Contact Movement Research Articles

4D signal enhancement using singular‐value decomposition: application to mapping oil–water contact movement across the Nelson Field

ABSTRACTA new method for time‐lapse signal separation and enhancement using singular‐value decomposition is presented. Singular‐value decomposition is used to separate a 4D signal into its constituent parts: common geology, time‐lapse response and noise. Synthetic tests which demonstrate the advantages of the singular‐value decomposition technique over traditional differencing methods are also presented. This signal separation and enhancement technique is used to map out both the original and moved oil–water contacts across the Nelson Field. The singular‐value decomposition technique allows the oil–water contact to be mapped across regions which would have been missed using traditional differencing methods. In particular, areas toward the edges of the field are highlighted by the technique. The oil–water contact is observed to move upwards across the field, with the largest movements being associated, as anticipated, with natural production. The results obtained are broadly consistent with those predicted by the reservoir simulator model. Singular‐value decomposition is demonstrated to be a useful tool for enhancing the time‐lapse signal and for gaining confidence in areas where traditional differencing fails.

The 4D seismic signature of oil–water contact movement due to natural production in a stacked turbidite reservoir

ABSTRACTCombined time‐lapse reservoir simulation and seismic modelling has been performed on both 1D and 3D models of a channelized turbidite reservoir. The models have been built using core, log, laboratory and seismic data from the Nelson Field (central North Sea) as a template. Oil and water movement in the main channels, channel margins and interchannel regions is investigated, with a particular focus being the effect of poor net‐to‐gross. The analysis confirms that saturation effects dominate the response whilst stress‐sensitivity effects play a minor role. The trough–peak signature in the seismic difference volumes formed by the sweep of the water can be continued and mapped slightly further than the channel margins. This characteristic 4D signature remains roughly intact, despite the complicated depositional architecture, and accurately delineates the area of moved fluid, but it needs additional calibration to combat the detrimental influence of the low net‐to‐gross. Signal strength is largely dependent on reservoir quality, but is also compromised by the net‐to‐gross, fluid distribution and, more critically, by the exact timing of the seismic survey. For example, a region of bypassed oil zone remains undetected as it forms early during the production. This work demonstrates that to understand fully the 4D signature at a quantitative level requires adequate knowledge of the fluid properties, but also, more critically, the geology.

Jotun Field reservoir geology and development strategy: pioneering play knowledge, multidisciplinary teams and partner co-operation – key to discovery and successful development

Accumulated knowledge from the early pioneering wells and subsequent exploration history led to the discovery of several fields in the Utsira High area during the 1990s. One of these, the Jotun Field, was discovered in 1994. The Jotun Field consists of three structures and is located on the western flank of the Utsira High, close to the eastern pinchout of the Tertiary submarine fan system. The reservoir at Jotun comprises Paleocene Heimdal Formation sands shed from the East Shetland Platform and transported across the Viking Graben area onto the Utsira High by high density gravity flow processes dominated by sandy turbidites. These distal gravity flow deposits display both thin-bedded sands alternating with shales and thicker, more massive sandstones (tens of metres thick). Minor sand injections occur throughout the field but are volumetrically insignificant. The production wells in one of the structures are completed in a slump and injection complex above thick massive reservoir sands. The Jotun Field development strategy was designed to optimize oil capture and minimize risk based on the interpreted reservoir geology. The initial development comprised 14 development wells: 12 horizontal producers, 1 water injector and 1 water disposal well. Production from the Jotun Field started in October 1999 and reached peak production in June 2000, with 140 000 BOPD. After exceeding initial expectations, declining production and rising water cut prompted an infill well programme, time-lapse seismic data acquisition and production logging in 2002. The first two wells were disappointing due to facies transition to interbedded sands and shales on the flanks of the structure and underprediction of oil–water contact movement. The newly available time-lapse seismic data were then integrated with production logging and updated depositional facies studies to evaluate additional drilling opportunities. The discovery, appraisal and development history of the Jotun Field serves as a good example of the key challenges in the Tertiary Utsira High play and the strength of applying multidisciplinary team efforts, partner co-operation and involvement to optimize asset value through tailored drilling and data acquisition programmes.

Jotun 4D: Characterization of fluid contact movement from time-lapse seismic and production logging tool data

Time-lapse (or 4D) seismic is a reservoir monitoring technology that has matured to the point where it can be considered a reliable reservoir surveillance tool. By analyzing differences of multiple seismic surveys acquired over a producing reservoir and by integration with conventional reservoir monitoring tools, 4D seismic data can provide valuable insight on dynamic reservoir properties such as fluid saturation, pressure and temperature. Many published case studies demonstrate that 4D seismic technology can optimize reservoir management and improve production efficiency. In this paper we describe the application of time-lapse seismic methods to the Norwegian North Sea Jotun Field to determine the extent of the oil-water contact (OWC) movement during the first three years of production.

Optimizing 4D fluid imaging

Integrated analysis of 4D seismic data and petrophysical data is used to produce probabilistic fluid and lithology volumes for monitoring reservoir performance on the Nelson Field. Petrophysical analysis of log data shows distinct fields for oil sand, water sand, shale and heterolithic‘ lithologies’ in acoustic impedance – Poisson's ratio space. Elastic inversion techniques applied to conventional 4D AVO datasets convert the reflectivity data to acoustic impedance, shear impedance, Poisson's ratio and angle impedances. The elastic inversion datasets are used to quantify oil–water contact movements through volume sculpting techniques. Well-derived relationships are used to predict 3D volumes of oil sand probability from three different seismic survey vintages: 1990, 1997 and 2000. Changes in oil sand probability due to production are verified by comparison with repeat production logs. Integrated volume interpretation of 4D far offset inversion difference (oil–water contact (OWC) movement) and oil sand probability shows areas of unswept oil, highlighting infill opportunities. Early results from infill drilling have validated the method, realizing the potential economic benefits of 4D seismic technologies.

Tibiofemoral contact points relative to flexion angle measured with MRI

Objective. To determine whether knee flexion influenced bony contact movements during flexion. Design. Accurate three-dimensional (3D) measurements of tibiofemoral bony contact points in vivo was performed using magnetic resonance imaging technology at 0°, 30° and 60° of flexion. Background. Magnetic resonance imaging is an accurate non-invasive tool for visualizing muscles, tendons, and bone, and provides precise 3D co-ordinates. Methods. Magnetic resonance imaging recordings were made from the right knee of 16 subjects with no history of knee dysfunction at 0°, 30° and 60° of flexion. Joint contact movements were reported as changes of the contact point's position on the medial and lateral tibial condyle with respect to a fixed reference point for each flexion angle. Results. The dominant motion of the centroid of the contact area was posterior with a concomitant inferior and lateral displacement when flexing from 0–30°. Increased flexion to 60° the contact points moved slightly anterior, superior and continued laterally. Comparing movements between the medial and lateral compartments, larger displacement magnitudes were observed laterally. Additionally, tibial rotations of 3–5° were noted relative to the femur. Conclusion. Based on magnetic resonance imaging co-ordinates and the rotated anatomical reference frame, the geometric equations to derive the contact point between the tibiofemoral articulating surfaces is a viable means to investigate tibiofemoral bony contact movement. Relevance Contact areas and pressure distributions have been reported using cadaveric specimens but interpretation of the results is limited. Other investigations have been restricted to sagittal plane movement. Using kinematic magnetic resonance imaging, accurate non-invasive 3D recordings of the normal knee at increments of flexion are possible. The normative baseline date can be compared against that of the pathological knee, such as cruciate ligament injury or the status of post-operative meniscectomy in order to examine skeletal joint motion and stability.

Short-term cell/substrate contact dynamics of subconfluent endothelial cells following exposure to laminar flow.

The manner in which fluid stresses are transmitted from the apical to the basal surface of the endothelium will influence the dynamics of cell/substrate contacts. Such dynamics could be important in the design of synthetic vascular grafts to promote endothelial cell adhesion. To examine whether the initial response of cell/substrate contact sites to flow depends on the magnitude of the applied shear stress, subconfluent monolayers of endothelial cells were exposed to flow at 10, 20, and 30 dyn cm-2 wall shear stresses for 20 min. Cell/substrate contact sites were visualized with total internal reflection fluorescence microscopy. Flow induced a rapid fluctuation in the membrane topography, which was reflected in dynamic changes in cell/substrate contacts. Exposure to flow caused marked changes in contact area. Contact movement occurred normal and parallel to the direction of flow. Contact sites demonstrated significant variability in contact area at 30 dyn cm-2 during the experiment but no significant movement of the contact sites in flow direction after 20 min of flow. Mean square displacements of the contact center of mass were described in terms of a directed diffusion model. Prior to onset of flow, contact movement was random. Flow induced a significant convective component to contact movement for 300-600 s, followed by reestablishment of diffusive growth and movement of contacts. These results suggest that fluid stresses are rapidly transmitted from the apical to the basal surface of the cell via the cytoskeleton.

The Precambrian basement: A major reservoir in the rifted basin, Gulf of Suez

The expected instructions from an exploration manager, to stop drilling and abandon a well where the bit hits the Precambrian basement, no longer applies. The fractured and altered Precambrian basement rocks are the most prolific reservoirs in the southern Gulf of Suez and the northern Red Sea rifts where hydrocarbons are produced from 8 fields, with porosity and permeability values up to 15% and 300 millidarcy, respectively. The surface and subsurface Precambrian basement rocks are related to the final stages of the tectonic–magmatic cycle of the Arabo-Nubian Shield and are composed of quartz–diorite, granodiorite, syenogranite, alkali granites and andesite porphyry, dissected by means of dykes, fractures and joints. Three main directions of fractures, northwest–southeast, northeast–southwest and east northeast–west southwest have been detected in the study area. The porosity and production rates of this reservoir, as well as the oil–water contact movement, depend mainly on the age, intensity and direction of the fractures, diagenetic processes and the dip and direction of the dykes and brecciated zones. The alteration processes reach their maximum intensity in the topmost section, known as the basement cover, where the solution and leaching has led to the enlargement of the fractures and vertical communications. The underlying fracture zone has been affected by differential alteration processes, creating zones of high and low vertical porosity and permeability. Thus, the reservoir potential of the Precambrian basement has been greatly underestimated.

Ultrasonic emission tactile sensing

This article describes an ongoing study for a new type of tactile sensing device which is based on instantaneous localization of acoustic emissions caused by touch and/or contact movement. The authors assume a sensor structure which consists of a flexible, spherical, fingertip-like body and a quadruple polyvinylidene fluoride (PVDF, a kind of piezoelectric polymer) sound-sensing matrix embedded at the center of the body. Any points on the spherical surface work as emission sources when touched, and the body transmits the waves inward. The PVDF matrix works as a wideband acoustic emission (AE) transducer which is capable of detecting arrival directions of the waves, packet by packet. This means it can independently resolve and localize a series of ultrasonic emissions caused by a touch and slip. In order to realize this type of tactile sensor, the authors consider two important questions: 1) What kind of ultrasonic emissions appear by touch, and are they detectable? 2) How can the multiple wave packets be resolved and localized instantaneously? For the first question, the authors develop a theory of wave generation at collision, and examine detectability by several experiments. For the second question, the authors show how their sound localization algorithm for an auditory sensor is applied. By assuming the use of this algorithm, and from several experiments under various contact and slip conditions, the authors confirm that the following features and tactile information are obtainable: 1) quick localization of touch and separation; 2) sensation of surface roughness under movements; and 3) quick detection of precursor of slip. >

Development of 550 kV 1-break GCB. II. Development of prototype

For pt.I see ibid., vol.8, no.3, p.1189-91, 1993. The development of a 550 kV 1-break gas blast circuit breaker is described. To reduce drive energy and sliding speed a new drive system, in which a contact conventionally fixed is moved in the direction opposite to the movement of movable contact, was adopted. As a result, size reduction becomes possible while maintaining reliability. It is also found that applying this 1-break gas circuit breaker to gas insulated switchgear greatly reduces its size. >

An impression technique to make a new master cast for an existing removable partial denture

When the master cast for a removable partial denture is lost and a well-fitting framework remains, it may be necessary to replace the master cast. A two-step impression procedure is described that combines the altered-cast technique and the use of a modified disposable tray. Finger pressure is maintained on the major connector throughout the making of both impressions, to prevent framework movement and loss of contact with prepared rest seats.

開極動作を模擬した遮断器内気流解析

開極動作を模擬した遮断器内気流解析

Three-phase contact line movement in systems with and without surfactant

The dependence of the receding contact angle on the speed of movement of the three-phase contact (tpc) after rupture of the thin liquid film during bubble/solid interaction has been investigated. The motion of the type on a quartz surface covered with an octadecylamine monolayer is described using molecular and hydrodynamic theories. For a surfactant-containing system (quartz/dodecylamine solution/air) it was found that the experimental results cannot be described completely by these theories. These discrepancies are thought to be due to surfactant transfer from the liquid/gas to the solid/gas interface during receding tpc motion, resulting in a decrease of the surfactant at the liquid/gas interface.

Touch‐responsive control apparatus for electronic musical instruments

A key-speed-responsive volume control apparatus for a keyboard-type electronic musical instrument includes a key switch associated with a key of the instrument, wherein a movable contact of the key switch moves out of engagement with a break contact and into engagement with a make contact upon depression of the key. A capacitor is charged following the movement of the movable contact out of engagement with the break contact and before engagement with the make contact. The capacitor is made to discharge at a first prescribed rate immediately after charging until the movable contact comes into engagement with the make contact, and then at a second prescribed rate until the movable contact disengages the make contact upon release of the key. The terminal voltage of the capacitor when the movable contact comes into engagement with the make contact is utilized for controlling the amplitude of a tone source signal corresponding to the depressed key, thereby providing a tone signal having an initial amplitude determined in accordance with the speed of key depression. Necessitating the use of only one capacitor for each key, the apparatus is suitable for fabrication in the form of an integrated circuit.

Distribution of Chopping Current for Copper Electrodes in Vacuum in Axial Magnetic Field

Previously developed models of chopping current distribution for contacts in vacuum without the presence of magnetic field are discussed. Justification for applying the maximum value asymptotic distribution for evaluation of the expectation of current chopping has been presented. The experimental results have served for the assessment of the axial magnetic field influence on the parameters of the chopping current maximum value distribution. The investigation was carried out in an almost resistive circuit, in a wide range of imposed axial magnetic fields from 0 to 500 mT, with the alternating current between 50 and 860 A. The electrodes were placed in a chamber where the pressure was kept below 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> Pa by means of continuous pumping. In order to eliminate the influence of the contact movement speed on chopping current, vacuum arc ignition was effected by a high-voltage impulse. Furthermore the interdependence of the chopping current and the magnetic field for copper electrodes is illustrated

A study of factors influencing muscle activity about the knee joint.

Several factors influencing the myoelectric activity of muscles surrounding the knee joint were studied using fine-wire monopolar electrodes. The muscles studied included the vastus lateralis, vastus intermedius, rectus femoris, vastus medialis, gracilis, sartorius, biceps femoris, semimembranosus, semitendinosus, tensor fasciae latae, medial head of the gastrocnemius, and lateral head of the gastrocnemius. Muscle activity was measured in response to unidirectional loads tending to flex and extend the knee, and to combined loads of flexion-adduction, flexion-abduction, extension-adduction, and extension-abduction. Results indicate that the individual muscle responses are dependent upon the direction, magnitude, and combination of external moments, as well as on the flexion angle of the knee joint. Muscle response appeared to be influenced by certain intrinsic mechanical characteristics of the knee joint that tend to change the moment arms of the muscles as the knee moves. For example, the substantial changes in quadriceps myoelectric activity with knee flexion, with constant load applied, can be related to the movement of the tibial-femoral contact changing the lever arm of the quadriceps mechanism. This study indicates that the mechanics of the knee joint must be taken into consideration while attempting to interpret or predict the load response of muscles crossing the knee joint.

Anatomical and biomechanical factors in the curve pattern formation of idiopathic scoliosis.

The maximum range of motion between two adjacent vertebrae without soft tissues was measured from C1-C2 down to L5-S and factors such as rotation, lateral bending, extension, and flexion, during surface contact movement of the facet joints, were investigated. Thirty human cadaveric spines were studied. It was found that the individual spines had a characteristic level-dependent difference in the capacity for elementary motions at the facet joints. Those segments with restricted motion capacity were termed "spinal nodes". The human spine usually has three to four spinal nodes between the skull and the sacrum. They are C7-T1, T4-T5, T8-T9, and T11-T12. This intrinsic structural character of the human spine is expressed as "nodal motion structure". We postulate that this structure plays an important role in the formation of curve patterns in idiopathic scoliosis and other spinal deformities.

A Mathematical Model of the Hawkins Woodbine Reservoir

A mathematical model of the Hawkins Woodbine reservoir was developed to predict individual tract and total fields reserves. Each of the field's predict individual tract and total fields reserves. Each of the field's 362 fault-block sand members was considered a uniform pressure tank, and contact movement was predicted with volume-depth curves. Adequacy of the model was verified by comparing actual and predicted contact movement rates for pre-unit operations. Introduction The objectives of the model-development phase of the Hawkins Unitization Engineering Study were to estimate individual tract and total primary field reserves and to appraise additional recovery possible with unitized operations. In addition, the Engineering possible with unitized operations. In addition, the Engineering Subcommittee recognized that if it developed a computerized field model to meet those objectives, it would have a tool that later would prove valuable in planning unit operations, including forecasts of production, drilling, and recompletion needs for maximum recovery and reservoir control. The need for the study arose when the Hawkins Unitization Working Interest Owners Committee requested the Engineering Subcommittee to estimate reserves. The owners believed that an acceptable field unit participation formula would allocate primary reserves to each tract plus a fair share of the increased recovery resulting from unitized operations. The Engineering Subcommittee recognized that the Hawkins field (having 45 fault blocks, 10 sand members, 327 tracts, and nearly 500 producing wells) would be difficult to model in necessary detail with a conventional finite-difference simulator. A three-phase, three-dimensional simulator would have been necessary for each of the 362 fault-block sand members, most of which are in partial communication with others. The subcommittee also partial communication with others. The subcommittee also recognized that a highly simplified, total-field modeling procedure probably would not provide the necessary detail for individual probably would not provide the necessary detail for individual tract reserves. Accordingly, the subcommittee chose the middle ground. It developed a model that included the detail of each well and each fault-block sand member, but avoided the detailed fluid-displacement calculations of a three-phase, three-dimensional finite-difference reservoir simulator. The model treats each fault-block sand member as a uniform pressure tank. Dimensionality is introduced with a volume-depth pressure tank. Dimensionality is introduced with a volume-depth curve for each sand member. Some areas of the field produce by water drive, others by gas drive, and some by depletion (solution-gas) drive. Certain areas contain only oil, some have gas and oil, and others contain only gas. To handle this wide variety of conditions, residual hydrocarbon saturations for the various drive mechanisms were input in the model, from which recovery efficiencies were determined. The model calculates new fluid-contact positions at the end of each year, using material balances on calculated fluid influxes and effluxes and volume-depth curves. The remainder of this paper describes the modeling procedure in a general way. There is as little reference as possible to specialized, one-of-a-kind challenges offered by Hawkins field and little mathematical detail. This approach reflects our belief that the modeling procedure we describe generally is applicable to geologically complex, multidrive reservoirs. Description of Reservoir Model In this section, we will describe our modeling procedure aided by a logic flow chart (Fig. 1). JPT P. 1545

Simulation of Naturally Fractured Reservoirs With Semi-Implicit Source Terms

Abstract Conventional reservoir simulation techniques prove to be inadequate when applied directly to the prove to be inadequate when applied directly to the study of fractured reservoir systems. Such systems are characterized by extremes in porosity, permeability, and saturation. The vast bulk of the permeability, and saturation. The vast bulk of the reservoir volume is occupied by relatively low-permeability, disjoint matrix blocks of various sizes surrounded by a small volume of high-permeability, interconnected fracture space. Our approach to this complex problem bas been to treat the matrix blocks as source and sink terms in an otherwise conventional simulation that models only the fracture system. The source/sink terms are functions of matrix rock and fluid properties with fracture saturation and pressure defining the boundary conditions. These functions are derived either by history-matching simulations or independently by laboratory experiments or single matrix-block simulation. This basic concept of a source/sink treatment is not unique to this work. However, the numerical formulation and implementation of these terms in the fracture simulation offers significant advantages over existing modeling procedures. The fundamental advantage of our approach is that these source terms are handled semi-implicitly in both the pressure and saturation calculations involved in pressure and saturation calculations involved in the fracture simulation. This avoids instability problems that are inherent in a sequential problems that are inherent in a sequential fracture-matrix solution and links more closely the behavior of the matrix and the fracture. Special techniques are developed for modeling the effects of fluid contact movement within a large simulation grid block and for treating receding gas-oil and water-oil contacts. Hysteresis effects are included in matrix blocks that begin to imbibe oil after drainage has begun. Introduction Conventional reservoir simulation techniques are not capable of adequately modeling large, naturally fractured reservoir systems. Extreme discontinuities in porosity, permeability, and saturation exist throughout the reservoir. Most of the fluids are found in very low-permeability, disjoint matrix blocks of various sizes, while most of the fluid mobility is in a small volume of high-permeability, interconnected fracture space. The distribution of fluids within the fracture is usually governed primarily by gravity segregation while the behavior of the individual matrix blocks depends on pressure, fluid environment, and matrix fluid saturation. Fluids can move readily throughout the reservoir in the fracture space, but fluids that reside in matrix rock must enter the fracture to move any great distance. The behavior of individual matrix blocks in response to various drive mechanisms has been studied experimentally by Crawford and Yazdil and has been simulated in two dimensions by Kleppe and Morse and Yamamoto et al. Other investigators have studied the single-phase pressure behavior of fractured reservoirs and its effect on pressure buildup curves. Kazemi investigated single-phase flow in a radial reservoir dominated by horizontal fractures. Closman simultaneously solved equations for flow between matrix and fracture and for flow along the fracture planes for a radial aquifer to develop relationships similar to those developed by van Everdingen and Hursts for water influx. Simulation of an entire reservoir system with multiple phases further complicates the problem and makes additional simulator modifications necessary. Asfari and Witherspoon have developed a modeling approach for reservoirs with a regular pattern of noncommunicating vertical fractures by pattern of noncommunicating vertical fractures by assigning constant pressures along each fracture. Several investigators have applied finiteelement techniques to the fracture-matrix flow problem. problem. Our approach to this complex problem has been to model the flow in the fracture system and to treat fluid transfer to and from the matrix much as injection and production are modeled in conventional simulators. Transfer of fluid into the fracture will be represented by a "source" term and transfer from the fracture to the matrix will be represented by a "sink" (or negative source) term. SPEJ P. 201

Reaction rates for Pt on GaAs

The rate at which GaAs reacts with Pt has been determined at selected temperatures between 300 and 400 °C. The amount of GaAs reacted is determined by measuring the movement of the original Pt Schottky-barrier contact into the GaAs. Data are presented which show the amount of GaAs reacted as a function of anneal time at several different temperatures. The reaction follows a parabolic rate law with activation energy of 1.6 eV. Some change in the electrical characteristics of the Schottky barrier is observed.