bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Mixing and Gravitational Segregation Between Natural Gas and Inert Cushion Gas on the Recovery of Gas from Horizontal Storage Aquifers
Authors: Kumar Anil , Kimbler Oscar K.
Published: December 2007

It has been proposed in the literature that certain economies might result from the use of an inert cushion gas, such as flue gas, during the storage of natural gas in aquifers. Where cushion gas is used, two types of displacement occur:

- miscible displacement at the natural gas-cushion gas boundary and

- immiscible displacement at the cushion gas-water interface.

Mixing and gravitational segregation occur during miscible displacement with the result that not all of the stored natural gas can subsequently be recovered. A calculation procedure, which considers the miscible boundary only, has been developed to calculate the recovery efficiency. This is tantamount to assuming that the aquifer water contacts only cushion gas throughout the operation and has no effect on the dynamics of the mixed zone between the natural gas and cushion gas. The calculation procedure was validated by displacements in a horizontal three-dimension radial consolidated sand model utilizing miscible liquids of differing densities. Excellent agreement was found over two complete injection-production cycles. Thus validated in the laboratory, the mathematical model was applied to a hypothetical storage aquifer to investigate the effect on recovery efficiency of several of the more important variables, including aquifer permeability and thickness and the density difference between the gases. The recovery efficiency during the second cycle was greater than the efficiency obtained during the first storage cycle. The per cent of injected gas recovered during a per cent of injected gas recovered during a particular storage cycle should increase with particular storage cycle should increase with the number of years of operation of the storage project.

Introduction

The underground storage of natural gas during the summer months is widely used by the natural gas industry to supplement the increased winter demand in urban areas. Furthermore, it enables pipe lines to be operated at nearly a 100 per cent load factor throughout the year. The increasing scarcity of depleted oil and gas fields has directed attention to the use of aquifers for such storage.

When aquifers are used, gas injected from the surface under sufficient pressure will desaturate the pore space and provide storage for the gas. Ultimately, the water saturation in the gas swept region may approach an irreducible minimum value.
Revitalization of Mara Field
Authors: Carmona R. , Graterol J. , Pina N. , Suarez O. , Lacazette A. , Frost E. , Gomez G. , Quinn T.
Published: December 2007

The Mara field is located onshore on the western side of Lake Maracaibo in Western Venezuela and the PDVSA affiliate, Maraven, S.A., holds the concession rights for the field. The field was discovered in 1951 and has been producing since that time, but has always been considered a marginal prospect at best since its inception. The advent of new technology in seismic, wireline logs and in detection and identification of natural fractures in the reservoirs has now made it possible to revitalize the field's production potential and significantly extend its productive life.

The reservoir rocks are of Cretaceous age, consist of carbonate lithofacies and are partially fractured. The new data and information from modern open hole wireline logs combined with the existing logs from the older wells, cores and production logs and borehole images were utilized to develop updated geological and petrophysical models. These models formed the basis for the Mara field rejuvenation and development plan. The new logs included Nuclear Magnetic Resonance (NMR), acoustic and borehole image logs. The borehole image logs were particularly useful in clearly identifying fracture zones as well as porous intervals that contribute to production. The NMR logs were useful in detecting the movable water zones for exclusion from the production intervals.

Additional core analysis including determination of pore shapes and sizes were used in developing the petrophysical model. Fracture density and orientation were successfully correlated with regional tectonic events to update the geologic model. The production history and recent production logs confirm the validity of these new models.

Introduction

The Mara field of western Venezuela provides an excellent opportunity to assess the impact of modem logging technologies on field development strategies because a large variety of various vintages of logs were collected during the long history of field development. Since discovery of the field in 1951, a variety of logs have been utilized to describe the reservoir and to develop geological, petrophysical, and reservoir models.

Only older E-logs were collected during the first phase of discovery and development although one density and two neutron logs were run in the last wells that were drilled (circa 1980). Suites of porosity, spectral gamma ray, resistivity, production, image, and Nuclear Magnetic Resonance logs have been run since reactivation of the field began in 1995.

The modern log information proved critical for developing updated geological and petrophysical models in this complex and highly variable carbonate reservoir. These models have improved the success and production rates of new wells, and provide a rational for future development of the field.
Use of a Computer to Predict the Results of an Explosive Stimulation in Oil and Gas Wells,
Authors: Laspe Charles G.
Published: December 2007

Economic application of the Talley-Frac method for the stimulation of production from oil and gas wells, production from oil and gas wells, requires careful engineering analysis of each application. A feasibility study should be made on each candidate well to determine the technical efficacy of such a treatment and to arrive at the optimum amount of explosive slurry to be loaded. This optimum should be synonymous which the greatest rate of return upon the well-stimulation dollar. Since the answer to the above questions involves an extensive amount of computation in their evaluation, automation of this evaluation by means of a digital electronic computer can extend the base of applicability. DATAFRAC is such a computer program written in FORTRAN IV language, and is capable of being run either on time-shared computers or in the batch mode on computers running in this environment. In just a few seconds, a complete economic feasibility study is performed which will determine whether or not a given well is a good candidate for explosive fracturing and the optimum amount of explosive to load in case the answer is in the affirmative.

Introduction

The technical and economic feasibility of using the TALLEY-FRAC explosive method for stimulation of the production of oil and gas wells can now be established using a recently developed computer program.
Delivery Prediction for Scheduling Operations
Authors: Hanson Donald H. , Root J. Paul
Published: December 2007

This paper describes an adaptive process which could be applied to the process which could be applied to the problem of delivery scheduling from gas problem of delivery scheduling from gas storage fields. Conceptually, the general problem is viewed as one of operating a system to fulfill specified requirements. A specific example is that of scheduling withdrawals from gas storage fields according to a forecasted schedule based on forecasted demand and peak day requirements. Interruptions peak day requirements. Interruptions or alterations in the planned schedule require an operating response and a technique for determining the optimum response. This paper presents a method that can serve as a tool applicable to the delivery prediction aspect of the scheduling problem.

Introduction

The control of systems through adaptive control process methods is gaining in scope and application. A synthesis of computer and mathematics has evolved heuristic techniques which permit the "law" governing the permit the "law" governing the optimization of a system to be abstracted. Applications include continental air defense, automobile traffic control, airline traffic control, fire control and long range missile control.

In order to optimize a system, a function must be developed which can be maximized or minimized in accordance with an objective. This function can include two classes of parameters. one class describes the dynamics of a physical system. The other class can be physical system. The other class can be considered external to the system but capable of influencing it.

Of particular interest to reservoir engineers is the problem of scheduling offtakes from a number of gas storage fields. In this case the external parameters are the demand schedule and the parameters are the demand schedule and the peak day requirement. peak day requirement.
Design and Implementation of a 22,600 ft Underbalanced Coiled Tubing Scale Cleanout in the Gomez Field, Pecos County, Texas
Authors: Adams L.S. , Overstreet C.C.
Published: December 2007

This paper reviews the design, implementation, and results of a 22,611 ft underbalanced coiled tubing scale cleanout project for the wellbore of the Fort Stockton Gas Unit 5–1. The Fort Stockton Gas Unit 5-1 is a deep, low pressure, high temperature, Gomez (Ellenburger) Field gas well.

Ellenburger formation is a fractured dolomite of Ordovician age. The formation has an average gross thickness of 1,600 ft with an average reservoir temperature of 335 F.

No remedial operations have been performed on the FSGU 5-1 since its completion in March 1970 (Figure 2). In July 1993, during bottomhole pressure data acquisition, an obstruction was tagged at 21,164 ft from surface. An attempt using a 1.5 in. bailer deployed on slickline was unsuccessful in obtaining any type of sample. However, on the basis of offset well data, an assumption was made that scale with major physical characteristics of calcium carbonate and iron oxide was causing the restriction. In August 1993, the well was acidized for the first time since initial completion with no effect to its production characteristics. Because the FSGU 5-1 was considered a prolific producer relative to offset production, it was determined to remain risk adverse and not attempt any further remedial activity.

Introduction

The recent development of reliable 100,000 psi minimum yield strength coiled tubing has provided an economic avenue for performing deep underbalanced workover operations. Coiled tubing technology can provide significant economic and technical enabling qualities versus conventional workover methodology.

Major areas of impact are, lower transportation cost, reduced rigup & teardown expense, less logistical coordination, reduced trip time of tubulars, elimination of kill fluids, reduction/elimination of reservoir damage, and elimination/reduction of safety hazards.

The Fort Stockton Gas Unit No. 5–1 (FSGU 5–1) produces from the Gomez (Ellenburger) Field located in the Delaware Basin on the southwest flank of the Central Basin platform (Figure 1). Development of the Gomez (Ellenburger) Field was initiated in 1963. The Average daily production from the FSGU 5–1 was 4.7 MMcf/D during the first quarter of 1996 with 900 psig well head backpressure Based on a detailed nodal analysis simulation study performed in August 1996 on the well, wellhead compression was installed reducing wellhead backpressure from 900 psig to 500 psig. Although a 1.6 MMcf/D production increase was realized from this compression project, the nodal analysis simulation study indicated the well's production could still be optimized by approximately 2.0 MMcf/D.

Based on offset well information, a 94% soluble scale interval beginning at 21,164 ft from surface existed and was restricting the well's inflow performance. From historic data, the probability that a surface acid treatment contacting enough scale surface area to dissolve it was minimal.

P. 207^
Business Analysis – A Hotbed for Strategy Ideas
Authors: Menghini Paul , Stang Roy
Published: December 2007

The rapidly changing business environment of the 1990's forced the oil and gas industry to develop new corporate and regional strategies to remain competitive. In support of strategy development, much attention has been given to analytical tools such as decision and risk analysis and probabilistic modeling What is often overlooked, however, is that for these tools to be effective, a solid foundation of information and a thorough understanding of the underlying business environment is required. The process of Business Analysis provides this understanding and serves as a "hotbed" for new strategic ideas.

This paper presents several business analysis tools which enhance awareness of the business environment and provide the foundation of information necessary for sound strategic modeling. Examples from a recent study show how tools such as influence diagrams, value chain analysis, benchmarking, competitor analysis, scenario development, and strength and weakness analysis are used.
Field Experience And Concept To Be Taken Into Account In A Fpso Design
Authors: Mastrangelo C.F. , Castro A.N.M.
Published: December 2007

This paper contains the main points which need to be addressed in the design of an FPSO, based on PETROBRAS's 13 years of experience in operating this type of production unit.

It is possible to analyze the experience as well as the problems that have occurred in previous tower-yoke and calm-yoke systems, to find good ideas and solutions for turret based systems.

During the design of FPSOs, designer must consider not only the most severe environmental conditions, but also the less severe conditions during which the Process Plant and other equipment, like turret swivels, will normally be used. We stress that less severe environmental conditions can be the determinant factor under which it will be dimensioned. The combined experience of the Naval and Offshore Industries, has assisted in the development of new concepts, related to FPSO conversion and new build constructions presently underway for PETROBRAS Future design will be aimed at producing oil and gas from fields located in deeper and deeper water depths.

Introduction and Background.

Stationary offshore terminal facilities utilizing Crude Oil Tanker Ships were employed by Oil Industry as early as fifty five years ago. At first, a tanker was simply connected to a single point mooring (Calm) by conventional hawsers where it was used as a combination buffer storage vessel and mooring platform shuttle tanker. A further step in the evolution of this type of unit came about in Brazil in 1975, when the installation of process facilities over a tanker ship main deck was developed.

This system began operating in February of 1979. The first concept was the TOWER-YOKE, then it changed to a CALM System, CALM-YOKE and nowadays TURRET System. Some reason for these changes, including adaptations necessary for the specific purpose of each project will be described.

In Brazil there are 6 FPSOs under construction and another 4 under conceptual and basic design. Experience gained from operating this type of unit has been useful when determining technical specifications and life expectancy design for future conversions.

FPSO technical team members are selected from both the Naval and Offshore Industries. This helps to create new concepts, enhanced design, and increased reliability.

The following phases of this first FPSO will be analyzed:

TOWER-YOKE.

CALM

CALM-YOKE

TURRET

Advantages of each one and problems occurred.

P. P.^ Moraes History.

All systems used the same tanker ship. The tanker Presidente Prudente de Moraes that was built in 1959 as a 33,000dwt crude oil tanker. She was Jumborized in 1974 to 52,000dwt. In 1979 the ship was converted into a FPSO with a 60,000bpd process plant capacity.

Main Characteristics of the vessel:

Length: 231.10m

Breadth: 26.00m

Depth: 16.87m

P. 699^
Novel Approaches to Profile Modification in Horizontal Slotted Liners at Prudhoe Bay, Alaska
Authors: Bond A. J. , Blount C. G. , Davies S. N. , Keese R. F. , Lai Q. J. , Loveland K. R.
Published: December 2007

The development of new techniques and materials for performing profile modification treatments in horizontal, uncemented slotted liner completions at Prudhoe Bay, Alaska is reported in this paper.

Historically, it has been difficult, if not impossible, to perform remedial profile modification treatments in horizontal slotted liners. The lack of annular isolation and uncertainties with conventional fluid placement posed seemingly insurmountable challenges. The development and field trials of two new techniques that address these problems are presented in this paper. The first approach uses advanced gel technology for fullbore, non-selective treatments for water shut off and selective placement for gas shut off. The second uses a new thixotropic cement slurry to place a chemical packer around the slotted liner for zonal isolation - opening the door for conformance treatments. Certain preliminary successes of these techniques have prevented the need for sidetracking wells to new locations or permanently abandoning zones. This has saved the operating companies significant wellwork expenditures.

Treatments have been performed on five wells to date with several more in the development stage. Treatment descriptions, operational rationale, and pre- and post-production trends are presented.

The horizontal slotted liner profile modifications performed are all technical successes with 60% of the treatments also economically viable. Even though it is early in the life cycle of these technologies, the successful treatments are encouraging and have opened up a large candidate pool. These new techniques and materials are promising options allowing remedial work in horizontal wells with uncemented slotted liners.
Successful Water Shutoff in a High-Temperature, High-Volume Producer - A Case History from the Ula Field, Offshore Norway
Authors: Bergem J. , Fulleylove R.J. , Morgan J.C. , Stevens D.G. , Dahl J.A. , Eoff L.S. , Enkababian P.G.
Published: December 2007

This paper presents field data from the successful use of an in-situ polymerisation water shutoff system in a hot (147 C), high productivity, high rate, well. Previously the chemical system had not been applied above 93 C or in such a prolific well. The job was performed by a team comprising the operator and two service companies. One service company supplied the selected chemical technology. The other service company supplied the means to deploy the system with the control of placement the job demanded. The success of the treatment resulted from a combination of factors. The job design ensured that oil production from the well would not be harmed even though complete mechanical isolation of the oil-producing zone within the wellbore could not be guaranteed. To ensure the oil-producing zone was not damaged, coiled tubing and packer placement was combined with dual injection to protect the oil. Wellbore and reservoir modelling of the pre-cool and gelant injection was used to estimate the required injection rates and volumes. Laboratory studies used field materials, and field conditions were used to check blocking times and possible problems. The pre-cool design was checked and enhanced by a pre-job injection trial.

Monitoring temperature and the pressure above and below the packer during the actual job allowed highly controlled "live" amendments to the injection regime.

Introduction

The Ula field lies in Block 7/12 of the Norwegian Sector of the North Sea (see Figure 1).

P. 843^
Evaluation of a Water Conformance Treatment in Prudhoe Bay Alaska
Authors: Chan K.S. , Bond A.J. , Keese R.F. , Lai Q.J.
Published: December 2007

The new Water Control Diagnostic Plots technique was found to be very effective for evaluation of a water conformance treatment conducted in Prudhoe Bay last year.

It determined the channeling as the main mechanism for poor conformance as seen in the diagnostic plots of offset production wells. Log-log plots of Water/Oil ratio vs time exhibited a characteristic behavior of channeling behavior. Post treatment well production history data of the offset production wells were plotted and compared with the pretreatment diagnostic plots. Change in slope or trend in Water/Oil ratio curves as used as a good indicator of successful problem correction and good treatments.

Introduction

The thick Prudhoe Bay Sadlerochit sandstone formation, which is at a vertical depth of 8,800 ft' is bounded by a gas cap and a bottom water aquifer. Portions of the field have been under waterflood since 1980. The field is producing approximately 0.9 MM BPD oil, 1.5 MM BPD water and 7 MMM SCFPD gas. As reservoir depletion continues, water and gas production rates continue to increase.

Most of the produced water and gas are re-injected. The majority of gas is re-injected into the gas cap. Some is made into miscible injectant for a tertiary recovery process. The water is treated and filtered and incorporated into the ongoing waterflood program. However, the capabilities of water and gas handling surface facilities are limited even after recently completing a series of plant expansion projects. Increasing water and gas production drives up water and gas handling costs and decreases oil production. As reservoir depletion continues, gas cap and enriched gas as well as waterflood water breakthrough occurs frequently at the producing wells. The Gas/Oil and Water/Oil contacts get closer and closer to the perforated intervals. The potential of bottom water and gas cap gas coning and channeling increases. The gas and water produced by these adverse mechanisms by-pass reserves and impede normal production.

The Diagnostic Plots

A new diagnostic plot technique has been developed to differentiate between mechanisms of excess water and gas production. The production data are used to plot in log-log the WOR, GOR or WGR (Water/Oil, Gas/Oil and Water/Gas Ratios respectively) and their derivatives versus time. Together with the completion and workover history, the excess water and gas production mechanism can be determined.

Figure 1 shows a comparison of WOR behavior for normal layered reservoir depletion and bottom water coning. This technique can be applied to oil or gas wells, vertical or horizontal wells. Figure 2 shows a case of rapid water entry occurring in a horizontal well. The drastic increase in WOR and its derivative indicate such a change after approximately 300 days. The mechanism is a near wellbore or cement channel problem.

P. 853^
Integrated Reservoir Management via Full Field Modeling, Pt. McIntyre Field, Alaska
Authors: Hagedorn K. D. , Coleman D. R. , Frank K. J. , Janes R. W. , Pospisil G.
Published: December 2007

Development drilling, depletion planning, and waterflood management have been guided by the use of a finely gridded full field reservoir simulation model (FFM) since startup of the Pt. McIntyre field in October 1993. A detailed geologic model formed the basis for development of the reservoir simulation model. A multicompany, multidisciplinary team used 3D seismic interpretation and data from over 7000 feet of core to provide the foundation for this geologic model. The full field model constructed from this geologic framework yields an excellent match to field history, including individual well matches, with very little "history matching" required. The model has been used to address a wide range of reservoir management issues in addition to providing conventional long-term reservoir performance forecasts. Development and infill drilling assessments, facility expansion evaluations, and individual well work forecasts have been based on FFM results. More novel applications of the model include waterflood optimization and hydrocarbon miscible EOR evaluation. The FFM has been the focal point for integrating geologic, petrophysical, reservoir surveillance, and surface facilities information to improve reservoir management decision making at Pt. McIntyre.
Matching the Ancient Filling of an Oil Accumulation to Improve the Reservoir Characterization
Authors: Filho J. D. Souto , Corrêa A. C. F.
Published: December 2007

A series of simulation runs are conducted to study the impact of reservoir heterogeneity and external geometry of the accumulation on oil distribution in the subsurface. The geologic model selected to this study was the Alto do Rodriges oil field, located in the onshore portion of Potiguar Basin (RN- Brazil). The fluid flow modeling is performed with a three-phase flow, three-dimensional commercial numerical simulator. The objectives of the study are:

- to investigate the effects of the internal heterogeneity (permeability barriers) in the ancient filling of a petroleum accumulation by using a vertically refined cross-sectional simulation model;

- to quantify the time required for hydrocarbon entrapment in the accumulation (geologic time); and

- to examine the factors that can affect the production mechanisms of the reservoir.

The methodology presented in this paper can be used to provide a better understanding of the mechanisms that control the fluid distribution in the reservoir. This method can also be used as a support for reservoir management, providing important contribution for the exploitation plan, including the dimensioning of improved oil recovery projects.

Introduction

An oil field is the result of a complex fluid movement in the subsurface. Its existence is directly related to the equilibrium conditions (static or dynamic) prevailing among the capillary, viscous and gravity forces acting in the reservoirs. Cap-rock properties, such as permeability and capillary entry pressure, play also an important role in the reservoir existence.

Due to the particularities of the hydrocarbon accumulations, consisting of a porous system saturated with fluids (water, oil and gas), it is important to understand the mechanisms responsible for its formation so that, from this knowledge, we can maximize the recovery factors of the producing zones. Numerical simulation is a fundamental tool for reservoir management, aiming to define the best conditions for exploitation of a given reservoir (or producing zone). Its application requires the selection of a physical model, which shall represent as accurately as possible the hydrocarbon accumulation to be exploited.

This work describes the application of the numerical simulation to a stage prior to the establishment of an exploitation philosophy for the field, that is, in the stage of elaboration of the geologic model of the accumulation.

The proposed working model objects to investigate the fluid distribution in the subsurface by considering its flow into the reservoir unit. This approach would allow us to raise, still in the beginning of the field productive life, the problems related to positions of fluid contacts, the influence of permeability barriers on the fluids distribution in the reservoir, and the definition of horizons in which the hydrocarbon flow is made easier.
Evaluation of Treatments for Control of fines Migration in the Ceuta Field in Venezuela
Authors: Colmenares F. J. , Padron A. , Boggio C. , Montoya F.
Published: December 2007

In the Ceuta field, an area located in Lake Maracaibo and assigned to Maraven, S.A. (a subsidiary of PDVSA) for exploitation, there has been a significant production decline during the producing life of wells. Production has dropped from 2000 BOPD to 50 BOPD in 10 months. HCl and HF stimulations have not been successful in restoring the lost potential.

Flow tests and the mineralogical analysis of cores from the area have shown that there is a very high content of fine clastic material, which has a very special characteristic: it moves through pores. When this material finds very small pore spaces, then it plugs them, which results in reduction of formation permeability.

In order to be able to control this problem and restore the permeability of the damaged formation, matrix treatments with Fluoboric Acid (HBF4) have been applied in several wells located in the Ceuta field. These treatments have made it possible to stabilize the clastic material. After the treatment, well production has remained stable for more than four years, and the average gain has been 1500 BOPD/well.

This paper is about the experiences and results obtained during a pilot test involving 5 wells.

Introduction

The Ceuta field is located in the southeastern area of Lake Maracaibo. Its production potential is around 70.0 MBOPD of net oil (37 API). This production potential comes from reservoirs belonging to the Misoa formation from the Upper and Lower Eocene B and C. This potential has been impaired by formation damage which, as proven, is due to fine migration.

Flow tests and the mineralogical analysis of some cores from the area have shown that there is a high content of clay particles such as kaolinite and "Mixed Layer" illite, which have a very special characteristic: they move through pores. When this material finds very small pore spaces, it plugs them, which results in the reduction of permeability in the medium.

In order to control this problem and restore the permeability of the damaged formation, matrix treatments with fluoboric acid have been applied in several wells located in the Ceuta field. These treatments have made it possible to stabilize these migratory clays, and production has remained stable for much longer, as compared with the results obtained when the traditional formulation was applied (12% HCl + 3% HF).

The purpose of this report is to share Maraven's experience involving the matrix treatment of formations having this fine migration problem.
Optimized Field Matrix Acid Stimulation Parameters in a Multi-Layered Reservoir Using Foam Diversion
Authors: Talabani S. , Hareland G. , Rajtar J. M. , Islam R.
Published: December 2007

Matrix acidizing stimulation treatment in a multi-layered reservoir may achieve a limited success because of poor acid diversion to layers of lower permeability. A foam is currently used to temporarily plug higher permeability layers, and divert more acid to the damaged layers.

A combination of new factors that optimize the foam design parameters were assembled into a simple equation. The equation is based on laboratory experiments conducted on Berea sandstone cores under low (100 psi) and high (3000 psi) average pressures. According to this equation the degree of acid diversion into the damaged, lower permeability layers in the field can be specified and controlled.

A few parameters control the success of the foaming-acidizing process., hence there are a few input parameters to the equation. During a field acidizing job, the optimum combination of these parameters can be found from the calculation of the Average Optimized Diversion Factor (AODF). The AODF indicates how successfully the acid is diverted to the lower permeabilitylayers during the foam and acid injections. Results from the laboratory experiments show that the Average Optimized Diversion Factor (AODF) indicates instantly, from the inlet pressure and the change in acid injection rate, if the damaged zone will be successfully stimulated.

In field applications, fast calculations of the AODF can predict the effective removal of the damaged zones with time, using the change in the acid injection rate, bottom hole inlet pressure, and the volume of the acid injected as input parameters. Increase of the AODF indicates that the removal of the damaged zone is progressing in the right direction.
PROKICK - an Integrated Software for Supporting Deepwater Well Control Operations
Authors: Sotomayor Gabriel P.G. , Santos Otto L.A.
Published: December 2007

This paper presents the development and application of a computational tool that emphasizes the integration process in the several phases of the well control operation. This tool, named PROKICK, provides the drilling personnel with information and several computational resources covering many aspects related to well control in deepwater drilling. The paper discusses relevant points of the software development, shows important features offered by the system and presents a typical deepwater well control case to illustrate the application of the software. The system can also be used as a very powerful instructional tool for training and certification programs in well control.

Introduction

Well control issues in very deepwater drilling are more complex and comprehensive due to specific problems found in such environments. Low fracture gradients, lengthy choke and kill lines, hydrate formation and gas inside the marine riser are some of these problems that call for more complex well control procedures and practices, sophisticated well control equipment and a very well qualified drilling crew. Thus, this complexity demands fast access to a huge amount of information previously stored or generated during kick incidents to warrant quick and adequate actions.

In this scenario, the utilization of integrated computer systems is a key component of the entire well control process. Available systems, however, are not specifically designed for very deepwater well control applications. Thus, a study was commissioned in Brazil to develop a well control integrated system that incorporates the Brazilian experience in drilling safety in very deepwater environments.

The software includes three modules:

- well design from well control standpoint and kick prevention that also includes information concerning well control equipment and rig crew training and certification;

- rig crew drills, kick detection and well closure; and

- killsheet and kick circulation out of the well.

The software package includes two expert systems (one dealing with anomalies during normal drilling operations that includes kick events and the other with diagnosis and correction of operational problems during the kick circulation) and a kick simulator for predicting wellbore pressure during the kick removal process. The utilization of the software is illustrated through a very detailed example of a kick situation in a typical Brazilian deepwater well.
Laboratory Tests for Wellbore Stability in Deepwater, Brazil
Authors: Santos H. , da Fontoura S. A. B. , Gupta A. , Roegiers J.-C.
Published: December 2007

Wellbore instability problems in some wells located in the deepwater portion of the Campos Basin presented a serious challenge to the economical development of the huge oil reserves already discovered. Identifying the real causes of the instability was essential to better design the wells. This paper describes the comprehensive laboratory test study for wellbore stability purpose conducted on preserved downhole shale cores. The paper presents the rationale for the tests, the most important results, and also the new tests developed to better investigate the reactions and characterize the rocks. The results show, as opposed to the initial hypothesis, the problem was mainly due to mechanical failure, rather than due to a chemical interaction between the rock and drilling fluid. This broad investigation has allowed a better understanding of the interaction mechanisms between the shale and the drilling fluid, indicating the need to reevaluate some of the existing concepts and procedures.
The Methodology of Decision Making in Global Problems of Russian Gas Industry Development
Authors: Sukharev M. G. , Stavrovsky E. R.
Published: December 2007

One of the most serious problems in planning of the development of large and old gas-supplying systems consists in optimal choice between several projects, when many technological, economical and other aspects are to be considered. The report presents a new methodology of multicriterial estimation and comparison of such projects which was applied to one of regional gas-supplying systems in Russia.
On the Erosion Velocity of a Cuttings Bed During the Circulation of Horizontal and Highly Inclined Wells
Authors: Martins A.L. , Campos W. , Liporace F.S. , Wei X. , Van Riet E.J.
Published: December 2007

Cuttings transport has been the topic of theoretical and experimental studies for many investigators, who have always focused, due to the complexity of the subject, on steady state flows. However, the adequate representation of the involved phenomena requires more realistic simulation of the process, which is typically transient. The test results presented here relates to the erosion of a solids bed, formed in a full scale flow loop, by different polymeric suspensions in annular flow, at several values of flow rates, wellbore inclinations and drillpipe rotational speeds. Adequate instrumentation allowed for the recording of the evolution of solids concentration and bed height as function of time. Analysis of the experimental data enables the prediction of the rate and time of erosion of the cuttings bed and can be used as guidelines for the optimization of the circulation of horizontal and highly inclined wellbores.

Introduction

The action of stopping drilling to flush cuttings out of the well is always a point of controversy among oilfield teams. The practice of circulating periodically the hole may avoid several operational problems during the drilling of a highly inclined wellbore. On the other hand, if minimum requirements for the cuttings bed removal are not achieved, circulation will be ineffective, time consuming and, in some cases, detrimental to wellbore stability.

The topic of drilled transport during drilling has been the subject of studies for many investigators (Iyoho, Sanchez, Peden et al.). who have all focused, on steady state flows. Martins et al. presented a discussion on the optimization of hydraulic parameters in the circulation of horizontal wells. In this study, the authors propose correlations for bed height prediction after circulation and for the critical flow rates for complete removal.

The development of drilling activities requires more realistic simulation of the process, which is typically transient, due to interruptions in the operations and instabilities of rock formations, which tend to generate higher amounts of solids than expected. Ref .4, for example, does not answer to the major question about the optimum time to circulate a well.

In the present work the authors propose a way to quantity the variation of the amount of solids removed from the annulus with time, during the circulation of horizontal and inclined wells. The main objective is to provide methods to evaluate the evolution of bed erosion for given hydraulic conditions. The study is based on an extensive experimental work conducted at University of Tulsa large scale physical simulator, as a cooperative program among PETROBRAS, SHELL INTL. E&P RTS and U. TULSA.
A Successful Short Radius Re-Entry with Aerated Mud in Venezuela
Authors: Ingold Charles , Salazar Julio , Carrasquel Jose , Vidal Jose , Ramirez Francisco , Gourgues Bernard , Paredes Juan Beltran
Published: December 2007

New horizontal wells drilled with aerated mud have proven to be a cost-effective way for drilling and enhancing well productivity. Reentry drilling operations using aerated mud have been used for over a year in Western Venezuela. A major operator considered for a long time to combine short radius technique and aerated mud to reduce cost per produced barrel. Several re-entry candidates appeared to be perfect for such an application.

A short radius drilling system, including articulated downhole mud motor and modified measurement while drilling (MWD) tools, combined with careful drilling engineering program has enabled a successful completion of the first two short-radius wells with aerated mud drilled in Latin America. The second of which resulted in a sixfold production increase over the average well in the area.

The first short-radius well was drilled in 13 days with 500 feet of displacement. The second well was drilled in 12 days and had 880 feet of horizontal drain (fig. 1 & 7).

This paper describes the operational aspects, and procedures followed. It emphasizes the equipment and rig selection, the training requirements, and the environmental and safety concerns. It also includes a comparison with other techniques.
Analytical Study of the Performance of Positive Displacement Motor (PDM): Modeling for Incompressible Fluid
Authors: Samuel G. Robello , Miska Stefan , Volk Len
Published: December 2007

Recent increases in the application of horizontal wells, in particular slim hole laterals, has triggered the need for more powerful downhole drill motors. To meet this need, motors require performance improvements which, in turn, requires development of a mathematical model.

This paper presents a mathematical model for the performance of positive displacement motors (Moineu type) for incompressible fluids. Generalized equations for the cross sectional area of the shalt, housing, volume generated and torque for multilobed motors help identify design improvements. The maximum motor torque requires an optimal relationship between the pitch of the motor and the diameter of the housing. A dimensionless index called the Performance Index (PI), helps generalize the various design parameters of the power section. Dimensionless performance plots establish a standard to compare the performance of actual motors to the ideal motor. Also, common parametric curves describe the effect of various design parameters on operating parameters.

Leakage and torque losses play an important role in the performance of a motor. These losses and their effects are also addressed. Numerical examples for incompressible fluids demonstrate the practical usefulness of the theory and optimal analysis.

Introduction

During the past two decades, extensive research and development have yielded highly efficient drilling systems to achieve cost reductions for high departure wells. The world wide acceptance of rotary drilling methods and tools made it difficult to introduce new drilling techniques. The current need to exploit low pressure oil reserves has required drilling more horizontal wells. Since many wells could probably be re-entered and completed with lateral holes, coiled tubing drilling technology (CTD) became of interest to service, major oil and gas companies. This almost mandates a downhole drill motor since coiled tubing cannot be rotated. Percussion hammer, positive displacement, turbine and electric motors can be use downhole but the positive displacement motor is currently preferred.

A variety of positive displacement motors are available but all have problems when used in coiled tubing drilling. Some simulation and performance studies exist for turbines, but no mathematical model adequately addresses performance of the positive displacement motor.
Percolation Modelling and Non-Newtonian Flows in Oil Reservoirs
Authors: Kadet V. , Polonsky D.
Published: December 2007

In this paper we had established the law for flow of viscous-plastic fluids in porous media with taking into account the inertial losses. Such rheological properties can be found in heavy viscous oils which contain components with high molecular weights. The obtained common relation between filtration velocity and pressure drop can be used for different applied simulations of heavy oil recovery from real reservoirs.

It has been considered the asymptotic properties of established macroscopic flow law for small and large velocities, and also investigated the correlation between macroscale limiting pressure gradient and parameters of microheterogeneity of the medium. A good qualitative agreement between the theoretical results and the experimental data was obtained. These data was taken for oil conditions of Arlanskoe field (Bashkortostan, Russia).

Introduction

The non-Newtonian behavior of many kinds of oils is a well-known phenomena for the reservoir engineering practice. That is why the problem of studying of this phenomena was in focus of investigators for a long time. However, at the most of the works it was not discussed the question about association between non-Newtonian properties of the macroscale flows and the microstructure of the porous media. The new analytical percolation approach was developed at last time. This approach allows to analyze wide spectrum of the problems of the underground fluid dynamics and gives the new understanding of the relations between peculiarities of the processes on the microscale and macroscale. Specifically, this methodology can be used for the investigations of characteristics of non-Newtonian fluid flows in porous media. In the previous works the nonlinear law for the Newtonian fluid flow in porous medium had been obtained with taking into account the inertial losses for the joints of capillaries and the phase permeabilities of a medium saturated by viscous-plastic fluids had been defined. Here we designed the model which allows us to obtain the nonlinear flow law of Binghamian plastic with consideration of the inertial losses. Also we carried out the qualitative comparison between our results and the experimental data for Arlansloe oil field (Bashkortostan, Russia). The two-phase displacement model had been investigated, and the relation between limiting pressure gradient and the saturation of porous media had been obtained for the case of steady-state flow.
Model for Predicting the Production Rate of Wells under Cyclic Steam Injection Process
Authors: Buitrago S. , Boccardo G.
Published: December 2007

In this work we present a methodology for matching and predicting the production rate behavior in time, for wells stimulated by cycle steam injection.

The production rate is given by the transient solution of the equation of the flow of a slightly compressible fluid in an infinite radial aquifer in a porous media. Also, expressions for the effective compressibility and permeability, based on experimental studies and production rate behavior from field data, are proposed

A function which gives the error between the production rate generated by the transient analytical model and the field production rate is presented. This function depends on the parameters associated to the expressions for the effective compressibility and permeability. A non linear global optimization technique to minimize the error function is presented in order to determine those parameters. The optimization technique combines a stochastic exploration of the domain of the error function and a heuristic calculation of a descent direction, in order to avoid stopping the algorithm at a local minimum.

The methodology was used to match the production rate behavior of several wells which have been cycle steamed in Costa Bolivar. In all cases, an excellent match with errors below 10% and similar parameters for the set of wells was achived.