Showing papers by "Mobil published in 1997"

Statistical characterization and stochastic modeling of pore networks in relation to fluid flow

Abstract: Flow properties of reservoir rocks can be computed from an accurate depiction of the porosity network in three dimensions available from synchrotron Xray microtomography. In order to relate computed transport properties to the input dataset, the complex pore networks must be described statistically. A porous media description was deemed adequate if a synthetic medium, possessing similar transport properties, could be generated from acquired statistical information. Synthetic media, based upon Berea sandstone extended variogram statistics, were generated with an actual slice from a 3-D microtomographic image as conditioning data. Control of local porosity variation was observed to be important in the stochastic simulation of porous media by the simulated annealing method, as inclusion of this higher order constraint data reproduced natural variations observed in pore-size distributions. Realizations with the traditional variogram as the only target in the objective function did not honor poresize distribution information. Permeability estimates by the lattice Boltzmann method indicated that the proper level of interConnectivity was not achieved during geostatistical modeling with only two point spatial statistics. Connectedness information, readily available from primary drainage capillary pressure data, forced permeability estimates of synthetic media in the direction of the permeability computed for the parent microtomographic image of Berea sandstone. As a result of this study, it was concluded that global spatial correlation statistics, for example, the traditional variogram, must be supplemented with local variability and connectivity information to adequately characterize a three-dimensional property distribution for fluid transport. Extended porosity spatial correlation structure, extracted from standard imaging techniques, and a capillary pressure drainage curve are perhaps sufficient to characterize a system in terms of pore size, connectedness, and permeability. However, more rapid algorithms are needed to introduce porosimetry information as standard practice in stochastic modeling by the simulated annealing method.

Process for making gas hydrates

Abstract: The present disclosure provides a process for continuously producing clathrate hydrate. This process includes the step of: (a) pressurizing a hydrate-forming gas to an elevated pressure and cooling the hydrate-forming gas below the gas-water-hydrate equilibrium point at the elevated pressure; (b) cooling liquid water below the gas-water-hydrate equilibrium temperature for the elevated pressure; (c) charging hydrate-forming gas at the elevated pressure into a reaction zone which contains a movable surface; (d) atomizing water in the reaction zone in contact with the hydrate-forming gas to form gas hydrate in the reaction; (e) depositing the gas hydrates on the movable surface; and (f) collecting the gas hydrates from the movable surface.

Reinterpretation of Depositional Processes in a Classic Flysch Sequence (Pennsylvanian Jackfork Group), Ouachita Mountains, Arkansas and Oklahoma: Discussion

Abstract: The Pennsylvanian Jackfork Group in the Ouachita Mountains of Arkansas and Oklahoma has conventionally been interpreted by many workers, including us, as a classic flysch sequence dominated by turbidites in a submarine fan setting; however, normal size grading and Bouma sequences, indicative of turbidite deposition, are essentially absent in these sandstone beds. They appear massive (i.e., structureless) in outcrop, but when slabbed reveal diagnostic internal features. These beds exhibit sharp and irregular upper bedding contacts, inverse size grading, floating mudstone clasts, a planar clast fabric, lateral pinch-out geometries, moderate to high detrital matrix (up to 25%), sigmoidal deformation (duplex) structures, and contorted layers. All these features indicate sand mplacement by debris flows (mass flows) and slumps. Mud matrix in these sandstones was sufficient to provide cohesive strength to the flow. Discrete units of current ripples and horizontal laminae have been interpreted to represent traction processes associated with bottom-current reworking. The dominance of sandy debris-flow and slump deposits (nearly 70% at DeGray Spillway section) and bottom-current reworked deposits (40% at Kiamichi Mountain section), and the lack of turbidites in the Jackfork Group have led us to propose a slope setting. Our rejection of a submarine fan setting has important implications for predicting sand-body geometry and continuity because deposits of fluidal turbidity currents in fans are laterally more continuous than those of plastic debris flows and slumps on slopes. A turbidite-dominated fan model would predict an outer fan environment with laterally continuous, sheetlike sandstones for the Jackfork Group in southern Oklahoma and western Arkansas, whereas a debris-flow/slump model would predict predominantly a slope environment with disconne ted sandstone bodies for the same area.

Alternate-path well screen having protected shunt connection

Abstract: An alternate-path, well screen made-up of joints and having a sleeve positioned between the ends of adjacent joints which acts as a manifold for fluidly-connecting the alternate-paths on one joint with the alternate-paths on an adjacent joint.

Metallized multilayer packaging film

Abstract: A metallized multilayer film comprising a film substrate having a polymer core layer, e.g., a polypropylene homopolymer (OOP), on at least one surface of which is a polymer skin layer having a lower melting temperature than that of said core layer, the exposed surface of skin layer having been treated, e.g., flame or corona discharge treated, prior to coating to increase its adherence to other materials, the film substrate containing a metal deposit, e.g., aluminum, coated on the treated surface of the polymer skin layers, and a polymeric, low temperature sealable coating (LTSC) comprising a copolymer of 10 to 35 wt.% of at least one alpha, beta-ethylenically unsaturated carboxylic acid, e.g., acrylic or methacrylic acid, with 65 to 90 wt.% of ethylene, an alkyl acrylate or methacrylate, acrylonitrile, or mixtures thereof on the surface of the metal deposit.

Potential risks when using seismic attributes as predictors of reservoir properties

Abstract: The advance of our ability to generate seismic attributes and the growing emphasis on production geophysics has led to the widespread use of seismic attributes as predictors of reservoir properties. In many cases, we can show — using seismic modeling or rock physics — a physically justifiable relationship between a seismic attribute and the reservoir property of interest. When this is true, we are able to greatly reduce the uncertainty of interwell predictions of reservoir properties.

Method for producing gas hydrates utilizing a fluidized bed

Abstract: An apparatus for producing gas hydrates includes a reactor vessel having a fluidized or expanded bed reaction zone. The reactor vessel has an upper portion and a lower portion, wherein a cross-sectional area of the upper portion is larger than a cross-sectional area of the lower portion. Water is introduced into the reactor vessel, and hydrate-forming gas is introduced, under an elevated pressure, into the lower portion of the reactor vessel. Preferably, the water and gas flow in a countercurrent manner through the reactor and into the fluidized or expanded bed reaction zone. The apparatus can include a mechanism for withdrawing unreacted hydrate-forming gas from the upper portion of the reactor vessel and recycling it back into the fluidized or expanded reaction bed. A defrosting device can be included with the reactor so that at least a portion of at least one wall of the reactor vessel can be defrosted. The invention further relates to methods for using a fluidized or expanded bed reactor to produce gas hydrates.

Method and apparatus for treating long formation intervals

Abstract: A method and apparatus for treating a long interval within a wellbore wherein a treatment fluid is delivered to selected levels within the interval by blocking flow to certain zones while allowing flow to others. A treatment tube extends substantially through the interval and is comprised of a perforated conduit which is open at its upper end and which has a plurality of openings spaced along its length. Each of the openings have a valve seat within said conduit at its entrance which is adapted to receive a valve means to seal and block flow through that opening. In operation, a treatment fluid is flowed through the treatment tube and out the openings into different levels within said wellbore. At desired intervals, valve means are introduced into the treatment fluid and are carried into the treatment tube to seat at a respective opening to thereby block flow through that opening while allowing continued flow through others

Erosion-resistant inserts for fluid outlets in a well tool and method for installing same

Abstract: A well tool having at least one alternate flowpath for delivering fluid to different levels in a wellbore wherein the flowpath is comprised of a conduit having a plurality of outlets spaced along its length which, in turn, are provided with inserts of erosion-resistant material to alleviate erosion of the outlets.

Alternate path well tool having an internal shunt tube

Abstract: A gravel-pack, well screen having an internal shunt tube positioned inside the screen for delivering gravel slurry to different levels within the well annulus during a gravel pack operation. The screen includes one or more joints with each joint includes a base pipe having a screen section therein. The internal shunt extends substantially throughout the length of the base pipe. Bolts, each having a passage therethrough, provide fluid passages between the exterior of the screen and the internal shunt tube near either end of the base pipe. During operation, slurry enters the internal shunt tube through the uppermost bolt and exits into the annulus through the passages in the lower bolts to distribute gravel to to different levels of the annulus.

The Carboniferous of Western Europe; the development of a petroleum system

Abstract: A consistent stratigraphic study of the western European Carboniferous Basin has allowed the generation of eight palaeogeographic timeslices. These illustrate a model of large scale eastern (dextral) tectonic escape on the northern side of a convergent margin and integrate the diverse tectonic and sedimentary settings observed within the basin as a whole. This model can be compared to the present day eastern Mediterranean, where a similar range of diverse tectonic settings are observed. Reservoir and source distribution is discussed for each time-slice along with the present distribution of Carboniferous oil and gas fields. Due to the diversity observed no unique play type can be distilled from the data to explain the distribution of hydrocarbons within the studied area.

Transalkylation process for producing aromatic product using a treated zeolite catalyst

Abstract: A heavy aromatics feed is converted to lighter aromatics products, such as benzene, toluene and xylenes by contacting a C9 + aromatics fraction and benzene and/or toluene over a catalyst comprising a zeolite, such as ZSM-12, and a hydrogenation component, preferably platinum The catalyst, complete with hydrogenation component, is treated to reduce aromatics loss Treatment includes exposure to steam and/or sulfur after incorporation of the hydrogenation component For additional stability and aromatics retention the steamed and/or sulfur treated catalyst is sulfided by cofeeding a source of sulfur In a further embodiment of the invention a low hydrogen partial pressure is employed to retain aromatics

High moisture barrier polypropylene-based film

Abstract: A polymeric film having improved moisture barrier characteristics and enhanced mechanical properties. The film has a base layer which includes a blend of a high crystallinity polypropylene having an isotactic stereoregularity greater than 93 %, a conventional isotactic polypropylene having an isotactic stereoregularity of from 90 % to 93 %, and up to 9 % by weight of a resin modifier.

Stress Magnitudes From Logs: Effects of Tectonic Strains and Temperature

Abstract: An improved method of calibrating in-situ stress logs has been validated with data from two wells. Horizontal stress profiles are useful for hydraulic fracture design, wellbore stability analysis, and sand production prediction. The industry-standard method of estimating stresses from logs is based on overburden Poisson's ratio, and pore pressure effects and outputs an estimate of minimum horizontal stress. The model proposed here adds effects of temperature and tectonics and outputs minimum and maximum horizontal stress magnitudes, which are particularly important to the successful completion of horizontal and deviated wells. This method was validated using data collected from a GRI research well and a Mobil well. Seven microfrac stress tests in GRI's Canyon Gas Sands well of Sutton County, TX, provided a means of comparing the predictive capability of different methods. First, one of the seven stress tests was selected as a calibration standard for the stress log. Then the results obtained from the two calibration methods were compared to stress magnitudes from the other six stress tests. This process was repeated using each of the seven stress tests as a calibration standard and comparing predictions to the other six. In every case, the method incorporating tectonic and temperature effects produced significantly more accurate values. In the Mobil well, pre-frac treatment breakdown tests were used to calibrate a log-derived stress profile. While reservoir pressure dominated stress variations, a significant deviation of the log value from the stress-test value in one layer was corrected when the method with tectonics and temperature was used.

Fluid bed process for para-xylene production

Abstract: Para-xylene is produced by toluene methylation by charging toluene and a methylating agent to a fluidized bed of catalyst at a rate sufficient to maintain the fluidized bed in a turbulent sub-transport flow regime, reacting the toluene with the methylating agent, and recovering para-xylene from the fluidized bed. The fluidizable catalyst is a microporous material having a Constraint Index of about 1 to about 12. The relative concentration of the catalyst particles having a major dimension of less than 40 microns is controlled at between about 5 and 35 weight percent. The catalyst particles have an apparent particle density of about 0.9 to 1.6 grams per cubic centimeter, a size range of about 1 to 150 microns, and average particle size of about 20 to 100 microns.

Common angle imaging with offset plane waves

Abstract: Migration is commonly used as a wavefield focussing tool in the study of the variation of reflection amplitude with offset (AVO), or with angle of incidence at reflectors. Migrations are typically applied to common offset or common incident angle sections. In many processing systems, common angle sections are formed by simple l-d transformations from offset to angle of common midpoint (CMP) gathers based on ray tracing. In this paper, we provide a wave-equation framework for migrating common incidence angle sections that have been formed from Radon transforms over offset in CMP gathers. Radon transformation of the scalar wave equation results in an independent wave equation for each offset plane wave. The offset plane wave equation is nearly equivalent to the zero offset wave equation, except for an additional term related to dip in the midpoint direction, and to offset ray parameter (angle of incidence at the surface). Within this framework, finite difference, pseudo-spectral, and Kirchhoff migrations for common angle sections can be easily adapted from existing algorithms. The availability of a wave equation for common angle sections allows rigorous and efficient application of wave equation techniques for AVO studies and complex structural imaging problems.

Two-side coated label facestock

Abstract: A label facestock structure is described which comprises a polymeric film substrate having on a first surface thereof (A) an adhesive anchor layer and on a second surface thereof (B) an ink base layer, the (A) and (B) layers are selected from the group consisting of: (i) a prime coating having on an external surface a functional coating of an interpolymer of (a) an ς,ς-monoehtylenically unsaturated carboxylic acid; and (b) a neutral monomer ester comprising an alkyl acrylate ester and an alkyl methacrylate ester; and (ii) an iminated polymer; or the (A) adhesive anchor layer is selected from the group consisting of: (iii) a mixture of the functional coating of (i) and the iminated polymer of (ii); (iv) a linear water dissipatable polyester condensation product; and (v) a polyester or the (B) ink base layer is selected from the group consisting of: (vi) a prime coating having on an external surface a functional coating of an acrylic copolymer; and (vii) a prime coating having on an external surface a functional coating of a styrene copolymer provided that each of the (A) adhesive anchor layer and the (B) ink base layer is different.

Reservoir architecture and porosity distribution, Pegasus Field, West Texas – an integrated sequence stratigraphic–seismic attribute study using neural networks

Abstract: This case study shows the benefit of using multiple seismic trace attributes and the pattern recognition capabilities of neural networks to predict reservoir architecture and porosity distribution in the Pegasus Field, West Texas. The study used the power of neural networks to integrate geologic, borehole and seismic data. Illustrated are the improvements between the new neural network approach and the more traditional method of seismic trace inversion for porosity estimation. Our procedure is straight forward but does require careful quality control to insure reliable predictions from the seismic data. Network training, test and validation data sets provide calibration of seismic attributes with well log data, optimize the network parameters, and estimate the performance of the system to predict hidden representative data. Comprehensive statistical methods and interpretational/subjective measures insure that only attributes providing true relationships and a physical basis are used in the prediction of porosity from seismic attributes. The result, a 3-D volume of seismic derived porosity estimates for the Devonian Reservoir interval of the Pegasus Field, provide our reservoir development team with a very detailed estimate of porosity, both spatially and vertically, for the field. The additional reservoir porosity detail provided, between the well control, allows for optimum placement of horizontal wells and improved field development.

Producing fluids from subterranean formations through lateral wells

Abstract: Method and apparatus for producing fluids from a production zone(s) by drilling and completing multiple laterals from a primary wellbore. One or more pre-formed window units are provided in a casing string before it is cemented in the well. Each unit is comprised of a housing having an inlet and two outlets, one of which forms the pre-formed window. The axes of the two outlets forms a relatively small angle (e.g. 1' to 10', preferably 3°) whereby a well string will follow a gently curved path as it exits through the window. A re-entry line from the surface can be attached to the housing so that a work-over string can be lowered into a selective lateral without having to shut-in production from the other laterals.

Another perspective on AVO crossplotting

Abstract: “Principles of AVO crossplotting” by Castagna and Swan (TLE, April 1997) raises some very interesting points and we would like to add to the discussion. Crossplotting the AVO attributes is useful for interpreting anomalies in the context of lithology and pore fluids. Also, crossplotting shows that there is a background trend for reflections from nonhydrocarbon related interfaces. This trend, which we call the fluid line, comes from correlations of rock properties. To relate AVO anomalies to rock and pore fluid properties, it is important to calibrate background (nonhydrocarbon‐related) seismic attributes to the background rock property trend. Once the trend is established then a quantitative interpretation of an anomaly can be made.