bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Technique Developed for Acidizing Gas Producing and Injection Wells
Authors: Justice W.H. , Nielsen Jens P.
Published: December 2007

Published in Petroleum Transactions, AIME, Volume 195, 1952, pages 285–288.

This paper describes an improved acidizing technique which has been applied in acidizing gas wells in the La Gloria field. Wells acidized in this manner exhibited a much greater increase in deliverability than wells acidized in the conventional manner. The acid is injected into the well in small slugs separated by a small volume of high pressure gas. The acid and gas are displaced from the tubing by high pressure gas to reduce the hydrostatic head on the well when the acid is recovered from the well. The well is opened for production as soon as the acid and gas are displaced. This procedure permits a very rapid recovery of the acid which results in large increases in the deliverability of the gas wells.

It has been found advantageous in the acidization of gas injection wells to inject the high pressure gas directly after the acid without backflowing the acid out of the well. This practice has made it possible to inject the gas in the injection wells of this field with a much lower pressure differential. This reduces the horse-power required to inject the gas and also decreases the number of injection wells required per reservoir.

Introduction

Results obtained by acidizing gas wells in the La Gloria field have varied considerably in the past. For this reason, a planned study of the acidizing procedure was undertaken in order to obtain more consistent results.

The Frio Sands of the La Gloria field are rather permeable and it was not necessary to acidize many of the wells when they were originally completed. At the completion of an eight year cycling program in several of the gas reservoirs, it became necessary to recomplete many wells in other reservoirs. It was found that the open flow potential of the wells recompleted in different sands was not as large as wells that were originally completed in that reservoir.

A study of the drilling records of several of these wells indicated that the sands had originally been subjected to considerable hydrostatic drilling fluid overload while the well was being drilled to the deeper sands of the field. It is indicated that during this eight year period, the drilling mud and water that were lost into the formation when the well was being drilled had formed a relatively impermeable zone around the well bore. This impermeable zone around the well bore made it very difficult to obtain high deliverability wells when the original wells are recompleted in other zones.
Use of a Dynamic Two-Phase Pipe Flow Simulator in Blowout Kill Planning
Authors: Rygg O. B. , Gilhuus T.
Published: December 2007

An underground blowout in Norwegian North Sea exploration well 2/4-14 was successfully killed by pumping heavy mud into the well from a relief well. As part of the kill planning, simulations by use of the dynamic two-phase pipe flow simulator OLGA were performed. The code, originally developed for two-phase hydrocarbon flow in pipelines and risers, was modified to handle injection of kill fluids and inflow from the reservoir. This paper presents the principles for the kill simulator, the results of the simulations and how these results were used in the design of the kill operation. Finally a comparison with observed data are presented.
Processing of Turbodrill Rotating Speed Signal with an Adaptive Noise Canceller
Authors: Liang Huaqing , Shao Zhongwu , Chai Qinzhong
Published: December 2007

A method for detection of weak turbodrill rotating speed signal is proposed on the basis of theoretical analysis and field test of the interference in mud channel through which the signal is transmitted from downhole to the surface. This method uses an adaptive noise canceller (ANC) to eliminate the strong pump interference and determines the speed through power spectrum peak detection. The principle of ANC is explained in detail. Computer simulation and laboratory tests have demonstrated the feasibility of a signal processor thus constructed.
New Rheological Correlation for Cement Slurries as a Function of Temperature
Authors: Ravi K. M. , Sutton D. L.
Published: December 2007

This paper presents results of a study conducted to determine the effects of elevated temperatures and pressures on cement slurry rheological properties. New correlations developed from this study provide a more accurate means for predicting friction pressures which might be encountered in actual cementing operations. Currently, there are no correlations available in the literature or being used in the industry which consider the effects of temperature and pressure on cement slurry rheology. The new correlation expands on the modified Bingham Plastic model introduced by Shah and Sutton.1 The critical fluid properties required for the pressure drop correlation, plastic viscosity and yield point, are shown to be influenced significantly by temperature. As a prerequisite to measuring cement slurry rheology accurately under temperature and pressure conditions, a new viscometer was designed and constructed. The new viscometer operates using the same principles as a conventional rotational viscometer, but slurry can be circulated and conditioned as it is heated and pressurized.

The study shows that when compared to temperature effects, pressure effects on rheological properties of cement slurries can be neglected. However more work needs to be done to confirm pressure effects. The temperature effects have been correlated and are presented in this paper.
A Method for Combined Jet and Mechanical Drilling
Authors: Butler T. , Fontana P. , Otta R.
Published: December 2007

A method has been developed for jet assisted mechanical drilling with fluid pressures of up to 34,000 PSI. This paper will present the most recent drilling results of an ultra-high pressure drilling system that integrates with existing drilling equipment, to provide two (2) fluid steams to the drill bit, one of which is highly pressurized. High rates of penetration over conventional drilling rates have been observed from field drilling results. Based on the most current field drilling projects, this paper will present details concerning the method for combined jet and mechanical drilling as well as actual field drilling results.
The Technical Ladder: A Historic Perspective
Authors: Sauer E. R. , White T. J.
Published: December 2007

While the concept of a technical ladder did not originate in the petroleum industry, it had an early introduction in 1946. The petroleum industry was not only a pioneer in its implementation and development, but an avid practitioner of its use, growth and success.

This paper recounts its introduction, development, changes in emphasis, reasons for success and disappointment, in hopes that such examination may lead to greater acceptance and more meaningful motivation of professional employees in times that differ materially from those in which the technical ladder emanated.
Multiscale Representation for Simultaneous Estimation of Relative Permeabilities and Capillary Pressure
Authors: Chardaire-Riviere C , Chavent G , Jaffre J. , Jun Liu
Published: December 2007

This paper proposes an improvement in a numerical method for the simultaneous determination of relative permeabilities and capillary pressure. It uses the results of only one laboratory flooding test performed under representative reservoir conditions. Relative permeabilities and capillary pressure axe estimated by using a least-squares technique after the one-dimensional saturation equation has been solved. The experimental data required are the outlet production, the pressure drop between the two faces and (or) local saturation profiles measured at different times in the sample.

The improvement described in this paper enables relative permeabilities and capillary pressure to be determined simultaneously as piecewise linear functions, thus eliminating the need for any closed-form formula representation. This improvement consists of the use of a multiscale approach to represent the parameters, coupled with a scale-by-scale optimization.

The validity of the method is first demonstrated with simulated data. With the multiscale approach, the minimization procedure converges in cases when standard parametrization fails to do so. Secondly, the method is applied to immiscible two-phase flow experiment. Very good matching is obtained.
Liquid Distributions in Porous Rock Examined by Cryo Scanning Electron Microscopy
Authors: Sutanto E. , Davis H. T. , Scriven L. E.
Published: December 2007

Determination of oil and water distributions in the pore space of reservoir rock is important in oil recovery. Several indirect methods, such as testing wettability of mineral surfaces, assessing capillary pressure and relative permeability behavior, and measuring electrical resistivity, have been practiced to estimate the oil and water distribution in porous rock. However, a direct method of determining liquid distributions in situ has been lacking.

Cryo-scanning electron microscopy (cryo-SEM) provides a means of visualizing oil and water in the individual pore segments of a porous rock. The liquid-bearing rock is frozen and kept cold at about 100 K. The frozen sample is then fractured, coated with evaporated chromium, and examined in a scanning electron microscope. Secondary and backscattered electron images and x-ray maps of the fracture surface identify the locations of oil and water in the exposed section of the pore space. Sometimes complementary fracture surfaces can be imaged. Series of the backscattered electron images illuminate the mechanisms of oil-water displacement in strongly water-wet and mixed-wet sandstones.
Vertical Permeability Measurement in New Reservoirs Using Tidal Pressure Changes
Authors: Wannell M. J. , Morrison S. J.
Published: December 2007

A new method of measuring vertical permeability is presented and successfully tested with field data. It takes advantage of naturally induced tidal pressure changes that occur in all reservoirs and can therefore be used at the appraisal stage. A single well drilled through a gas liquid contact is required - ideally in an offshore field. The pore volume compressibility is also measured using tidal data and compared with core measurements.
Design and Interpretation of Injection/Falloff Tests for Coalbed Methane Wells
Authors: Zuber M. D. , Sparks D. P. , Lee W. J.
Published: December 2007

This paper presents the results of a study undertaken to investigate the reasons why data from injection/falloff tests of coalbed methane wells were not interpretable using conventional well test analysis techniques and the results of a field study to investigate completion effectiveness during injection tests. The pressure transient test data obtained using the old injection/falloff test design were found to be interpretable only by history matching analysis. A modified test design is presented. A field example is presented which illustrates how application of the modified test design resulted in easily interpretable data using conventional well test analysis, techniques. Spinner surveys run during injection tests showed that breakdown/ballout treatments are required prior to simultaneous testing of multiple coals in cased-hole completions to ensure adequate communication between the well and all target coal seams.
Pulsed Neutron Log Interpretation Case Histories from Inland and Offshore South Louisiana
Authors: Thomson J. C. , Klimo C. R.
Published: December 2007

In the Louisiana Gulf Coast and offshore areas accurately determining water saturation (Sw) and identifying problems in cased wellbores can be difficult. Reservoir potentials may be unknown because of poor or nonexistent mud and core data, incomplete logging data and sketchy production histories. Wellbore environments that are unknown and/or difficult can render cased hole formation evaluation misleading and difficult to interpret. Without accurate Sw values and other diagnostic data, successful completions and reserve estimates may be difficult.

Pulsed neutron logging has been a primary evaluation technique for many operators analyzing economics before recompletion. This is especially true in older wells with limited reservoir information and unusual well/casing mechanics. Estimating reservoir pressures of gas zones, identifying production problems in producing wells and in new wells with stuck drillpipe, and applying oxygen activation techniques to evaluate potential well problems in flowing conditions are the applications frequently seen in the Gulf Coast.

This paper presents detailed case histories of successful recompletions, hydrocarbon determination, and production/drilling problem identification in unusual or difficult reservoirs and boreholes. Interpretations were derived from Dual-Burst* TDT* measurements and confirmed by production results and/or other wireline log and core evaluations. Comparisons are made with previous pulsed neutron measurements and openhole evaluations to evaluate the measurements in difficult logging conditions.
Comprehensive Physical and Numerical Modeling of a Horizontal Well
Authors: Islam M. R. , Chakma A.
Published: December 2007

Petroleum engineers have depended largely on empirical models for multiphase flow in pipelines and horizontal wells. While empirical models have been proven to be adequate in some cases (depending on flow regimes), they do not give any theoretical basis and, therefore, an extension of these models to much more complex flow, such as horizontal wells, is not justified. Despite recent advancement in horizontal well technology, little has been done in the areas of physical and mathematical modeling of horizontal wellbore itself. No study has been reported on three-phase (water-oil-gas)flow or gas-liquid flow when the liquid phases show emulsification of oil and water.This paper addresses the problem of both physical and mathematical modeling of horizontal wellbores. Experimental results gave insight into the type of flow occurring in a horizontal wellbore. This observation was used in developing a comprehensive mathematical model of the horizontal wellbore. Finally, the wellbore model is coupled with a reservoir simulator and a series of numerical tests is performed to study the effect of pressure drop in the wellbore on the performance of a horizontal well. The usefulness of this new modeling technique is pointed out vis a vis conventional modeling techniques.
How To Develop a Coalbed Methane Prospect: A Case Study of an Exploratory Five-Spot Well Pattern in the Warrior Basin, Alabama
Authors: Ely J. W. , Zbitowsky R. L. , Zuber M. D.
Published: December 2007

This paper summarizes MetFuel Inc.'s experiences in conducting a pilot" test of the coalbed methane potential of an undeveloped area in the southern Black Warrior Basin. The pilot project was designed to gather baseline reservoir data, determine the viability of further development by field experience, and learn how to complete and stimulate coal seams in this area. The pilot project provided valuable insights in terms of drilling practices, defining target intervals, hydraulic fracture geometry and height growth, perforation placement, canister test procedures, and reservoir permeability versus stress. A wealth of baseline reservoir data was also collected. Continued production from the pilot project wells is required to determine the economic viability of large-scale development in this area.
Well Test Requirements for Evaluation of Coalbed Methane Development Potential
Authors: Semmelbeck M. E. , Lee W. J.
Published: December 2007

This paper presents methods for designing and analyzing prefracture and postfracture injection/falloff tests and multirate production tests in coalbed methane reservoirs. These tests should be conducted on selected wells in a coalbed methane pilot test. Pilot testing is the best way to evaluate the productive potential of coalbed methane reservoirs. A properly designed testing program can minimize the expense and maximize the reliability of estimating reservoir properties that are essential to a thorough evaluation of a coalbed methane reservoir.
A Comparison Between Predicted and Measured Walking Beam Pump Parameters
Authors: Tripp H. A. , Kilgore J. J.
Published: December 2007

This paper quantifies the accuracy of a state-of-the-art computer program used to predict the performance of walking beam pumping systems. The program used for the predictions includes models of the fluid and rods, which are coupled along the rods, at each taper, and at the subsurface pump. An extension of the Doty and Schmidt pump model is used to simulate the down-hole pump. The method of characteristics is used to solve the coupled partial differential equations that describe the forces and motion along the sucker rod string and in the liquid column. In addition, the program considers motor slip and rotating and articulating inertia in calculating.the pumping unit speed variations

Comprehensive comparisons between field measurements and predicted parameters of 92 wells with depths ranging from 810 to 10,800 feet are given. In addition, comparisons between measured and predicted values are used to illustrate the effects of various details in modelling pumping systems. These comparisons show that when wells are carefully modeled, good agreement exists between measured and predicted parameters.
New Developments To Improve Continuous-Flow Gas Lift Utilizing Personal Computers
Authors: Schmidt Z. , Doty D. R. , Agena B. , Liao Tianlu , Brown K. E.
Published: December 2007

The design of continuous gas-lift installations has been examined in detail. Procedures are outlined showing how system analysis can be used to select optional components including tubing size, flowline size, surface operating pressure, perforation shot density, etc. An improved procedure is presented for the construction of the gas-lift performance curve, based on the gas injection rate rather than the GLR. Also, the importance of using the actual gas-lift valve performance relationship rather than the Thornhill Craver choke equation is addressed. It is shown that utilization of the Thornhill Craver choke equation can result in serious design errors. The two most commonly used unloading design procedures are examined with modifications and improvements being recommended. Finally, it is shown how software for the personal computer can be used to readily implement these ideas.
Horizontal Well Stimulation Results in the Austin Chalk Formation, Pearsall Field, Texas
Authors: Dees J. M. , Freet T. G. , Hollabaugh G. S.
Published: December 2007

Since 1985, Oryx Energy Company has used horizontal drilling and completion technology in the Pearsall Field of South Texas for increasing production rates and developing reserves in the naturally fractured Austin Chalk formation.

This paper reviews the application of various stimulation techniques in horizontal wells based on field experience with over 20 Austin Chalk wells. The lateral hole lengths range from 150 to 4,800 feet. The three stimulation methods discussed are water fracs, acid washes, and acid fracs.
Synergistic Effects in the Polymer Treatment of Producing Wells
Authors: Zaitoun A. , Kohler N. , Coffin P.
Published: December 2007

Some polymers used as water control agents in the treatment of producing wells are also good clay stabilizers. Both a nonionic polyacrylamide (PAM) and a biopolymer (Polysaccharide G) induce a selective reduction of relative permeability to water of natural sandstones without affecting the relative permeability to oil, although the presence of adsorbed polymer in the core increases the irreducible water saturation. The same polymers are shown to stabilize montmorillonite clay dispersed in sandpacks by lowering the critical salt concentration (CSC) below which clay is released. Adsorption of such polymers in clayey sandpacks also prevent, to some extent, the swelling of montmorillonite clay, with PAM having greater efficiency than Polysaccharide G. The treatment of a heavy-oil horizontal well producing in a poorly consolidated sandstone reservoir by an innovative process using PAM as the base polymer has confirmed good lab results. The treatment induced a decrease of both the water cut and sand cut, thus markedly improving well performances.
Reserve Pit Drilling Wastes - Barium and Other Metal Distributions of Oil and Gas Field Wastes
Authors: Deuel L. E. , Holliday G. H.
Published: December 2007

This study was conducted to evaluate the distribution of barium (Ba), chromium (Cr), lead (Pb), Zinc (Zn), arsenic (As), iron (Fe), manganese (Mn), sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg) in drilling wastes relative to the point of discharge into the reserve pit. Metals are conserved species (from a mass balance point of view) and serve as index parameters for establishing materials variance and associated chemical composition of reserve pit solids.

A large (> 50,000 bbl) reserve pit was divided into 6 sections, then sampled by taking 12 cores within each section down to consolidated native soil. Location samples were blended in the field yielding one composite sample for each section. Section composites were subsampled for analysis then biended together to yield one pit composite. Section samples and the pit composite were analyzed according to procedures recommended by Louisiana Office of Conservation. The volume of solids and concentration of regulated metals was greatest near the point of discharge. There was good agreement between weighted metal averages determined for section samples and pit composite values, suggesting from a mass balance perspective, that metals are not randomly distributed in reserve pits. EPA SW-846 method No. 3050 digest (1984 edition) provides a good index for total metals, except for barium. Barium can be accurately determined for drilling fluids using conventional spectrometric analysis by modifying the amount of sample and volume of nitric acid used to partition barium from the solid phase.
Oil Property and Composition Changes Caused by Water Injection
Authors: Eakin B. E. , Mitch F. J. , Hanzlik E. J.
Published: December 2007

Cores from a newly drilled observation well close to a long-time water injector showed 20% lower residual oil saturations than anticipated. Laboratory measurements were made on four live oils at 215° F and 3015 psia to study this phenomena. The results showed: –residual oil volumes decreased by 18%,–density of the live oil increased up to 10%,–Stock Tank Oil gravity dropped 3° API,–the bubble-point pressure dropped by 82%, and–viscosity of the oil in the reservoir tripled.

All the changes observed are detrimental to the later recovery of the residual oil remaining after a water flood.
A Field Case Study of Replacement Well Analysis: Guymon-Hugoton Field, Oklahoma
Authors: Ebbs D. J. , Works A. M. , Fetkovich M. J.
Published: December 2007

This study analyzed the initial pressure data and the performance results of replacement wells drilled in 72 sections of the Guymon-Hugoton Field, Oklahoma. Reservoir lateral continuity was confirmed and the current 640 acre well spacing was determined to be adequate for effective drainage of the field.
Effects of Steam Quality on Cyclic Steam Stimulation at Cold Lake, Alberta
Authors: Ho D. W. , Morgan B. T.
Published: December 2007

Reservoir simulations of cyclic steam stimulation (CSS) at Cold Lake show that both the oil recovery level, and the efficiency of the process as measured by the oil produced/heat injected ratio (OHR), are independent of steam quality. However, with constant volume (rather than constant energy) injection, the calender day oil rate (CDOR) decreases with a reduction in steam quality. Therefore, the higher the steam quality the more economic the CSS process becomes. Present boiler technology enables a practical maximum of 80 percent quality steam.

The study also demonstrates that a temporary reduction in steam quality results in a temporary efficiency gain for the same cumulative energy injection, accompanied by a corresponding drop in CDOR. The reduction has no permanent impact on well performance in the subsequent cycles, since the CDOR rebounds to normal levels after higher steam quality injection is resumed.

Leming pilot field data show that an uneven steam quality split resulted in some wells consistently receiving higher quality and others receiving lower quality steam. Nevertheless, analysis indicates that each well still received approximately the same energy due to flow nozzle meter calibration. The net result was no harmful effect on well performance and recovery, consistent with the simulation predictions. As a result, accurate wellhead steam quality measurements are not deemed necessary to further optimize performance.
Comparison and Analysis of Radioactive Tracer Injection Response With Chemical Water Analysis Into the Ekofisk Formation Pilot Waterflood
Authors: Skilbrei O. B. , Hallenbeck L. D. , Sylte J. E.
Published: December 2007

This paper documents the design, operation, analysis and use of two different radioactive tracers, tritium and iodide-125, which were injected in the Ekofisk Formation Pilot Waterflood Project. This paper also describes how chemical analysis of water produced in the offset producers during the pilot project was successfully analyzed, interpreted, and used as a second tracer method.

Both tracer methods were used to evaluate waterflood mechanisms and were invaluable to the overall interpretation of the Ekofisk Formation Pilot. A comparison of both methods is made to demonstrate their repeatability for possible future use.

During the pilot water injection program, clear responses from the injected radioactive tracers were identified from the three production wells within the pilot. Analysis of the produced water from these wells was carried out in the laboratories of IFE ("Institutt for Energiteknikk") in Oslo with an accuracy within 1–2 percent.

Chemical composition of the produced water was monitored during the same tracer injection period which showed a direct correlation. The large differences in sulfate concentration between Ekofisk formation water and the injected seawater makes this ion a good alterative to the more ideal radioactive tritium tracer.

Careful analysis of the various tracers in the Ekofisk Formation Pilot confirmed that both waterflood recovery mechanisms capillary imbibition and viscous displacement were contributing to the overall waterflood recovery. This was a key element in the interpretation and simulation of the pilot.
Analytical Modelling of 2-D Flow in Gravity Stable Secondary Gas or Water Drives
Authors: Schulte A. M. , Niko H. , Swinkles W.
Published: December 2007

Up-dip gas injection or down-dip water injection into a dipping oil reservoir leads to a stable displacement for a certain range of injection velocities. Two (extreme) models are available to predict the steady-state tilt angle of the injectant/oil interface: the fully segregated-flow approximation and the fully diffuse-flow approximation. The predictions of these models may differ considerably and a good criterium to judge the validity of the approximations is not available. A new 2-D analytical model has been developed that takes into account both along-dip and across-dip flow and establishes a link between the two approximations. It predicts the tilt angle and velocity of the injectant/oil interface and iso-saturation lines in the invaded zone for any situation in between fully segregated and fully diffuse along-dip flow. The model can also be used to gain insight into the relative importance of the effects caused by the injection well and the validity of the steady-state solution. This paper outlines the new model, concentrating on the gas injection process. Example calculations are presented that show good agreement between numerical simulations and the predictions of the 2-D model.
Casing Collapse Analysis Associated With Reservoir Compaction and Overburden Subsidence
Authors: da Silva F. V. , Debande G. F. , Pereira C. A. , Plischke B.
Published: December 2007

Pressure decline associated with production induces compaction of high porosity reservoirs and overburden subsidence in fields of the North Sea Chalk Basin. More than ninety casing failures have been observed in this area which are related to the increase of axial and radial loads on the wellbore.

A numerical technique was developed to describe the mechanism of casing failure in compacted reservoirs as well as in associated overburdens. A 3D finite element modelling procedure was set up to simulate and predict the onset of casing failures. Important characteristics of this numerical model are the introduction of the concept of sliding interfaces and the transfer of deformation parameters from a large scale displacement (field) to a more refined scale analysis (casing).

This 3D finite element simulation identified the failure modes and allowed an appropriate revision of casing design throughout the field area. Furthermore, it has been demonstrated that the revised design solutions extend the casing lives for a large number of years.
Careful Planning and Sophisticated Laboratory Support: The Key to Improved Acidisation Results
Authors: Nitters G. , Hagelaars A. M. P.
Published: December 2007

The decision to treat oil and gas wells with acid is often based on the general belief that acid will dissolve any skin damage and/or part of the rock matrix. Often acid recipes are selected on the basis of experience in other areas, usually with a fair amount of subjective engineering judgement. As a result the success rate of acid treatments is sometimes rather disappointing.

Proper evaluation of a formation's response to matrix acidising requires knowledge of the various parameters before the acid-response testing. Mineral composition and potential sources of formation damage, e.g. invaded barytes, can be identified by the application of sophisticated instrumental analysis techniques such as X-ray diffraction (EDX) and scanning electron microscopy coupled with automated mineral identification by complex image processing.

Correlation of analytical results on core samples before and after treatment with acid with the acid response curves helps to explain the phenomena observed in the tests. Automated mineral identification based on EDX analysis and scanning electron micrographs of the relevant samples may provide additional information without which differences in the response of closely related samples might remain unexplained.

The application of these procedures in the design of acid treatments for a number of Dutch gas wells resulted in an improved acid treatment design and more successful stimulation treatments. A total of seven gas wells, producing from a reservoir with a rather unusual rock composition, were treated, resulting in a total production gain of some three million m3/day, more than twice that expected on the basis of previous stimulation experience.

The paper illustrates how a carefully planned acidising campaign can benefit from a thorough laboratory study and fruitful cooperation between research and operating company.
Hydraulic Fracture Stimulation of Permeable North Sea Oil Wells
Authors: Clancey B. M.
Published: December 2007

The vast majority of fracture stimulations conducted to date in the North Sea have been hydraulically propped fractures of tight sandstone gas reservoirs or acid fractures of carbonate oil reservoirs. This paper demonstrates that hydraulic fracturing technology is applicable to permeable sandstone formations and can enhance the economic viability of marginal North Sea oil reservoirs.

In 1989, Mobil North Sea successfully conducted its first hydraulic fracture stimulation of a North Sea oilwell in the A45 well on the Beryl Alpha condeep production platform. The formation stimulated was the Triassic Lewis Unit I Sandstone, characterised by average permeability of 10 md (streaks over 100 md), and capable of producing 500 – 1000 BFPD. The stimulation was successful in increasing the well's PI from 0.7 BPD/psi to 1.4 BPD/psi and resulted in post-frac production rate of 2400 BOPD.

Technical highlights of the stimulation were the use of large propping material to achieve maximum fracture conductivity, and the use of resin coated proppant to minimise its flowback. The formation stimulated was at 16,155ft MD with wellbore inclination of 55°.
Gas Blockage by Nonaqueous Foams
Authors: Hanssen J. E. , Haugum P.
Published: December 2007

This paper reports some results of on-going research efforts to develop a method to reduce undesired gas production in oil wells by using foam as a barrier. Exploitation of the gas-blocking properties of foam by using it as a gas-coning barrier is an old idea that, to our knowledge, still has not been applied successfully. An attractive means of achieving a favorable barrier geometry is by using low-density non-aqueous foaming-agent solutions. This work is, to our knowledge, the first study of non-aqueous foams as gasblocking agents. We are focusing on two alcohols using fluorinated well-stimulation surfactant formulations. The ability of foam to reduce gas mobility in porous media was measured by a gas-blockage test. Most experiments reported are for a model system, but some data at higher temperature and in the presence of crude oil and brine are included. Experiments in porous media show that non-aqueous foams are capable of producing the same drastic changes in flow patterns as aqueous gas-blocking foams. Gas blockage is shown to be possible over an extended period, or at high pressure gradients, with a non-aqueous foam. The effects on gas blockage of varying the absolute permeability, porous-medium length, and temperature are also reported.
Cybernetics And Management By Systems In Petroleum Exploration And Production
Authors: Hinterhuber Hans
Published: December 2007

HINTERHUBER, HANS, Member AIME, AGIP SpA, Direzione Mineraria, San Donato, Milan, Italy

This paper was prepared for the European Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in Milan, Italy, April 4–6, 1968. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal, provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

This paper will:develop certain basic concepts about the nature of cybernetics,show how these relate to the management by systems,demonstrate how management by systems applies to the most efficient operation of petroleum exploration and production, andsuggest some possible exploration strategies for use at possible exploration strategies for use at different management levels.

Introduction

The vast growth in size, complexity, and diversity of operations of the modern petroleum company has made the managerial petroleum company has made the managerial function exceedingly difficult, but even more essential to the success of the enterprise. Modern petroleum exploration and production is characterized by its ever-increasing specialization, necessitated by the enormous amount of data, the complexity of techniques and of theoretical structures within every field.
Asphaltene Deposit Removal: Long-Lasting Treatment With a Co-Solvent
Authors: Trbovich M. G. , King G. E.
Published: December 2007

Introduction

Asphaltene problems are increasing on a wide scale in the petroleum industry. The deposition of these materials has been increasingly noted in production wells of CO2 floods and in miscible drive floods, after acid stimulations in asphaltic crude oil formations, and as pressures in older fields near the depletion point.

Many reservoirs produce without evidence of asphaltenes until the oil stability is disturbed. After the initial problems with asphaltenes, even those caused by a single use, catalytic behaving stimulus such as an acid job, many wells continue to exhibit problems long after operations return to normal.

Numerous remedies to remove asphaltic deposits and stabilization methods to control the deposition have been tried with varying amounts of success. This paper presents a review of the mechanisms that contribute to asphaltene precipitation and laboratory and field results of a class of solvent/stabilizer chemicals that has shown very good performance in removing asphaltic deposits, restoring production, and in preventing some upsets for extended periods of time.
Rock Properties of Berea Sandstone, Baker Dolomite, and Indiana Limestone
Authors: Churcher P. L. , French P. R. , Shaw J. C. , Schramm L. L.
Published: December 2007

A complete understanding of the various rock properties is essential in determining the rockfluid interactions that take place during coreflood experiments. Although Berea sandstone, Baker dolomite and Indiana limestone have been used by the petroleum industry as reference materials, very few data have been reported in the literature regarding their basic rock properties. This paper contains petrographic and petrophysical data for these rock types. Twelve representative samples were selected to study the variability and the relationship of several rock properties, including mineral content, grain and pore size, porosity, permeability, specific surface area, mercury capillary pressure, and electrokinetic properties.

The results indicate: 1) the Upper Berea sandstone samples studied exhibit correlations between porosity, permeability, specific surface area, and various parameters obtained from the mercury capillary pressure analyses that may be used to predict certain rock properties, 2) Baker dolomite and Indiana limestone contain a small amount of clays and organic matter, 3) These carbonates show a bimodal pore throat size distribution based on mercury capillary pressure analyses, and 4) The surface charges of these rocks are very dependent on the brine composition and pH.

The specific surface area and surface charge data can be used to determine the amount of chemical retention during corefloods using these or similar reservoir rocks. This information is necessary to optimize chemical processes used in the oilfield.
Aqueous Tracers for Oilfield Applications
Authors: Hutchins R. D. , Dovan H. T. , Sandiford B. B.
Published: December 2007

As an oil field matures, the need for reservoir information increases. Improved geological descriptions are frequently necessary for the implementation of numerical modelling or improved oil recovery techniques. Frequently this description can be enhanced by tracer studies. Detecting the location of faults between wells is one specific use for tracing fluid flow. Tracer studies have also been used to complement the information provided by other reservoir characterization methods such as pulse and interference testing. The primary importance of tracer testing is that it provides direct proof that fluid flow has progressed from point A to point B, showing that communication paths exist. In addition, measured tracer breakthrough times are quite useful for inferring the flow characteristics of the reservoir. If the tracer program is poorly designed, the apparent absence of tracer detection at point B may lead to incorrect decisions affecting the management of the reservoir. We will discuss the proper selection and usage of chemicals for tracer testing. Limitations and precautions for individual chemicals will be demonstrated with test data from several field tests. The objective of a tracer test design must be known before a proper test can be implemented. Environmental aspects and analysis of certain tracer materials will also be addressed.
Improved Calculation of Casing Strains and Stresses in a Steam Injector Well Simulator
Authors: Rodríguez-Prada Héctor
Published: December 2007

This paper describes the modifications implemented in a steam-injection well simulator to model casing strains and stresses produced by the injection/production of hot fluids. These modifications allow the calculation of the axial, radial and hoop stresses, and the axial and radial displacements induced by temperature and pressure changes. With these calculations, it is possible to predict tension and compression failures and casing bursts or collapses, produced by excessive pressures and temperatures. The calculations take into account the thermal and mechanical effects simultaneously.

The recommended API calculation is only valid for inner diameter-thickness ratios larger than 20, but since casings with an inner diameter-thickness ratio of less than 20 are not uncommon, an expression was developed to calculate the maximum burst resistance for any casing thickness. The energy distortion theory was used in the analysis of the combined stresses. All of these calculations can be carried out at any point along the casing and with any boundary conditions.

Comparisons with other models reveal several differences. The calculated stress values differ because other models do not consider the effects of the reactions at the fixed points, and do not report the radial and hoop stresses, which are important for the cementation.

A good prediction of the casing strains and stresses provide valuable information to avoid possible well failures which are very costly and time consuming.
3D Fluid Flow Behavior in Heterogeneous Porous Media Characterized by Geostatistical Method
Authors: Guérillot D. R. , Lemouzy P. , Ravenne Christian , Galli Alain
Published: December 2007

An accurate understanding of the internal architecture of a reservoir is required to improve production forecasts. Due to the lack of information between wells, a geostatistical model is used to generate equiprobable lithofacies simulations between wells. Then, after assigning petrophysical parameters to these lithofacies, 3D fluid flow simulations are performed in these 3D geometries.

Variations of the geostatistical parameters implies differences on the production forecasts. Before giving some comments on die fluid flow behavior, the geological investigations and the main characteristics of the geostatistical model are recalled.

For an actual case, a methodology is proposed for a better integration of the geology into the reservoir evaluation process. The multidisciplinary approach proposed is illustred on synthetic examples.
An Improved Method for Heavy Oil Fields Production and Cost Optimization
Authors: Uzcategui Elio Antonio , Vasquez Hebert Ramon
Published: December 2007

Electricity, pumps and rig time are the major costs associated with beam pump artificial lifting method in heavy crude oil.

In reducing operation costs, which are mainly associated with sand production, high viscosity, high GOR and rod flotation, Maraven has successfully tested the progressive cavity pump in Bolivar Coast fields.

The application of the method has reduced energy consumption over 60%, increased well production an average of 12% and reduced rig activity more than 40% in extraheavy and heavy type crude oils. This equipment was also tested in extraheavy oil slanted wells with excellent results.

The application of this method through an in house computer program has saved 10 million dollars/year in Maraven operational costs. It is expected to extend this program to other areas.
Laboratory Development of Emulsion Technology for Pipeline Transportation of Viscous Crude Oils
Authors: Chien Sze-Foo
Published: December 2007

Emulsion pipeline technology is a simple and cost-effective method for transporting viscous crude oils. A drastic reduction in the apparent viscosity of the oil-in-water emulsion makes this technology feasible.

This paper presents and discusses the laboratory experiments to explore emulsion properties that will be the basis for the design and operation of the emulsion pipeline. Examples are presented to show the characteristics of the test results. A list of publications and U.S. Patents associated with the emulsion pipeline technology is included.
Evaluation of Full Wave Sonic Data by Analysis of Instantaneous Characteristics and Colorgrams
Authors: Knize Stanislav
Published: December 2007

Evaluation of full wave sonic (FWS) data for rock properties such as fractures and dipping boundaries often requires qualitative analysis of visually distinct wave patterns. Conventional waveform plots do not reveal all the information available from FWS data. With the application of an analytical method called "Instantaneous Waveform Characteristics" (IWC) analysis and with the use of color encoded displays called "colorgrams", additional FWS characteristics, helpful to formation description, can be observed and interrelated.

The characteristics used in the IWC analysis are the instantaneous phase, the instantaneous frequency, and the complex waveform magnitude called "sonic transmissivity". Changes in these characteristics as observed in the colorgrams are excellent qualitative, locally sensitive, indicators of variations in rock properties. The transmissivity indicates formation attenuation, especially in fractured intervals. The instantaneous phase enhances the reflections from fractures and boundaries, and reveals their presence and dip. The instantaneous frequency shows the effects of dispersion due to abrupt changes within the formation.

The application of the IWC analytical method is demonstrated with several examples. The IWC colorgrams from three different wells are displayed and analysed: a test well with core information, a naturally fractured well, and a cased hole before and after hydraulic fracturing. All these examples illustrate how the IWC method, enhanced with colorgrams, broadens our analytical understanding of FWS well log data, provides new fracture and dip indicators, and assists in geological interpretation.
Bitumen Occurrence & Distribution in Upper Zakum Field
Authors: Arab H.
Published: December 2007

Bitumen was observed in Upper Zakum Field since long time and found to be restricted mainly at the Northeastern margin of the field.

Bitumen occurrence at the Northeastern flank of Upper Zakum Field is originated from bacterial biodegradation and/or water washing of lighter molecular hydrocarbons.

Bitumen definition and recognition can be made by wireline logs as well as by core observation, thin sections, SEM study, polished rock sections under reflected light, and production/injection data aid.

By utilizing the above facilities, the Bitumen distribution in Upper Zakum reservoirs is defined laterally and vertically. As a result, the Bitumen occurrence is increased downwards as well as the Bitumen area which allows to delineate the Bitumen area for each reservoir.

Bitumen as a heavy molecular hydrocarbon is distinguished into two aspects, greasy and dry. In both cases, Bitumen tends to coat and/or fill the pores, hampering the fluid pathway. This consequently, resulted in a low production/injection performance.

Finally, the Bitumen in place has been calculated in the main reservoirs of Thamama 1, 2 & upper part of Thamama 3.

This amount of Bitumen is hardly to be produced, thus, has to be considered separately during any future/injection scheme.