bluuebunny/crossref_metadata_2025 huggingface dataset:
Disposal of Mercury Sulfide and Residual Ash by Deep Well Injection
Authors: Brkic Vladislav , Omrcen Ivo , Omrcen Bozidar
Published: December 2007

INA Oil Company, Plc. Zagreb is a Croatian company engaged in the exploration and production of oil and gas, refining and distribution of petroleum products. An enormous quantity of hazardous waste is generated in oil and gas production and thus has to be disposed in a permanent and safe manner. In recent years, INA has been disposing waste by injection into exploration dry wells and production depleted wells.

A specific waste disposal problem has arisen in the process of gas and condensates in Molve, Kalinovac, Stari Gradec and Gola fields. Namely, mercury-sulfide, sulfur slurry and heavy metals have been separated during the production of gas and condensate.

Mercury-sulfide has been separated in the process of active coal utilization. The disposal of active coal saturated with mercury-sulfide is a very complex issue. So far, the methods of mercury-sulfide disposal have not been ecologically acceptable. However, on the basis of new experience and knowledge in that field, waste dispersed in a bentonite suspension may be disposed in a permanent and safe manner into appropriate geological formations. In the same way, when combusting various types of industrial and municipal waste, the problem of residual ash disposal emerges. Such residual ash contains heavy metals which may be permanently disposed by using the above mentioned method. This paper deals with the experience of waste disposal by deep well injection in the Republic of Croatia.
Rig Waste Reduction Pilot Project
Authors: Satterlee K. , van Oort E. , Whitlatch B.
Published: December 2007

Shell Exploration and Production Company (SEPCo) initiated the Rig Waste Reduction Pilot Project in 2001 to further its goals toward Sustainable Development. SEPCo ran the pilot project on two contract drilling rigs and a drilling and production platform. After characterizing and measuring the waste streams, 26 potential waste reduction strategies were considered for implementation. A preferential hierarchy for consideration was used: reduce, reuse, recycle, recover, and dispose. SEPCo found that its drilling discharges and non-hazardous oilfield waste (NOW) comprised the lion's share of the total waste and therefore represented the greatest opportunity for reduction. SEPCo used a combination of solids control efficiency, cuttings dryer technology, and new bulk mixing technology to reduce mud use by up to 20% and mud component packaging by up to 90%. Solid waste (consumables and trash) also comprised a large volume of waste. SEPCo implemented a sorting, compaction, and recycling process for this waste stream to reduce landfill disposal. This paper describes the process used by SEPCo to develop the pilot project, the strategies implemented, and the effectiveness of those strategies.
Options for the Recycling of Drill Cuttings
Authors: Page Paul W. , Greaves Chris , Lawson Rosey , Hayes Sean , Boyle Fergus
Published: December 2007

It is estimated that the UKCS produces between 50,000 to 80,000 tonnes wet weight of oily drill cuttings annually. With the implementation of OSPAR Decision 92, and given current offshore technology, it is no longer possible to discharge cleaned oily cuttings to sea. Increasingly stringent legislation also makes it likely that cuttings derived using water-based muds will not be discharged to sea in the future.

Although several commercially available treatment processes can remove oil from oil based mud (OBM) cuttings, there are few satisfactory outlets for the residual solid material most of which currently goes to landfill. In light of the legislative changes, increased focus on duty of care, and commercial considerations, viable alternatives are being sought for the recycling and reuse of large volumes of material from future drilling programs.

This paper examines possible options for converting drill cuttings into reusable secondary products and discusses the advantages and disadvantages of each option when considered against the criteria of environmental impact, technical risk, logistics, liability and cost. Examples of the research and pilot trials currently being undertaken to assess the feasibility of these options is discussed, as well as work being carried out to establish the variation in chemical composition of cuttings in the UKCS, since tolerance to the variation in the chemical characteristics of drill cuttings is a major issue for most of the end uses.
A Biodegradable Chelating Agent is Developed for Stimulation of Oil and Gas Formations
Authors: Frenier W. W. , Rainey M. , Wilson D. , Crump D. , Jones L.
Published: December 2007

Chelating agents are materials that are used to control undesirable reactions of metal ions. In oilfield chemical treatments, chelating agents are frequently added to stimulation acids to prevent precipitation of solids as the acid spends on the formation being treated. These precipitates include iron hydroxide and iron sulfide. In addition, chelating agents are used as components in many scale removal/prevention formulations. This current study is related to development of improved and biodegradable polyaminocaboxylic acid chelating agent formulations.

Chelating formulations based on ethylenediaminetetraacetic acid (EDTA) have been used extensively to control iron precipitation and to remove scale. Formulations based on nitrilotriacetic acid (NTA) and diethylenetriaminepentaacetic acid (DTPA) also are in use. Each of these materials has problems: 1) EDTA and DTPA have low solubility in hydrochloric acid and are not biodegradable. 2) NTA is acid soluble and biodegradable, but has a lower stability constant for iron than EDTA (or DTPA) and may be classified as an animal carcinogen. This paper describes the development and field-testing of formulations containing hydroxyethyliminodiacetate (HEIDA) salts for use in oilfield stimulation fluids.

Sodium HEIDA can be used in all of the formulations requiring EDTA-type chelating agents, including those for iron control during acidizing, scale removal treatments, and well cleanout operations. HEIDA biodegrades much more easily than EDTA or DTPA and has a much smaller environmental footprint (biodegradation, less material and less toxic corrosion inhibitors) than these chemicals. HEIDA is more soluble in HCl than EDTA, and therefore can control more Fe3+ than EDTA. The new formulation can be used to dissolve calcite and gypsum scale. It also can be used in acidic or alkaline well cleanout formulations with surfactants and mutual solvents. Field trials have shown that HEIDA formulations can be 1:1 substitutes for EDTA in oil and gas well treatments.
Vapor Recovery of Natural Gas Using Non-Mechanical Technology
Authors: Goodyear Mark A. , Graham Alexandra L. , Stoner John B. , Boyer Brian E. , Zeringue Lyle P.
Published: December 2007

There are approximately 250,000 tank batteries in the United States1. These tanks store crude oil and condensate prior to transportation to sales via pipeline, barge or trucking. The sources of the vent gases from tanks are from flash, standing and working losses. There are approximately 8,000 to 10,000 mechanical vapor recovery units (VRUs) installed at oil production sites with four tanks typically connected to each VRU2. Most of these tanks are fixed-roof storage tanks.

This project demonstrated the use of an alternative method for handling low-pressure natural gas that is typically vented to the atmosphere, flared or recovered with a mechanical compressor by oil and gas production facilities. This application used a venturi jet ejector as a device to compress natural gas from crude oil/water storage tanks to an intermediate pressure for use at the location or ultimate injection into the sales pipeline.

Upon injection of the oil into the storage tanks, lower molecular weight hydrocarbons dissolved in the crude oil come out of solution or "flashes" when the pressure drops as the oil enters the tank. The storage tanks are typically downstream of a low-pressure vessel such as a two or three phase separator or heater treater. The hydrocarbons that flash include methane, ethane, volatile organic compounds and hazardous air pollutants. These gases collect in the plenum of the fixed roof storage tanks that are typically used in oil and gas production operations.
Effect of Well Deviation on Slurry Friction Pressures
Authors: Pandey Vibhas J. , Goel Naval
Published: December 2007

Increase in friction pressure with the onset of proppant stages in a hydraulic fracturing treatment is a known phenomenon. With the introduction of proppant, the hydrostatic pressure due to the column of proppant-laden slurry increases and causes a reduction in surface pressure. However, it has been consistently observed that the apparent decrease of the surface pressure is less than the value calculated on the basis of increase in hydrostatic pressure alone, indicating that the excess is due to the additional friction imparted by the solids in the slurry.

When hydraulic fracturing treatments are carried out in deviated wells, the contribution of hydrostatic pressure to overall reduction of surface pressure may not be very significant, depending on the well deviation. The effect of well deviation on slurry friction is rarely reported in literature. As a result, a few correlations are available to predict slurry friction losses in deviated wells. To study the effect of inclination on proppant-laden slurry, bottom hole pressure (BHP) data are needed. Therefore, in the present study over 400 hydraulic fracturing treatments were selected, and around 100 of those with BHP data were analyzed. Results from the analyses indicated that the friction pressure observed in the slurry stages of deviated wells were significantly higher than those in vertical wells. Based on the observations, a new correlation is developed to incorporate the contribution of well deviation on slurry friction. Variables in the correlation include: proppant concentration, flow rate, tubular diameter and angle of deviation.

The developed correlation was then used to predict proppant friction in other wells, which were not considered in the study. The correlation predictions were also compared with other correlations currently used in the industry. The comparison shows a better prediction from the developed correlation. The correlation is easy to use and is being incorporated into the fracturing treatment simulator for field usage.
Coal Bed Methane Production
Authors: Simpson David A. , Lea James F. , Cox J. C.
Published: December 2007

Provided that certain conditions are met, Coalbed Methane (CBM) wells have demonstrated the capacity to continue to produce a significant proportion of their peak production rates at very low reservoir pressures. Low reservoir producing pressures require low bottom-hole and surface pressures. Chief among the conditions for high production rates is being able to manage water at low surface pressure. Minimum-net-positive-suction-head considerations limit artificial lift options. The dew point at low pressures allows large volumes of water to move as vapor—rendering mechanical separation equipment ineffective and leaving solids behind at inconvenient places. Temperature changes in buried piping condense water vapor and create both corrosion and pipe-efficiency problems. Low separator pressures preclude easy methods to remove liquid water. This paper addresses the design considerations for these low-pressure operations and related artificial lift systems
Effect of Non-Uniform Skin on Finite Conductivity Horizontal Well
Authors: Toufik Belhouchet , Tiab Djebbar , Jokhio Sarfraz
Published: December 2007

This paper investigates the performance of horizontal wells under the combined influence of wellbore friction, wellbore storage, and formation damage. A new model is proposed wihich couples wellbore, reservoir, and non-uniform skin, and takes into account the change in flow regime from laminar to turbulent along the wellbore.

In the conventional perspectives, wellbore damage may be viewed as an additional pressure drop, is correct only for infinite-conductivity wellbore with uniform damage. It is shown in this paper that the wellbore damage may not be viewed merely as an additive pressure drop due to skin in the presence of friction inside the long horizontal section of the well. Wellbore hydraulics change the flux distribution (inflow profile) along the wellbore and, thus, result in additional pressure drop in the reservoir and across the skin zone. Horizontal wells, for a number of reasons, are unlikely to have smooth distributions of damage along their trajectories. Thus, segmented well testing would be ideal tool to estimate the skin, Si, of each segment especially in the zone where more severe damage is expected, because it delivers a detailed picture of the skin distribution along an extended horizontal well.

Finite conductivity solution approaches to infinite conductivity solution at high conductivity values and high wellbore radius. The appearance of bi-linear, linear, and radial flow regimes depends upon the length of the well; for long wells, linear and bi-linear flow regimes are observed, and they are masked in the case of short wells. The perforation number effect appears only in the damaged case, when the open-hole scenario deviates from the two other cases. Another important factor, that affects the behavior of the pressure, is the dimensions of altered permeability region; the higher the radius of filtrate penetration, the higher the volume of affected region and therefore, the higher the loss in pressure. The effect of k/ks is more severe in small wells. Another correlation which allows determine kx directly from the intersection point with the half slope is presented using a new method of interference test interpretation of different segments with each other in the same well. Isolated segment testing would lead to the estimate the local skin factor, a possible indication of uneven damage distribution and a necessary variable for the optimization of matrix stimulation. Thus designing of a remedial treatment, both the type and the location of permeability damage must be considered.

Several examples are included to illustrate the use of the model developed.
Effective and Ineffective Strategies for Mud Removal and Cement Slurry Design
Authors: Frigaard I. A. , Pelipenko S.
Published: December 2007

Uncontrolled flows of reservoir fluids behind the casing are relatively common. In worst cases these can lead to blow out, leakage at surface, destruction of subsurface ecology and potential freshwater contamination. Often, safe abandonment of such wells is not possible. A significant cause of flows behind the casing is ineffective mud removal during primary cementing.

The ideal situation is that drilling mud is displaced all around the annulus and that the displacement front advances steadily up the well at the pumping velocity. Even better is that the wide and narrow sides of the front advance at the same speed. Conversely, if the fluid on the narrow side of the annulus does not move, or moves very slowly, a longitudinal mud channel can result. Although the possibility of a narrow side mud channel and benefits of a steady state displacement have been recognised since the mid-1960s, there is still little quantitative understanding of when steady state displacements occur.

In this paper we present new results on the displacement of cementing fluids along eccentric annuli. We show that for certain combinations of the physical properties there will be a steady state displacement front. Furthermore, we are able to give an analytical expression for the shape of the front and indications of how the shape changes with the key physical parameters of the cementing process. These results are novel and have interesting implications for effective mud removal and complete zonal isolation during primary cementing.
High Pressure Nitrogen Injection for Miscible/Immiscible Enhanced Oil Recovery
Authors: Necmettin Mungan
Published: December 2007

High pressure nitrogen injection is being considered as an enhanced oil recovery process for a naturally fractured thick carbonate reservoir containing light oil underlain by an infinite aquifer. The objective is to maintain reservoir pressure at such a level as to increase the ultimate oil recovery economically. In this paper, some of the pre-injection evaluation studies are described. (1). Slim tube displacement tests showed that injecting a small bank of produced C2-C6 hydrocarbon solvent ahead of nitrogen lowered the minimum miscibility pressure (MMP) from 5,300 psi to 3,500 psi, a reduction of about 34 percent. (2). Oil recovery experiments in one meter long, 10 millidarcy permeability homogeneous cores gave an increase of 15 percent in oil recovery at 1.2 pore volumes of nitrogen injection at 3,500 psi injection pressure if miscibility is achieved. (3). A small volume, single well nitrogen injection test in the field resulted in increase of the average daily oil rate by 3 m3 under miscible conditions.
Condensate Performance Trends in Trinidad Gas Reservoirs
Authors: Jemmott Susan , Hallam Richard , Maharaj Shivanand
Published: December 2007

The Cassia, Flamboyant, Immortelle, Mahogany, and Amherstia fields currently produce over 1.4 bcf/d for the Trinidad domestic gas market and Atlantic LNG Projects (Trains I and II). By early 2004 the gas rate should increase to about 2 bcf/d when two new projects start-up. These fields, plus the older Teak field are located in the Columbus Basin off the southeast coast of Trinidad.

The six fields have produced gas from 35 reservoirs, which are at depths from 5084 ft tvdss to 13,000 ft tvdss, and with initial pressures from 2305 psi to 7420 psi. The fluid samples and production data show that the gases are condensates. The gas is a mixture of biogenic and thermogenic gas, and the initial condensate yields vary from 1 b/MMscf up to 50 b/MMscf. For most fields, it was found that the condensate yield increased with depth or reservoir pressure.

The reservoirs exhibit a number of production mechanisms, including volumetric, volumetric with compartmentalization, and water-drive (weak to strong aquifers) (with or without compartmentalization). The paper reviews the condensate recovery factors, and produced yield trends for the different reservoirs and the different production mechanisms. It was also observed that for many of the waterdrive reservoirs that the condensate yield increased in late-life when water breakthrough occurred.

An analytical approach was used to predict whether near wellbore condensate banking would occur in the Trinidad reservoirs. The model and field data both showed that near wellbore condensate banking was not a major issue in these reservoirs because of the high permeabilities and low drawdowns. However, banking could occur in some low permeability reservoirs or if a well was produced with a large drawdown.
Synchronized Optimization Effort Significantly Reduces Drilling Time in Mature Valhall Field, Norwegian North Sea
Authors: Smith Richard , Simpson Mike , Wicker Armin K.
Published: December 2007

This paper describes a team approach adopted on Valhall to limit the occurrence of wellbore instability, lost circulation and stuck pipe problems by the development and implementation of field-specific operational practices while drilling in the Overburden. It will highlight the benefits of an 11-3/4" application specific liner that has been upgraded from a contingency liner to a planned intermediate liner in the drilling programme. Details will be presented explaining the importance of planning for success and dedicated offshore engineering support. Knowledge management tools and processes were used to help refine these procedures and practices over a period of 24 months.

During this time one key performance indicator, Dry Hole Days /10000ft has been improved by approximately 40% in wells drilled at an inclination higher than 50 degrees through the overburden. More importantly, the primary goal of setting 9 5/8" casing in the reservoir has been achieved successfully in the last 6 wells when previously failure to accomplish this was common.
Three-Phase Relative Permeability of Petroleum Reservoirs
Authors: Pejic Dragan , Maini Brij B.
Published: December 2007

This paper presents a critical review of recent experimental and theoretical developments in the area of three-phase relative permeability along with a comparative evaluation of several models for estimating the oil relative permeability under three-phase flow conditions.

Reported experimental data on three-phase relative permeability were screened for reliability and completeness and three representative data sets were selected for use in evaluation of the prediction techniques. Eight different prediction models were selected for evaluation. Each model was tested with the three selected data sets for its ability to match the experimentally determined oil relative permeability under three-phase flow conditions.

It was found that none of the models predicted all of the tested data sets with high accuracy. However, there are models that give significantly more reliable predictions of three-phase oil relative permeability compared to the other models.
Fire and Ice: Gas Hydrate Transportation - A Possibility for the Caribbean Region
Authors: Taylor Mark , Dawe Richard A. , Thomas Sydney
Published: December 2007

Natural gas hydrates, NGH, are crystalline solids composed of water and natural gas where individual gas molecules exist within cages of water molecules, CH4.nH2O where n≥5.75. NGH can contain up to 160m3 of methane per 1 m3 of hydrate. Hydrate technology development has focused on using gas hydrates to convert gas to a solid (GtS) to transport natural gas to market as a low cost solution to managing associated gas in regions lacking in gas infrastructure and/or market. There could be possibilities for NGH for transport of natural gas from Trinidad to the Caribbean Islands at volumes much less than those normally considered for LNG, but still commercial to the whole transport chain from producer to consumer.

Compared to alternative technologies such as LNG and gas to liquids, GtS hydrates conversion is relatively simple, low cost and does not require complex processes or extremes of pressure or temperature. It can be small-scale, modular and particularly appropriate for offshore associated gas applications. Put simply, the hydrate production concept amounts to adding water to natural gas and ‘stirring'. However, a comprehensive understanding of hydrate behaviour is necessary to design the technology for transoceanic gas transportation.

This paper describes a hydrate slurry production process and its integration into a system for delivering gas for small scale utilities in regions of the world that lack gas pipeline infrastructure. In particular, we discuss the market potential of gas transport by hydrate, present some laboratory and pilot scale studies of results on the stability of hydrates produced in a continuous stirred tank reactor, and consider the implications of these results on the process design and overall economics and the challenges to be met before the technology can be commercialised.
Automated Methodology for Field Performance Optimization Developed with Horizontal Wells
Authors: Nakajima L. , Schiozer D. J.
Published: December 2007

The main task of reservoir engineering is the development and management of a petroleum field in order to improve the profitability of a reservoir by raising production rates with minimum costs or increasing ultimate reserves. The performances of many horizontal well projects around the world demonstrate their effectiveness in achieving this objective, especially in offshore fields. However, this type of well has more complicated interaction with the reservoir, since its behavior is a function of a high number of parameters. The purpose of this paper is to present an automated methodology to optimize reservoir performance with horizontal wells, by using numerical reservoir simulation to provide the production forecast.

The methodology is developed through the performance analysis for individual wells, group of wells and field. The objective of this analysis is to identify the parameters that define horizontal wells productivity, to realize a comparison between wells performances, and to investigate the causes of inadequate field and wells performance. The analysis is based on selected objective-functions: net present values, cumulative oil, gas and water productions and water injection. The methodology is developed to propose changes to optimize a strategy set previously. A concept of well neighborhood is used to allow simultaneous changes, which yield a lower number of simulation runs.
A Comprehensive Approach to Modeling Sanding During Oil Production
Authors: Nouri Alireza , Vaziri Hans , Belhaj Hadi , Islam Rafiqul
Published: December 2007

Sand production has been a major dilemma facing operating oil companies over many years, sometimes substantially increasing production costs. On the other hand, a very controlled solid production can enhance oil production. A dependable predictive model is vital for planning production strategies in order to optimize well production. To date, despite several research studies, sand production remains the nightmare of petroleum engineers.

Even though many researchers have tried to predict sand production in the past, none of them suggested a comprehensive model that takes care of a variety of mechanisms at different points and different times. Moreover, rare models predict sanding rate and volume along with sanding initiation. This paper presents a comprehensive numerical modeling of sand production that appreciates the different behavior of the medium near and far well-bore from early to late life-time. Sanding criteria were adopted according to the physics of the problem, by taking the sequential nature of sand production into consideration.

The numerical model that was used not only assesses sand production qualitatively but can also give the sanding rate at different times. This was used to model the observations of sand production in a large block test, and the sanding rate and volume generated from numerical modeling agreed with experimental results. With each stage of increased drawdown or depletion, a burst of sand took place which enlarged the cavities initiated from the perforations. The expansion of the cavity was soon stabilized and this behavior was predicted by numerical modeling. Moreover, besides considering shear and tensile failure of the material, the possibility of volumetric failure has been discussed.
Integrated Global Optimization of Displacement Efficiency in Hydrocarbon Reservoirs
Authors: Yang Daoyong , Zhang Qi , Gu Yongan , Li Luhua
Published: December 2007

In this paper, an integrated numerical technique is presented to implement global optimization of displacement efficiency in hydrocarbon reservoirs. This technique chooses the net present value (NPV) as an objective function, which accounts for production- and injection- performance as well as reservoir performance. The flowing and various artificial lifting methods are incorporated into the production performance models, which have been successfully applied in more than forty oil fields. Meanwhile, the reservoir geological model is improved by continuous monitoring and surveillance. Then the objective function is maximized to generate the optimum field production-injection strategies at different development stages using a hybrid genetic algorithm (GA). Such an integrated technique can maximize the displacement efficiency in a fixed well pattern and/or an oil field under different practical constraints. This technique is applied in a water-alternating-gas (WAG) miscible flooding reservoir, and the field performance has shown that the displacement efficiency is significantly improved and the production-injection rates are well controlled. The field water-cut remains low and stable, though the gas-oil ratio is slightly higher than the original ratio. This method can be applied to develop the optimum production- and injection- strategies in a hydrocarbon reservoir so that the displacement efficiency is maximized and the reservoir life is extended.
Optimum Design and Control of the Production-Injection Operation Systems in Petroleum Reservoirs
Authors: Yang Daoyong , Zhang Qi , Gu Yongan
Published: December 2007

This paper presents a systems engineering approach to implementing optimum design and control of the production-injection operation systems. At first, a production performance model including flowing and different artificial lifting methods is modified from a well basis to an oil field basis. Secondly, the modified model, the injection models and surface pipeline network are integrated with a reservoir model in which the reservoir geological model is updated by continuous monitoring and surveillance. Finally, either the oil rate or the net present value (NPV) can be chosen as an objective function and optimized by a non-numerical algorithm so that the global optimum parameters for both producers and injectors are obtained. This systematic approach has been successfully applied in more than forty reservoirs. These field applications show that this technique can determine not only the optimum production operation methods for a newly discovered reservoir but also the optimum production- and injection- strategies for an existing reservoir. The success rate is over 85% for determing proper production operation methods among individual wells in a new reservoir. For a reservoir currently under production, the reservoir pressure can be kept in an appropriate range with slight increase in the water-cut and the gas-oil ratio. Thus such an integrated technique can be applied to increase the oil recovery and to extend the reservoir life.
Review of Case Histories of Two Shallow-Gas Reservoirs in China
Authors: Sheng Ruyan , Li Zhenquan , Liu Hua , Xiang Xiyong
Published: December 2007

Shallow-gas reservoirs (SGRs) in Shengli Oil Fields of China are mostly lenticular lithologic gas reservoirs controlled by structures, which are small-sized scattered gas reservoirs different from mid-deep structural reservoirs. Before 1980s, development of SGR often relied on experience to meet the need of practical gas demand, and matching techniques could not come into being. From middle term of 1980s, as gas being in short supply, a series of studies have been launching and better results have been getting. Gudao and Gudong shallow-gas reservoirs are two biggest SGRs in Shengli Oil Fields, which have similar geological factors but obviously different development results. Based on brief introduction on main geological characteristics, this paper describes chief similarities and differences and indicates some problems that should be paid attention to during gas production. Major methods used in Gudao include utilizing abandoned oil wells and/or water injection wells transferred as gas wells originally, high rate of gas production, later sand control and fine gas reservoir characterization during last production stage. Comparison with Gudao, which has better geological factors, overall development results of Gudong are advanced, such as ultimate recovery factor and utilization efficiency of gas wells etc. The main reasons including six aspects are as following: 1. Pay much attention to basic geological research. 2. Optimized gas reservoir engineering design. 3. Utilization of gas recovery techniques such as initial sand control. 4. Adoption of economic and effective measures such as drainage gas production during mid-later production stages. 5. Following the tracks of development plan and finding production potential continuously. And, 6. Introduction of modernized reservoir management methods. There are particular geological characteristics and development laws for SGR. So long as scientific and reasonable development strategies are taken, development results and economic benefits like mid-deep structural reservoirs could be gained as well.
Advances in Horizontal Oriented Perforating
Authors: Benavides Simon P. , Myers William D. , Van Sickle Edgar W. , Vargervik Kristian
Published: December 2007

Perforating in highly deviated or horizontal wells presents any service company with serious technical challenges. Attempting to maintain wellbore and perforation tunnel stability by perforating in the direction of maximum stress compounds the complexity of the perforating job. Ensuring that orientation remains valid while navigating through severe doglegs requires detailed pre-job design planning supported by applicable research data.

This paper discusses advances in horizontal oriented perforating in long horizontal sections designed to optimize perforation efficiency and production. The techniques and results discussed are applicable to any horizontal or highly deviated well where orientation of charges to maintain wellbore stability and control sand production is critical. New developments to navigate through severe doglegs and maintain orientation are significant contributions to perforation technology. Some of the results and experiences encountered while performing an oriented perforating job in a 2246-m horizontal section in a North Sea well for a major operator also discussed in this paper. A world record was set by perforating a total of 1496 m of the horizontal section in a single trip with orientation successfully verified. Additional discussion is presented on the testing and research that preceded the job.

As demonstrated in positive results from the North Sea well, perforating with oriented charges in horizontal sections will play a key role in the future to assist operators optimize production from new or declining fields.
Producing Trinidad Solids Free: A Retrospective Sand Control Completion Study
Authors: Krieger K. D. , Pucknell J. K.
Published: December 2007

Trinidad&s prolific reservoirs often require sand control completions to mitigate detrimental solids production. Cased-hole gravel packs, open-hole gravel packs, frac packs, and screen-only completions have all been implemented offshore in Trinidad; this paper summarizes lessons learned from these wells. In 2001 a retrospective study on the completion history in five of Trinidad&s Eastern offshore gas fields was initiated to help bridge the gap between previous completion performance and future wells requiring a step change in rate and reliability. The project goals were to compile a comprehensive data set of Trinidad sand control completion information, understand well failure mechanisms and recommend best practices for future well design. Outcomes from the 75 well study include a correlation from failed sand control completions leading to more conservative gravel sizing criteria and improved prediction of formation sanding potential. Where competent sand control completions have been installed, draw down restrictions have been relaxed enabling gas wells to produce at high rates. Several recommendations from the retrospective have been incorporated into the 2002 completion designs and are believed to be contributing factors towards the increasing reliability observed.
Different Techniques to Calculate Horizontal Permeability and Initial Water Saturation: Case Study
Authors: Fernandez Gustavo Jorge , Grinberg Mario , Valenzuela Marta
Published: December 2007

A case study is presented to compare results between a deterministic and probabilistic hybrid flow unit approach (FU) based on core-log analysis and classical models based on log and petrophysical interpretations in Chihuido de la Sierra Negra Field. Neuquén basin, Argentina.

The base of this paper comes from an exhaustive and detailed reservoir characterization model performed by a multidisciplinary team following the FU approach1. The objective of this work is to obtain more realistic values of OOIP and to compare different calculation techniques to achieve reliable absolute horizontal permeability and initial water saturation values.

The permeability obtained from different approaches was tested with several core data points available in the field. The main conclusion is that the permeability derived from FU was more accurate than the generalized relationships. The initial water saturation calculated was validated with field data and preserved cores. Besides, values obtained by FU-capillary pressure also were more precise than those models using straight well log data.

These improvements in reservoir description have provided the opportunity to increase the amount of OOIP and justify reliable recovery factors. The accuracy in the determination of initial water saturation and absolute permeability shown on this work allow us to apply this technique in any numerical simulation model.
A Comparative Analysis of Pressure Transient Behaviour of Undulating and Horizontal Wells
Authors: Göktas Baris , Ertekin Turgay
Published: December 2007

Since the early 90&s, the use of horizontal wells has become increasingly more popular in the development of oil and gas fields. Advances in drilling technology such as Measurement While Drilling (MWD) and Logging While Drilling (LWD) with accumulated knowledge/experience enable cost effective and more sophisticated horizontal wells to be drilled. Nevertheless, drilling a horizontal well that is perfectly parallel to the bedding plane is still distant from reality. All horizontal wells, to a certain extent, follow a sinusoidal trajectory merely because of steering problems, natural undulation of layers as well as presence of non-uniform layer thickness. In horizontal well applications ten to fifteen feet amplitude undulations are often considered as precise placement. Although MWD and LWD procedures minimize the possibility of exiting pay zones, while drilling horizontal wells in relatively thin formations there is always a real possibility to leave the pay zone even for a short period of time.

A number of studies have appeared in the literature for pressure transient analysis of horizontal wells for rapid determination of permeability anisotropy, skin factors and average pressures. However, none of these forward and their accompanying inverse solutions discusses the validity and applicability of the offered protocols if the horizontal well in actuality is undulated. In this study, we analyse pressure transient response of undulating wells using a previously developed numerical model that can accommodate various types of well architectures including undulating wells. Our objective in this paper is to demonstrate when analytical solutions for pressure transient analysis of horizontal wells are still usable and when they become unusable for various undulation configurations studied, and show how numerical well test analysis procedures can be utilized when analytical models are inadequate.

Example scenarios investigated in this paper show that the presence of intensive undulations in well trajectories may significantly shorten and even may overshadow the transient flow period that is already endangered by the presence of wellbore storage affects. Under these conditions the use of a numerical model, with options for undulating well architectures, will be necessary for accurate analysis of pressure transient data.
Snubbing Provides Options for Broader Application of Underbalanced Drilling Lessons
Authors: Schmigel Kevin , MacPherson Larry
Published: December 2007

Abundant experience with underbalanced drilling technology shows that many reservoirs do not perform at maximum potential when exposed to overbalanced drilling fluids. Broadening this lesson to benefit a greater number of wells requires the adaptation of current snubbing technology to meet a growing range of applications.

This paper examines the hydraulic rig assist (HRA) snubbing technology commonly used in horizontal drilling and considers the methods and equipment required for other applications. Using field examples from drilling and well service operations, the paper identifies key procedures and components needed to control well pressure at the surface and still allow the movement of tools and equipment.
The Quantification of Hydrocarbon Reserves in Thinly Laminated Shaly-Sandstone Formations
Authors: Pritchard Tim , Colley Nick , Bedford Jonathan
Published: December 2007

Many deltaic and turbidite reservoirs contain significant hydrocarbon reserves within thinly laminated sand-shale intervals, often poorly characterized using conventional wireline technologies. This paper reviews the problems and existing methods of quantifying hydrocarbon reserves in these formations, and proposes a flexible integrated interpretation strategy used to both quantify hydrocarbon reserves and associated errors.
Improved Solids Control Technique for Onshore Drilling Operators in Trinidad
Authors: Sinanan Burt
Published: December 2007

For the first time in Trinidad's onshore drilling history, a "closed loop" chemically enhanced centrifugation has been added to a drilling rig's solid's control system. This technology termed "Dewatering" was implemented to achieve environmental, waste minimization and drilling operations benefits on the Carapal # 1 and Corosan #1 wells in the Catshill field, Central Block, Trinidad.

Data from Corosan #1 is presented and analyzed in this paper. Savings on waste minimization amounted to 3.2% of the well cost and savings on non-productive time / drilling operations amounted to 1.4% of the well cost. A total of 4.6 % of the actual well cost has been saved though dewatering of drilling mud and drilling waste.

This innovative means of solids controls and its results has sparked interest among many onshore Trinidad operators whose drilling programs target deeper than usual prospects. This project clarifies the methodology implemented and benefits attained in a locally novel approach to managing drilling mud and waste.
Towards Sustainabilty: The Trinidad and Tobago Scenario, focusing on Strategic Environmental Planning and Energy Policy
Authors: Rajnauth Jerome J.
Published: December 2007

Sustainable Development is often viewed as economic entity and emphasis has been placed on fostering production growth, investment and market depth and breadth. The environmental, political and social dimensions have frequently been neglected. Therefore sustainable development should be viewed as a concept that frames the relationship between economics, environment, social and political dimensions in a radical new way. It demands both new ways of thinking and new designs for organizing at the international, national, organizational and individual level.

Trinidad and Tobago as a developing nation has been encouraging sustainability but key strategic environmental planning and energy policy issues are often neglected. These strategic environmental planning and energy policy issues are important to encourage not only the economics but also environmental, social and political dimensions of sustainable development.

This paper seeks to address some of the strategic environmental planning and energy policy issues that are pertinent in accomplishing sustainability. Strategic Environmental Planning issues of risk management, collaboration, business strategy and competitive advantage would be addressed as well as energy policy issues such as integration, renewable resources, efficiency in energy consumption and energy security.
Resolving Uncertainties in Historical Data and the Redevelopment of Mature Fields
Authors: Agbon I. S. , Aldana G. J. , Araque J. C. , Mendoza A. A. , Ramirez M. E.
Published: December 2007

In Venezuela, a new national hydrocarbon policy has revitalized interest in increasing gas production. Activities have included the recovery of gas from matured fields, especially those with a history of pressure maintenance by gas injection. In some cases, there exist high uncertainties in the accuracy of the historical data (fluid production and injection, initial fluid properties and composition, etc.), leading to difficulties in estimating remaining gas reserves and the formulation of reliable field re-development plans.

This paper examines the problem of historical data uncertainties in the rejuvenation of mature fields. A volumetric balance analytical method is developed for estimating remaining field gas reserves in the face of data uncertainties. A matured field from San Tome, Venezuela is used as a case study. The paper concludes that the volumetric balance analytical method can be used to narrow the range of uncertainties in gas reserves estimation in addition to Monte Carlo simulation.
Scratching Additional Oil in South Sumatra Matured Oil Fields, Indonesia
Authors: Aprilian Salis , Kurnely Kun , Novian Kiagus
Published: December 2007

This paper disscusses a comprehensive study on scratching additional oil in the matured fields of Pertamina South Sumatra, Indonesia, by employing an integrated multidisciple synergy team and project management approaches. The teams consist of geophysicists, geologists, reservoir engineers, operation/production and facility engineers, and ones from supporting department such as finance, logistics, HSE, HRD, IT, etc. The project called Production Enhancement Projects (PEP) was established in 2001 and divided into phases.

The first phase of PEP that was assessing detailed subsurface and surface facilities data has been done successfully resulting in 45.6 MMBO of additional oil reserves within 12 selected existing matured fields. Besides, the upside potentials are identified as a surprising result of the study1). An extra investment was spent in developing appropriate plan and rejuvenating production infrastructures. However, a significant gain production was obtained through several successful twin drilling wells, outsteping, deepening, and workovers.

Plan of further development for each field has been proposed including the evaluation of economics and environment aspects by considering in-depth GGRP (geophysic-geology-reservor-production) study and intensive discussion among team leaders, team members, and management. After prioritizing the proposed work plan, several implementations of well work (such as: reopening; re-perforating; reparation; sidetracking, twin drilling; etc.) showed some successful results. In year 2002 two wells were drilled and resulted additional oil reserves up to 100 MMBO that proved the upside potentials of oil located in deep zones of the existing fields.