bluuebunny/crossref_metadata_2025 huggingface dataset:
Petrophysical Properties of Ferron Sandstone During Two-Phase Flow: Implications for Heterogeneity in Tertiary Deltaic Reservoirs
Authors: Miller M. A. , Yang Huade , Holder J. T. , Jounus M. J. , Gray K. E. , Fisher R. S.
Published: December 2007

This study was part of a comprehensive program of quantitative characterization of heterogeneity in fluvial-deltaic reservoirs, using the Ferron, Utah outcrop as an analog reservoir. A suite of petrophysical properties were measured simultaneously in the laboratory for over sixty specimens, representing different geologic facies, flow units, and barriers. Properties included porosity, permeability, electrical conductivity, shear and compressional wave velocities, and quasi-static moduli, measured under simulated reservoir conditions during two-phase steady-state flow of gas and brine, in both drainage and imbibition. Petrographic data on each sample were also gathered, including quantification of detrital and authigenic phases, thin-section porosity, textural and grain-size distribution analyses. Centrifuge capillary pressures on plugs from the laboratory test specimens were also measured. Minipermeameter determinations of test specimen air permeabilities were conducted in companion studies. Statistical studies were conducted to relate petrophysical data to petrographic information in an attempt to examine the correlation of petrophysical data with geologic genesis and diagenesis. Reasonable correlations were obtained for most of the data, that may be of use in other similar fluvial-deltaic environments. These types of correlations may also be of use in discerning expected statistical distributions of petrophysical data other than permeability.
Fight Sand With Sand - A Realistic Approach To Gravel Packing
Authors: Sparlin Derry
Published: December 2007

Gravel packing is one of the oldest and most useful methods for controlling loose sand in wells. This art has advanced considerably with the studies of proper gravel sizes, improvements in the manufacture and design of screens and the multitude of tools to help get the gravel in place.

A significant improvement was the pressure packing technique. By placing pressure packing technique. By placing gravel outside the casing a higher flow capacity can be expected. Radial flow equations show that productivity increases as much as 50% can be obtained. However, seldom are such good results achieved and it is rare when good productivity is maintained.

Existing gravel packing techniques and literature are aimed at trying to use the largest possible gravel size. Much thought has gone into retaining a high flow capacity but controlling the sand has been secondary. In fact, many experts claim that it is necessary that formation fines be continuously produced through a gravel pack in order to produce fluids. To do that a relatively large gravel size must be used.

We have looked at gravel packing with the idea of using the smallest possible gravel size that will not decrease the productivity of a well. It can be proven that productivity of a well. It can be proven that the use of gravel only slightly larger than the formation sand if properly placed in the well will actually increase productivity.

A new gravel placement technique has been developed and field tested using small gravel. This technique uses no special tools or equipment and can be done in a fraction of the time that many gravel packs presently use. It results in an almost presently use. It results in an almost ideal pack which gives perfect control of the formation and high production rates are retained. A unique slurry is used which departs dramatically from all known gravel packing procedures. packing procedures.
Multifacies Modelling of Fluvial Reservoirs
Authors: Egeland Thore , Georgsen Frode , Knarud Ragnar , Omre Henning
Published: December 2007

A stochastic model for the for the facies architecture of fluvial reservoirs is presented as well as a computer program called SISA designated to simulate from the model. While previous papers (Georgsen and Omre [7] and Georgsen et al. [6]) have offered complete mathematical presentations, the one at hand emphasizes the geological setting and intuitive descriptions of the model. The model includes totally -1 different types of facies; background, channel sand, sheetsplay sand and barriers. The translation of geological information into input to SISA is explained. Two kinds of examples are shown: One synthetic with a few number of facies-bodics and one real from a fluvial north sea. field. The aim of these examples is to emphasize the following features; location and behaviour of facies-bodies; relation between different types of facies and conditioning on well-observations. SISA produces realizations of the models honoring well observations
Analysis of Slack-Off Force Transmitted Downhole in Coiled-Tubing Operations
Authors: Gu Hongren , Newman K. R. , Hauglund L. F.
Published: December 2007

This paper presents an analysis of the relation between the slack-off force and the force transmitted downhole when coiled tubing is slacked off or set down at the surface. It is generally believed that the force transmitted downhole cannot be larger than the slack-off force at surface. An analysis for coiled tubing in deviated wellbores shows that the force transmitted downhole can be smaller or larger than the surface slack-off force, depending on the well deviation profile and buckling conditions. Analytical solutions of the forces for constant-curvature well profiles are presented to explain the relation. The reason is that when coiled tubing contacts the wall of a curved well, the belt friction also plays a role in supporting the tubing weight and hence, affects the force transmitted downhole. The use of a computer tubing-forces model to calculated the forces for general well conditions is described. The results are compared with published solutions for vertical wells and explained for a field case of deviated well.
Overbalance Perforating and Stimulation Method for Wells
Authors: Handren P. J. , Jupp T. B. , Dees J. M.
Published: December 2007

Underbalanced perforating is generally accepted as the petroleum industry standard for perforating. This paper presents the concept, the mechanics, the procedures, potential applications, and the results of perforating by a "new" convention of perforating that incorporates the use of overpressured wellbores. This procedure can also be used in wells with existing perforations if an overpressured surge is used. Oryx has successfully used overbalanced perforating and overbalanced surging procedures in more than 50 wells. This paper will highlight some of the case histories that have used these techniques.
A Method to Select Resin-Coated Proppants
Authors: Dewprashad Brahmadeo , Abass H. H. , Meadows D. L. , Weaver J. D. , Bennett B. J.
Published: December 2007

This paper describes a procedure that can be used to select the resin-coated proppant to be used for a particular hydraulic fracturing application. Using this procedure, samples of proppant were cured in a carrier fluid under simulated downhole conditions and the elastic properties, thermal displacement, and time-dependent characteristics (creep) of these samples were determined at different temperatures. Testing involved measuring the time-dependent axial strains for a given load and temperature. Another phase of testing involved loading a cylindrical sample to a predetermined axial load, then increasing temperature slowly until failure occurred. The physical and mechanical properties of these consolidated resin-coated proppant samples were measured to establish a guideline for application of rock mechanics in selecting resin formulations for optimum well performance after a hydraulic fracturing treatment.
Development of Composite Coiled Tubing for Oilfield Services
Authors: Sas-Jaworsky Alexander , Williams J. G.
Published: December 2007

As coiled tubing services expand to meet the challenges of the oil and gas industry, limitations of steel tubulars continue to temper the potential impact of this workover service. Presently, coiled tubing used in well servicing operations is milled from modified A-606 High Strength Low Alloy (HSLA) steel, with yield strengths ranging from 70 ksi to 100 ksi. Although current coiled tubing services can performed safely and reliably with conventional steel coiled tubing, the behavior of the isotropic metal limits the yield pressure and tensile load capability of the tube.

Composite Coiled Tubing (CCT) offers the potential to exceed the performance limitations of isotropic metals, thereby increasing the service life of the pipe and extending operational parameters. CCT is constructed as a continuous tube fabricated from non-metallic materials to provide high body strength and wear resistance. CCT can be tailored to exhibit unique anisotropic characteristics which optimally address burst and collapse pressures, tensile and compression loads, as well as high strains imposed by bending. This enabling capability expands the performance parameters beyond the physical limitations of steel or alternative isotropic material tubulars. In addition, the fibers and resins used in CCT construction make the tube impervious to corrosion and resistant to chemicals used in treatment of oil and gas wells.

Based on the performance of prototype specimens constructed and tested to date, the service life potential of CCT is substantially longer than that of conventional HSLA steel pipe when subjected to multiple plastic deformation bending cycles with high internal pressure. In addition, CCT is expected to provide the ability to extend the vertical and horizontal reach of existing concentric workover services. This paper reviews the limitations of conventional HSLA steel coiled tubing, explores the design criteria requirements for CCT, and discusses the results of tests performed on numerous CCT prototype specimens.
Single-Phase or Multiphase Blowdown of Vessels or Pipelines
Authors: Norris H. L. , Puls R. C.
Published: December 2007

In order to predict the consequences of a leak or rupture of a pipeline or vessel, or to design a controlled pressure release system, a method of predicting the mass efflux is required. Although a large body of literature exists on blowdown simulation for vessels or short pipes, relatively little analysis and experimentation has been performed for the depressurization behavior of pipelines. In addition, the impact of the thermodynamics of multicomponent hydrocarbon fluids has been relatively unexplored. A mechanistic homogeneous equilibrium model applicable to both vessels and pipelines has been written. Since fluid thermodynamics are evaluated external to the model, single or multicomponent fluids can be simulated as well as single or multiphase flows. In addition, a series of small scale blowdown experiments has been made using both gas bottles and coiled tubing. The coiled tubing has a length to diameter ratio of 60,000, comparable to that encountered in field piping. Air, carbon dioxide, and carbonated water have been used in the experiments. Excellent agreement between the model and experiments has been obtained, along with excellent agreement with at least one field data set.
Acid-Resistant Microfine Squeeze Cement: From Conception to Viable Technology
Authors: Heathman J. F. , Carpenter R. B. , Sanders G. S. , Wedman M. L.
Published: December 2007

This paper focuses on the development and field application of an acid resistant, microfine portland cement composition. This specialized cementing system has been developed for remedial water and/or gas shut-off squeeze operations in the Prudhoe Bay Field of Alaska.

Because of the unique properties of microfine cements and the requirements of this application, new laboratory and field test procedures have been introduced. A full-scale mixing and pumping test was conducted prior to field application of the new Portland cement system. This testing was performed to ensure proper performance of the cement in a field environment. Slurry properties after mixing and pumping through 17,300 ft. of coiled tubing are presented. To better illustrate the sequence of lessons learned, several case histories and prior microfine cement designs are discussed.
Thickening Time Test Apparatus Provides Method of Simulating Actual Shear History of Oilwell Cements
Authors: Purvis D. L. , Mueller D. T. , Dawson J. C. , Bray W. S.
Published: December 2007

A reliable prediction of cement thickening time is central to the success of oilwell cementing operations. The amount of time that a cement remains "pumpable" is dependent on several factors, including shear rate history. Current industry testing methods, however, allow for only a single rotational speed of the consistometer slurry cup during a thickening time simulation. This, in turn, relegates the range of shear rates found within the cup to those due only to the changes in the Theological properties of the cement. Yet, oilwell cements encounter a much wider range of shear rate conditions during placement due to changing surface pump rates and variable wellbore geometries. The physical attributes of oilwell cements, including thickening time, are influenced by this shear rate history.

A conventional pressurized consistometer, fitted with a variable speed motor, is combined with a standard slurry cup containing a helical screw paddle (HSP). This device provides the basis for comparative thickening time testing. Computer modeling allows for an actual depiction of the shear rate history to be integrated into a thickening time evaluation. This information was used to program a modified consistometer to replicate the shear rate, temperature, and pressure conditions found during placement.

Presented are the comparisons of standard API thickening times, thickening times with the HSP rotating at 150 revolutions per minute (RPM), and thickening times with the HSP in actual shear rate history simulations. The results indicate that thickening times are shortened in a low shear rate environment. At higher shear rates, the differences in thickening time among the three testing methodologies are minimal. Knowledge of the actual shear rate encountered during a cementing operation and a slurry’s susceptibility to changes in thickening time due to shear rate history, is vital to predicting the true thickening time of the slurry under downhole conditions.
New Well Completion and Stimulation Techniques Using Liquid Jet Cutting Technology
Authors: Peters A. D. , Henson S. W.
Published: December 2007

Liquid jet cutting technology has made rapid advancement in industries for manufacturing, industrial cleaning and mining. Commonly, pressures from 5000 psi to 60,000 psi are used. In recent years, a number of downhole assemblies have been developed to utilize this technology for use in the oil industry. This paper will cover the development of two such techniques that are capable of creating tunnels in the formation rock up to ten feet in length by one inch in diameter in cased hole or open hole wells. The original design of the downhole assemblies will be discussed. New data on the lab and field testing of the effectiveness of creating tunnels in a variety of formation rocks, jetting with aqueous and acidic fluids will be mentioned. The results will show substantially improved penetration rate when jetting with HCl in carbonate rocks and improved penetration rate when pumping with polymer additives. These techniques provide new options in completing and stimulating zones in a variety of applications. The techniques discussed will provide completion engineers with selective, controlled options for initial completion, stimulation or workover. The resulting tunnels are superior to perforations in length, and diameter and leave no compaction. This paper will also serve to inform the industry of the significance of liquid jet cutting for a variety of downhole applications.
Hydraulic Fracture Modeling in Formations Exhibiting Stress-Dependent Mechanical Properties
Authors: Poulsen D. K. , Abass H. H.
Published: December 2007

Although most fracturing treatment design models assume that the behavior of the formation being fractured can be approximated by linear elastic theory, many formations, particularly unconventional ones such as coalbeds and poorly consolidated sandstones, exhibit sufficiently nonlinear behavior to invalidate this assumption. Methods are developed and presented for generalizing fracture design models and net fracturing pressure analysis to consider nonlinear stress-strain behavior.
Realistic Fracture Conductivities of Propped Hydraulic Fractures
Authors: Milton-Tayler David
Published: December 2007

Preliminary results of an experimental programme to determine the significance of dual phase flow in propped fractures are presented. Gas-water flows are considered. The results demonstrate that, even in cases of minimal water production, effective permeabilities may typically be reduced by a factor of 2, or more. In severe cases of water production, permeabilities may be less than 20% of their single phase values.
Influence of the Permeability Anisotropy Ratio on Large-Scale Properties of Heterogeneous Reservoirs
Authors: Duquerroix J- P. L. , Lemouzy Pierre , Noetinger Benoit , Romeu R. K.
Published: December 2007

When performing fluid-flow simulations, up-scaling techniques must be used because of the required coarse grids. For this purpose, algebraic formula, combining arithmetic and harmonic averagings, extension of Cardwell and Parsons’s results, derived from perturbation techniques are proposed taking into account the anistotropy, either natural or due to the reservoir geometry. These formula are valid for 2D or 3D problems and are very little computational time consuming compared to direct numerical methods. Moreover they integrate rigorous mimima and maxima thus showing the global uncertainty on equivalent permeability determination. They proved to work well for large permeability contrasts and anisotropy ratios either for simple log-normal or geostatiscally generated media.

In the first application case numerical calculations were carried out for the upscaling of isolated cells. In the other case well test simulations were performed either with the original fine grid or further coarser grids.
Noniterative Phase Equilibrium Calculation in Compositional Reservoir Simulation
Authors: Stenby E. H. , Wang Peng
Published: December 2007

An efficient, non-iterative flash calculation algorithm has been developed for equation of state (EOS) compositional reservoir simulation problems. In this algorithm, the flash calculation is carried out by solving two sets of linear equations. The solution of these equations is the mole number of each component in each phase. The phase saturation can thus be obtained without solving the Rachford-Rice equation1. Tests against many PVT data sets show that the new approach gives the same results as those computed by the fugacity iteration based on the EOS. However, the computation time is reduced significantly.

A series of reservoir simulations has been conducted by an EOS compositional reservoir simulator, UTCOMP, with this new flash approach. Comparisons are made with those performed by UTCOMP with a rigorous fugacity iteration of the Peng-Robinson5 EOS. The results obtained by these two methods are in very good agreement. However, a considerable reduction of the CPU time is generally accompanied by using the new approach. For the runs in which an immiscible displacement process takes place in the reservoir, the computational burden in the phase behavior calculations is reduced by around 90%. Correspondingly, the reduction of the total simulation time is as much as 65%. Besides, it is found that the number of components used affects on the CPU time of the simulations much less with the new approach. These observations may lead to the time used for an EOS compositional reservoir simulations with the new approach being comparable to a black-oil simulation without sacrificing computational accuracy.

Also in this work an attempt is made to employ the non-iterative approach as a tool for providing the initial guess for the rigorous EOS iteration. A considerable reduction of the CPU time is still observed.
Predicting Capillary Crossflow in Layered Reservoirs
Authors: Haq S. , Reis J. C.
Published: December 2007

A model that predicts capillary crossflow into the layers adjacent to a high-permeability layer during waterflooding is presented. A material balance on the injected water that includes the water loss to the adjacent layers by capillary imbibition is solved by Laplace Transforms to obtain equations for the areal extent of the watered zone and the fraction of displaced oil coming from the adjacent layers.
Full-Field Gas Storage Simulation Using a Control-Volume Finite-Element Model
Authors: Sonier Fernand , Lehuen Pierre , Nabil Raouf
Published: December 2007

This paper presents the actual case history of Saint-Clair-sur-Epte (France), a fourteen year old underground gas storage in a very large aquifer. This gas storage shows two topics of interest: it is partially filled with inert gas; the economical interest and the technical feasibility of injecting a significant quantity of inert gas prior to filling the storage with natural gas have been shown.Its geological structure is made with two partially connected reservoirs; the understanding and quantification of gas moving across the two reservoirs are crucial for the management of this gas storage.

The second item, as above, is the subject of this paper. Simulations and history-matches have been performed initially with a finite-difference model using a cartesian local grid refinement technique.

Following this, a general-purpose model including a control-volume finite-element (CVFE) method has been used. The purpose is to check and confirm the ability of this method to perform real reservoir studies, i.e. simulating large 3-dimensional full-field multi-phase reservoirs.

As far as we know, it is the first published full-field study performed with a control-volume finite-element method simulator, and it confirms previous conclusions from theoretical and specific pattern example papers. This type of simulator can be an excellent alternative to flexible gridding techniques used in finite-difference simulators. The following shows some of the advantages over the finite-difference techniques: The entire reservoir can be gridded as required without using any special techniques for local grid modifications.The numerical diffusion is as isotropic as possible, so that the grid-orientation effect is controlled.The representation of zones of interest, singularities and discontinuities is more accurate and flexible.
A New Scaling-Up Method To Compute Relative Permeability and Capillary Pressure for Simulation of Heterogeneous Reservoirs
Authors: Lemouzy P. M. , Romeu R. K. , Morelon I. F.
Published: December 2007

Recent high-resolution tools and novel characterization techniques lead to simulate very detailed geological descriptions of heterogeneous reservoirs. To perform full-field displacement simulations, scaling-up techniques must be used because of the required coarser grids. Pseudoization methods are commonly used to get the relative permeability and capillary pressure curves. But they all consider 2D flow to realize the scaling-up. We propose a three-dimensional approach. When capillary forces are important inside the reservoir, the capillary pressure may be considered as nearly constant inside a coarse grid-block. This assumption enables to compute directly the fine grid-block saturations and the average coarse grid-block saturation for a given capillary pressure. For each fluid phase, we then compute the effective phase permeabilities of the coarse grid-block by means of an absolute permeability scaling-up method applied to phase permeabilities of the fine grid-blocks in 3D. Then renormalizing the resulting phase permeabilities by the average absolute permeability yields the average relative permeabilities curves for the three directions of space.

Application of this technique, using an algebraic computation of average permeability adapted to heterogeneous media, will be presented for complex fluviatile cases, characterized by a large amount of shale inclusion at small-scale. Comparison of numerical simulations of oil-water flow on high-resolution descriptions, and on the corresponding scaled-up coarse models, shows the efficiency of this method. We recommend to apply this method to reservoir with low gravity segregation, with rocks exhibiting medium to low permeability and high capillary forces, and moderate injection rates.
A Simple Cubic Equation of State for Hydrocarbons and Other Compounds
Authors: Mohsen-Nia Mohsen , Moddaress Hamid , Mansoori G. A.
Published: December 2007

A new simple two-constant cubic equations of state for hydrocarbons, hydrocarbon mixtures, and other non-associating compounds is introduced. This equation of state is based on the statistical mechanical information available for the repulsive thermodynamic functions and the phenomenological knowledge of the attractive intermolecular potential tail contributions to the thermodynamic properties. This new two-constant-parameter cubic equation is in the following form: Zm=PvRT=v+1.3191ℓmv-ℓm−(∑i∑jaij)/RTT1/2(v+∑iℓi)

where lm=1/43∑i∑jxixjlij+∑ixilii,, lij=lii1/3+ljj1/33/8; aij=1−kijaii ajj1/2 and aii=0.48748 R2Tcii5/2/Pcii and ℓii = 0.064662 RTcii/Pcii

It is shown that this equation of state is more accurate than the Redlich-Kwong equation, which has been considered to be the best two-constant-parameter cubic equation of state. This new equation is applied for calculation of thermodynamic properties of hydrocarbons and other non-associating fluids and fluid mixtures of interest in the oil and gas industries.
Compressibility Factors for Naturally Occurring Petroleum Gases.
Authors: Piper L. D. , McCain W. D. , Holditch S. A. , Corredor J. H.
Published: December 2007

The Sutton gas specific gravity correlation gives values of pseudocritical properties which, when used with the Dranchuk and Abou-Kassem (DAK) representation of the Standing and Kate (SK) chart, currently provide the most accurate estimates of compressibility factors for naturally occurring petroleum gases. However, other correlations must be used to account for the presence of acid gases. A new gas specific gravity correlation is presented which takes into account the effects of the acid gases and nitrogen. The new correlation provides more accurate estimates of the compressibility factor than can be obtained by current methods and also eliminates the need for involving additional correlations to correct for the presence of acid gases and nitrogen. The new correlation was developed using a set of 1482 data points, ranging in composition from lean sweet to rich acid gases.
Gas Production Improvements Using Ejectors
Authors: Green A. J. , Ashton Kevin , Reade A. T.
Published: December 2007

Falling wellhead pressures drastically reduce the productivity and economics of a well. If there is a supply nearby of high pressure gas, the well productivity can be increased by using the high pressure energy in an ejector.

An extensive programme of laboratory tests and offshore trials has been carried out to prove and optimise ejector design for offshore application. This has included the use of "flexible" multiple nozzles to allow continued effective operation as well pressures reduce. Existing design methods have been significantly improved and embedded into user-friendly software, which has been validated against the results.

Ejectors were installed on two platforms in the Phillips operated Hewett Gas Field in the Southern sector of North Sea. Trials have proven very successful, with increases in gas production ranging from 15 to 25 MMSCF/D. In both cases a payback on investment of only a few weeks was achieved. Further opportunities for ejector installation are now being actively sought. Investigations for the use of ejectors for multiphase boosting are continuing.
An Innovative Approach to Argyll Field Abandonment
Authors: Prise G. J. , Stockwell T. P. , Leith B. F. , Pollock R. A. , Collie I. A.
Published: December 2007

This paper provides the completion/drilling engineer with an innovative perspective on the technicalities of well abandonment and gives an insight into the first major well abandonment project in the UK sector of the North Sea. The paper discusses the planning and preparation of this novel approach to well abandonment. Details of the equipment utilized and an operational overview are also presented.
New Oil-Based Drilling Fluid Reduces Oil on Cuttings
Authors: Oakley D. J. , Halliday George , Begbie R. J. , Turner J. B.
Published: December 2007

North Sea environmental legislation imposes limits on the amount of oil on cuttings (OOC) discharged to the marine environment when using oil-based drilling fluids. This paper presents the laboratory development by International Drilling Fluids (IDF) of a conceptually new type of oil-based drilling fluid designed to reduce OOC, and the results of field trials undertaken by Amerada Hess Limited (AHL) with this fluid.

A recent research study sponsored by the Drilling Engineers Association (Europe), as project DEA(E) 17, identified under controlled laboratory conditions, the critical physical and chemical variables which affect OOC. It was found during this study that the use of conventional oil-wetting surfactants promotes spontaneous imbibition of oil into the internal pores of cuttings, causing an increase in OOC. Minimising or eliminating the use of strongly oil-wetting surfactants in oil-based fluids was identified as a desirable research objective in oil-based mud development, to reduce OOC.

Onward laboratory work has identified polymers, soluble in low-toxicity mineral-oil, such that polymer-based invert oil emulsion drilling fluids can be formulated to provide all the essential properties of 50/50 oil-water ratio oil-based fluids. Two field trials by AHL in Blocks 31/26 and 39/1-2 using this polymeric oil-based fluid resulted in an 18% reduction in OOC to below the critical 100 g/kg limit and a 35% reduction in mud losses per foot on the second trial well. Fluid properties were stable, and the wells completed ahead of schedule. Field trials have validated this new concept in oil-based drilling fluid design to reduce OOC.
The First Successful Downhole Barium Sulphate Scale Dissolving Operation
Authors: de Vries Hans , Arnaud Fabrice
Published: December 2007

An industry first was achieved by successfully dissolving 200 kg of barium sulphate scale from the upper part of the tubing in a well on the Alwyn North field in the North Sea. This well experienced rapid and very severe sulphate scale build-up resulting in the tubing retrievable safety valve being stuck in the open position. A new scale dissolver was used for the first time in this operation and successfully removed enough scale to reinstate the well. A full workover was prevented with a total cost saving of about £1 million.

This paper describes the well history, the investigation, the scale removal alternatives and the laboratory tests performed on the scale dissolver. It discusses the operation design, the operation itself and the scale dissolving results and concludes with a description of the wireline re-instatement operations. It also highlights the continuous advancement in success and capability of the through tubing workover.
Colloidal Silica Cement: Description and Use in North Sea Operations
Authors: Bjordal Audun , Harris K. L. , Olaussen S. R.
Published: December 2007

New cement slurry formulations containing colloidal silica have been used in North Sea primary cementing operations to help control annular gas migration, enhance slurry "turbulent flow" characteristics without solids settling, and aid cement bonding to formation and casing. Colloidal silica slurries have been successfully placed as lightweight lead cements in intermediate casing operations, and have effectively sealed annuli in gas storage wells and in horizontal completions.

Silica cementing additives have been used often for gas migration control, slurry stability, and high-temperature applications in the North Sea. However, because of its extensive specific surface area (500m2/g), colloidal silica adds additional benefits. Colloidal silica is more efficiently handled in offshore operations because less bulk material is required. The reduced volumes also reduce overall slurry cost. Because colloidal silica particles are so fine, there is virtually no settling of the base material in containment offshore.

A discussion of colloidal silica slurry properties is contained in this paper. Performance properties are presented in relation to each of its various well applications. A case history of a horizontal well is also given that describes the practical use of colloidal silica cement.
Optimising Shale Drilling in the Northern North Sea: Borehole Stability Considerations
Authors: Wong Sau-Wai , Kenter C. J. , Schokkenbroek Hans , De Bordes Pieter , van Regteren J.
Published: December 2007

The drilling mud weight and the mud composition are two key operational parameters that can be adjusted to prevent hole-instability problems. This paper discusses the methodology and the borehole-stability model employed for optimising the drilling mud weight for the drilling of deviated wells in the northern North Sea. In the course of the project, a shale coring programme was implemented so that the rock strength could be characterised, and leak-off-test data were analysed to estimate the in-situ stress. A comparison is made with field observations
The Physical and Biological Impact of Processed Oil Drill Cuttings: E&P Forum Joint Study
Authors: Minton R. C. , McKelvie D. S. , Caudle D. D. , Ayers R. C. , Smith J. P. , Cline J. T. , Duff Angus , Blanchard J. R. , Read A. D.
Published: December 2007

This paper reports the key findings of a multidisciplinary study established by the E&P Forum to examine the environmental effects of drill cuttings with different oil concentrations resulting from treatment with solvent extraction and thermal processes. The study examined the physical characteristics of the cuttings, deposition on the seabed and the impacts on the seabed fauna and on fish.

Concentration of oil on cuttings ranged from 15.8% for unprocessed cuttings to less than 1% for thermally treated cuttings. The removal of oil resulted in dry, dispersive cuttings which would be deposited in lesser amounts over a greater area compared to unprocessed cuttings.

Environmental effects were greatest for untreated cuttings. Solvent extracted cuttings showed some effect but there was evidence of recovery of the benthic fauna within the timescales of the study (8 months). For most of the experiments, there was little difference between the thermally treated cuttings and the controls. There was evidence of a threshold for effects at a concentration of oil in sediment of approximately 1000 ppm. Model predictions of cuttings deposition showed that the area of seabed affected by oil concentrations in sediment greater than 1000 ppm was small for both solvent extracted and thermally treated cuttings.

Both solvent extracted and thermal processing of oily cuttings, and the subsequent discharge of the treated cuttings, appears to result in negligible or short term environmental effects.
Recent Advances in the Handling, Makeup, and Running of C.R.A. Tubulars
Authors: Harris David , Jaensch Manfred
Published: December 2007

Significant advances have been made in the last three years in the non-marking handling of Chrome Resistant Alloy (C.R.A.) tubulars both with power tongs and handling tools.

Marking of casing and tubing by the dies of power tongs and the inserts in the slips of spiders and elevators has long been known to be potentially damaging, particularly in wells with corrosive environments.

This paper outlines the developments made in the industry during the last three years and the creation of special tools and power tongs to overcome these problems. Particular emphasis will be made on the complete cycle from pipe mill to running in the hole.

This will cover the make up of couplings to the pipe body in the mill, the transportation of tubulars to the rig site and the handling from pipe rack to rig floor.

Also to be covered will be the make up and testing of downhole completion assemblies prior to the job.

Actual make up of connections with "non marking" power tongs and running with special slips are the major new developments described.

It will be shown how all factors such as joint weight compensation, guidance yoke system, stabbing, etc. can all contribute to the successful running of C.R.A. tubulars.
Rig Automation-Drilling: The Proving of the Concept
Authors: Houston S. J.
Published: December 2007

1993 will see the culmination of six and a half years effort in the development from first principles of the Rig Automation-Drilling Proof of Concept equipment.

It is timely that Offshore Europe ’93, whose venue is adjacent to the International Drilling and Downhole Technology Centre where the project was sited, provides the ideal opportunity to present the results of the project, explore some of the problems encountered, successes experienced and lessons learned.

The most significant aspect of this project is the benefit of collaboration between Operators, Drilling Contractors and Equipment Suppliers to develop and demonstrate that innovative technology proven in other industries is suitable and relevant to the oil and gas drilling operations.

This 1,000,000 lb hook load modular singles rig, hydraulically powered and using programmable logic control, has been installed onshore and has been put through its operational routines with development as necessary to demonstrate the concept. This concept is capable of meeting the increasing needs for maximum safety with minimum cost operations.

The RA-D concept, in whole or part, is applicable to many drilling scenarios whether onshore or offshore, modular or highly mobile. The paper will discuss some of the applications and will show the benefit to Operators and Drilling Contractors. The project demonstrates that the application of the RA-D concept yields cost reductions in the drilling operation and, whilst all these are not yet capable of being physically demonstrated, a number of field studies and individual equipment assessment studies have provided encouraging indicative results.
An Integrated Full-Field Compositional Simulation of an Offshore Deepwater Development
Authors: Olsen O. T. , Cohen M. F. , Nagarajan N. R.
Published: December 2007

This paper describes technical enhancements to an existing compositional reservoir simulator, and the improved simulation results achieved in a full field simulation study of the Smørbukk Sør Field. The paper also describes a multi-discipline approach in the execution of a simulation study, and the cooperation between Mobil's U.S. technical center and a European affiliate.

The technical enhancements made to Mobil's compositional simulator PEGASUS were (a) improved interfacial tension corrections to relative permeability in miscible flooding, (b) a variable bubble-point and composition with depth function based upon chemical equilibrium, and (c) application of the Babu-Odeh analytical horizontal well model. These features were not available in compositional reservoir simulators at the time the study was conducted.

The interfacial tension correction for miscible flooding provided production performance predictions that could be used with confidence in the evaluation and selection of the optimum production mechanism for the Smorbukk Sør field. The variable composition with depth correlation demonstrated that a gas cap is not likely to exist considering the measured bubble point gradient. The horizontal well model function confirmed that improved productivity could be achieved with fewer development wells, thus contributing to the selection of the most cost effective development scheme.

The primary purpose of the study was to compare the impact of gas and water injection on ultimate recovery and production performance. Secondary objectives were to determine maximum productivity with the fewest number of production wells, and to maximize recovery at peak production. While simulation results marginally favored water injection, gas injection was considered the preferred production mechanism because of gas disposal considerations.
Arresting Production Decline in a Mature North Sea Oil Field
Authors: Wolodkiewicz D. E.
Published: December 2007

Classical reservoir engineering techniques were utilised to characterise water movement in the South Brae Field and determine areas of remaining oil reserves. Exploiting these remaining oil reserves has flattened the rate of production decline in this mature North Sea peripheral waterflood. After producing over 115,000 BOPD on plateau, South Brae experienced a severe 76%/year production decline rate. Prolific oil producers experienced water breakthrough and accounted for the dramatic drop in the field oil rate. An interdisciplinary approach to describe the reservoir and review production and injection history led to identification of work to exploit bypassed oil. South Brae oil production decline rate has been arrested and is essentially flat as a result of implementing such work.

The reservoir engineering techniques used on South Brae have identified several areas of the field which were relatively unswept. Exploitation of these areas of remaining oil potential has been accomplished by through-tubing work without the need of costly rig intervention. One area identified as having remaining oil potential has resulted in raising a 200 BOPD well at a 96% watercut to over 2,100 BOPD at less than a 1% watercut. The well has been producing at this higher rate since the work was completed 5 months ago (October 1992).

The techniques used to identify areas of unswept oil potential in South Brae could be used on other mature peripheral waterfloods. Redirection of water injection to affect areas of remaining oil potential has shown positive oil rate benefits at South Brae.
Basal Waterflooding of a Tight Chalk Field With Long Horizontal Fractured Injectors
Authors: Nederveen Nijs , Damm Michael
Published: December 2007

The Gorm Field is a tight chalk oil field, which has been producing for twelve years. This paper describes how the results of a production development study, including reservoir simulation, have been used to conceptually change the water injection strategy as implemented in two earlier pilot projects. Furthermore, the initial results of the first well implemented as part of the revised strategy, namely a waterflood using horizontal basal water injectors, is presented.
Piper Field: Improved Reservoir Characterisation
Authors: Little E. A. , Simlote V. N. , Bedrock Martin
Published: December 2007

This paper demonstrates the benefits of the application of a synergistic approach in furthering the understanding of the layered nature of the Piper Field. Core, log, FMT pressure and fluid redistribution information obtained from the eight well Piper B Redevelopment Predrilling programme are discussed. The integration of the Piper B results necessitated a reassessment of the Piper Alpha data and led to an improvement in the reservoir characterisation in terms of layer permeability definition, flow behaviour, pressure and aquifer influx. This improved understanding of the reservoir led to the definition of an initial selective completion policy for the Piper Field redevelopment. The primary objective of this policy is to reduce the potential for water override in problematic high permeability layers and thereby improve the sweep of the less prolific layers by closer targeting of injection support. Such an approach allows improved reservoir management, greater flexibility in scheduling remedial work and is oriented towards maximising ultimate recoverable reserves by optimising the sweep in individual sand layers prior to their abandonment/isolation for water shut off purposes.
Study of Mechanisms for NORM in Gas Production Facilities in the Antrim Shale of the Michigan Basin
Authors: Ortiz Isaias , Anthony R. V. , Pope D. H.
Published: December 2007

Naturally occurring radioactive materials (NORM), has been observed in conjunction with natural gas production operations in certain Antrim gas wells in northern Michigan. Chemical analyses on field derived water samples from Antrim wells were compared with geologic and engineering Parameters using geologic and completion data in an attempt to determine the source and mechanisms associated with these observations.

The sources of the scale are unknown and potentially hazardous if radioactive levels exceed OSHA Standards. Mitigation measures could be costly and jeopardize the economic viability of the play.

NORM Antrim gas production facilities tested were found to be associated with barium sulfate scale which formed in central separators as well as in individual wells. Low levels of barium were found in waters from most wells, while sulfate was found in only some wells. Two models were developed based on the results of this study. One model assumes that sulfate is migrating from other formations. The other model assumes that the cause of the problems may be due to the mixing of waters and chemical reaction with oxygen, carbon dioxide, and/or bacteria either contained in the Antrim gas or migration from the Antrim outcrop a few miles north of the producing fields. The oxygen and bacteria, contained in the fresh water, may be reacting with pyrite to cause the formation of sulfate. Sulfate in tum is reacting with the naturally occurring barium and radionuclides to form the barium sulfate scale that is being observed in the field. However, from a Chemistry mass balance view, additional oxygen is required than can be supported by fluid migration alone. Other sources of oxygen would have to be introduced.
The Benefits of Applying Technology to Devonian Shale Wells
Authors: Voneiff G. W. , Gatens III J. M.
Published: December 2007

Applying technology to Devonian Shale wells can increase present value profit by $30,000 to $150,000 per well in a typical drilling program by improving stimulation treatment design and results. An intermediate level of technology application is best, costing $6,800 above what a typical operator currently spends. The key objective of the technology application is to optimize the stimulation treatment using a layered reservoir description with accurate formation properties. An accurate layered reservoir description minimizes inappropriate stimulation treatments, consistently resulting in treatments that are close to the optimal treatment.
Natural Gas Markets: What to Expect after Order 636?
Authors: Thompson S. E.
Published: December 2007

Today's Gas Industry has in front of it, its greatest opportunity to recapture its lost market share of the early 1970's. The industry has struggled through many of the restructuring problems, and has a. positive political environment to resolve the remaining problems.

This paper describes the outlook of the future of natural gas markets after the implementation of FERC's Order 636, the final order for natural gas deregulation.
Geometries and Other Parameters of Two Medina Group (Clinton) Gas Storage Fields in Pennsylvania and Ohio
Authors: Pees S. T.
Published: December 2007

The upper "Clinton" sandstones pose gas storage problems. Migration of injected gas may occur over larger areas than expected.

The Medina Group Whirlpool Fm. sandstone (lower "Clinton") occurs as distinct depositional features with vertical and lateral seals. It earlier served for storage in the Pennsylvania Corry field. It deserves attention.