity, temperature, cementation, maturity, and maps of shows.

Possible Water Vapor Condensation in Rocket Exhaust Plumes

In an attempt to explain the observed radiance in the exhaust plume of an Apollo engine, the possibilities of any condensation by homogeneous nucleation under the conditions in the plume flowfield are examined. It was found that only H2O could condense, the other species present in the exhaust, H2, remained unsaturated. Under the assumption of steady-state homogeneous nucleation, the accumulation of condensate as a function of the streamline coordinate has been computed from the Oswatitsch integral with empirical information gathered in previous experiments. Condensation is thus estimated to occur at about 45 m downstream of the nozzle exit. However, it has been found that the steady-state nucleation assumption may not be valid here, and the previous estimate may be too optimistic. Condensation under nonsteady homogeneous nucleation conditions would result in delayed condensation onset or none at all. A potentially useful alternative way of estimating condensation in plumes is outlined. Finally, keeping in mind that condensation may be induced by binary or heterogeneous nucleation, both of which favor earlier condensation onset, we conclude that condensation is not impossible in this exhaust plume.