bluuebunny/crossref_metadata_2025 huggingface dataset:
Real-Time, Downhole Hydraulics Modelling Helps Operator Drill the Well and Run Liner Under a Narrow Fracture/Pore Pressure Window Condition
Authors: Peng S. , Hodder M. , Kay M. , Milton A.
Published: December 2007

The measurement of Annular Pressure-While-Drilling (APWD) is widely used as a vital tool today; however, measurement of pressure while running the casing or liner is not available. This paper presents field data demonstrating the use of a real-time, downhole pressure modelling software to provide vital downhole hydraulics. This software was used recently on two critical North Sea wells to ensure that drilling and running of casing and liner could be done within safe margins under a narrow fracture/pore-pressure condition. The description of the hardware set-up and real-time parameters used and its communication with the central, data-logging computer are also included.

In order to verify the accuracy of the software, the computed pressure data was compared with that measured by APWD while tripping in and out of both wells. The measured data during tripping was recovered from the tool memory after the trip. Results demonstrated the close correlation between the calculated and measured data that was observed prior to running casing/liner. This gave the rig crew confidence to rely on the hydraulics information given by the software when running the liner. The software was then used to guide the casing crew to run the liner successfully.
Completion Architecture: A Methodology for Integrated Well Planning
Authors: Sinha S. , Yan M. , Jalali Y.
Published: December 2007

We examine how well completion design is governed by subsurface characteristics, surface environment, and state of technology. We present a methodology of well design that takes into account geology, drilling, reservoir, and operational characteristics and constraints. The method selects pertinent configurations for well trajectory, formation completion, and wellbore components to segment, route, lift, and monitor the flow stream. We discuss how this methodology is derived from case histories in land, platform, and subsea fields.
UBD Creates A Step-Change In Drilling Performance In Syria – A Case Study
Authors: Zonjee Peter , Farren Niall , Hanouf Mohammed , Davidson Ian , Zuber Patrick
Published: December 2007

The Al Furat Petroleum Company (AFPC) has achieved a step-change in drilling performance since the introduction of Under-Balanced Drilling (UBD) in September 2002 in the Omar field. To date 7 wells have been drilled using the UBD technique resulting in up to 55% reduction in drilling duration per well, 16% reduction in drilling expenditure and 17% reduction in cost per meter drilled.

This step change has been achieved due to the following advantages that UBD technology offers when compared to traditional methods. Using UBD: A contingency casing, or liner, can be omittedA slim casing design can be used whilst well functionality is maintainedWell control events associated with high pressure / low volume kicks, can be quickly, efficiently and safely dealt withThe average rate of penetration in the ‘UBD’ section is increased up to 100% due to the lower mud weight used (up to 2.5-5.0ppg reduction in mud weight)

An additional advantage has been the capability to identify and characterise hitherto undetected hydrocarbon zones.

The integrated team approach adopted has proven key to the successful introduction and uptake of UBD technology in AFPC's operations. The success has established UBD as one of the strategic technologies to improve drilling performance and reduce overall well construction costs.

This paper describes the step-change in drilling performance in AFPC's operated Omar field through introduction of UBD technology. Additionally, Project Management aspects and HSE approach used to successfully and safely introduce this technology are included.
Optimum Selection of Underbalanced Techniques
Authors: Alajmi Saad E. , Schubert Jerome J.
Published: December 2007

The growth pattern of attractive new concepts, such as Underbalanced drilling (UBD), can be expected to follow an "S" shaped growth curve (Fig. 1).1 Much UBD technology is still considered relatively new, and probably just leaving the Early Adopters stage. The key to success in moving underbalanced drilling up the growth curve lies in a good understanding of the technology, careful planning (including full consideration of the risks), disciplined execution, and effective dissemination of technological information. Otherwise, early adopters can pay dearly for taking up the flag of new technology.

Several papers have been published discussing UBD processes as well as the benefits achieved from this technology. However, few papers have examined on the criticality of planning for UBD operations. A new research project has begun with the purpose of providing a detailed study in how to achieve proper planning for UBD operations in order to achieve success in drilling the well. This study emphasizes formation stability, well control, environmental restrictions, minimum formation damage, hydraulic analysis, and guaranteed economic incentives. Finally, we present an easy-to-use computer program has been developed to help in designing underbalanced drilling operations.

This paper reports the results of this project and demonstrates the use of the computer program and how it can be used as an easy and practical reference to determine the proper underbalanced drilling technique to apply to a particular situation.
Using a Novel Fiber Cement System to Control Lost Circulation: Case Histories from the Middle East and the Far East
Authors: El-Hassan Hassan I. , Abbas Raafat , Jarouj Haitham , Munk Trevor
Published: December 2007

Eliminating or controlling lost circulation during drilling or cement operations is a costly and time-consuming process. Traditional treatments include lost circulation materials (LCM), cement, crosslinked polymers, dilatent slurries, reinforcing plugs, and silicate systems. The general practice is to cure the losses before proceeding to the cementing operation. The mixed results of such treatments plus the fact that cementing operations sometimes proceed even with partial or total losses have led to the development of a new advanced-fiber cement system (AFCS). This paper will discuss the properties and the mechanism of the AFCS and its successful applications as a solution to lost circulation in the Middle East and the Far East.

AFCS forms a fibrous network across highly permeable formations, induced and natural fractures, and vugular formations to prevent and stop the losses during remedial or primary cementing operations. Unlike conventional fibers that normally are difficult to disperse in the cement slurries and tend to plug surface and downhole equipment, AFCS does not suffer from such drawbacks.

Laboratory tests have shown the effectiveness of AFCS in plugging different hole sizes. The efficiency of this system was enhanced in the laboratory when combined with high-performance lightweight cement slurry (HPLW), an optimized particle size distribution system. Several jobs in Abu Dhabi showed substantial success rates compared with traditional lost-circulation treatments. This was confirmed by cement returns to surface and cement coverage across the lost-circulation zones.

Other field locations utilized AFCS in cement plugs, top jobs, and primary cementing operations through different float equipment, liner hangers, and even coiled tubing without any plugging problems.
Short Radius TTRD Well with Rig Assisted Snubbing on the Veslefrikk Field
Authors: Grinde Jan , Haugland Torstein
Published: December 2007

During the turn of the year to 2003 the sidetrack A-19 A was drilled from the motherwell A-19 as a Through Tubing Rotary Drilling (TTRD) well, on the Veslefrikk Field in the Norwegian sector of the North Sea.

A whipstock with holes to produce the motherwell through was set in the 5 in. liner. 4 1/8 in. polycrystalline diamond compact (PDC) bit and 2 7/8 in. high torque motor with adjustable kick off (AKO) setting of 3.8° were run on 2 7/8 in. drill pipe through 5 ½ in. tubing.

The sidetrack started with 25° inclination and the wellpath was horizontal after 24 m true vertical depth (TVD) drilled. An average dogleg severity (DLS) of 42° /30 m was achieved in the build up section. An 80 m horizontal section was drilled and geo-steered using gamma ray (GR) and multi propagation resistivity (MPR) measurements. The same bottom hole assembly (BHA) was used for the horizontal section as for the build up section of the sidetrack.

A pre-perforated 2 7/8 in. liner was installed in the 4 1/8 in. open hole.

The operations were performed using a Rig Assist Snubbing (RAS) unit in cooperation with the rig system. The pre and past-drilling operations were performed in underbalance while the drilling operation was in overbalance through the snubbing BOPs.

The motherbore and the sidetrack were set in production immediately after the liner was run.

In the future Statoil are looking at performing a similar drilling operation in underbalance. It should then be possible to make a sidetrack in approximately 10 days.
Optimal Horizontal Drilling of Hard and Abrasive Unayzah Sandstones
Authors: Simpson Michael , Zhou Shaohua , Treece Mark , Rondon Carlos
Published: December 2007

The first ‘Unayzah horizontal well (W-4) with a 5-7/8″ lateral was drilled with considerable difficulty. The 5,732 ft lateral at 14,000 ft TVD traversed the most productive, albeit hardest and most abrasive section of the ‘Unayzah B with average unconfined compressive strength of 22,000 psi, with hard streaks up to 35,000 psi; and internal angles of friction ranging from 39 to 60°.

Drilling horizontally, the TCI bits were subjected to increased bearing stress and gauge wear. Moreover, they had to be run on PDM's for directional control at minimum bit speeds of 130 – 170 rpm, in the sliding and rotational modes respectively, which substantially cut on bottom rotating time. The PDC and Impregnated bit performance diminished drilling horizontally, as did PDM stator and bearing life with static BHT of 278° F. However, since W-4 required a pilot hole, and two sidetracks it offered a unique opportunity to compare drive mechanism, TCI, PDC, TSP and Impregnated bit performance at equivalent TVD's and formations in the same well.

This paper presents a summary of primarily 5-7/8″ lateral drilling experience in the ‘Unayzah B reservoir along with cost and performance comparisons with other ‘Unayzah horizontal wells. Valuable lessons learned are also discussed.
New-Technology Application to Extend the Life of Horizontal Wells by Creating Uniform-Flow-Profiles: Production Completion System: Case Study
Authors: Qudaihy D. S. , Nughaimish F. N. , Sunbul A. H. , Ansari A. A. , Hembling D. E. , Faraj O. A. , Voll B. A.
Published: December 2007

Horizontal wells have dominated the conventional wells due to their increased production rates, improved recovery efficiency, increased reservoir drainage area, and delayed gas and water coning. However, non-uniform flow profiles can result in premature water / gas production, loss of production and reserves, and decrease in profitability, which will shorten the life, and defeat the purpose of a horizontal well.

This paper will describe a new production technology system that will optimize production, delay water / gas coning, eliminate / minimize annular flow, and ensure uniform inflow along the lateral at the cost of a minute pressure drop in long, high-rate horizontal wells. Case history will be presented from Saudi Aramco, where this production technology, combined with sand control technology, has resulted in significant saving for the operator, and improved production in horizontal offshore oil wells.
Automated Drilling Application for Gaining Higher Efficiency on Extended Reach Wells
Authors: Hofschröer Martin
Published: December 2007

The relatively conservative behaviour in the drilling industry with respect to implementation of new technology will not survive any longer. More and more difficult formations, extended reach drilling, extreme environmental conditions on the rig locations and increasingly smaller reservoirs need to be explored and are just calling for combined efforts of all parties involved in the drilling process. Experience and application of state of the art technology is the correct answer.

Whereas on Offshore installations, usually gaining higher day-rates, sophisticated technology has been widely accepted already, on movable land rigs it is very often just the opposite. Drilling contractors might not care as they are paid by dayrate. However, if the bore-hole quality is bad, down time has to be faced which is paid on lower rates if at all. Operators will just win since well quality and drilling performance improves. Offshore technology and safety standards will step by step find their way onto land drilling rigs.

The drill bit, pushed downwards by heavy weight drill pipes, is rotated either via Top Drive or via Rotary Table, high pressure mud powers the downhole motors, carries the cuttings upwards and cools the bit down. Simple!
New Performance Motors Set New Benchmarks in Drilling Performance
Authors: Reich Matthias , Oesterberg Marcus , Regener Thorsten , Kent David , Nawfal Nick , Al Khames Shaker
Published: December 2007

The elastomer and its bonding system has always been the one of the most critical areas in downhole motor design. The elastomer's physical properties change due to temperature or from reactions with certain chemicals commonly used in drilling applications. This limits both the motor's operational temperature range and the chemicals that can be used in the mud system. While drilling with a conventional motor, heat is concentrated in a regular elastomer power section's lobes forming hot spots which contribute to a premature heat aging of the elastomer. Today, however, a new manufacturing process for stator tubes permits the forging of a pre-contoured lobe configuration — significantly reducing the elastomer content in the power section. This new design broadens motor capabilities by allowing heat to radiate faster from the thin elastomer and significantly improving the motor's mechanical and volumetric efficiency.

The power output of all sizes of positive displacement downhole motors has more than tripled during the past fifteen years. For example, today's 4–3/4″ motors are significantly stronger than the 9–1/2″ motors built in the 1980's. The latest step change in motor power was achieved in the manufacturing processes that eliminated 60%-80% of the elastomer used in the power section's stator.

These latest generation downhole motors are used as performance motors — delivering over 50% more power output compared to the previous generation motors of the same length and diameter and permitting the operator to select more aggressive bit designs. As a result, operators have experienced Rates of Penetration (ROP) improvements of 100%-300%. In addition, high speed configurations with bit speeds up to 1200 RPM are used in hard and abrasive formations with temperatures up to 160°C (320°F). These configurations outperform previously used turbines where the motors have greater torque capabilities while maintaining full steerability throughout the entire run. Typical performance drilling applications cover re-entry, deepwater and extended reach wells in all parts of the world.

This paper describes the technical features of the latest generation downhole motors in detail and documents their capabilities with case histories from various worldwide applications.
Rotary-Steerable Technology Proves to be Economically Successful in Offshore Arabian Gulf Fields
Authors: Porter Dean S. , Al-Faraj Hasan
Published: December 2007

In the Arabian Gulf, a rotary-steerable system utilizing "point-the-bit" technology decreased the well-construction cost in two Saudi Arabian offshore oil fields. Drilling offshore, in many (if not all) parts of the world, is an expensive adventure. "Point-the-bit" technology has successfully and consistently controlled capital expenditures for wells in these offshore fields and, in head to head comparisons, has cost less money when compared to the conventional drilling systems that had previously been used.

When it comes to offshore operational costs, time is a nemesis. The application of "point-the-bit" technology as a way to help solve this problem by permitting the economical completion of a quality borehole will be discussed in this paper. A major concern has been that the phenomenon known as "hole-spiraling" which has created hole-quality issues. These issues range from tortuous paths, torque-and-drag frictional forces, key-seating or sump effects, and poor log responses to name just a few of the problems. Thus, when the quality of a borehole and the time it takes to drill it are considered less than desirable, the drilling process and its resultant effects increase well costs and reduce operational efficiencies.

Several case histories within two offshore fields will be presented in this paper. These case histories will show that having the capability to make adjustments to downhole drilling tools "on-the-fly" makes for better steering control and creates better hole geometries. Correctly applying "point-the-bit" rotary-steerable systems on these wells demonstrates the value-added potential of this technology.
Productivity-Based Method for Selection of Reservoir Drilling Target and Steering Strategy
Authors: Kharghoria A. , Cakici M. , Narayanasamy R. , Kalita R. , Sinha S. , Jalali Y.
Published: December 2007

We present a heuristic method of delineating reservoir regions with favorable production potential for well placement. The method uses basic concepts of proxy formulation for well productivity to relate the production potential of a well placed in any region in the reservoir, to the basic properties of that region (petrophysical, dynamic, geometrical). These properties may be readily obtained from any history-matched or data-conditioned reservoir model. Therefore, a productivity potential map for the reservoir can be easily generated. Also, the relevant properties relate to parameters measurable in an LWD operation. We use this technique to simulate the impact of alternate steering strategies on well path and productivity. This requires a fine-scale model of the region designated for drilling (i.e., model prior to upscaling). The influence of additional LWD measurements on reservoir trajectory and expected well performance can therefore be assessed with this technique (e.g., impact of NMR-derived permeability). We also examine how this method may be applied when multiple geological scenarios are conceivable for the area targeted for drilling. We apply a simple technique for model aggregation that proves effective in identifying drainage areas that are optimum or near-optimum in an overall sense. Therefore, a well placed in the region identified by the aggregate model shows a performance with respect to the underlying geological models that is best or not far from it.
Simulation of Time-Dependent Wellbore Stability in Shales Using a Coupled Mechanical-Thermal-Physico-Chemical Model
Authors: Freij-Ayoub R. , Tan C. P. , Choi S. K.
Published: December 2007

The interaction of the drilling fluid with the formation rock is a key factor that determines the time-dependent stability of wellbores in shale formations. The analysis of wellbore stability in shales requires modelling of various coupled processes that are dependent on the relative properties of the drilling fluid and formation pore fluid. These processes include mud pressure penetration, thermal diffusion, chemical potential mechanism and poroelasticity. These processes affect the formation pore pressure, stresses and deformation. The critical drilling fluid properties include mud type, weight, temperature, and type and concentration of free ions.

Numerical simulations are conducted to model the effect of coupling the various processes on wellbore stability in shales. The simulations used a finite element code SHALESTAB that solves the specific coupled differential equations which describe these processes. It is found that the use of a cooler drilling fluid with a higher salt concentration and the appropriate mud density, viscosity and surface tension reduces the formation pore pressure and helps to enhance the stability while the use of a hotter drilling fluid with a lower salt concentration and less favourable mud physical characteristics has the reverse effect. The coupled simulations show that incorporating the chemical potential and mud pressure penetration mechanisms, depending on the mud properties, can reduce the formation pore pressure. For an effective assessment of wellbore stability in shales, the analyses need to take into account these complex coupled time-dependent processes.
Applying Electrophoresis Technique to Study Adsorption of Surface Active Agents on Reservoir Rocks
Authors: Elmofty S. E. , Shokir E.M. El-M.
Published: December 2007

Interfacial behavior of fluids in contact with sandstone is governed to a large extent by their surface electrochemical characteristics, pH of the surroundings, concentration of the dissolved ionic species and the existence of any surfactant control surface properties. In this study electrokinetic properties of sandstone are reported as a function of the pH and in the presence of different concentrations of sodium chloride, modified natural polymers and anionic and nonionic surfactants. Mechanisms of adsorption of the previous mentioned surfactants on sandstone are discussed. Measurements of wettability and a correlation between the electrokinetic results are investigated. The surface electrochemical characteristics of the sand was found to play a governing role in determining the mechanisms of adsorption of the studied surfactants.
Empirical Equations for Water/Oil Relative Permeability in Saudi Sandstone Reservoirs
Authors: Al-Fattah Saud M.
Published: December 2007

Relative permeability data are essential for almost all calculations of fluid flow in petroleum engineering. Water/oil relative permeability curves play important roles in characterizing the simultaneous two-phase flow in porous rocks and predicting the performance of immiscible displacement processes in oil reservoirs. This paper presents new empirical equations for calculating water/oil imbibition relative permeability curves. The models of relative permeability were developed using experimental data from 46 displacement core tests from sandstone reservoirs of Saudi fields. Three empirical equations are presented to calculate oil relative permeability, water relative permeability, and the endpoint of the water relative permeability curve. The relative permeability models were derived as a function of rock and fluid properties using stepwise linear and nonlinear regression analyses. The new empirical equations were both evaluated using the data utilized in the development and validated using published data, which were not used in the development stage, against previously published equations. Statistical results show that the new empirical equations developed in this study are in better agreement with experimental data than previous empirical equations, for both the data used in the development and validation stages. The new empirical equations can be used to determine water/oil relative permeability curves for other fields provided the reservoir data fall within the range of this study.
Pressure and Compositional Gradients in Reservoirs
Authors: Montel F. , Bickert J. , Hy-Billiot J. , Royer M.
Published: December 2007

The search for the optimal development of a field involves proper knowledge of the composition of the fluids that impregnated the reservoirs. The development scheme could be strongly affected by the connectivity between the different reservoir units. After their migration into the trap, the fluids are shaped by various forces, among them, gravity has the most striking effect and was widely studied. In many cases there is evidence for the contribution of other forces like thermal gradients. Taking into account all the phenomena, to establish a consistent picture of fluids distribution in the field is an important challenge for the petroleum industry. Reciprocally the actual fluid distribution can be used to assess the connectivity of the different panels and layers. In that case, all the possible compositional redistribution mechanisms have to be taken into account.

In some circumstances, particularly in recent mature and permeable petroleum systems, hydrocarbon accumulations are subjected to gas fluxes, which lead to non-conventional fluid distribution. There are already a number of tools available for calculating the compositional gradient within a reservoir, including the contribution of gravity and thermal gradient. In many field cases, however, the calculated profile differs from actual. The discrepancies are imput to another external force: the mass flux of light component at the reservoir boundaries.

In this paper, the authors present the modeling of diffusion fluxes across the reservoir and point out how the diffusion fluxes can reveal the permeability barriers through the pressure and the compositional profiles.

Drawing on a field example, this paper provides a methodology for dealing with dynamic reservoir fluid systems. The model matches the observed compositional gradient and corresponding PVT properties. It allows reliable connectivity assessment in cases where gravitational modeling fails.
Improved Reservoir Description using Surface Oil Viscosity Data
Authors: Umeh N. , Isehunwa S. , Okorafo C. , Owolabi S. , Agu I. , Olare J. , Biambo T.
Published: December 2007

Subsurface oil viscosity data are usually not readily available for most reservoirs, as they are expensive to acquire. On the other hand, surface oil viscosity is routinely measured and therefore readily available for all producing wells. A method has been developed for converting the surface viscosity to reservoir viscosity data, using SPDC’S "Field A" as a case study.

Surface oil viscosity data from all producing wells in "Field A" where collected from SPDC-West Production Chemistry laboratory and converted to reservoir viscosity using a simple method that utilises relevant PVT data. The method allows a better and more detailed subsurface description of reservoir viscosity in line with facies variations. The study also shows that reservoir oil viscosity could be lower in some sands than previously estimated. This gave a significant impact on reserves in one of the reservoirs where scope to increase the booked reserves by about 60 MMstb was observed. Opportunity to also increase the constrained offtake of 2300 b/d to 3000 b/d in some planned new wells was also observed.
A New Scaling Equation for Modeling of Asphaltene Precipitation
Authors: Jamialahmadi M. , Ahmadi K.
Published: December 2007

The amount of asphaltene precipitated is a crucial factor in determining the degree of permeability impairment of the reservoir rocks. It is useful to know how much asphaltene precipitates as a function of temperature, pressure and liquid phase composition. The objective of this work is to present a simple and accurate mathematical model, capable of predicting the amount of asphaltene precipitated at a given operating condition.

Extensive new experimental data for the amount of asphaltene precipitated in an Iranian crude oil has been determined with various solvents and at different temperatures and dilution ratios. All experiments were carried out at atmospheric pressure. The experimental data obtained in this study were used to examine the scaling equations proposed by Rassamdana et al. [1,2]. We introduced a modified version of their proposed scaling equation.

Our observation showed that the results obtained from the present scaling equation are in good agreement with experimental data at low value of dilution ratios. The properties of complex asphaltenes are not considered in this simple model. We strongly recommend this model for laboratory experiments and core flood tests which are often performed at atmospheric pressure and practically at low value of dilution ratios.

Introduction

Asphaltene precipitation is one of the most common problems in both oil recovery and refinery processes. In oil recovery, especially in gas injection, formation of asphaltene aggregation, following their deposition causes blocking in the reservoir. This makes the remedial process costly and sometimes uneconomical. Unfortunately, there is no predictive model for asphaltene problem treatment. Hence it is necessary to predict the onset of asphaltene precipitation, as a pre-emptive measure. The major questions in facing such problems are " When" and " How much" heavy organic compounds will precipitate in operational condition. Over the years, many researchers have tried to find the answer. They introduced experimental procedures or even analytical models, but a fully satisfactory interpretation is still lacking. The problem is very difficult mainly because of the fuzzy nature of asphaltene and the large number of parameters affecting precipitation.
Low-Resistivity Pay (LRP): Ideas for Solution
Authors: Souvick Saha
Published: December 2007

Low-resistivity pay (LRP) has been a long-standing problem in formation evaluation. Though LRP occurs both in carbonates and sandstones, it is more common in sandstone reservoirs. Because of LRP, one may overlook the zone or compute high water saturation (Sw) leading to "condemning" the zone or underestimating the reserve.

Because of the complexities that contribute to LRP, the cause must be determined before an appropriate solution can be applied. LRP can occur because of several reasons, such as, deep invasion by conductive borehole muds, "classic" clay problem (i.e. cffect of cation exchange capacity, CEC), presence of capillary bound water, conductive minerals (such as pyrite), fractures, micro-porosity, laminated formations and high angle wells (anisotropy effect). When more than one of these effects is present in the formation, the solution is even more difficult. Nevertheless, once the reason of LRP is understood, several logging tools and/or interpretation techniques can be applied to compute accurate Sw. In Nigeria where reservoirs are mainly sandstones, the predominant effect of LRP is due to clay, capillary bound water, laminated

formations and high angle wells. New logging technologies including new modern resistivity (both wireline and LWD), magnetic resonance, elemental spectroscopy and high-resolution borehole images contribute significantly to solving for LRP problems.

Finally, after correcting for Sw in LRP, the new Sw needs to be validated. The validation can be done with core data; there are two common methods, direct Sw measurements from oil-based mud cores 1 and computing from capillary pressure data. Direct Sw measurement is rather expensive procedure, whereas Sw from capillary pressure data can be computed easily with knowledge of the height above free water level and core plug permeability. Thus, finding the cause, applying the right technique to compute accurate Sw and validating the result by core integration can solve LRP problem. This will lead to improved decision in well completion, reserve estimation and reservoir simulation for accurate production forecasting.
Intelligent Well Completion: Status and Opportunities for Developing Marginal Reserves
Authors: Konopczynski Michael , Ajayi Arashi , Russell Leigh-Ann
Published: December 2007

Marginal reserves are hydrocarbon accumulations too small or too difficult to recover economically by themselves under prevailing fiscal terms. Stacked reservoirs containing marginal reserves are often passed over in favour of more prolific zones containing economic volumes. The opportunity to develop the marginal reserves in conjunction with other marginal reserves, or with larger reserves by commingling (and by doing so make them economic) is sometimes overlooked by operators due to government regulations prohibiting commingling.

This paper explores the concept of developing marginal and/or other reserves by commingling using intelligent well technology. It reviews the current status of intelligent well technology and government regulations on commingling in a number of regions. The potential for exploiting marginal reserves in the North Sea, Nigeria and the Gulf of Mexico is also considered.
Simulation of Intelligent Well Completion Predicts Oil Recovery Increase in a Commingled Production Scenario: A Case Study
Authors: Ajayi Arashi , Konopczynski Mike
Published: December 2007

Water coning has been observed to have a negative impact on the productivity of producing wells. This situation often results in reduction of recoverable oil reserves. The application of Intelligent Well Technology (IWT) offers an operator the opportunity to manage this adverse effect and improve productivity of such wells. IWT provides an operator the capability to remotely control, monitor and manage multiple horizons in a given well. Application of the technology has provided significant value, through the ability to control multiple zones independently, reduce total number of wells, reduce future costly well intervention, and accelerate production of zones to maintain a plateau for extended period of time.

This paper presents the results of a simulation case study carried out in a Gulf of Mexico field. The study objective was to assess the capability of an IWT completion to control excessive downhole water production and maximise total oil volume in a three layer reservoir system. A dynamic optimisation technique was used in the reservoir simulator to independently control the Interval Control Valves (ICVs) in each zone to achieve the desired production objective. The ICVs are modelled as downhole chokes that are connected to a standard well model. The optimisation procedure monitors these chokes while the simulation is running and controls them as required.

The results show that the IWT system was able to minimise the volume of water produced by the well in the studied coning condition when compared to conventional system. This is mainly due to the choking capability of the ICVs. We also estimated an oil recovery increase of about 63% when compared to a conventional system. Potential applications of the technology should be assessed with regard to well/reservoir objectives.
A Comprehensive Numerical Simulation Model for Non-Darcy Flow including Viscous, Inertial and Convective Contributions
Authors: Belhaj H. A. , Agha K. R. , Butt S. D. , Islam M. R.
Published: December 2007

In this paper, a comprehensive numerical simulation model is introduced to resolve the problem of non-Darcy flow in porous media. As represented by this model, both pressure gradient and velocity profile predicted are based on the two viscous terms of Darcy and Brinkman, Forchheimer’s inertial term and Navier-Stokes’ convective term. At the point of departure from the Darcian domain to the non-Darcian domain it has been found that this model predicted the dimensionless term "Be" to be zero which agrees with Forchheimers model prediction. At 5% deviation from the Darcian flow the proposed model predicts "Be" to be 0.0756 as compared to 0.0526 predicted by Forchheimers model. The difference is due to higher flow velocity prediction by the proposed comprehensive model.

The proposed model is expected to have wide applications in the field of reservoir simulation and fluid flow in porous media in both gas and oil reservoirs. Replacing the traditional model used to predict pressure gradient at any point of space and time by the proposed model would resolve the problem of inaccurate predictions associated with non-Darcy flow. This model predicts the correct pressure gradient and flow velocity regardless of the source of deviation. The model is continuous in Darcian regime as well as non-Darcian regime.
Development Evaluations of Lenticular Shallow Gas Reservoirs with Bottom Water in Shengli Oilfields
Authors: Sheng Ruyan , Cui Chuanzhi , Ding Liangcheng
Published: December 2007

Shallow gas reservoirs are widely distributed in China and mostly occur at depths shallower than 1500 metres (4921.50 ft). These occur as lenticular and marginal reservoirs, with small and scattered reserves, with quite complex gas-water relationship and edge/bottom water in the majority of sand-bodies. Each sand-body forms an unattached and closed gas-water system, but there is limited elastic energy in the aquifer. The production performance of one of such reservoirs is as follws: –Per-well initial gas rate is rather low with fast decline.–The reservoir has a gas drive to weak elastic water-drive.–Water incursion has obvious influences on production results.–Wellhead pressurse could be used to represent the changes of formation energy, for it is impacted little by wellbore accumulated liquid.–Finally, formation damage resulting from drilling, perforating etc. has noticble influences on the gas wells’ performance.

Thus the main factors that could decide reasonable well rates should be the following factors: Efficient utilization of formation energy, reservoir structure should not be destroyed, accumulated liquids in the wellbore should be continuously removed. In addition better development results can be achieved through initial sand control and edge/bottom water fingering/coning should be minimised.

The purpose of this paper is to have a review of the parameters and the performance of the Shengli oil reservoirs. It could be used for reference for similar type of reservoirs.
Improved Safety of Rig Automation with Remote Monitoring and Diagnostics
Authors: Levett Bryce
Published: December 2007

Rig automation has focused on improving safety with equipment designed to reduce manpower/human interaction and assume repetitive tasks and operations. As more parts of a drilling rig become automated, there has been a change in how rig personnel interact with equipment. A system of remote monitoring, diagnostics and technical support has been developed to make this interaction more seamless and expand the focus of rig automation. Case studies are presented in this paper of actual field conditions where the remote monitoring system eliminated hazardous operations, discovered operational "bad habits", and identified areas requiring additional training. Use of the remote diagnostic system prevented the need for physical contact between human and machine in order to solve problems. Documented field incidents have shown benefits of increased safety in many areas when using remote monitoring and management compared to operations without.
Standardised Procedures for Work Permits and Safe Job Analysis on the Norwegian Continental Shelf
Authors: Botnevik R. , Berge O. , Sklet S.
Published: December 2007

Promoting safety in an offshore environment where more than 2/3 of the workforce travel between different operating companies and installations represents a continuous challenge since the procedures and requirements are different from installation to installation. The Work Permit (WP) system and the use of Safe Job Analysis (SJA) represent essential operational safety barriers required in the daily management of work and safety on oil and gas installations.

Through a process of dialogue and participation, involving the offshore community a standardised procedure for WP and SJA has been developed and approved for implementation on all production installations on the Norwegian Continental Shelf (NCS). The objective of this industry wide change is to improve safety and working conditions offshore through the use of standardised procedures and practices.
Harmonization of the Kazakhstan Environmental Legislation with EU and North America: Issues and Opportunities
Authors: Zhunussova Maira A. , Iskakov Nurlan A.
Published: December 2007

Does legislation help to achieve better quality of the environment? This paper intends to answer this question. Kazakhstan legislation on the protection of the environment was shaped under the Soviet period of economic development and served a planned economy with a very authoritarian style of government, administration and management. During the so-called "transition period", the intention to move towards a market economy has considerably changed the environmental legislation, although many previous regulations remain in force. This mix of planning and market legislation, regulations and standards proved to be inefficient to protect the environment.

The oil industry has a great influence on a country's economic development and environmental quality in the areas of its activity. The industry's genuine desire to protect the environment while pursuing its business goals is facing obstacles in the form of unjustified restricted permitting rules and limit settings, causing unnecessary expenses, which otherwise could be invested in more efficient environmental actions.

The difference between EU or US legislation and that of Kazakhstan is not in the amount of legal documents. This difference lies in the approach to environmental protection which is quite contrary to that of the EU and the US. The former Soviet countries base their approach on setting rigid standards (considered the most stringent in the world). There is a large gap, however, between the declared standards and the real economic abilities of enterprises, existing technology, and economic/social capacity to meet these standards.

Therefore Kazakhstan's regulatory authorities pay growing attention to the environmental legislation recommendations of international organisations such as UNDP, OECD, USAID, etc.

This paper highlights the experience of Agip KCO in collaboration with the government in the development of codes and standards in the HSE field. The protection of the environment in this extremely sensitive region has been one of the top priorities right from the beginning of the exploration stage in the Caspian Sea. Some results associated with the Kazakhstan environmental legislation are reviewed, and ongoing improvements as well as the suggested ways of harmonization are presented.
Meeting the Challenge – Compliance With Environmental Legislation on Offshore Oil Industry in China
Authors: Lu Shixin , Xia Ning
Published: December 2007

Like most developing countries in the world, China also faces more and more pressures to protect her marine ecosystems. After nearly 20 years dedication, the government developed a policy and legislative framework to promote marine environment protection. This framework consists of a series of national and local environmental laws, regulations and standards. It is indicative of the system approach China is taking toward marine ecosystem and biodiversity protection. Some areas, which involve legal limitations and permitting requirements, have had an impact on the offshore oil industry.

Based on the viewpoint of a join-venture offshore oil operator, who experienced 20 years operation in South China Sea, this paper is intended to summarize our understanding of these framework structure elements. In order to draw a clear picture of the laws & regulations framework listed at the end of this paper, we will mainly focus on the following: 1) the general environmental legislation structure; 2) key environmental protection laws & regulations; 3) how legal requirements effect the varying phases offshore oil operation. The findings of this paper could help others better understand this framework of regulatory requirements, foresee the future changes of regulations, and be better prepared to meet the challenges.
A National Offshore Petroleum Safety Authority for Australia
Authors: Craddock Richard J.
Published: December 2007

In 2002 the Australian Commonwealth and State/Northern Terriotory (NT) Governments agreed to the formation of a National Offshore Petroleum Safety Authority (NOPSA) to administer safety in the offshore upstream petroleum industry. Legislation was passed by the Commonwealth in November 2003 establishing a NOPSA. It is proposed that the NOPSA will commence in January 2005.

The issues associated with the development of a NOPSA and managing the transition from the current multi-regulator system to a single National offshore petroleum regulator for safety are immense. An overview of these issues, and the processes are provided in this paper.
Evaluation of Contractor HSE Performance Based on Lagging Indicators: Is there a Better Way?
Authors: Knode Tom , Cook Pat
Published: December 2007

Tremendous improvement has been made in the safety performance of the upstream exploration and production activities of our industry in the recent past. The oversight of contractor performance by the operators as well as advancement in technology risk management and hazard awareness are all key elements of this success. The results mean we have a safer work environment and a continuation of our license to operate.

However, one of the recent trends in contractor oversight by operators has been the delegation of the HSE performance evaluation from the HSE function to Procurement. Although this migration incorporates HSE into the business (which is always welcome) it may have negative consequences based on knowledge and competency of the issues. In question is the process of assessing the safety performance of contractors without understanding of the risk profile. Another concern is the assumption the method of collection of inputs is comparable since injury rates are derived using a common formula. This can put stress on a system that is not necessarily absolute.

A better method of evaluating HSE performance would be to include a balance of leading and lagging indicators as well as an investigation of the policies and programs that lead to the overall performance of the contractor. With a more comprehensive evaluation, there will be a better understanding of relative performance of the contractors including their weaknesses and strengths. A more comprehensive evaluation will also place less stress on the lagging indicator measurement system.
Recent Experiences: Building Waste Management Facilities in Remote Areas
Authors: Sedlock Evan , Hoffmann Rob , Ainodion Jimoh , Pegors Steve , Gonzalez Fidel
Published: December 2007

Many exploration and production (E&P) operations are located in developing countries or remote locations that often have poor infrastructure. Commercial waste management facilities of adequate quality may be nonexistent or prohibitively distant, and production expansions are filling the capacity of existing facilities at the E&P sites. ChevronTexaco's business philosophy includes continually improving processes to minimize pollution and waste. As part of our ongoing efforts to improve E&P waste management efforts, we are identifying cost-effective and environmentally protective alternatives for waste management including building new on-site facilities and equipment, evaluating available off-site options, and developing local businesses and infrastructure. We then optimize the selection of alternatives for each location using an overall waste review process.

This paper will highlight recent and planned investments in our international waste management facilities including: In Venezuela in 2002, the company commissioned a U.S. $1.8 million state-of-the-art facility that is designed to handle a broad spectrum of wastes from the Boscan oil field.In Sumatra, Indonesia, a subsidiary of ChevronTexaco has reviewed its waste management strategies and developed comprehensive plans for additional waste management facilities and stand-alone equipment totaling U.S. $6.0 million that is awaiting governmental approval. This is in addition to several recently commissioned major facilities for improved management of oily wastes including a slurry injection facility and five soil bioremediation facilities.In Nigeria, plans are underway for a variety of new waste management facilities totaling U.S. $28 million including a landfill, incinerators, slurry injection, and a sewage treatment plant.In Kazakhstan, the company's joint venture Tengizchevroil has initiated design and construction of a U.S. $16 million integrated waste management facility. The facility will include a landfill, a recycling and treatment area, and a reception facility with a weighbridge. In 2004, the landfill and key site infrastructure elements will be commissioned.