bluuebunny/crossref_metadata_2025 huggingface dataset:
Trinidad's First 500Mmcfd well: Fact or Fiction?
Authors: Kromah M. J. , Lumsden P. J. , Hennington E. R. , Brayshaw A. C.
Published: December 2007

Existing and projected supply conditions in Trinidad's gas market require that, as a key strategic objective, BP Trinidad and Tobago (bpTT) build upside deliverability into its portfolio of producing gas wells.

By challenging well performance limits many gas wells in Trinidad now have the potential to produce at rates in excess of 150Mmcfd. In conjunction with prudent reservoir management practice, the widespread deployment of low drawdown completions should allow these production technical limits to be pushed even further. Concurrently optimising the sand face completion, production string and topside facilities, so that system ‘chokes’ are moved downstream, are also seen as key to unlocking this potential.

In December 2001 bpTT's Amherstia field set a Trinidad production record with a single well delivering in excess of 210Mmcfd through 7″ tubing. As part of its existing field development plans in 2003 bpTT plans to raise the single well deliverability bar even higher, towards the 300MMcfd mark.

Elsewhere in the world ‘super-bore’ completions have successfully delivered rates beyond 400Mmcfd1. Within the bpTT portfolio of future field development options there exist reservoir segments, which through the use of ‘super-bore’ completions have the potential to deliver Trinidad's first 1/2 Bcfd well.
Offshore Well Testing and Productivity Evaluation Methodology: Plataforma Deltana Project, Eastern Venezuela Basin
Authors: Da Prat Giovanni , Lindo Octavio , Quintero Eduardo , Molina Rolando , Martinez Jose Antonio
Published: December 2007

This work presents the well-test management design and interpretationmethods that have been implemented to evaluate the exploratory wells of thePlataforma Deltana Project, in the Eastern Venezuela basin. The proposedmethodology has been applied to an exploratory well drilled in this project, itis an offshore gas-condensate well located near the border of Venezuela andTrinidad & Tobago. One important aspect that is emphasized in this work isthe need to test exploratory offshore wells to obtain the basic reservoir andwell productivity parameters, and to provide an estimate of the recoverablereserves associated to the well drainage area. The methodology is based on theintegration of seismic, geology and petrophysical information, to optimize thedesign and time of the tests. In order to elaborate the particular well testingprogram in the best economical way, time is a critical factor in any offshorewell, in addition to get focused on layer evaluation and determining producingfluids properties. In this work the evaluation results obtained from theimplementation of this methodology in two sands is presented.
3D Geocellular Modeling in a Complex Structural Setting: El Furrial Giant Oil Field Venezuela
Authors: Laval A. , Auxiette G. , Echeverria I.
Published: December 2007

This paper presents the building of a geocellular static model of El Furrial, giant oil field in Venezuela. El Furrial field, located in the north of Monagas state, was discovered in 1986. It originally contained about 7 billion STOIIP. The field is approximately 13 km along strike and 7 km wide. It produces from two reservoirs identified as the Naricual and Los Jabillos Formations. The gross thickness of the two reservoirs is about 2500 ft. The oil composition in the Furrial Field changes rapidly with depth from that of a conventional oil (28 °API) at the top of the formation to that of an immovable tar mat, principally as a result of an increasing alphaltene content of the crude.

This full field model is set in highly structural complex reservoir. A new software&s chain, RML (Reservoir Modelling Line) was used and has allowed to build an accurate 3D model respecting the most important geological constrains of the field data. Five separated but integrated applications allow to take into account complex structural setting as well as petrophysical data and a high diversity of sedimentological environments which composed the reservoir.

Two first applications (GeoSurf and GeoSim) are used to build an accurate structural framework integrating complex surfaces and more than 60 main faults. A new simulation option (Pluri gaussian algorithm) of stochastic application (Heresim) provides a better solution to restore complex channel or bar architecture and to attribute properties parameters. The resulting very high resolution geocellular grid (about 350 million of cells), have been successful up scaled in term of rock type, porosity and permeability with the 2 last applications (SimGrid and SimUp) to obtain a coarse model of about 900 thousand cells to be used in dynamic simulations.

Using such a line of applications had permitted to get a very integrated model and to be secure of the existence of a very close link between the resulting static and dynamic models.
Modeling of Reservoir Compaction and Casing Integrity Evaluation Using Reservoir Simulation
Authors: Abou-Sayed Ahmed S. , Meng Fanhong , Noble John E. , Guo Quanxin
Published: December 2007

The paper discusses the impact of reservoir production on wellbore integrity and survivability when the compacting reservoir behaves as a deformable permeable body. The discussion is carried out using results of a numerical geomechanics model developed for estimating reservoir compaction, the subsequent surface/mudline subsidence; and the displacements, stresses and strains along the wellbore trajectories. The model has the unique aspect of efficiently coupling rock geomechanics with the actual reservoir simulation results. The input data include such relevant reservoir properties as pore volume compressibility, net-to-gross, porosity; corner point coordinates of each block from the reservoir simulator (the simulator blocks are identical to the elements used for the geomechanics model), wellbore trajectories and rock properties of the overburden. The deformation, stress and strains in the rock and along the well casings are evaluated at distinct time intervals. The initial, intermediate and final reservoir pressure profiles calculated by the reservoir simulator are central to the calculations. The model also has explicit analytical relationships that can be used to represent distinct variations in overburden lithologies.

In the model the reservoir is divided into many elements, where each element is approximated as a strain nucleus. The model estimates rock deformation in a semi-infinite body using a basic strain nucleus solution. The displacement field within the overburden, induced by reservoir compaction, is generated by integration of the Green&s functions derived in the model using the basic strain nucleus solution.

For any specific well trajectory, the model approximates the deformations and stresses in and above/below the reservoir that are generated on the well casing due to reservoir pressure depletion. The calculated deformations include rock movement within the overburden and displacement along the well trajectories, possible fault movements or bedding plane slippage as well as mudline/surface subsidence.

In this paper the physics and mechanics of the modeling approach are briefly described, followed by some examples. Numerous reservoirs have been evaluated using this model in order to analyze reservoir compaction and related mudline/surface subsidence, and to assess the casing integrity of reservoir wells. The evaluated cases have included onshore, offshore and deepwater offshore scenarios. There have been discreet, "isolated," single reservoirs, as well as multi-reservoir situations and offshore deep-water reservoirs. The results from these analyses have assisted in devising improved strategies for reservoir exploitation and management.
Oil-Base Borehole Image Applications in Thinly Bedded Sand Shale Sequences
Authors: Pavlovic Mitch D. , Mollison Richard A. , Payne C. J. , Gomez German
Published: December 2007

Micro-resistivity borehole image logs are well-established tools of geologist and reservoir engineers. These data are used for detailed reservoir description, providing high-resolution structural and sedimentological data. For thinly laminated turbidite sequences, they are often the only practical method of determining the distribution of net pay thickness in the absence of whole core data. Additionally, micro-resistivity images are used to help select intervals for formation testing and perforation.

The increasing use of oil and synthetic oil-base mud systems to reduce drilling risks and improve drilling efficiency has created an environment that prohibited the use of conventional micro-resistivity imaging devices. Thus, it was imperative to develop a new micro-resistivity imaging technology for oil-based mud systems. This paper summarizes the development and successful application of a new oil-base micro-resistivity imager (EARTH ImagerSM) that brings well-accepted resolution and formation response characteristics of conventional micro-resistivity imaging technology to the non-conductive drilling mud systems.

Combining the EARTH Imager with advanced open-hole logging instruments, such as the multi-component induction log (3D ExplorerSM), significantly improves petrophysical evaluation of thinly bedded sand-shale sequences. The interpretation model is built on a combination of high-resolution information from borehole image logs and the 3D Explorer horizontal and vertical resistivity data. These data are used in the Laminated Shaly Sand Analysis (LSSASM) petrophysical model to determine laminar sand resistivity, hydrocarbon saturation, and net sand pay. In our experience, such an approach provides a volumetrically balanced system that is highly reliable for predicting the production potential of an exploration well, a critical step when allocating resources for new development projects.
Fuzzy Logic Applied to Lithofacies and Permeability Forecasting Case Study: Sandstone of Naricual Formation, El Furrial Field, Eastern Venezuela Basin
Authors: Hambalek Nancy , Gonzalez Reinaldo
Published: December 2007

Lithological description and permeability values estimation using core-derived information of wells with just electric logs is an old problem in reservoir characterization. In essence, the problem consists in finding some explicit relation between log and core data in those wells that contain both types of information. Then, describe reservoir features (derived from core data) of wells with log information only. There are many methodologies (and concepts) that have attacked this subject with major or minor success: statistical techniques, hydraulic units, petrofacies, geostatistical methods, neural nets, fuzzy logic, etc.

Applied fuzzy logic is the matter of this article. Fuzzy logic allows quantifying qualitative information and modeling complex not lineal relations. It invites the use of "partial truths" between the "completely false" and "completely true" alternatives and allows the consideration of the whole spectrum of possibilities between these alternatives. When it is applied to reservoir characterization, it accepts the premise that any interpretation is possible although some interpretations are more likely than others. Consequently, values can be proposed to the whole gamut of variations present in the prediction of rock parameters.

In this paper, fuzzy logic theory is applied in order to establish a narrow relation between well logs and the seven rock types (lithofacies) of the sedimentological model that describes a very complex reservoir in eastern Venezuela. Core analysis of five wells and the established fuzzy relations are used to get the lithofacies description and possible values of permeability in eighteen wells of the same area having only electrical logs.

On the other hand, the efficiency of the algorithm here developed is verified against a control well with both log and core data. In addition, sensibility analysis was done considering the number of cores involved in the data base, and taking into account the capability of this approach describing from the most basic lithology (sand or shale), to the most detailed seven categories above mentioned. The results are very satisfactory and open the possibilities for future research and applications.
Application of Aphrons Technology in Drilling Depleted Mature Fields
Authors: Rea Anthony B. , Alvis Efren Cuellar , Paiuk Benjamin P. , Climaco Juan Miguel , Vallejo Manuel , Leon Eduardo , Inojosa Jorge
Published: December 2007

Depleted zones are intrinsic to most mature reservoirs throughout the world. The associated issues of effective, safe and economically viable well construction, completion and workover within low pressure environments become more challenging on a daily basis.

This paper discusses the application of aphron drilling fluid technology, which offers a unique alternative option that can significantly improve the operational and economic aspects for continued development of these marginal assets. The authors will detail the development of the unique micro-bubble technology and its successful application in a mature and depleted field in Mexico.
Advanced Drillstring Dynamics System Integrates Real-Time Modeling and Measurements
Authors: Chen David C-K. , Smith Mark , LaPierre Scott
Published: December 2007

This paper presents a newly developed drillstring dynamics system designed to avoid resonance and to reduce vibrations. The system integrates real-time dynamics modeling with real-time downhole vibration data to provide accurate modeling results and data analyses. Unlike conventional BHA dynamics software that is run for well planning or post-run analysis, this system uses real-time data (e.g., WOB, inclination, DLS) to produce real-time updates of critical rotary speeds. The updates are then displayed along with the rotary speed to show if the rotary speed is too close to one of the predicted critical rotary speeds. In addition, the modeling results can be compared with actual real-time downhole vibration data to corroborate the actual downhole condition. This paper will show why real-time modeling is more accurate than the conventional stand-alone modeling. Field runs of the new system in the GOM have demonstrated the accuracy of modeling is critical in avoiding harmful vibrations.
Increasing Solid Expandable Tubular Technology Reliability in a Myriad of Downhole Environments
Authors: Escobar Carlos , Dean Bill , Race Brian , Waddell Kevin
Published: December 2007

Since the spectacular arrival of solid expandable tubulars four years ago, customers have embraced this technology as a revolutionary well constructionand production solution. Through innovative technical development and equipmentreliability, solid expandable tubulars continue to grow in acceptance anduse.

Solid expandable tubulars have been used successfully to reach requiredtotal depth (TD) with adequate completion size, slim the well constructionprocess, and overcome abnormal pressures encountered down hole while drilling.In addition, this technology has been used to rejuvenate wellbores for welldeepening, casing reinforcement for stimulation, as a solution for corrosionproblems, and to cover leaks and perforations. As a result, the overall cost ofdrilling and production operations has been reduced.

This expansion process requires the successful integration of the followingconditions and equipment: casing capable of surviving in-situ reformingfriction reduction between the expansion cone and the casingexpandable flush joint connectioncontainment of hydraulic pressures during the entire expansion processsurviving expansion in downhole environment

During the last four years, solid expandable tubulars have been installed inmore than 113 wells. Reliability has improved from an average of 67% in 2000, to 83% in 2001, to over 95% in 2002. In the past, the reliability of solidexpandable tubulars has been measured by a limited set of criteria for jobsuccess. The reliability definition should be expanded to include otherperspectives of the total system.

This paper will discuss actual downhole conditions, including well control, lost circulation, and high temperature/high mud weight, in which solidexpandable tubulars were used as a successful solution. This paper will alsodiscuss additional measurement perspectives with the goal of creating a 100%reliable technology.
A Method for Isolating Pressure-Depleted Zones with Solid Expandable Tubulars
Authors: Moore Melvin J. , Wright Jon C. , Winters Warren J. , Chan Daigle
Published: December 2007

A method called "scoping" for installing solid expandable tubular (SET) drilling liners across pressure-depleted zones has been developed and demonstrated. High overbalance pressures associated with pressure-depleted zones are known to interfere with conventional SET expansion. Scoping is a dynamic expansion method that keeps the expandable tubing in continuous motion thus reducing risk of stuck pipe and SET failures related to differential sticking. This paper describes how scoping is performed and how it worked in a test well.
Benchmarking: Can it be Applied to Government Regulation of the Energy Sector?
Authors: Bradshaw-Niles Penelope , Ellis Ruel
Published: December 2007

Benchmarking is one of the most successful management strategies being employed in all industries, including the public sector today. The successes enjoyed by public sector officials have made governments more receptive to the fact that corporate style benchmarking may be applied to the public sector.

The continued importance of the energy sector in Trinidad and Tobago's economy makes it essential that the regulatory framework for the industry is current and responsive to the changing needs of an industry where dynamism and technological changes are the norm. Appropriate management tools should be identified and employed to achieve this.

This paper examines the use of benchmarking to identify opportunities for improving organisational effectiveness at the Trinidad and Tobago Ministry of Energy in its regulation of specific aspects of the upstream sector. The factors to be considered in selection of benchmarking partners are also discussed.

The findings suggest that benchmarking is useful in recognizing best practices, determining areas for organizational improvements and also for achieving institutional strengthening through relationships with benchmarking partners.
A Process for Planning New Developments in an Upstream Gas Business
Authors: Maharaj Shivanand , Hennington Eric , Daniel Michael , Wibowo I. Tenny
Published: December 2007

BP Trinidad and Tobago LLC (bpTT) has an upstream gas business with large process and export capacity, significant market growth opportunities, and a large portfolio of development and exploration opportunities. With such an asset, there must be a process to facilitate and guide capital spending decisions that underpin a strategy for delivering a gas growth agenda. The process must encompass development engineering and subsurface assessment to a level of accuracy so as to identify pre-investment opportunities that can be leveraged towards future growth. In the short to medium time frame, the questions of timing and volume of next gas supply are key questions to be answered. The process must include a mechanism to value exploration prospects so that the ordering of opportunities recognises multiple, risked outcomes, and hence, assists in the framing of longer-term developments. A successful process can reveal the future in terms of critical decision points, key drivers that impact financial performance, optimal capital spending profiles, and help guide the pace of growth. The subject of this paper is the process that bpTT is using to help guide its aggressive gas growth agenda.
Making Great Decisions in Development and Exploration Mexico Fields, Applying Bright Lights of the Latest and Multidisciplinary Well Completion Technology
Authors: Ballinas Javier
Published: December 2007

Technology is and always has been nothing more than the application of the human mind to the task of finding a new or better way. The development and application of a wide array of sophisticated technologies will be the hallmarks of the successful of many companies in future decades.

The industry is using now multidisciplinary technology such as 3D and 4D seismic, high propped hydraulic fracturing, tubingless well designs, multiple completions, high resolutions logging tools, reservoir numerical simulation, expert systems, and optimized multiple perforating systems for hard rock, etc.

Just in Mexico North Region wells, the tubingless completion integers advanced stimulation practices with reservoir analysis to improve production results from low permeability formations. Stimulation procedures still depend on the well completion method utilized.

Propellants use incorporates better results on early production of the treated wells and improve the benefits before and after propped frac jobs. The concept of combining the propellant into a sleeve form with the perforating gun is unique and this technology shows promise of solving many of the inherent perforating problems for which solutions have been needed.

Gun perforating and well stimulation have been inseparably entwined from the beginning. Shaped charges have been established as the most efficient method of obtaining communication between a cased borehole and the formation of an oil or gas well.

The most significant problem encountered in high propped frac jobs has been the presence of fracture entry restrictions arising from perforation friction, flow tortuosity and fracture friction. The combination perforating/propellant systems have met with encouraging results both as a perforation breakdown method, and as a tortuosity/near-wellbore damage stimulation method before a propped frac operation.

The industry will employ these excellent technologies to improve the prospects of locating new reservoirs and then to enhance the capabilities to produce them most efficiently. This paper will address differents topics and field applications in Mexico and worldwide of the innovative technology described.
Reservoir Aspects of Smart Wells
Authors: Glandt Carlos A.
Published: December 2007

A well equipped with intelligent components is considered SMART only when it maximizes its value over the life of the project. The definition of the adequate level of intelligence is the outcome of a multidisciplinary discussion that focuses on the well and reservoir management. To effectively realize the value associated with these technologies Shell set up a Global Implementation Smart Wells Team at its E&P Technical Center. Jointly with asset teams from around the world it has reviewed more than 80 projects over the last 3 years. The main result of this work is a faster and more meaningful implementation effectively realizing the value associated with these technologies. An important byproduct of this work is a list of identified well and reservoir opportunities where smart completions can add significant value. This paper reviews these opportunities and provides selected examples.
The Use of Aisi 4320 Sucker Rods at Corrosive Environments as a Field Experience
Authors: Ramírez G. , Poli M. , Salas F. , Olmos D. , Ameglio A. , Tapia R.
Published: December 2007

The present paper has for purpose to describe the experience with the use of AISI 4320 steel sucker rods in the corrosive environments of Unidad Económica Rincón de los Sauces (Neuquén - Argentina) of Repsol-YPF and show the results obtained until now.
Oilfield Scaling - Part II: Productivity Index Theory
Authors: Bedrikovetsky P. G. , Gladstone P. M. , Lopes R. P. , Rosário F. F. , Silva M. F. , Bezerra M. C. , Lima E. A.
Published: December 2007

Barium sulphate scaling during waterflooding causes formation damage mostly near to production wells, because high velocity near to wellbore provokes intensive mixing and accelerated chemical reaction between barium and sulphate ions.

The mathematical model for steady state oil-water flow towards producers accounting for chemical reaction is developed, and an analytical solution is found. It allows obtaining a productivity index formula for PI decline prediction.

The main result of the work is proportionality between the inverse to productivity index and time.
Introduction Of A New Generation Of Induced Gas Flotation Equipment-A Case Study
Authors: Movafaghian Shaya , Chen James , Wheeler Stephen Scott , Guidry R. W.
Published: December 2007

Induced Gas Flotation (IGF) technology is well known in the oil industry for its effective treatment of produced water to meet environmental oil-in-water discharge requirements.

This paper presents technical considerations for development of a new generation of IGF units, a discussion of the process kinetics, and actual operating data and performance analysis of a full size four-cell WEMCO® cylindrical depurator.

A pilot test program was developed and executed in collaboration with ChevronTexaco Overseas Petroleum on platform Gathering Station Mike, located offshore in Cabinda Province, Angola. Pilot data indicates the flotation kinetic rate for the oil removal from a four-cell cylindrical depurator is comparable with a conventional depurator.
Geosteering Horizontal Wells using Resistivity Anisotropy obtained in an Offset Vertical Well
Authors: Coutinho M. R. , Matsdorf M. , Ortiz A. , Reynolds L. , da Silva A. C.
Published: December 2007

Traditional resistivity logging instruments, when logged in vertical wells through horizontal beds, evaluate the horizontal resistivity (Rh) of the formation. The response of the laterolog tool in the same environment, however, is also sensitive to the vertical resistivity component (Rv). Used alone neither tool is able to resolve the thin beds or evaluate resistivity anisotropy. However, with computer inversion software, data from both tools can be combined to quantify zones of resistivity anisotropy, as well as accounting for various environmental effects such us invasion and shoulder beds improving bed boundary definition.

This paper proposes a new approach, combining NMR logs data with the above technique, in order to obtain improved geological and petrophysical models, using field data. The models, with more accurately parameterized vertical, horizontal, true and invaded zone resistivity values (Rv, Rh, Rt, Rxo), as well thin bed boundary definition, are coherent across a range of reservoir formation types, and are then applied to help drill more precisely (and evaluate more accurately), a horizontal well in the same formation.
New Pump Schedule Generator for Hydraulic Fracturing Treatment Design
Authors: Gu H. , Desroches J.
Published: December 2007

A typical hydraulic fracturing treatment executes a pump schedule that includes pad fluid volume and proppant stage concentrations. The automatic generation of such a schedule by a computer program is highly desirable. The generation of a pump schedule for hydraulic fracturing is an inverse problem. The fracture length and the proppant distribution inside the fracture are specified as input, together with formation and fluid properties, and a pump schedule generator (PSG) determines the amount of fluid and proppant needed in every stage of the schedule.

In this paper, a lag-length concept is implemented in a new PSG to control the distance between the proppant flow front and the fracture tip. The lag-length is necessary to prevent premature bridging and screenout in many situations. In this new PSG, the lag-length is automatically determined to generate an optimum schedule that uses the minimum pad volume to avoid premature screenout. The PSG is based on a pseudo-3D fracture model, and schedules can be designed for conventional (non tip-screenout) or tip-screenout treatments.

The schedule generator has been used to study the effects of proppant size and fluid types on the fluid and proppant stage volumes in a schedule. Lag-length is dependant on proppant size and other treatment conditions. The results of this study show that the application of the new PSG can benefit the fracture treatment design process. In particular, they highlight that changing the proppant size cannot be significantly changed independently from other pumping parameters.

The schedule generator is also shown to be a valuable tool in the selection of fracturing fluids. By comparing pump schedules required for a particular fracture performance - as given by desired length and proppant pack characteristics - the selection of a particular fluid can be made based on the optimum pump schedule for each fluid rather than using a fixed, or "typical," schedule in a particular field for different fluids.

Ultimately, the PSG is a primary tool to select the means to achieve a desired fracture conductivity within given operational constraints. It allows to compare all potential options: changing the proppant size, attempting a tip screen out design or changing the fluid system.
Analysis of Collapse Failures on Production Tubing During Steam Injection Process Assisted by Computer Simulations
Authors: Inciarte G. , Nieto L. , Bello A.
Published: December 2007

The alternate steam injection consist in force the reservoir to a cyclic sequence of heating and cooling process injecting hot water steam (500°-600° F) in order to improve the mobility for the extra-heavy crude in the reservoir, this is a very common practice for secondary recovery on the Tía Juana and Lagunillas fields, located in the eastern side of the Maracaibo Lake.

A destructive collapse failure on the production tubing was observed over the last wells exposed to this injection process. The investigation of the failure includes field visits, laboratory tests, and the computer simulations.

The study was prepared using a computer program able to create the different temperature profiles for the different scenarios and link them with the simulations for load cases, the results demonstrate the deterioration effect of temperature on the mechanical properties of the tubing, with particular interest on the expansion of the fluid trapped between the casing and the injection tubing, leading the collapse failure (AFE Analysis).

The analysis of the production tubing movement and buckling due to the thermal effect, ballooning and Hook's law is also included.
Comparison between Local Refinement and Open Boundary Techniques for Simulation of Large Oil Fields
Authors: Risso V. F. , Schiozer D. J. , Wendland E.
Published: December 2007

The use of computer models allows the forecast of the behavior of oil fields and the optimization of the production process. Usually, the simulation is hindered by the size of the field, the number of wells, the complexity of the system, and the amount of data necessary to guarantee the reliability of the model. This work addresses the reduction of computational effort, maintaining the level of precision of more complex simulations, when the interest is just in a certain area of the field, for example, in the forecast of the behavior of mature fields. There are several ways to accomplish fast simulations of this type of problem. Two techniques were studied in this work: local refinement and the simulation with open boundaries. For the evaluation of local refinement technique several different grids were tested. For the analysis of the simulation with open boundaries, the original field was decomposed in smaller units and the flows through the boundaries were represented by virtual wells. Models with variable number of virtual wells in each boundary were tested. Using the developed methodology it was possible to reduce significantly the time of simulation maintaining a reasonable precision.
Gas Lift Trouble Shoot Analysis Using Fuzzy Logic
Authors: Mata Daniel , Hernandez Ali , Chirinos Nicolas , Montoya Diego , Strefezza Miguel
Published: December 2007

Trouble shoot analysis of wells on gas lift is a very complex task, which requires knowledge and experience on behalf of the production optimization personnel. The complexity of the diagnostic process stems from the fact that a considerable number of possibilities can take place in a normal operation of a well on gas lift and the ever-present uncertainties of the quality of the data needed for the calculations.

The goal of a trouble shoot analysis is to determine the cause of any malfunction of the gas lift equipment or any other component of the completion that is limiting the well's production capability. The result of the analysis will determine the type of action needed to be taken in the field, which will eventually translate into maintenance cost.

The gas lift trouble shoot analysis is based on the fact that any of the valves installed in the well can be the operating valve. For a given point of injection, a force balance determines which valves could be open. If a valve is open and the gas pressure at depth is greater than the tubing pressure, the gas flow rate through the valve is calculated depending on how open the gas lift valve is. For the same given point of injection, the flowing bottom hole pressure is calculated and compared with the one predicted by the inflow equation. Then, for each possible point of injection or scenario, using fuzzy logic the gas injection mass balance and deviations from what the inflow equation predicts are used to determine the most probable point of injection.

This paper describes the most important principles underlying a gas lift trouble shoot analysis and how it can be integrated using fuzzy logic analysis to handle the complexity of the lifting process and the uncertainties of the data.
Approval Process for New Oil and Gas Field Development in Trinidad and Tobago
Authors: Rajnauth Jerome , Rudder Marc , Bradshaw-Niles Penelope
Published: December 2007

The Ministry of Energy and Energy Industries has the responsibility under the Petroleum Act to approve new oil and gas field developments. During recent years, many new fields have been developed and it is expected that this trend will continue in the future. Furthermore exploration work in deep and ultra deep waters will continue.

This paper describes the general process of approval by the Ministry of Energy and Energy Industries as well as information requirements related to new field development.

The authors hope this paper would be useful to any company involved in oil and gas exploration and development in Trinidad and Tobago and also those companies willing to invest here in the future. It is also the intent of the author that this information will be useful to other regulatory bodies around the world.
Liquid Inventory Management in Wet Gas Pipelines
Authors: Su C. , Rydahl A. , Shea R. H.
Published: December 2007

Production and transportation of wet gas in large diameter pipelines necessitate several operational issues to be addressed. Of particular interest is the liquid inventory management, which is essential to ensure efficient and save operation of the pipeline. This paper quantifies several options for liquid inventory management in such pipeline systems.

Often pipeline configurations include parallel pipelines. This allows for flexibility in operation of the pipelines, but at the same time introduces additional potential liquid inventory problems. At normal production rates, flow would tend to evenly distribute between two parallel pipelines with the same diameter since friction will be the dominant cause of flow resistance. At reduced production rates liquid would start to build up in the pipelines and unless proper attention is given, the in-situ liquid volumes may quickly exceed those of available separators and slug catchers.

The liquid build up can start at different rates for the two pipelines if there are differences in the pipeline profiles. Liquid build-up will also be influenced by how the liquid splits between the two pipelines at the pipeline inlets. Liquid buildup will increase the resistance of the flow in a pipeline.

The wet gas will often have an affinity to flow through the pipeline with less liquid buildup and thus less resistance. At the same time the parallel pipeline will produce less wet gas and thus gradually build up more liquid, as the production through that pipeline gets lower. Essentially the system is in an unstable condition and eventually one pipeline could end up with so much liquid that flow through it would cease. Very likely, the only remediation in such a case would be pigging.

Different scenarios are investigated to illustrate these potential problems and several suggestions to managing and operating the pipelines are presented.
Micro-Flux Control: The Next Generation in Drilling Process
Authors: Santos Helio , Leuchtenberg Christian , Shayegi Sara
Published: December 2007

Drilling wells for oil/gas has been increasingly challenging with the companies moving towards difficult environments. The problems faced in these locations range from very narrow margin between the pore (or collapse) and fracture pressures, pore pressure uncertainty, to high pressure and high temperature wells. Wells drilled in these scenarios using the conventional drilling method often do not get to total depth (TD), and even so, drilling can be extremely risky, with several kick/loss situations.

A new drilling method1 has been developed to overcome these problems, allowing a much safer condition, reducing the risks, and also permitting the wells to be drilled to TD much cheaper. Drilling is taken to the limit in a safe manner, extending each phase as much as possible, using the entire available mud weight window for that well.

The method uses the new concept of micro-flux control, which is based on detecting a minimum loss or influx of fluids, and instantly adjusting the return flow and, consequently, the bottom-hole pressure to regain control of the well. The well is drilled closed at all times, and the return flow from the well is compared to the predicted and ideal one, allowing detecting the discrepancies in a very short time.

This paper describes the basis of this new method and steps taken so far in the development. Field tests will be done very shortly, after the method has been tested in a simulated well condition. The use of this method allows wells to be drilled where today it has been impossible, extending today's technological limits way beyond the current boundary.
The Development and Application of a Software to Assist the Drilling Engineer During Well Control Operations in Deep and Ultra Deep Waters
Authors: Santos O. L. A. , Mendes J. R. P. , Ribeiro P. R.
Published: December 2007

This paper presents the development and application of an integrated computational tool to assist the drilling engineer regarding prevention and detection of a kick and its circulation out of the well when operating in deepwater and ultra deepwater drilling scenarios. This tool, called UNIKICK, provides the drilling personnel with information and several computational resources covering many aspects related to well control in those drilling scenarios.

The most important features provided by the system are as follows: (a) link to databases containing regulations, standards and operational procedures to be accessed from the rig site; (b) a module to display well control information and calculations such as kick tolerance, swabbing pressure, tripping and riser safety margin; (c) a killsheet which is calculated and displayed, automatically; and (d) an interface to show graphically the expected pressure behavior at selected points inside the well and fluids production during the kick removal process.

Through the interface, the user enters the data necessary to the calculation of the killsheet and to the simulation of the pressure behavior inside the wellbore and the flow rates of the fluids from the well, using a built-in kick simulator. This simulator was developed specifically for the system and accounts for the two-phase nature of the mixture of gas and drilling fluid and for the peculiarities of an ultra deepwater well/rig equipment configuration. The interface also displays the output data generated by the simulator in a graphical format together with animation capability for the gas that is circulated out the well.

To illustrate the usage of the system, the paper presents the results for three horizontal well control cases ranging from 1000 to 3000 meters of water depth.

The paper also suggests that the system can also be used as a very powerful instructional tool for training purposes.
Can We Visualize Drilling Fluid Performance Before We Start?
Authors: Galal Mohamed
Published: December 2007

The standard criterion for selecting a drilling fluid has been eliminating borehole instability and related problems. On the basis of current field experience, the drivers for developing formation-stabilizing agents and fluid technology always were related to basic concepts, such as quantitative mineralogy, dispersion tests, and swelling measurements, among others. This approach can exclude more important factors, including, but not limited to, geo-mechanics and pressure balances, that have a direct impact on the fluid deliverables, as well as overall drilling performance. The current thought process is ineffective at applying benchmarks, preventive measures, and risk assessment for most drilling operations. Further, it created a poor database that does not link quantitative fluid performance with borehole instability problems.

The paper presents a novel approach to the fluid selection process based on a unifying decision algorithm (decision tree). The challenge involves correctly identifying the relevant parameters and successfully applying the correct weighting to each of these parameters in the decision process based on the specific conditions of each project. By numerically incorporating all possible variables into a worksheet, the output recommendation should clearly rank each possible fluid option, the associated engineering risks, and provide a clear road map for realistically planning, executing, and measuring operational deliverables.

The objective of this work is to establish a universal definition for fluid selection criteria and to establish a base line, or road map, for data gathering to guide the process. The success of this approach also supports the idea of incorporating several high-performance fluid systems into one category, where each fluid has clearly defined performance measures supported by sound technical data. This process will facilitate an improved fluid selection process and increase chances for successfully completing challenging projects on time and under budget.
Fibrous LCM Sweeps Enhance Hole Cleaning and ROP on Extended Reach Well in Abu Dhabi
Authors: Cameron Charles , Helmy Helmy , Haikal Mohamed
Published: December 2007

Extended reach wells pose some unique problems to the drilling operation in the management of hole cleaning and torque and drag. Cleaning the hole without inducing an excessive equivalent circulating density (ECD), resulting in down-hole losses, can be a major issue when drilling extended reach wells. The reduced mud weight / fracture gradient window can limit pump rate making it difficult to achieve adequate solids transport, particularly in long 12 1/4" tangent sections.

Experience on world record extended reach drilling (ERD) operations led to the discovery that certain fibrous lost circulation materials (LCM) have the ability to enhance hole cleaning and dramatically reduce torque and drag in high angle and horizontal well-bores, as well as control losses. Optimised drilling practices, together with the application of engineered hole cleaning sweeps, can greatly improve drilling efficiency in extended reach wells.

This paper focuses on the successful application of fibrous LCM sweeps on the first extended reach well to be drilled in Abu Dhabi by the Abu Dhabi Company for Onshore Oil Operations (ADCO). In response to difficulties sliding in 12 1/4" hole, hole cleaning sweeps were routinely pumped from 9,462 feet, in the 63 degree tangent section, to final TD in 8 1/2" hole at 17,525 feet. Coupled with pipe rotation, these sweeps increased the rate of cuttings return to surface by up to 50% and frequently resulted in major improvements in the drilling rate. The effectiveness of these sweeps was monitored on surface at the shakers by visual means and downhole by means of annular pressure monitoring tools in the bottom hole assembly.
Multilateral Well Experience in Tight Clastic Reservoirs with Low Primary Recovery
Authors: Patra T. C. , Ghosh U. K. , Singh Raghuvir
Published: December 2007

Kalol field has multi-layered reservoirs with 11 pay horizons. Layers VII and X have better sand thickness. Gross lithology is mainly siltstone. The permeability ranges from moderate to poor and the primary reservoir drive mechanism is depletion. The reservoir pressure has declined from super-hydrostatic to substantially sub-hydrostatic at present. The productivity of vertical wells has fallen sharply and the field production rate has decreased. The well spacing is 600-700m, static bottom hole pressure shows high degree of variation. Two areas in sand KS-VII and KS-X were selected for drilling of multilateral wells. The wells have been drilled and put on production. The results are encouraging and the technology is proved to be an effective option for redevelopment of the field.
Managing the Government Gas Business in Oman using Hydrocarbon Field Planning Tool™
Authors: van Ravesteijn-Scott Elaine , van Berkel Jean
Published: December 2007

This paper presents a best practice workflow for managing the countrywide gas business in the Sultanate of Oman using Hydrocarbon Field Planning Tool (HFPT™). A Shell proprietary tool, HFPT is part of the FrontEnd Suite of applications that include the reservoir simulator MoReS and provides the capability for rigorous, integrated, subsurface-to-surface production forecasting for up to 25 years. HFPT hence facilitates the medium-to-long term planning and management of Oman's gas and gas-condensate fields and infrastructure development by accurately modelling the demand-supply balance of gas within the entire Sultanate.

HFPT provides a more realistic forecast than a stand-alone reservoir simulation for each field and, as such, can help with decisions regarding how to make the most efficient use of current assets while optimising future investments in new fields.
A Generalized Hyperbolic Decline Equation with Rate-Time and Rate-Cumulative Relationships
Authors: Chen Shing-Ming
Published: December 2007

Nearly all the decline curve equations used today are based on the Arps hyperbolic equation1. Many engineers prefer to use the exponential decline, which is a special case of the hyperbolic decline, to perform the decline curve analysis because it is easy to apply. Difficulties in using the hyperbolic equation are attributed to the decline rate variation with time and the changing initial rate or time in the production forecast.

Reference 2 presents a generalized rate-time hyperbolic equation which can successfully resolve the above difficulties in predicting the future rate. For the reserve estimate, however, the needed rate-cumulative equation is not being discussed.

In this paper, a rate-cumulative equation is derived for the reserve estimate. Using the generalized rate-time and rate-cumulative hyperbolic equations, the decline curve analysis can be performed to predict the future rate and estimate the recoverable reserve. These equations are further generalized to accommodate the multiple decline periods which may occur in the production forecast due to field or well optimization.