bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation Damage History in the Mature Fields of Campos Basin Offshore Brazil
Authors: Rodrigues V. F. , Neumann L. F. , Miura K. , Tinoco F. L. , Netto J. B. M. L. , Daher J. S.
Published: December 2007

The Campos Basin mature fields, offshore Brazil, including the Marlim Field, are usually referred to as the World's deepwater field laboratory. The development of these fields was driven by the Brazilian state energy needs throughout the seventies and eighties, which induced a strategy of accelerating the projects implementation and anticipating their first oil. This sense of urgency is still dominant in Brazilian oil politics and has recently enabled the country to reach its oil self-sufficiency. That scenario throughout the last two decades encouraged risk assumption as well as the implementation of a considerable number of new technologies. Fifteen years after the first oil production from Marlim it seems that more engineered solutions are replacing the daring initiatives and the concise studies carried out in the beginning. Those years also testified an outstanding evolution of the drilling and completion technologies. The development advance to deeper and deeper waters brought up unpredicted problems such as wax deposition and hydrate formation. Thus, the history of the mature deepwater fields of Campos Basin offers great opportunities for learning, in a wide perspective. This paper summarizes the history of the damage and main completion troubles associated to Campos Basin deepwater mature fields. The aspects of prediction, prevention and remediation of the formation damage associated to drilling, sand control, stimulation, fines migration, organic deposition, scale, souring and other minor issues are addressed. The paper also presents some statistical data, predicted and unpredicted problems, and the ways they have and are currently handled. The technologies evolution and the most recent challenges are also shown. It is our belief that other deepwater mature fields to be developed and the new systems to be designed will certainly benefit from the experiences and lessons learned in the deepwater mature fields of Campos Basin.
Using Water Maps for E&P Environmental Protection and Remediation
Authors: Kofoed Val O. , Rollins Paul
Published: December 2007

This paper introduces a water-mapping technique that is particularly well suited to certain environmental protection and remediation tasks associated with petroleum production. In this procedure, electrodes are used to charge water systems with a low voltage electrical current. As the current flows through the water between the electrodes, it emits a magnetic field whose shape, depth and direction are characteristic of the surrounding aqueous network (Biot-Savart Law). This field is then read at the surface by a specially tuned receiver. The data thus generated can be used to create maps indicating the attributes of various subsurface water systems, including flooded oil fields.

The proven benefits of this mapping procedure are especially apparent in relation to water flooding and steam stimulation. As oil recovery techniques, these practices have significant benefits for the environment. By making existing oil fields more productive, they reduce the need for the development of new fields, thus avoiding the attendant ecological disruptions. In both maximizing their efficiency and minimizing their environmental impact, water-flooding practices are aided by water-mapping technologies.

When water and steam are forced through the chambers of an oil field, they sometimes emerge in unexpected places— carrying heavy crude. Such unanticipated surface expressions pose serious risks of environmental damage and lost production. By charting the potential flow paths of these floods, and identifying possible surface expressions, water maps help reduce the ecological impact and improve the productivity of flooding practices.

Furthermore, when groundwater has been contaminated, water maps play a critical role in remediation efforts. The greatest challenge in addressing groundwater contamination is gaining an accurate understanding of the complex web of channels and reservoirs which lie hidden below the surface. Remediation teams cannot deal with polluted water flows until they know where they are flowing. Here too, advanced groundwater maps offer critical information to those charged with protecting the environment. After detailing the theoretical science behind this technique, the paper will analyze the environmental implications of a recent deployment in the E&P industry.
A Mimetic Finite-Volume-Discretization Operator for Reservoir Simulation
Authors: Alpak Faruk O.
Published: December 2007

Accurate representation of complex reservoir geology using non-orthogonal meshes, upscaling of high-resolution geostatistical reservoir models including cross-flow effects, and strongly heterogeneous anisotropic permeable media such as cross-bedded sands and thin-bedded turbidite channels all individually or in combination give rise to simulation models with full-tensor permeability fields. Such anisotropic multiphase flow problems can be solved accurately on arbitrary non-orthogonal structured and unstructured meshes using the mimetic finite volume method. The discretization operator of the mimetic finite volume method satisfies conservation laws, and theorems of vector and tensor calculus on non-orthogonal, non-smooth, structured and unstructured computational meshes.

In this paper, we demonstrate the formulation of a three-dimensional variant of the mimetic finite volume method for corner-point geometry hexahedral meshes. We also discuss the results and issues associated with the implementation of the mimetic finite volume discretization operator in a parallel, fully-implicit research reservoir simulator developed using a general compositional formulation. Simulation results are presented for a variety of cases involving flow through geologically complex systems.
Foam-Assisted Lift—Importance of Selection and Application
Authors: Price B. P. , Gothard B.
Published: December 2007

The use of foamers to remove water from wells that are challenged by hydrostatic head pressure is common practice. The success of the process, however, is predicated on the proper selection of candidate wells, the proper selection of foaming agent, and application.

Foam assisted lift does not work on all wells. At a time when resources are in short supply, dividends are returned by applying resources to candidate wells that have been thoroughly screened to improve the success rate related to foam assisted lift technology. Properly formulated foaming agents will offer better value and return on investment than marginally performing products. Comprehensive evaluation of the application is critical to achieving the desired results of a foam assisted lift program.

Experience has demonstrated the importance of selection and application to the success of foaming agents. Foam assisted lift for economical production of adolescent and mature wells adds tremendous value and is a viable alternative for challenges related to liquid loading. Continuous improvement based on well changes must be considered as a significant part of the process.

Adopting a comprehensive process related to a deliquification strategy will allow for extended success of foam assisted lift programs, improved production rates and revenue, and improved resource utilization related to a better return on capital and resources expended.
Advances in Inhibitive Water-Based Drilling Fluids–Can they Replace Oil-Based Muds?
Authors: Patel Arvind , Stamatakis Emanuel , Young Steve , Friedheim Jim
Published: December 2007

This paper discusses the systematic design and development of high performance water-based muds and provides insight into the unique chemistry and inhibition characteristics of various amine inhibitors. Equally important, performance correlations of inhibitive systems in laboratory testing as compared to state-of–the-art inhibitive systems are included.

Invert emulsion drilling fluids have long been effective in drilling reactive shale. Developing high performance (highly inhibitive) water-based drilling fluid that would perform like invert emulsion drilling fluid has long been cited as the ultimate technical goal of the drilling industry. Progressive development of inhibitive water-based drilling fluids based on amine chemistry has made some impact on reaching this goal. Amine-based inhibitive drilling fluids have steadily gained popularity with service and oil companies.

However, these fluids have not always been completely successful in inhibiting the hydration of highly water-sensitive clays. The short-comings are particularly evident when drilling highly complicated and reactive shale formations. Keeping this in mind, an innovative highly inhibitive water-based drilling fluid has been systematically designed with the performance characteristics of oil-based muds.

The newly developed high performance water-based mud (HPWBM) comprises a unique polymeric amine shale intercalator for shale inhibition, an amphoteric polymeric shale encapsulator, a high performance lubricant/anti-accretion agent and a specialized fluid-loss additive. The newly developed HPWBM performed like an oil-based mud in laboratory testing as well as in offset wells using invert emulsion drilling fluids (OBM) due to highly complicated and reactive shale formations.
Parallel Automatically Differentiable Data-Types for Next-Generation Simulator Development
Authors: Younis Rami , Aziz Khalid
Published: December 2007

We develop and analyze an algorithmic framework and library of parallel automatically differentiable data-types written in the C++ programming language. In addition to representing variables and discretized expressions on a simulation grid, the data-types hide algorithms employed behind the scenes capable of automatically computing the sparse analytical Jacobian. Using the library, reservoir simulators can be developed rapidly by simply writing the residual equations, and without any hand differentiation, loops, or any other low-level constructs. The key challenge addressed is a technical development to enable this to run fast. Faster than if any of several existing automatic differentiation packages were used, faster than any purely Object Oriented implementation, and at least as fast as if a development team implemented hand-optimized residuals, analytical derivatives, and Jacobian assembly routines.

This is achieved by extending a generic programming technique specific to the C++ programming language known as Expression Templates. The extension enables its application to handle nested abstract types including sparse vector composites. Consequently, the library implementation can handle the complexity of any reservoir simulation model with optimal use of microprocessor hardware.

We demonstrate the ease of use of the library by presenting an efficient and rapidly developed fully-implicit simulator. Performance analysis is performed with varying grid size and is bench-marked with structured implementations. The tests are run with widely used compilers on standard microprocessors.

Introduction

Next generation simulators aim to simultaneously (1) leverage current technology to solve today's problems most efficiently, and (2) be easily extendable to leverage tomorrow's technology to solve tomorrow's problems most efficiently. Towards this, the General Purpose paradigm makes conceptual abstraction of equations and unknowns to achieve extendability to a wide range of formulations and recovery processes 1,2,3,4. Another kind of conceptual abstraction is on numerical formulations and solution processes, and aims to address extendability to evolving computer technologies and solution algorithms.

Motivation. Next generation simulator designs translate both conceptual abstractions into appropriate software-engineering abstractions. In this fashion, typical designs are made up of modules in a multi-layered framework 5,6,7,8. Each layer consists of modules with well defined interfaces that implement a certain level of functionality. Higher-layer modules implement increasingly complex functionality by using lower-layer modules. Apparent advantages of taller hierarchies are greater flexibility, extendability, and reliability.
Modeling, Upscaling, and History Matching Thin, Irregularly-Shaped Flow Barriers: A Comprehensive Approach for Predicting Reservoir Connectivity
Authors: Stright L.
Published: December 2007

Accurate modeling of flow path connectivity is critical to reservoir flow performance prediction. Flow path connectivity is controlled by the complex shape, extent and spatial relationships between pay intervals, their intersection with wells, and the existence of flow barriers between wells. This reservoir heterogeneity can be captured in a flow simulation model as facies patterns among cells and as effective properties within cells (porosity and permeability). However, fine-scale, irregularly-shaped flow barriers between cells cannot be accurately represented with pixel-based modeling techniques.

To preserve these important fine-scale geological features at the flow simulation block scale, an additional modeling variable is introduced as the edge of a model cell. This cell edge is a continuous or categorical value associated with the cell face and is defined in conjunction with the cell centered property which is often reserved for facies types and/or petrophysical properties. An edge model is created that captures the facies and edge properties as a vector of information at each cell location. For the flow simulation model, the edge properties are easily translated into transmissibility multipliers.

Using the example of 3D shale-drapes attached to channel-sand bodies in a deep water depositional setting, a methodology is presented in which these shale drapes are accurately upscaled and history matched to production data while maintaining the geological concept that describes the drape geometry. The perturbation parameter in history matching is the continuity of the shales as an edge property.

More generally, this coupled modeling of cell-center and cell-edge allows for more flexible reservoir modeling, opening up the potential for modeling and history matching complex geological features effectively at the scale that they are relevant, without additional computational cost of flow simulation.
Use of Diatomaceous Materials for Heavy-Metal Recovery From Oil and Gas Produced Water
Authors: Obanijesu E. O. , Dada E. O. , Bello O. O.
Published: December 2007

Production potentials of massive offshore oil and gas reserves represent a promising source of energy security for the world. However, recent developments in environmental pollution control are drawing attention to the problem of persistent hazardous metal content of produced (formation and injected) water from oil and gas reservoir that are discharged everyday from offshore facilities. The removal of heavy metal has become a very important industrial problem. Present methods for metal recovery from produced water are becoming increasingly undesirable for a number of reasons. The continued success of metal recovery from produced water hinges on the development of new technology.

In this study, a pilot-scale packed-bed reactor has been developed in order to investigate influences of process parameters and their interactions on the recovery of metals from produced water using diatomaceous material. The material was formed into a packed configuration to provide a high adsorbent area-to-aqueous solution volume ratio. Activated carbon and ion-exchange resin were tested for comparison. The results obtained show that flow-rate, residence time, metal concentration loading and packed-bed geometry significantly influenced the efficiency of the reactor system metal recovery and have to be considered in the design of large-scale system. An optimum residence time of 2 hours has been found to give the metal recovery capacities of 60%, 76% and 80% for the ion-exchange resin, diatomaceous material and activated carbon respectively. The sequestered metals were efficiently eluted from the diatomaceous material using different elution solutions for different metals. Selectivity of adsorbent for specific metals can be manipulated on the uptake and elution sides of the process. Present study also revealed that diatomaceous material can be regenerated and used many times over just as conventional adsorbents or ion-exchange resins in process wastewater purification as well as metal recovery processes.

The application of the packed-bed reactor using the readily available diatomaceous material is therefore recommended for economical and cost effective large-scale purification and recovery of metals from oil and gas produced water loaded with metals.
Successful Experiences for Water and Gas Shutoff Treatments in North Monagas, Venezuela
Authors: Perdomo Lenin , Rodríguez Héctor , Llamedo Maria , Oliveros Luis , González Edwin , Molina Osmel , Giovingo Claudio
Published: December 2007

Normally, the average on success rate of water shut-off treatments in the world ranges between 40% – 50%. This average is lower for gas shut-off treatments. In North Monagas, Venezuela, where some hard conditions are present, such as high bottom hole temperatures (over 280 F), in some cases very tight reservoirs which complicates a matrix penetration of any gel treatment without overcoming the fracture gradient, in other cases naturally fractured wells which complicates the effectively fillout of all fracture nets; this success rate could decrease even more, making the treatment not economically attractive.

In order to obtain a high success rate in North Monagas, it was designed a special aqueous polymer gel with a low viscosity to handle the difficulty of matrix penetration without overcome the fracture gradient, and delay its crosslinking process for a period of long time due to very low injected rates. Also, it can maintain its blocking properties at temperatures over 290 F without the need to inject cool-down pads; it can perform effectively even gas shut-off treatments, taking into account its difficulty due to higher mobility than water and oil.

Carefully studied Coiled Tubing (CT) operations were carried out taking into account the hard conditions already described, without damage other oil producing zones. Several case histories are showed in this paper, including some gas shut-off operations, with the results obtained in each one. As a result, higher water/gas shut-off success rate than the typical average (40% – 50%) was achieved.
Eliminating Hammer Injuries in the Oil Field
Authors: Bull Brad , Neal Greg
Published: December 2007

A majority of onsite injuries in the energy services industry result from the use of hammers to make and break wing union connections. These injuries almost universally occur during rig-up and rig-down of high-pressure manifold equipment. The injuries can be immediate or long-term issues that usually arise from the strain experienced when swinging a hammer. This paper discusses the development and testing of a safer alternative to the current method of tightening connections called the pneumatic union driver (PUD),1 which uses compressed air as the power source to tighten connections.

The current hammer union has been a staple of the industry since it was patented in 1942.2 This connection has historically been made by repeatedly striking the lug face with a sledge hammer. Most personnel use a sledge hammer in the range of 4 to 10 lb, and each connection is typically struck from 4 to 8 times. Because locations may have 20 to 80+ connections, a typical job can present personnel with as many as 600 opportunities for injury. Hammering jobs are also typically assigned to the least experienced personnel and often performed in adverse environmental conditions (i.e. dark, cold, wet, hot, etc.).

The PUD is a modified pneumatic chipping hammer designed to apply controlled impact energy to the current hammer union. The PUD is placed on a hammer union using an adapter that fits over one lug and aligns the tool bit with the next lug. When the trigger is depressed, the chipping hammer repeatedly strikes the lug. This impact energy reduces friction in the connection. While the lug is being impacted, a moderate amount of force (20–30 lb) is applied to the handle of the tool to tighten the connection. This paper details the testing and performance requirements for the PUD. Comparison testing with conventional hammers indicated that the time required to tighten connections for both methods was approximately the same.
Drilling Simulation vs. Actual Performance in Western Canada
Authors: Hareland G. , Nygaard R. , Virginillo B. , Munro H.
Published: December 2007

During the past two years a drilling performance simulator has been applied in a pre-drill mode to more then 50 wells with an average depth of 3000 meters in Western Canada. The main goal of applying the simulator was to optimize the drilling performance by increasing rate of penetration (ROP) and decreasing drilling time and costs. To maximize performance the correct bits, hydraulics, operating parameters and pull depths were selected in advance. The drilling simulator uses offset well drilling data and records to generate the apparent rock strength which is then correlated to the formations depths for the new well to be drilled. Multiple combinations of drill bits and operating parameters are simulated to obtain the optimum drilling solution for the next well. The results indicate very good match between predicted and actual field results for ROPs as well as total drilling times and well costs. The simulation approach initially easily matched pacesetter performance of previously drilled wells in the mature field and then by further applying the simulator new pacesetters where set improving performance overall with more then 15 percent. The presimulated optimized results were sent to the field and during the drilling of the well the field data was overlaid with the presimulated field data to compare progress. During the drilling follow-up the bit wear and apparent rock strength calculated from the field data were compared to the presimulated to evaluate the current status of the bit and drilling progress. The follow-up process gave room to take immediate actions and a baseline for communication with the field and office during daily meetings.

This paper presents the commercially available simulator and multiple cases which compares the pre-simulated to the actual performance. The results clearly indicate the large potential for the use of such a simulator in drilling operations.
Application of Rock Strength in Drilling Evalution
Authors: Nygaard R. , Hareland G.
Published: December 2007

Different sources can be used to develop rock strength information along the wellbore. Such strength information is important when assessing the stability of the wellbore, selecting mud weights and designing casing programs. However, there are other areas, especially in drilling, where rock strength information is applicable, but still underutilized.

A methodology is developed to estimate drilling time and bit wear before drilling if rock strength is known. To estimate drilling time and bit wear, effects of other parameters like drilling parameters, well bore size and drilling bit design has to be normalized. This methodology has been used to estimate drilling time and estimate bit wear and further evaluate drilling performance while drilling.

After drilling the additional information has been used to conduct a post analysis and transfer knowledge from well to well. The advantage of this methodology is it eliminates the effect of geological variability when comparing performance between wells and fields.
New Era of Formation Evaluation While Drilling of Complex Reservoirs in Saudi Arabia
Authors: Al-Fawwaz Abdullah , Al-Mashrafi Nedhal , Butt Parvez , Fareed Abdul
Published: December 2007

Within the Saudi Aramco organization, complex reservoir formation evaluation is regarded as a key discipline – fulfilling a critical role in maximizing production and facilitating accurate estimation of reserves. The timely acquisition of high quality and detailed petrophysical properties of the various reservoirs in Saudi Arabia is central to this role. Towards this end, Saudi Aramco Reservoir Description Division (RDD) introduced a new-generation multi-functional Logging While Drilling (LWD) technology into Saudi Arabia, for evaluation of on-shore complex carbonate as well as offshore clastic reservoirs.

The traditional LWD measurements of propagation resistivity, gamma ray, density and neutron porosity along with advanced gamma ray capture spectroscopy measurements were compacted into a single collar. The electronic pulsed neutron source required for the spectroscopy measurements also provides a much improved neutron porosity measurement.

This technology has been used in a number of Saudi Aramco horizontal wells in carbonate and clastic reservoirs. The data from these wells has been comprehensively evaluated. The results of the evaluation of the data acquired by the new tool and conclusions about the tool's introduction into Saudi Arabia are summarized in this paper.
EOS-Related Mathematical Model To Predict Sulfur Deposition and Cost-Effective Approach of Removing Sulfides From Sour Natural Gas
Authors: Guo Xiao , Du Zhimin , Mei Haiyan , Fu Dekui , Wang Xun , Yang Xuefeng
Published: December 2007

Sulfur deposition in the formation, the vicinity of the wellbore and the production line, may significantly reduce the inflow performance of sour gas wells and increase operation cost. The work of sulfur deposition prediction and removal are increasingly performing in sour natural gas reservoirs of South China. In this paper, a gas-liquid-solid mathematical model to predict sulfur deposition, has been developed based on the characteristics of composition and phase behavior of gasliquid system. i.e., the phase behavior of gas-liquid system is calculated in light of EOS, and the elemental sulfur is considered as a non-ideal solid described by virtue of regular solution theory. The EOS-related mathematical model proved to successfully match and predict sulfur deposition via some test examples. In addition, two formulated desulphuring agents of sulphone-amine solution and MDEA reinforcing solution are presented based on the solubility of H2S, CO2 and their mixture in water. The influences of operation conditions and other factors on desulphuring agents were investigated through both indoor and industrial experiments, and the results indicated that these two formulated desulphuring agents could effectively increase the rate of removing sulfur and also overcome the problems encountered during microbial oxidation of removing sulfides. The preliminary work can help engineer evaluate accurately sulfur deposition and remove effectively sulfides so that the impact of sulfur deposition on gas production is minimized during the development of sour natural gas reservoirs.
Myths and Realities in Upscaling Reservoir Data and Models
Authors: Ringrose Philip S.
Published: December 2007

Reservoir modelling practice has developed into a complex set of numerical algorithms and recipes for modelling subsurface geology and fluid flow. Within these workflows a number of myths have sometimes been propagated, especially in relation to (a) methods for handling net-to-gross, (b) implementation of upscaling methods and (c) conditioning of reservoir models to well data. This paper discusses different practices in the use and upscaling of reservoir data and models, by comparing two end-member approaches: (i) the net-to-gross method and (ii) total property modelling. Implications for upscaling and conditioning reservoir models to well data are discussed, and recommended practices are suggested. A set of analytical solutions is proposed to test and quantify typical errors and misunderstandings which can be embedded in reservoir modelling workflows.
Identification of Production Potential in Unconventional Reservoirs
Authors: Grieser Bill , Bray Jim
Published: December 2007

Unconventional natural gas systems include fractured shale gas (FSG), tight gas sands (TGS), basin center gas (BCG), shallow basin methane (SBM), and coalbed methane (CBM). Recently, more operators are focusing attention on shale reservoirs. The most notable shale play being developed in the north Texas region is the Barnett shale. This success has encouraged operators to investigate producing potential of the Woodford and Caney shales in Oklahoma.

Shale plays are unique in that they often are both the source rock and producing rock contained in the same package. This duality leads to difficulty in log and reservoir interpretation. To date, conventional log interpretation has proved inadequate in identifying producing potential. Simply perforating areas of high porosity and pumping massive hydraulic fracture (MHF) treatments do not always yield commercial production results. Identifying areas of high producing potential using gamma ray, density, resistivity, and sonic transit time to locate high total organic carbon (TOC) has also yielded mixed production results.

We believe the addition of mechanical properties of the rock can help identify shale intervals with a high propensity to contain natural fractures and a high probability to create a fracture network during hydraulic fracturing. We propose a linkage between the mechanical properties of the rock and the hydraulic fracture network created during a MHF treatment and the resulting production outcome. Desirable combinations of mechanical properties are selected to help locate areas in the shale that have a propensity to fracture as a network with sufficient aerial extent to impact production results. We use these mechanical properties in addition to TOC and porosity to select fracture initiation sites and give a qualitative assessment of producing capacity. In this paper, we describe calculated log parameters that illustrate this technique.
Better Porosity Estimate of Gas Sandstone Reservoirs Using Density and NMR Logging Data
Authors: Hamada G. M. , Abushanab M. A.
Published: December 2007

Neutron/density measurements have been used to derive formation porosity. While this yields acceptable results in clean liquid-filled lithologies (sands), the effects of lithology, hydrocarbon fill (gas), and formation heterogeneity in shaly sands increases the uncertainty in computed porosities. The technique of using combined NMR relaxation times and bulk density data described in this paper significantly reduces uncertainty in derived logging parameters through elimination of the neutron log. This removes the need to correct for flushed zone

This paper describes the application of DMR technique in cored wells in a gas field, Western Desert, Egypt and it discusses the results obtained, limitations and benefits, along with the data acquisition requirements. Field examples demonstrate the importance of the (DMR) technique in place of the use of NMR or conventional logs separately in determining formation porosity and gas saturation in tight gas sand reservoirs.
Producing the Well by a Compensated Pump
Authors: Buchman Smil S.
Published: December 2007

The production cumulative index (bbl/psi) or CPI, is the relation of the cumulative production versus the decline in the reservoir static pressure. This recorded index shows that the reservoir produces more bbl/psi static pressure as the reservoir static pressure decreases. The increase in the CPI can also be seen in a DST during the build up period. The increase in the CPI is explained by a better use of the reservoir energy when the production is lifted for shorter distances above the perforation. To increase the CPI it is necessary to produce the well by a compensated pump. This is a pump which is not driven by the intake fluid. Producing the well by a compensated pump increases the well efficiency in rate and cumulative production by about 200–250%.

1. Introduction

The static pressure and the cumulative production are the two most important reservoir parameters. The static pressure represents the reservoir physical status, and the economical status is represented by the cumulative oil and water recovered during the production activity. Accordingly, maximizing the ratio between the recovered production versus the well static pressure decline, is the main goal of the production activity. This ratio is called the cumulative production index (CPI) and it is defined in bbl/psi. The well production recorded data shows that the CPI is variable and increases continuously as the reservoir static pressure decreases. Producing the well with the maximum CPI is the target of good production practice.

2. Recorded Well Production Activity

a. The well cumulative production The oil reservoir is a huge sealed volume of permeable and porous rock. The reservoir is always sealed because after recovering the liquids from the underground the reservoir static pressure declines and actual never rebounds. The reservoir pores store the liquids and the permeability allows it to flow from the reservoir into the well bore. The only source of energy used to move the production through the pay zone and up into the well is the expansion of the reservoir fluids. Table 1, shows the Wilcox reservoir1 static pressure decline versus the cumulative production recovered:

Table 1. Wilcox Reservoir, Cumulative Production Index

The data shows a CPI increase from 1,850 to 17,020 bbl/psi or an efficiency increase of 920% versus a static pressure decrease from 3793 to 3277 or 86%. As the reservoir static pressure declined the well produced appreciable more oil per psi reservoir static pressure decline.

Yates Field2 production history is another example of the increase in the CPI as the reservoir static pressure declined.
Meeting the Environmental Challenges in Cementing
Authors: Håheim Ståle , Scoggins W. Chrys , Lebo Stuart , Ø. Pedersen Rikke
Published: December 2007

With the oil industry moving into increasingly sensitive areas, the call for environmentally friendly cement chemicals is more important than ever. The focus on minimizing harmful chemical usage, and finding suitable replacement additives for cement systems, without compromising the properties of the slurry has been a priority for a long time.

Within the North-East Atlantic area, where environmental legislation is defined by the OSPAR commission1, there is a definitive list of products that are considered to be non-harmful to the environment, known as PLONOR (Pose Little Or NO Risk).2

This paper describes the development of some PLONOR cementing additives, the first use of an all-PLONOR cement slurry in the Norwegian sector of the North Sea, and the proposed use of a low fluid-loss, gas controlling cement slurry containing only PLONOR additives.

The challenge was to find a defoamer, dispersant and fluid loss additive from the chemicals on the PLONOR list. Although it is the additive with the lowest loading in the cement system, the defoamer was the biggest challenge. Since defoamer is required in all cement slurries, finding a PLONOR alternative was the most critical. The new dispersant and the fluid-loss additives are based on existing technology, but the challenge was to make the allowable PLONOR chemistry fit the functional requirements for use in a cement system.

One milestone of the project was achieved in January 2006, when the first ever cement job using only PLONOR additives was pumped in the North Sea. This was a slurry for a 13 3/8" casing that was used as a field test for the new PLONOR defoamer.

An operator has recently committed to pump the first PLONOR low fluid-loss, gas-tight cement slurry. This means that the next milestone is within reach in the near future.
Permeability Upscaling Techniques for Reservoir Simulation
Authors: Salazar M. O. , Villa J. R.
Published: December 2007

Upscaling reservoir properties for reservoir simulation is one of the most important steps in the workflow for building reservoir models. Upscaling allows taking high-resolution geostatistical models (107-108 grid blocks) to coarse scale models (104-105 grid blocks), manageable for reservoir simulation, while retaining the geological realism and thus effectively representing fluid transport in the reservoir 1,2. This work presents a study of the effectiveness of different available techniques for permeability upscaling and the implementation of a new technique for upscaling of relative permeability curves based on the numerical solution of a two-phase system and the Kyte and Berry method3.

The reference fine scale model considered in this study is a conceptual fluvial reservoir based on the Stanford V model4. The reference fine scale isotropic and locally heterogeneous permeability distribution was upscaled to different upscaling ratios by means of analytical (static) and numerical single-phase (pressure solver, dynamic) techniques. Two-phase flow simulations were performed on the reference fine grid and upscaled models using a comercial black-oil simulator. Arithmetic, harmonic, and geometric averages were defined for static upscaling of the permeability distribution. The dynamic upscaling process considered one-phase and two-phase upscaling. One-phase upscaling considered upscaling of the permeability distribution and two-phase upscaling considered upscaling of the permeability distribution and relative permeability curves.

Flow simulation results for waterflooding in the coarse scale model indicated relevant discrepancies with the fine grid results. Compared to fine-scale, flow results of the single-phase upscaling process indicated that the coarsest upscaled models did not match the water breakthrough times, water cut values, or well pressures from the reference model. The finer upscaled models reproduced the reference results more accurately than the coarser models. The two-phase dynamic upscaling technique implemented in this work resulted in the best match with the flow simulation results of the fine grid model. Results show that the most accurate upscaling scheme should be defined using the two-phase dynamic upscaling technique on the model with the smallest upscaling ratio.
Novel Chemistry Eliminates Post-Cleanup of OBM Filter Cakes from Openhole Laterals
Authors: Jones A. G. , Luyster M. A. , Ali S. A. , Needham W. J.
Published: December 2007

A key objective for any completion process is to avert troubletime and minimize unplanned events. The novel cleanup systems discussed in this paper were designed to work within the planned completion program, which means they do not need special tanks, lines, or equipment. One of the cleanup systems acts as its own spacer and can also be used to displace oil-based mud (OBM) from the wellbore. The system provides a delay so that operations can proceed and subsequently clean up the residual filter cake. The other system is a brine-based system that also provides a delay. Both have been successfully applied to production and injection wells. Developers of the systems gave consideration during the R&D process to optimizing openhole displacements. This paper discusses the engineering and chemistry of both systems with respect to providing a "delay" so the completion can proceed as planned.

System development in both cases included testing and simulations performed to meet pre-planning criteria that included the need to effectively displace the lateral section while maintaining positive well pressure during the completion phase. Other critical criteria were effective cleanup of the residual OBM filter cake and the ability to mitigate system upsets upon initial production.

Field results presented in this paper are from several recent openhole completions offshore Cabinda, West Africa, where the new cleanup systems were applied to alleviate post cleanup of OBM filter cakes. The paper also explains the engineering of the displacements, impact on the completion operations phase, and the production results.
Multizone Completion With Accurately Placed Stimulation Through Casing Wall
Authors: Hinkie Ron , Howell Matt
Published: December 2007

With a combination of (1) stimulation sleeves that are installed as part of production casing strings and (2) packers whose sealing elements expand by swelling when contacted by certain chemicals, operators may isolate and fracture-stimulate multiple payzones as part of the well-completion process.

The sleeve and swelling packer system (SSPS) enables accurately located, pinpoint stimulation of several payzones through the casing wall. The stimulation sleeves, rated to 10,000 psi differential pressure, can be opened or closed in a single coiled-tubing (CT) or jointed-pipe trip. Opening the sleeve permits zonal stimulation through the selected sleeve and diverts the flow through ports in the sleeve. After stimulation, cleanup is assisted by flowing all lower zones simultaneously. Sleeves can be shifted (opened and closed) (1) mechanically, (2) with a hydraulic shifting tool, or (3) by ball activation.

There is no limit to the number of stimulation and production sleeves that can be run in a single casing string. Once the well is completed, the sleeve will function as a standard production device, allowing full wellbore access. Stimulation sleeves have been subject to extensive laboratory and back-yard testing.

Augmenting the function of the stimulation sleeve is the swelling packer. This packer is also installed as part of the completion string; rubber elements bonded to the tubular portion swell on contact with oil-base drilling muds, formation crudes, and other formation liquid hydrocarbons. Packer elements will not swell in fresh water. Packer-swelling action creates a seal in open hole; swell time is adaptable to suit the environment. A summary of the swelling packer's features follows: Manufactured to any casing diameter.Slimmer pipe allows for thicker rubber.Thicker rubber allows greater swelling for higher differential pressure.Greater packer length increases differential pressure capability.Packer elements swell to seal irregular boreholes.Packer elements heal themselves after damage.Reliability of the swelling packer concept has been proven in more than 1,000 field applications.
The Beta Distribution and Its Application to Petrophysics
Authors: Gullco Robert , Anderson Malcolm
Published: December 2007

The Beta distribution in n-dimensions is introduced to describe the proportions of the mineralogical components existing in a certain stratigraphic interval (the porosity is included as a "mineralogical component"). The justification for doing so is empirical. The model allows the calculation of well logging parameters, such as GRma, GRsh, shale density, etc., without having to introduce them by "eye". It also allows the probabilistic calculation of the rock composition at each depth when there are more mineralogical components than logs: that is, there is a shortage of equations. In addition to this, the Beta model can be used to test the hypothesis that the relationship between any two components can be regarded as random, which should have applications in reservoir characterization.
Hydrocarbon Potential Monitoring of By-Passed Pay Zones Using TDT and CHFR Logs
Authors: Hamada G. M.
Published: December 2007

The ability to detect and evaluate bypassed hydrocarbon and track fluid movement in sandstone reservoir is vital in the quest to improve production and increases recovery. The main technique, which has been used for monitoring reservoir saturations, is TDT tool. But, it was hard to interpret the TDT data in the low formation water salinity reservoirs. This problem can not be solved because it is related to the theory itself of TDT measurement, which depends on salt content in formation brine.

Cased Hole Formation Resistivity tool (CHFR technique was proposed to overcome many of the pulsed neutrons tool limitations. This technique is called Cased Hole Formation Resistivity tool (CHFR). Based on the actual CHFR logs recorded through wells of studied oil field in Sinai, which are presented and discussed in the present work, a comparison study was done between the two available techniques, TDT and CHFR as methods for reservoir saturation monitoring, in addition to the results of open-hole resistivity logs as reference runs. It was found that water saturations calculated from CHFR logs were more accurate than TDT log in most of the cases, and that the quick look of CHFR logs always agrees with its quantitative interpretation, which gives the trust to relay on quick look of CHFR log, if a fast decision is required. While the quick look of TDT log was found to be very tricky, in most of the cases: often does not agree with its quantitative interpretation

Cased Hole Formation Resistivity tool (CHFR technique was proposed to overcome many of the pulsed neutrons tool limitations. This technique is called Cased Hole Formation Resistivity tool (CHFR). Based on the actual CHFR logs recorded through wells of studied oil field in Sinai, which are presented and discussed in the present work, a comparison study was done between the two available techniques, TDT and CHFR as methods for reservoir saturation monitoring, in addition to the results of open-hole resistivity logs as reference runs. It was found that water saturations calculated from CHFR logs were more accurate than TDT log in most of the cases, and that the quick look of CHFR logs always agrees with its quantitative interpretation, which gives the trust to relay on quick look of CHFR log, if a fast decision is required. While the quick look of TDT log was found to be very tricky, in most of the cases: often does not agree with its quantitative interpretation
Field Study Results Improve Squeeze-Cementing Success
Authors: Cowan Michael
Published: December 2007

Correlations and practices that improve squeeze-cementing success in a wide range of applications were developed from a series of field studies conducted between 1992 and 2000. The first study began with analysis of a database of 137 squeeze operations. Statistical analysis of data for successful first-attempt squeeze operations from this database identified practices and correlations that significantly improved the success rate for squeeze-cementing operations. The correlations developed from this initial data were applied in other operating areas and refined over time.

Prejob injection test data can be used to select basic cement type, recommended cement volume, and cement fluid loss based upon correlations developed from these studies. Guidelines for placement procedures and pumping techniques were developed from successful field operations.

While these practices have significantly improved success in a wide range of applications and geographical areas, squeeze cementing continues to defy standardization. The success of most squeeze-cementing operations is directly related to the skill and experience of those designing and executing the operation.

These practices are presented as a reference point for engineering and operations staff for design and execution of squeeze-cementing operations. For those skilled in squeeze cementing, this information may be confirmed by others' experience and knowledge to improve success and increase understanding of squeeze cementing.