bluuebunny/crossref_metadata_2025 huggingface dataset:
Miscibility Variation in Compositionally Grading Reservoirs
Authors: Høier Lars , Whitson Curtis H.
Published: December 2007

Minimimum miscibility conditions of pressure and enrichment (MMP/MME) have been computed using an equation of state (EOS) for a number of reservoir fluid systems exhibiting a compositional gradient with depth due to gravity/chemical equilibrium. MMP/MME conditions are calculated using a multicell algorithm developed by Aaron Zick, where the condensing/vaporizing (C/V) mechanism of developed miscibility is used as the true measure of minimum miscibility conditions, when it exists. The Zick algorithm is verified by detailed 1D "slimtube" simulations with elimination of numerical dispersion. The miscibility conditions based on the traditional vaporizing gas drive (VGD) mechanism are also given for the sake of comparison, where it is typically found that this mechanism overpredicts conditions of miscibility.

Significant variations in MMP and MME with depth exist for reservoirs with typical compositional gradients, and particularly for near-critical oil reservoirs and gas condensate reservoirs where the C/V mechanism exists. An important practical implication of these results is that miscibile displacement in gas condensate reservoirs can be achieved far below the initial dewpoint pressure. The requirement is that the injection gas (slug) be enriched somewhat beyond a typical separator gas composition and that the C/V miscibility mechanism exist. This behavior results in many more gas condensate reservoirs being viable candidates for miscible gas cycling than previously assumed, and at cycling conditions with lower cost requirements (i.e. lower pressures) and greater operational flexibility (e.g. cycling only during summer months).
A Novel Approach to Characterize Dynamic Interaction Between Super Permeability Layers with Vertical - Faults and Their Affect on Flood Front Movement
Authors: Al-Shahri Ali M. , Al-Muraikhi Ahmed
Published: December 2007

Managing the Ghawar Field with super permeability layers and vertical faults, with a mission of maximizing oil recovery with the lowest cost, is a challenging task. Super permeability layers are associated with high productivity where the flow is confined to 10-20 feet layer in a 250 feet thick reservoir. After producing part of the reserves, 3-D seismic and horizontal drilling clearly indicate the existence of fault systems. Vertical faults can be connected to the super permeability layers in certain locations of the field.

Pressure testing happens to be a powerful reservoir characterization tool when integrated with geological and geophysical data as well as specially designed horizontal wells. This paper describes the planning, execution and results of series of extensive field testing which were performed to understand reservoir large-scale flow features (faults or joints).

Data integration has resulted in characterizing fluid movement to be governed primarily by systematic large scale flow features which are almost parallel to both flood- front movement and to the maximum horizontal stress direction. The horizontal isolated super permeability layers are a secondary source of water movement, since it is dynamically supported by the faulting system. Diagnostic tools were developed and implemented to address the issue of when can the super permeability be produced to advantage and when it should be avoided, by considering the dynamic interaction between the two systems.

P. 737
New Fast, Stochastic, Boolean Simulation of Fluvial Deposits.
Authors: Viseur Sophie , Shtuka Arben , Mallet Jean-Laurent
Published: December 2007

It is now a fairly common practice to characterize fluvial reservoirs via stochastic simulations of fluvial deposits. Three criteria are used to evaluate various simulation processes. They are:honoring input data (usually well data);defining fluvial heterogeneity boundaries; andspeed.

There are two major branches in 3D stochastic simulations: pixel-based and object-based. The pixel-based method distributes property values rather than the heterogeneities. It is fast but the boundaries between heterogeneities are often blurred and do not reveal geological features. The object-based (or boolean) method distributes the heterogeneities directly and can therefore produce well-defined feature boundaries. However, object-based methods often involve a simulated annealing process which converges slowly.

In this paper, we will present a new, straightforward object-based conditional simulation process that honors the input data, produces well-defined heterogeneites and works reasonably fast.

The revolutionary step that makes this possible is a well data segmentation process and a channel generating process that we have developed. This processing enables us to rethink and redesign the entire object-based simulation process. As a result, we are able to, in a reasonable amount of time, produce multiple realistic realizations of a fluvial environment that honor well data and other geological information.

P. 697
A New Method for Saturation Measurements in Core Flooding Experiments
Authors: Bruining Johannes , Nguyen Buu-Long , Slob Evert
Published: December 2007

In this paper we present an application of Frequency Domain Reflectometry (FDR) – an electromagnetic technique that measures the dielectric response of a transmission line. Such a response is related to the electric permittivity and conductivity distribution along the transmission line. In our experimental set-up the sample core replaces the dielectric material of a coaxial transmission line sample holder.

We use a recursive relation to derive the multiple reflection coefficient which is a function of the electric properties of the porous medium and thus a function of the water saturation.

We present an inverse modeling procedure which allows reconstruction of water saturation profiles from the measured multiple reflection coefficients. For the inverse modeling we use the Polak-Ribière conjugent gradient algorithm to extract the saturation distribution.

We show numerically and experimentally that the simulation profiles inclusive the position of the Buckley-Leverett shock front can be followed by a single measurement of the multiple reflection coefficient.

The results of our numerical experiments validate the inverse modeling procedure introduced in this paper.
Predicting Sand Erosion in Chokes for High Pressure Wells
Authors: McLaury B.S. , Shirazi S.A.
Published: December 2007

Sand from reservoirs is carried along with oil and gas in producing wells. This sand can cause severe erosion resulting in failure. A variety of fittings are especially susceptible to erosion damage. For example, geometries that redirect the flow such as elbows experience erosion. In these cases, the particle momentum resulting from the mean flow drives the sand into the wall resulting in erosion. Several researchers have investigated this form of erosion. However, only a few studies have investigated the erosion in chokes where the erosion can even be more severe. In fact, chokes can experience failure due to erosion in a matter of a few days in high pressure gas wells. The present work uses computer simulations to examine the erosion in chokes. The simulation consists of three parts: solve the flow field (velocities, pressure, turbulent kinetic energy), determine sand trajectories, predict erosion resulting from sand impingement information. This paper presents the results obtained during each of these parts for three cases that examine the effect of pressure drop and shape on the severity of erosion. The results obtained from the model are in good agreement with field observations.

P. 769
Commingled Production Wells: Experiences in Lake Maracaibo, Venezuela
Authors: Ferrer Fernando J.
Published: December 2007

For many years, commingled production has not been considered as a valid alternative to produce marginal fields. In fact, oil regulations in many countries do not allow this technique because it could affect the final recovery.

Venezuela is no exception to this practice, however some new technologies are arising to change this situation and make commingled production a valid alternative to improve the performance of marginal fields.

Most reservoirs in Block I Lake Maracaibo are already very depleted, so a plan has been designed to recover and increase remaining reserves. Among some other technologies such as slim hole and infill drilling, commingled production plays a key role in reservoir rejuvenation plans.

In this paper the basic fundamentals of this practice are discussed, showing a new methodology to estimate composite IPR curves, procedures and techniques used to quantify contribution from individual zones and criteria to select suitable well candidates for this purpose. Some results of a pilot test carried out in Block I Lake Maracaibo area are presented in order to show the benefits of commingled production.

P. 801
Alternatives to Monte-Carlo Simulation for Probabilistic Reserves Estimation and Production Forecasting
Authors: Mishra Srikanta
Published: December 2007

This paper describes three alternatives to Monte-Carlo simulation: (a) the first-order second moment method, (b) the point estimate method, and (c) the first-order reliability method, for the assessment of uncertainty in reservoir engineering calculations. These techniques are proposed as more suitable than Monte-Carlo simulation when information regarding parameter uncertainty is limited, the forward model is computation intensive, and/or the probability associated with only a limited number of model outcomes is of interest.
Method for Handling the Complexities Associated with History Matching the Performance of a Highly Stress-Sensitive Formation
Authors: Yang Zhengming , Ershaghi Iraj , Mondragon Julius J. , Hara Scott
Published: December 2007

This paper presents aspects of formation stress sensitivity influencing the successful simulation of the Tar Zone in Fault Block IIA of the Wilmington Oil Field in Los Angeles County, CA, USA. The Tar Zone is a slope and basin clastic type reservoir. The significant compaction experienced during the primary phase and the subsequent rebound during the following waterflooding created a complex case of reservoir definition for projection purposes. Uncertainties regarding stress effects on physical properties such as porosity, permeability, compressibility and formation thickness complicated the representation. The history matching attempts revealed the insufficiency of using conventional compaction models in the appropriate modeling of the compaction-rebound process. A new compaction-rebound feature was developed based on rock mechanics considerations and was incorporated into a commercial simulator, Computer Modelling Group's STARS™ simulator. This method allows for meticulous representation of the spatial dynamics of compaction/rebound based on the local pressure field.

A successful history match of the primary and waterflooding production was achieved with the new compaction/rebound algorithm. The model was successfully tested by predicting the 20 acre steamflooding pilot. The case under consideration is unique and relates to high pressure and temperature steamflooding. The proposed methodologies have widespread application in other stress-sensitive heavy oil reservoirs.
Effect of Brine Salinity and Crude Oil Properties on Relative Permeabilities and Residual Saturations
Authors: Filoco Paulo R. , Sharma Mukul M.
Published: December 2007

Centrifuge experiments were conducted on Berea cores to measure the drainage and imbibition relative permeabilities in two phase and three phase systems. Two crude oils, Prudhoe Bay and Shell Mars crude were used in our tests. No effect on oil recovery was obtained in the drainage experiments when the crude oil was displaced by air at connate water. However in the imbibition experiments the oil recovery increased significantly with the salinity of the connate brine. The salinity of the displacing brine had no significant influence on the oil recovery. The relative permeability curves obtained during drainage were also found to be insensitive to the salinity of the brine. However the imbibition relative permeability curves show a strong salinity dependence. A comparison of the two crude oils and a nonpolar mineral oil indicates that the more water-wetting Mars crude oil shows a higher oil relative permeability at the same bond number compared to the mixed-wetting Prudhoe Bay crude oil. The salinity dependence of the residual saturations and the relative permeabilities clearly indicate that the change in wetting properties of the rocks surfaces from water-wet to mixed-wet during the drainage process is an important factor controlling the imbibition relative permeability curves. This clearly suggests that the performance of waterfloods will be strongly affected by the composition of the crude oil and its ability to wet the rock surfaces, the salinity of the connate brine in the reservoir, and the height above the o/w contact.
Fracture/Stylolite Characterization Using Stochastic Modeling in Zone-II Reservoir, Offshore Abu Dhabi
Authors: Bushara M. N. , Arab H. M.
Published: December 2007

This work evaluates effects of open fractures and sty lolite networks on total permeability of Zone-ll reservoir system. Database is compiled from detailed analysis of cores, dipmeter and FMS/FMI images. Geostatistical 3D stochastic models were built for 23 cored wells containing matrix permeability, fracture and stylolite densities, along with empirically computed maximum principal strain (εmax) from fractures. The magnitudes of strain tensor are taken to be proportional to the aperture of fractures in a direction predicator to their orientation. Comparison of upscaled average surfaces of these data with test permeability values suggests that there is a genuine permeability contribution from fractures in the reservoir. A technique is developed to transform matrix permeability realizations so as to honor test permeability, predict fracture permeability fieldwide, and better account for water breakthrough trends.
Effect of Dolomitization on Relative Permeability and Its Interpretation by Network Model
Authors: Namba Takao , Ishibashi Masatoshi , Tanaka Hiroki
Published: December 2007

Core and log data review for an Upper Jurassic carbonate reservoir in Middle East indicated that log derived dolomite content has correlation with relative permeability data. This result motivated further petrographical and mineralogical analyses, which revealed that dolomitization occurred in two stages. The dolomitization during the early stage displaced original grains by dolomite, and the further dolomitization displaced calcite cement (isopachous fringing cement) by rhombic dolomite crystals, which homogenize pore-throat system.

Pore network model was utilized to understand the observations, highlighting the gas-oil system in this paper to avoid wettability uncertainty problems which is inherent in oil-water system on carbonate rocks. The drainage gas oil relative permeability data of a high dolomite content sample (dolostone) with a well sorted pore-throat system was successfully duplicated by the pore network model. Although quantitative interpretation was not achieved for a dolomitic limestone sample with a complicated pore-throat system, the trend of gas relative permeability change due to the homogenization and enlargement of pore-throat system by dolomitization, which was modeled by Weibull function, was reproduced by the network model.
Reservoir Simulation Optimises the Development of the Yibal Field
Authors: Cook R. C. H. , Lozano J. A.
Published: December 2007

This paper presents the ongoing development, by horizontal drilling, of the giant Yibal Field, Oman. In particular, the paper discusses the substantial improvement in new well performance as a consequence of comprehensive reservoir simulation modeling.

Yibal field development consists primarily of drilling new horizontal sidetrack producers from watered-out vertical wells. Two rigs are occupied full time in Yibal drilling, on average, 38 horizontal sidetracks per year. During 1997, a portfolio of eleven dual porosity simulation sector models was built covering more than 90% of the Yibal Field. New wells are now directed at the remaining oil targets imaged by these simulation models. Some 70 of these ‘smart’ wells have now been drilled. The running average initial net oil rate is 950 m3/d which represents a 12% improvement versus the 1996 wells. The watercut trend has improved even more and now averages just 21% versus 41% for the 1996 wells. This is particularly important as field production is now nearing its gross capacity constraint. As a result of simulation modeling and the drilling of ‘smart’ wells, Yibal Field production is now 35×103 m3/d which represents an all time high after thirty years of field production history.

To ensure that the current gains are not lost, work has already begun upon a new portfolio of fine grid simulation models. It is anticipated that the increased model resolution will image the smaller oil targets which will be pursued in future as well spacing shrinks under continuous infill drilling. Much of this future drilling will involve novel techniques such as slimhole sidetracks, underbalanced coiled tubing slimhole sidetracks and multilateral drilling, both conventional and slimhole. A number of these techniques are currently being trialed at Yibal.
Real-Time Artificial Lift Optimization
Authors: der Kinderen W. J. G. J. , Dunham C. L. , Poulisse H. N. J.
Published: December 2007

Shell has introduced a computer infrastructure for on-line, real-time production optimization. Several years of experience have been captured in a range of application packages, from well test management to optimization software for gas-lift, electrical submersible pumping, beam pumping, and injection systems.

Recent developments include a well test optimization algorithm (called WellDone) that analyses test-separator measurements in real time. Another area of innovation is online, multi-phase production measurement using simple, readily-available instrumentation. Field tests confirm that the liquid production of a well can be estimated and trended from the pressure drop across an (existing) flow line restriction. This DeltaP method can be used for enhanced well test scheduling, and for continuous measurement of the incremental gas utilisation factor (IGUF), i.e. the response of a gas-lift well to changes in lift gas injection rate. In another new development, gas-lift wells which exhibit unstable behaviour can be stabilised by active control of the production choke. The potential benefits of this novel DynaCon technique have been demonstrated in the laboratory and a field trial is on-going.
Regional Basin Modelling: An Approach to understand Shelfal Carbonate Reservoirs of the Oxfordian and Kimmeridgian in Offshore Abu Dhabi
Authors: Al-Suwaidi A. S. , Aziz S. K.
Published: December 2007

Exploration activities in Abu Dhabi have traditionally been focused on the reservoir zones of the lower Cretaceous Thamama Group and the Jurassic Arab and Araej Formations. The carbonate reservoirs developed along the eastern flank of the Oxfordian - Kimmeridgian intra-shelf depression in offshore Abu Dhabi received less attention, until recently when commercial oil accumulations in structural traps were discovered. A multidisciplinary study using sequence stratigraphic approach resulted in clarifying the geometry and the chronostratigraphic relationships of the identified sequences. The study included regional seismic data, litho-biofacies studies, geochemical analysis, strontium isotope age dating and well logs from over 50 wells.

After the deposition of the Callovian Upper Araej member, a differentiated carbonate platform was initiated in early Oxfordian in offshore and western onshore Abu Dhabi where tectonic subsidence coupled with sea level fluctuation controlled the geometry, deposition and the distribution of variable lithofacies that ranged from organic rich limemudstones in the depressed area to porous and permeable bioclastic packstones. grainstones and dolomites in the shallow waters along the eastern flank of the intra-shelf basin.

Detailed study resulted in identifying four 3rd-order sequences in the Oxfordian to Middle Kimmeridgian stages in the offshore area. Sequence-1 is entirely Oxfordian and is deposited during transgressive and highstand periods dominated by aggrading and prograding geometries. Sequence II is Lower Kimmeridgian and represented by a well-defined lowstand system tract followed by short-lived transgressive and highstand system tracts. Sequence III is mainly deposited during a lowstand period capped with a shelf margin wedge system tract. Finally, Sequence IV was deposited entirely during transgressive and highstand periods on an undifferentiated platform with minor depression in the western area. Two type I sequence boundaries have been interpreted at the top of Sequences I and II in the shelfal area. The best reservoir developments occur in the bioclastic packstone and grainstone facies deposited during the highstand periods below the Sequences I and II boundaries where the reservoir units are characterized by porosities of < 20% but with very high permeabilities reaching a few Darcys. The basinal facies of Sequence I exhibits the best source potential in the intra-shelf basin, whereas the remaining sequences show marginal source rock richness.
Distribution and Origin of a Tar mat in the S. Field (Abu Dhabi, U.A.E.)
Authors: Carpentier B. , Hue A.-Y. , Marquis F. , Badr A. E. R. , Al Aidarous A. A. , Al-Baker S.
Published: December 2007

This study has been conducted to investigate the distribution and origin of bitumen (tar mat) occurring in the Thamarna Zone B reservoir (Upper Kharaib Fm., Lower Cretaceous) of the S. Field in Abu Dhabi.

The main objective was to assess the continuity of the bitumen rich interval and its possible role as an intra-reservoir permeability barrier potentially responsible for the pressure anomalies recognized at the field scale during oil production.

Detection of bitumen was performed on 68 wells using petrophysical data, Rock-Eval and electrical-log derived methods. The result provides a realistic 3D image of the tar mat distribution at the field scale.

Biomarker analysis suggests that there is no difference in origin nor maturity between the tar mat and the overlying oil. Comparison between bitumen location, sedimentological facies, petrophysical properties, field structural history, present-day and paleo-OWCs were used to decipher the process and timing of the tar mat deposition.

Results, Observations and Conclusions

A tar mat (4 to 23 ft thick) is present in the crestal part of the field and is located at the base of Thamarna Zone B, increasing the role of vertical permeability barrier formed by the underlying "Dense Limestone". The bitumen is clearly associated with the low porosity zone located at the base of the Thamarna B and seems to be never present in the water leg nor related to the present day or paleo-OWCs. The formation of the tar mat is probably post-Dammam (Eocene) in age and is likely to be due to flowing down of a gravity segregated heavy fluid which is eventually trapped in the low porosity base of the reservoir.

Applications

The results demonstrate that the bitumen rich interval is not responsible for the pressure drop during production and will not play the role of permeability barrier between the central and northern part of the field where gas injection is planned. The provided 3 D distribution of the bitumen volume allows a better estimate of the OIP (oil in place).

Technical Contributions
Feasibility Study for Seismic Monitoring of Gas Injection
Authors: Nishida Akio , Ito Toru , Suzuki Koichi , Sato Makoto , Shimada Nobusuke
Published: December 2007

In this study, seismic monitoring of injected gas in a carbonate reservoir was investigated using multidisciplinary approach which consisted of geological/reservoir modeling, reservoir flow simulation, rock physics and seismic modeling. A case-study was conducted over the Lower Cretaceous carbonate reservoir offshore Abu Dhabi.

The gas saturation and reservoir pressure data were obtained from the reservoir flow simulation. The velocity data of dry rock samples under the various conditions were also obtained from rock physics study. These outputs were converted to the velocity model using Gassmann 's equation. The calculated velocity from Gassmann's equation is well correlated with velocity from laboratory measurements. Therefore we can confirm that the Gassmann's equation is applicable to estimate the velocity of the gas saturated reservoir rock.

Based on the velocity model, synthetic seismic sections before and after gas injection were constructed in order to verify the influence of gas flood. As the results, amplitude difference between the two synthetic seismograms was observed at top and bottom reflectors of the reservoir zone. This amplitude variation is caused by both gas saturation change and pressure change. Although further investigation is needed to detect the cause of the variation, this study indicates the possibility of seismic reservoir monitoring
The Successful Redevelopment Of Existing Wells Using Multilateral Drilling Techniques
Authors: Tantawi Ibrahim , Taylor Randolph , Russell Rick
Published: December 2007

In the Zakum field multilayered carbonate reservoirs are separated by hard, impermeable layers. The field was developed during the past 20 years with conventional deviated (and, more recently, horizontal (wells, with openhole completions. Because production in certain older wells had begun to decline, various techniques to boost production were investigated. Trials showed that using multilateral drilling techniques to access the reservoir's individual layers offer a significant improvement in production rates. Subsequent drilling of several multilaterals substantiated the trials findings. The reservoirs' layered nature and the existing well designs required use of innovative directional drilling tools and techniques. Case histories demonstrate the techniques used and the resulting improvements in production.

Several multilateral re-entry wells with as many as six horizontal branches have been drilled into this article's subject reservoir. Lateral sections as long as 2,500 ft have been achieved, often including turns of up to 180 (to optimise production rates. Sidetracking out of existing casing and from open hole has been required with build rates exceeding 60(/100 ft. A unique non-articulated drilling motor and measurement-while-drilling system has been used with very successful results. Production rates from the multilaterals have improved significantly. It can thus be concluded that the use of complex multilaterals provides an economically and technically viable solution to the reservoir's declining production.
Laboratory Studies of Gravity Drainage Mechanism in Fractured Carbonate Reservoir - Capillary Continuity
Authors: Sajadian V. A. , Danesh A. , Tehrani D. H.
Published: December 2007

In the well fractured carbonate reservoirs the gas/oil gravity drainage from the gas-invaded zone is the dominating oil producing process. When the gravitational forces exceed the capillary forces, the matrix blocks which are surrounded by gas, will release their oil.

The results of our experimental works reveal that, depending on the interfacial tension, spreading coefficient, rock wettability, and surface roughness, there is a critical fracture aperture size, tfc. When the fracture aperture is more than tfc, the continuity is via solid compressed spacers and/or oil film around them, which at actual reservoir conditions it may be considered as non-effective capillary continuity. Whereas for the case that the fracture aperture is less than its critical value, the capillary continuity is mainly through liquid bridges which due to their high transmissibility will result in an effective capillary continuity between blocks.

Two new definitions for horizontal fracture capillary pressure based on the type of capillary continuity have been presented. Laplace formula and pressure difference between the fracture gas and the matrix oil may be used for calculation of fracture capillary pressure for non-effective and effective continuity, respectively.
Experimental and Numerical Modeling of Sulfur Plugging in a Carbonate Oil Reservoir
Authors: Al-Awadhy F. , Kocabas I. , Abou-Kassem J. H. , Islam M. R.
Published: December 2007

Many oil and gas reservoirs in the United Arab Emirates produce large amounts of sour gas, mainly in the form of hydrogen sulfide. In addition to creating problems in the production line, wellbore damage is often reported due to the precipitation of elemental sulfur in the vicinity of the wellbore. While there have been several studies performed on the role of solid deposition in a gas reservoir. However, the possibility of sulfur deposit in oil reservoirs has not been investigated in the past.

This paper presents experimental results along with a comprehensive wellbore model that predicts sulfur precipitation as well as plugging. The experiments are conducted in a core (linear system). Both analytical and numerical modeling are performed in a linear coordinate system. Data for the numerical model are obtained from both test tube and coreflood experiments. By using a phenomenological model, the wellbore plugging was modeled with an excellent match (with experimental results).

The crude oil was de-asphalted prior to conducting the experiment in order to isolate the effect of asphaltene plugging. A series of coreflood tests was carried out to observe sulfur precipitation and plugging in a carbonate rock. Significant plugging was observed and was found to be dependent on flow rate and initial sulfur concentration. This information was used in the phenomenological model that can be incorporated in the wellbore numerical model.
External Corrosion of Gas Transmission Lines
Authors: Dos Santos Alfredo
Published: December 2007

This paper aims at highlighting the importance of decision making at design stage concerning materials selection and other measures for corrosion control and their relationship with environmental modes of pipeline degradation.

Two cases of gas transmission lines which experienced chloride stress corrosion cracking and corrosion under insulation are discussed to illustrate the shortcoming of selecting materials for internal corrosion control without regard to risks of external corrosion due to exposure to soil and atmospheric environments.

The paper concludes that knowledge and anticipation of all potential corrosion mechanisms at design stage are pre-requisites for long term pipeline availability and economic operation.
A Major Revamping Project with Minor Disruption to Operations
Authors: Coupaud Jean-François , Yahya Amer , Tailliart Jean-Marie
Published: December 2007

"An ageing oil field is like an old man: it must be handled very gently". To keep it alive, you may need major surgery, but it has to be done extremely carefully in order to avoid putting it into an irreversible state of shock. Our 25 year-old field was in desperate need of rejuvenation, by means of breathing support and complete overhaul of the nervous system; it also had to give up smoking.
Application of EOS to Optimize the Design of an Early Production Scheme of an Onshore Oil Field in Abu Dhabi
Authors: Braek A. M. , Almehaideb R. A. , Hughes R.
Published: December 2007

This study is aimed at optimizing the design of surface facilities of an early production scheme for an onshore Abu Dhabi oil field. The current design of separation facilities is modular, and thus improvements in performance are possible with a better understanding of PVT properties of the oil produced. This is performed by optimizing the multistage separator process for the range of properties of oil processed by the facilities.

This paper describes the characterization of the crude oil processed by the facility using the 3-parameter Peng-Robinson Equations of state to describe the phase behavior and fluid properties using reservoir fluid data and an analysis of production data. After characterizing the fluids from each production well in the reservoir, the streams are mixed and the overall characterization of the total reservoir crude oil is used to optimize the design of the current facilities. This overall characterization of the crude oil is checked and compared to field analysis from the current operating facility.

Current production facilities consist of one production separator followed by a free water knockout tank. Results show that optimum separation requires a multi-stage scheme versus the two-stage scheme being used now. Up to 2-3 % increase in oil volumes produced may be achieved by using an optimized 3-stage separator design consisting of high and medium pressure production separators followed by the free water knockout tank.
TOTAL ABK Operations Training Simulator
Authors: Ahmad Nadir
Published: December 2007

During 1997-1998, TOTAL ABK installed a Process Training Simulator prior to the implementation of a substantial gas processing facility upgrade which involved, revamping of existing and addition of some new processes. A high degree of interaction between previously independent processes was introduced and these modifications, increased plant and operating complexity. The training simulator allowed training of operations personnel by simulating the effects of these new interactions as well as preparing them to operate in fact, what was a completely new plant configuration.

Having gained from this technology, TOTAL ABK further developed the content of the simulator model, to include more aspects of the operating process. The simulator is now installed in the offshore location and is used to train different levels of personnel.

This paper describes the Training Simulator and benefits gained from this experience.
Study of a Possible Miscible Flood in Bu Attifel Field
Authors: Zekri A. Y. , El-Agile Ibrahim , Cousin Libya E.
Published: December 2007

Many methods have been investigated in the laboratory and in the field for improving oil recovery. Today technology and economics on the average leaves two barrels of oil in the ground for each barrel recovered worldwide. On the other hand the recovery factor of Bu Attifel field is around 50% which indicates a substantial amount of oil remains in the ground after primary & secondary recovery processes are completed. This remaining oil is an EOR target.

Many techniques have been proposed and used to recover the remaining oil such as chemical, miscible & thermal flooding techniques. Due to the nature of the reservoir and the current state of economics and technology miscible flooding has been selected to be investigated to improve the oil recovery in Bu Attifel field.

The work used laboratory measurements to investigate the possible use of lean gas , rich gas or CO2 in Bu Attifel field. The work consist of phase behavior , minimum miscibility pressure determination of Bu Attiful oil and lean gas, minimum miscibility composition determination of enriched gas.
Acid/Sour Gas Management in the Petroleum Industry
Authors: Jamaluddin A.K. M. , Bennion D. B. , Thomas F. B. , Clark M. A.
Published: December 2007

Due to decreasing world demand for elemental sulphur, the economics of recovering sulphur from sour natural gas has become unfavorable. At the same time, air emission standards and regulations are becoming increasingly stringent, increasing the economical strain on oil and gas companies producing sour natural gas. Hydrocarbon producing companies are in search of environmentally-friendly and cost-effective methods for dealing with acid gas, which is produced in association with sour natural gas.

In recent years, compressed acid gas re-injection into a porous formation has emerged as a viable alternative to sulphur recovery with the added advantage of eliminating air emissions. As an alternative, some operators also solubilize the sour/acid gas into disposable formation water and dispose acid water into porous formation. In addition, to take advantage of high solubility of acid/sour gas into light hydrocarbon solvent, some operators are also injecting light hydrocarbon solvent containing acid/sour gas into the depleted oil leg as a miscible flood enhanced oil recovery (EOR) technique. Laboratory tests and results will be presented in this paper which illustrate the pros and cons of all these alternative processes to manage the produced acid/sour gas in the petroleum industry.
Estimation of Formation Properties Using Multiprobe Formation Tester in Layered Reservoirs
Authors: Badaam H. , Al-Matroushi S. , Young N. , Ayan C. , Mihçakan M. , Kuchuk F. J.
Published: December 2007

Vertical interference tests across stylolite zones were carried out in a number of wells using the wireline multiprobe formation tester as a part of the reservoir characterization for the pilot gas injection areas in a Middle East Carbonate reservoir. For each test, the pressure and flow rate at the sink probe and pressures at the horizontal and two vertical observation probes were recorded as a function of time. For the interpretation of the pressure measurements from these tests, a detailed reservoir model was constructed based on the field geology and openhole logs, particularly resistivity images. Vertical communication across tested zones and individual layer horizontal and vertical permeabilities are obtained. High permeability zones were identified with some lateral continuity across wells. Some zones were found to be local permeability barriers with well developed stylolite zones. The results will be used in the modeling of a pilot gas injection study.
New Array Resistivity Measurements: Physics and ME Case Histories
Authors: Strack K-M. , Frenkel M. A. , Koleman J. M. V. A. , Mezzatesta A. G. , Talabani S.
Published: December 2007

When searching for hydrocarbons, electrical logging methods play a fundamental role in differentiating between water and oil-bearing formations. Special logging devices have been successfully used for this purpose. However, with the increased requirements to better understand more complex reservoirs and the need for drilling deviated and horizontal wells, higher resolution measurements and appropriate interpretation techniques are now required for accurate formation evaluation.

During the past 5 years, we have developed galvanic and induction types array resistivity devices and inversion processing to gain a better under-standing of these more complex reservoirs. While the array induction, as an industry standard, addresses these issues for resistive muds, the new array laterolog addresses them for conductive muds. The application range for both tools extends to different mud environments. It can also been shown that these tools deliver complementary formation information in a joint interpretation mode and also better resolution with reduced uncertainty.

The raw data, which is acquired as a time series is processed for improved signal-to-noise ratio, and then input directly into an inversion software package. This package yields optimized formation parameters and their uncertainties.
Performance Evaluation of Horizontal Wells
Authors: Kuchuk Fikri J. , Lenn Chris , Hook Peter , Fjerstad Paul
Published: December 2007

In this paper, the use of various measurements for performance evaluation of horizontal wells is presented. First, determining formation pressure and permeability distributions along the wellbore by using the Multiprobe Formation Tester Packer-Probe Module pressure transient interval tests are investigated. It is shown that reservoir pressure measurements along the wellbore give local as well as reservoir scale information about how the reservoir is being depleted and how cleanup takes place. Second, a horizontal well buildup test interpretation is presented to show that minimizing the wellbore storage effect is crucial for system identification as well as for parameter estimation. Third, the productivity of horizontal wells is explored because it has been difficult to determine the horizontal well productivity due to their long length in the formation compared with vertical wells and inadequacy of measurements during drilling and production. Using field examples, we show that the new integrated production logging measurements can be used to assess horizontal well productivity by identifying productive zones, fluid entries, and determining the fluid distribution (oil, gas, and water) in the wellbore. We also show how reservoir heterogeneity affects the reservoir pressure distribution. The field examples indicate that horizontal wells have permanent water sumps, regardless of whether they produce water. In these wells, we show that when a large percentage of the wellbore cross section is filled with water, reduced oil entry oecurs. Performance simulations for these horizontal well indicate 30 to 50 percent productivity reduction when they are compared with their full potential.
New Procedure for Horizontal Well Test Design and Interpretation in Heterogeneous Reservoirs
Authors: Falade G. K. , Konwar L. S. , Mohammed Sabry A'Alim.
Published: December 2007

This paper presents case histories of horizontal wells transient pressure test interpretations conducted in a carbonate reservoir. The development of non-conventional techniques for interpreting some short-time horizontal well test pressure responses are presented.

Horizontal well trajectories as well as fluid flow dynamics can introduce complexities into the horizontal well test pressure response data. In many of such cases, horizontal well tests are not amenable to analysis using conventional methods of well test interpretations. However, for those wells where the early radial and the early linear flow regimes are observed, a test interpretation method developed as ‘The Gradient Intercept Method’ could be used to implement complete test interpretation satisfactorily. The method precludes the need for the development of late radial flow regime, and consequently, the long shut-in time generally associated with horizontal well testing and the attendant loss of oil production can be averted. A numerical model with PEBI grids is also constructed using a well test simulator to confirm the results obtained from gradient intercept method.

For cases where the primary objective of a well test program is the assessment of wellbore skin effect, the Short Time Skin Test (STST) is introduced. The STST is essentially a wellbore monitoring technique used in a time-lapse fashion to evaluate wellbore damage. Both the Gradient Intercept and the STST methods are illustrated with field examples to demonstrate their applicability.
Site Specific and Integrated Waste Management Plan for Oil and Gas Exploration Production
Authors: GENESTE Philippe , GRANDPRAT Michel , SUTTON Catherine , VIDALIE Jean-François , DRAPIER Maurice
Published: December 2007

TOTAL Exploration Production (TEP) has assumed a commitment in the implementation of a Waste Management Plan, fully integrated as a part of the Environmental Management System on each oil and gas E&P site. The strategy is a step by step process based on : waste inventory, reduction at source, recycling, toxicity minimisation, treatment and pre-treatment, final disposal. Produced wastes are varied : oil base mud cuttings, oily sludge and mud from water treatment, oily paraffinic emulsion, spent chemicals and lubricants, scrap materials, household waste from base camps, contaminated soils from a spill area in case of incident.

Waste segregation and recycling is always a priority, depending on process conditions and available local possibilities. Waste reduction at source is systematically considered : use of recycling drilling fluids, slim holes to minimise cuttings volume, choice of desaromatized fluids for toxicity reduction, etc. Environmental Performance Indicators are selected and closely monitored to detect the exact waste generation, detect any harmful effects and establish mitigating measures.

Waste treatment techniques are specifically designed according to local regulation and good oil industry practices. Various techniques such as stabilisation/solidification, landfill disposal, treatment in authorised centres are applied when no other alternative is available. Improved combustion using special burners is preferable and much more environmentally satisfactory than conventional ground flaring.

Some methods are innovative and integrated in a comprehensive R&D Program : biotreatment is a method for which successful pilot field tests have been achieved in France (landfarming tests using oil base mud cuttings, and composting in biopiles). After the favourable results obtained, it was decided to apply the method to oily wastes from an E&P site. Two basic treatment routes are being investigated : bio-slurry, dynamic and static composting. The technique will be applied as an industrial waste treatment process in a dedicated "bio-centre".
Thermophilic Bacteria in UAE Environment Can Enhance Biodegradation and Mitigate Wellbore Problems
Authors: AlMaghrabi I. , Chaalal O. , Islam M. R.
Published: December 2007

Several strains of thermophilic bacteria were isolated from the environment of the United Arab Emirates. These bacteria show extra ordinary resistance to heat and have their maximum growth rate ranging from 45C to 80C. This paper investigates the potential of using these facultative bacteria for both in situ and ex situ bioremediation of oil spills and microbial enhanced oil recovery. In a series of batch experiments, bacterial growth was observed using a Computer Image Analyzer following a recently developed technique.

Experiments show clearly that the growth rate is high in the presence of crude oil. This is coupled with a rapid degradation of the crude oil. These bacteria were found to be ideal for breaking down long-chain organic molecules at a temperature of 80C, which is the typical temperature of the light oil reservoirs in the Gulf region. These bacteria were also prolific at 45C, which is the typical ambient temperature of the region in the summer months. The same strains of bacteria are also capable of surviving in the presence of saline environment that can prevail in both sea water and reservoir connate water. This observation prompted further investigation into the applicability of the bacteria in microbial enhanced oil recovery. These bacteria were found to decompose crude oil as well as asphaltenes. Most of UAE crude oils are asphaltic and pose serious production problems of near-wellbore plugging. Thermophilic bacteria can effectively clean damaged wells and the vicinity of wellbores.

Similarly, the bacteria appeared to breakdown the microstructure of waxy materials. Even though, this did not yield to high degradation rate, the permeability damage due to wax deposition could be mitigated.

Finally, mathematical models were developed for determining the degradation rate in the presence of thermophilic bacteria. Corrections are made to accommodate both the effect of growth and propagation in the porous medium in the vicinity of the wellbore. Excellent match was found between experimental and numerical observations. Predictive runs were conducted to observe the role of various governing parameters prevalent in both environmental and enhanced oil recovery schemes.