bluuebunny/crossref_metadata_2025 huggingface dataset:
Cementation of Horizontal Wellbores
Authors: McPherson S. A.
Published: December 2007

This paper outlines the cement slurry design methodology used to cement one of the world’s longest horizontal well bores. The work detailed has been carried out on ‘M-Site’ of BP Amoco’s Wytch Farm Development on the south coast of Dorset, England, over the past 4–5 years. Of the 17 wells, so far completed on M-Site, none have required remedial cementing work and all reservoir sections exhibit satisfactory zonal isolation, as confirmed by bond log results. The formations to be drilled exhibit very low fracture gradients, with the possibility of losses during the cement job constantly present.

The discussion compares and contrasts cementing techniques between vertical and horizontal casings. It looks at procedures and concerns common to both, then describes how downhole temperature calculation and some lab testing techniques, were modified to account for the nature of the horizontal well bore. Output from the computer temperature simulator confirmed assumptions made earlier in the project. Details of the slurry design criteria and testing procedures are discussed. The slurry properties included zero free water and low fluid loss, along with considerable thickening times, to allow for correct placement.

The discussion includes hole cleaning measures, and the influences of mechanical contribution, such as centralisers and pipe movement. Spacers and flushes with controlled flow regimes have been used to provide optimum mud and solids removal. In addition, an outline of the computer simulation programme used for well bore analysis is shown to be invaluable to the design engineer, by allowing modification of many inputs very quickly.
Deep Offshore Fluid Evaluation/Connectivity Study
Authors: Levaché Denis , Montel François , Walgenwitz Fréderic
Published: December 2007

In the case of deep offshore reservoirs the connectivity between the different parts of the reservoir appears to be a crucial problem to assess the reserve for each well and therefore for the development scheme.

A decisive input to this connectivity problem could be brought by a multidisciplinary approach between three different skills: ✓Organic geochemistry✓Water geochemistry✓PVT and thermodynamics

This presentation shows how these different skills were integrated in the case of a deep offshore field to give an overall picture of the fluid distribution and of the connectivity between the different parts of the reservoir encountered by the discovery and appraisal wells.

The field is divided into two turbiditic systems of Oligocene and Miocene stratigraphic age. The Miocene system is not significant in this field but the fluid properties in this reservoir give important information on the migration and oil alteration process. The Oligocene reservoir is divided into three turbidite channels and six sheets or levees.

The fluid distribution in the reservoir is modelled by different mechanisms. Each mechanism could be characterised from specific data using advanced data interpretation techniques.

Detailed reservoir fluid compositions, gas logging, gas isotopic measurements and residual salts analyses performed on cores samples are some of the key data used in this study.

The intrinsic limitations of the different techniques are stressed and the meaning of the observed gradients and breaks are discussed.

Two main mechanisms are responsible for the composition gradients in the fluid system: gas flux through the entire fluid system and biodegradation.

The channels, levees and sheets are laterally connected, but not vertically in the wells.

Thermodynamic modelling of the dynamic process leading to the actual reservoir fluid distribution is presented and the consequences on fluid properties profile are derived. Through this example, this paper provides the methodology to deal with dynamic reservoir fluid systems and gives to petroleum engineers the way to avoid many traps during the evaluation procedure.

The main contribution is the integration of several data interpretation skills to reach one of the most difficult objectives of formation evaluation: the connectivity level of the different compartments of a reservoir.
Nonlinear Regression Analysis of Well-Test Pressure Data with Uncertain Variance
Authors: Onur Mustafa , Kuchuk Fikri J.
Published: December 2007

The main objective of this study is to explore the use of parameter estimation techniques that handle cases where error variances (weights) in observed well-test data are uncertain. There are two main sources of uncertainty: 1) The gauge resolution and 2) measurement environment. Many gauges are used in well testing are not well characterized in terms of accuracy and resolution. The measurement environment in the wellbore is very noisy because of high frequency events in the wellbore (any producing interval), eg phase segregation. Because of these uncertainties, in this study, we investigated the use of parameter estimation methods based on the maximum likelihood and presented a new efficient method based on this method. The maximum likelihood method enables one to estimate error variances in pressure data along with the unklnown formation parameters. It is shown that the new method is efficient and powerful in estimating formation parameters from well-test data with uncertain variance. A simulated interval test from the multiprobe wireline formation tester in a single layer system as well as a field interval test in a three layer cross-flow system are used to demonstrate the applicability of the proposed methods.
Advanced Sand Control Completion With Permanent Monitoring
Authors: McKay G. , Bixenman P. W. , Watson G.
Published: December 2007

Permanent downhole monitoring can provide valuable information for production decisions without the need to perform an intervention to gather data. This type of technology has been excluded from sand control completions because of the complexity of placing measuring devices in the production interval.

This paper describes the completion design of an openhole, horizontal, gravel-packed completion with permanent monitoring equipment in the production interval. As is typical for gravel-packed wells, the completion is run in two trips: the sandface completion is run in the first trip, and the upper completion is run in the second trip. The sandface completion includes two hydraulic lines in a U-tube configuration with a hydraulic wet connector at the top of the completion string. The completion is gravel packed using an alternate path technology that decreases the risk of a failed gravel pack placement due to hole collapse or losses. It also allows placement at lower flow rates, thus reducing the risk of damaging the hydraulic control lines. The upper completion is run and stabbed into the hydraulic wet connect. The hydraulic lines provide a continuous, environmentally protected conduit for the fiber-optic line. Once the upper completion is run and the wet connect is tested, the hydraulic lines are flushed and the fiber-optic (distributed temperature sensor) is installed.
Trends in the Effectiveness of Petroleum Exploration and Development Drilling in the U.S. Gulf of Mexico OCS Region, 1977–1998
Authors: Iledare Omowumi O.
Published: December 2007

As the large and easy-to-find petroleum reservoirs are discovered, petroleum discovery rates are expected to decline over time. Consequently the unit cost of reserves additions will tend to increase because of resource depletion effects. However, the more recent declining trend in finding costs of petroleum reserves and recent sharp increase in finding rates in the U.S. Gulf of Mexico Outer Continental Shelf (OCS) have provoked debates on the role of technical progress on the OCS as an emerging offshore oil producing frontier. This paper reviews trends in the effectiveness of exploration and development drilling in the Gulf OCS region. An analytical model of exploration and development drilling effectiveness is developed, estimated, and applied. The empirical results suggest strong statistical evidence of overall diminishing returns on exploration and development drilling on the OCS. The results also show that the positive impact of technical progress and economic incentives is significantly mitigating the depletion effects on the finding rates and the finding costs of petroleum reserves during our sample period. These results are, however, conjectural.
Produced Water Treatment and Hydrocarbon Removal with Organoclay
Authors: Doyle D. H. , Brown A. B.
Published: December 2007

We present a new technology for removing free and dissolved hydrocarbons from oilfield produced water. Organoclay completely removes free hydrocarbons from wastewaters and also removes dissolved hydrocarbons including benzene, toluene, ethylbenzene, and xylene (BTEX). When used in conjunction with a polishing stage of granular activated carbon, organoclay removes free and dissolved hydrocarbons to levels well below current water quality standards.

Organoclay is produced by combining sodium montmorillonite clay with a cationic quaternary amine salt, which replaces adsorbed sodium by ion exchange. Resulting clay surfaces become organophilic.

Hydrocarbons are removed from water by adsorption. The quaternary amines create organic "pillars" between the clay platelets that increase the interlamellar distance and facilitate the formation of a hydrocarbon partition.
A Novel Approach to Resources and Reserves Determination
Authors: Zolotukhin A. B.
Published: December 2007

Oil and gas reservoirs represent a classic example of systems which description is associated with uncertainty.

Quality and quantity of data at the exploration stages and early phases of field appraisal and field development planning is not sufficient for an adequate application of complex software programs based on detailed information about the reservoir/fluids properties. Lack of data makes an overall estimation of resources and reserves made by conventional deterministic and/or probabilistic methods more subjective and, therefore, less reliable.

Methods of fuzzy mathematics have shown to be an excellent tool for handling uncertainties in a scattered environment, i.e. in situations when statistics is not available and probabilistic methods can fail. Instead, fuzzy mathematics enables to directly incorporate the input data uncertainty in analysis, to handle uncertainties in a most natural way and, therefore, to reduce the risk of subjective judgement and to avoid biased decisions.

The paper describes a novel approach to resources and reserves determination based on fuzzy systems theory and focuses on several examples of its application. It is shown, in particular, that volumetric evaluation of oil-in-place can be effectively done by using fuzzy numbers and interval calculus resulting in cumulative possibility distribution curve for resources of oil of a single field. In case of evaluating resources of a basin this technique coupled with the fractal analysis of resources results in the cumulative possibility distribution curve for the entire basin and enables to determine unexplored potential of the basin, or yet-to-find resources.

Evaluation of [recoverable] reserves can also be effectively done by methods of fuzzy mathematics. A new technique of reserves determination based on a simple analytical model coupled with fuzzy calculus is discussed in the paper. The model accounts for wells’ interference and allows to optimise the total number of wells to be drilled.
Screen Selection for Sand Control Based on Laboratory Tests
Authors: Gillespie George , Deem Calvin K. , Malbrel Christophe
Published: December 2007

Oil and gas production from unconsolidated/weakly- consolidated sands requires a production screen in the hole to inhibit the movement of formation sand and keep the hole open. For open hole completions where the sand control screen directly retains the formation sand, proper screen selection is necessary to provide optimum life and minimum sand passing. Several screen sizing selection criteria are available in the literature such as Saucier, Coberly, Schwartz and others. However, these rules may not always be applicable, especially when premium screens, with metal meshes are used. These screens may use multi layers of wire mesh and its complex shaped pore opening may result in retention performance quite different from wire wrap screen slots.

Experimental work has been done on a very fine (d50 = 115- 130 μm) uniform (uniformity coefficient = d40/d90= 3) and a non-uniform (uniformity coefficient = ca 7) sands on a series of commercial screens segments. These screens include standard wire wrap and also premium grade screens. The testing consisted of pressure drop measurements and sand retention while the screen is subjected to a fluidized stream of sand. Analysis of the data provides a method of measuring screen performance during and after filter cake bridging/building. Utilizing this data, screen performance, i.e. comparative lifetime and sand passing can be projected based on a maximum a pressure drop across the screen assembly. This analysis method is applicable for any type of screen and formation.

Where possible, the results from the experimental tests are compared to prior literature screen selection methods. Graphs of the normalized data allow for a logical selection of the appropriate screen for a given formation sand.

Technical Contribution: A new procedure for the selection of production screens applicable to any formationA comparison of the new method with prior literature methodsA comparison of performance of wire wrapped screens and premium screens.
Improved Uncertainty Management in Field Development Studies through the Application of the Experimental Design Method to the Multiple Realisations Approach
Authors: van Elk Jan F. , Guerrera Lupo
Published: December 2007

The structured multiple realisation approach is emerging as an important tool for uncertainty estimation and management of hydrocarbon reserves. The approach quantifies the reserves uncertainty, by identification of the key uncertain parameters for the reservoir description and by subsequent modelling of the reservoir response for a manageable number of combinations of values for these parameters. However, when this modelling requires reservoir simulation, the approach may lead to a significant time and manpower commitment.

This paper presents a rational approach for optimising the choice of simulation runs, using the method of experimental design. The methodology is designed to capture reserves uncertainty and to provide insight into its management within the development context, while minimising the reservoir simulation effort.

In this method the reservoir simulator is treated as a black box. The input parameters to the simulation incorporate the key uncertainties, while the output (for example, the reservoir recovery response) is uniquely determined by the input. The output examined can be any parameter of importance to the field development decisions. The design ensures the input parameter set for the series of simulations is constructed so that the maximum information can be obtained from a minimum number of runs. Results for any given output parameter from the different runs are condensed into a response function for that parameter. This function typically can include non-linear responses and interactions between inputs. An uncertainty distribution for the parameter can be immediately derived. The method also allows for successive refinement of the response function, by adding additional simulation runs.

When using this approach for ultimate recovery uncertainty estimation, not only is the reservoir simulation effort for reserves quantification reduced, but an increased understanding of the field response can be gained for robust development decision making.

The paper will present the application of the methodology to the Field Development Study of the Legendre North and Legendre South Fields.

The Multiple Realisation Approach at Woodside

Introduction

The Multiple Realisation Approach has been used at Woodside since its introduction into the NWSV in early 1995. This method aims at:establishing a structured uncertainty estimation and management process, andensuring technical study integrity.

Introduction

The Multiple Realisation Approach has been used at Woodside since its introduction into the NWSV in early 1995. This method aims at:establishing a structured uncertainty estimation and management process, andensuring technical study integrity.
Drilling Wastes Treatment and Management Practices for Reducing Impact on HSE: ENI/Agip Experiences
Authors: Ferrari G. , Cecconi F. , Xiao L.
Published: December 2007

A growing awareness and sensitivity of the environmental pressure on E&P industry activities has changed rapidly in world-wide. One of the major troublesome environment complications is the mud exhaust and cuttings disposal problem.

This paper reveals the recent experiences of our Drilling Unit in approach to fluid wastes treatment and management exercises in drilling operations toward minimum impact on HSE. In particular, some innovative wastes treatment and re-using technology approaches are discussed together with case studies to affect how waste mud and cuttings are handled, treated, disposed, and reused. Apart from waste and cuttings treatment, management and disposal processes the presented paper illustrates also Agip policy, Italy regulatory limits on environment issues.

The described new treatment processes can be carried out at well site for all types of operation fluids. After suitable treatment, the wastes can be turned out as useful materials favoring both in situ and for other producing industries.

Good and properly treatment, management and disposal of drilling cuttings and exhaust mud can make oil & gas well drilling more compatible with natural environmental requirements. The reduction of environmental impact became a benefit due to less volume (40%) of wastes generated, less transport (20-30%) used, less accident risks during the transportation witnessed, and zero or minimum wastes to disposal sites were brought.

From different operation case histories of our unit, water (60%) from dehydration of WBM and oil (10%) recovered after clean up from oily cuttings are re-utilized for mud service company at rig site. The treated solids (cuttings and components of mud) are no longer wastes to be disposed but raw materials for 1) cement producing plants 2) bricks and expanded clay producing plants and 3) for land restoration.

The experiences, obtained by Eni/Agip up to date provided the very encouraging results not only from cost saving point of view but also as a great contribution to improvement of environmental impact of our activities. The great contribution was derived from: reducing operation duration;less volume of wastes production;zero or minimum discharge drilling wastes;wastes materials as raw materials for re-use: treated liquid (water and oil) is reused for mud built up, dilution and rig cleaning; treated solids are reused as useful materials.
Layer Productivity Prediction Based on Wireline Logs and Formation Tester Data
Authors: Liu C. B. , Schwab K. , Lin X. J. , Chun Kuang Li
Published: December 2007

The development of an integrated approach to testing, producing and/or stimulating layered reservoirs for oil companies in China, which significantly reduces total operating costs by streamlining operations, has been successfully implemented.

This method links the data from standard open hole and nuclear magnetic resonance (NMR) logs with wireline formation test data and the data from reservoir and petroleum engineering applications.

The methodology entails the following stages: -Calibration of a NMR derived permeability indicator by means of wireline formation testing and/or core data.-A full petrophysical analysis incorporating all available reservoir properties in order to estimate relative and phase permeabilities.-These results are then combined with: formation pressures and PVT data from wireline sampling or production tests run in neighboring wells (or simply from regional knowledge); and, completion parameters. All are entered into a nodal analysis program to simulate layer performance.

Results are predicated on a range of wellhead/downhole pressures and skin factors and the predicted flow rates and water cuts are displayed.

The paper will discuss the methodology of this approach in detail - it's strengths and its limitations. Case studies comparing prediction and actual test/productions results complete this paper.
Pushing the Envelope – Extending the Limits of Current Drilling Technology
Authors: Kamaruddin Sazli , Md Zin Che’ Lah , Sering Lancelot , Good Alan , Khun Lim Hong
Published: December 2007

The practical application of new technologies, including rotary steerable drilling systems are overcoming previous limitations in directional drilling to make designer, multilateral and extended reach wells easier to drill.

In this paper, the authors will discuss the tremendous value that can be achieved through application of winning technology and teamwork that has been proven as an effective tool in maximizing business opportunity in Asia Pacific.

Multilateral wells offer tremendous advantages including reducing the size of platforms, surface locations, subsea completions and total wells required to fully exploit a hydrocarbon reservoir. However, such complex 3 dimensional well applications can be severely limited by a number of factors including: Prohibitive well costsRig sizing considerationsLess than optimal directional controlTorque and dragUnreliable WOB transfer and poor hole cleaningEnvironmental considerations.

One technology having a significant impact on such designer well applications are rotary closed loop drilling systems. These systems provide enhanced drilling-while-steering efficiency and improved hole quality. It comprises a non-rotating steering unit, a downhole guidance system, formation evaluation (with optional LWD) and downhole pressure monitoring. These tools can automatically guide the bit to a preprogrammed target and two-way surface communication allows rigsite engineers to adjust the well trajectory to meet drilling objectives and redirect the wellpath based on real-time formation logs. This eliminates the "wait and see" aspect of drilling which often results in less than optimal well placement, unnecessarily complicating the forward directional plan for the well or missing the target all together.

In 1998 Petronas Carigali Sdn. Bhd. commenced the Sotong field development in offshore Peninsular Malaysia. The objective was to efficiently drain marginal reserves using multilateral Level 4 technology. The wellpaths are precisely placed in an optimal position using rotary steerable technology in order to ensure maximum production life of well. Modern communications systems has allowed this technology to transfer real-time wellsite data from rigsite to shore. The critical well path decisions can be made in real time by the team in the office and relayed to the wellsite instantaneously and changes can therefore be made immediately.
The Optimum Junction Depth for Multilateral Wells
Authors: Brister Ray , Oberkircher Jim
Published: December 2007

Placement of the multilateral junction is one of the most critical elements in the design of a multilateral well. A misplaced or mal-performing junction can have an adverse effect on an otherwise successful multilateral project. The optimum placement of the junction is a function of reservoir, geological, drilling, and completion criteria. The list may include such criteria as reservoir development strategy, pressures & heterogeneity, geological structure, lithology, wellbore stability, multilateral junction integrity, directional drilling requirements, logging requirements, artificial lift design, and completion type. These combined factors have a direct economic impact on the success and viability of the project.

This paper describes a process whereby the proper junction selection criteria can be evaluated in light of pertinent technical and economic criteria and examines lessons learned from case histories with junction problems.
Evaluation of CO2 Injection with Three Hydrocarbon Phases
Authors: Wang Xiaowei , Strycker Arden
Published: December 2007

This paper presents results of a slim tube test and detailed 1D-simulation studies of a hydrocarbon system involving three hydrocarbon phases. The principle objective of this study was to evaluate the effect of CO2 injection with three hydrocarbon phases on oil recovery.

The Schrader Bluff (Alaska) equation-of-state (EOS) predicts that two hydrocarbon liquid phases will be formed at reservoir temperature and pressure during CO2 injection. A slim tube test utilizing a 77.5 mole% CO2-22.5 mole% NGL solvent was performed on a freshly made recombination of separator samples collected from the Schrader Bluff E-20 well. Detailed 1D-simulation studies following the test were conducted using an EOS compositional reservoir simulator developed at the University of Texas (UTCOMP).

Both laboratory test and simulation results showed the formation of a second liquid CO2-rich phase. Using UTCOMP, the conducted laboratory slim tube results were successfully history matched. The simulation runs also showed that lumping the CO2-rich second liquid phase into the gas/oil phase, as done by commercial simulators, resulted in 5% lower oil recovery. Additional studies showed that oil recovery was sensitive to the reservoir temperature and pressure. Four-phase relative permeability values generated by different models also had a significant impact on oil recovery.
Fractured Reservoir Characterization Using 3D AVD
Authors: Pan Renfang , Li Mei
Published: December 2007

Fracture, especially the directional fracture genetic with structural stresses, characterizes anisotropy and orientation to fractured reservoir, which can be detected by 3D AVO analysis.

AVO, amplitude variation with offset, conventionally is applied to detect hydrocarbon reservoir, especially gas bearing sands due to its Poisson’s ratio changes that constantly related with the status of in-situ saturation of hydrocarbon. Shuey’s function formulates dual available parameters – intercept P and gradient G, their imparity reflects the differential combination of lithology, petrophysics and hydrocarbon saturation. Consequently, at a specific point of fracture zone, anisotropy of strata would cause discrepancies of P & G values between different directions horizontally, this would be significant to structural fracture and gain maximum at conjoint set perpendicular to and parallel to fracture orientation. Therefore, vector analysis of AVO parameters from 3D AVO methodology leads to detail interpretation of fracture spacing and density.
The Reservoir Prediction And Gas Indication of Two Gas-Beaing Structures in CD Basin
Authors: qin Fengrong
Published: December 2007

This paper will summarize the methods of reservoir prediction and gas indication of structures TJ and YK with a sandstone reservoir on the beach-shallow lake facies—lake basin bog facies at the Quaternary age in the CD basin. It provides an effective technical system for solving the problems of a distinguishing reservoir from other kinds of rock and distribution of the formation containing gas, a thin layer and complex reservoir rock, and the unreliable seismic data because of the layer of gas. The results show that the exploration idea should be the complement of the lithology element. In addition to the idea of finding a structure for gas, the saddle zone between the two structures may be a potential area located in the zone of sandstone development deposited on the river-channels under water during the Quaternary.
Evaluation on Results of Multiple Infilling & Adjustment in Sazhong Area
Authors: Guo Wankui , Yan Yaru , Liu Bing , Liu Qi
Published: December 2007

This paper conducts analysis on problems occurred during the development of Sazhong Area in Daqing Oilfield such as small reserve controlled by basic well pattern, low ultimate recovery efficiency, etc. It introduces the solution of infilling adjustment, analyzes and evaluates on full scale various production indexes like production rate, formation pressure, control degree and production situation of different formations, effect in old wells, and ultimate recovery efficiency, etc. after each infilling adjustment. Result shows that recovery efficiency can be improved by 6–8% after primary infilling adjustment, 4–5% to 45.5% after secondary infilling adjustment, and to 47.48% after tertiary infilling adjustment. It was realized that only when certain well pattern density was reached through reasonable division of formation series and multiple infilling adjustment, can we improve the control degree of various kind of formations and the ultimate recovery efficiency, and develop the continental heterogeneous reservoir with high efficiency and high quality.
The Research and Application of Assistant Decision System for Economic Development and Production in Tarim Oilfield
Authors: Jiang Tongwen , Longde Sun , Lian Zhanggui , Hu Haidong
Published: December 2007

With the inner oil market joining up the world market and the establishment of oil company, the developmental target is changing from yield to economic benefit. According to the balance theory of profit and loss, the Assistant Decision-Making System for Economic Development and Production in Tarim Oilfield has been developed. It has four subsystems: the well open/shout-down assistant decision-making subsystem (the economic minimum yield, the economic maximum water cut); the well stimulation assistant decision-making subsystem (the economic minimum oil increment); the infill development assistant decision-making subsystem (the economic pattern arrangement), and the production benefit evaluation subsystem (the benefit evaluation, objective cost, target yield). This system have is characterized by reliability, flexibility and visualization for use by on-the-spot engineer. It can make a fitted combination of economic evaluation to engineering and of production to market.
An Experimental Approach to Prediction of Asphaltene Flocculation
Authors: Wang J. X. , Buckley J. S.
Published: December 2007

Many of the existing models that have been developed to predict the onset of asphaltene flocculation rely on approximations to a full thermodynamic treatment of asphaltene phase behavior and on parameters that are not available except by fitting HTHP data to the model. A much simpler approach has been developed based on experimental measurements of refractive index (RI) at the onset of flocculation for precipitants representing a range of molecular sizes.

The onset of asphaltene flocculation is often reported in mixtures of oil, solvent, and asphaltene precipitants. In this work, direct measurements of RI replace estimates of solubility parameters. RI is readily measured and is a good indicator of the ability of the oil to maintain a stable dispersion of asphaltenes. Tests with stock tank oil samples have shown that there is a common trend relating RI at the onset of instability to precipitant molecular size. This observation facilitates predictions of asphaltene instability for a wide range of conditions from as few as one or two onset determinations with precipitants of known molecular size. Results obtained at ambient conditions for stock tank oil can, in principle, be extended to reservoir conditions using standard PVT and compositional data, as demonstrated in this paper.
Corrosion Testing of Inhibitors to Protect Welds against Slug Flow in Deepwater Conditions
Authors: Skogsberg Lillian A. , Miglin Bruce P. , Ramachandran Sunder , Bartrip Keith A.
Published: December 2007

Corrosion inhibitors are used to protect deepwater facilities against internal corrosive attack. This can particularly occur in the slug flow regime. In this article, the testing of corrosion inhibitors to protect against slug flow in deepwater locations is described. A testing protocol for corrosion inhibitors that evaluates the corrosion performance of weld metal, the heat affected zone (HAZ) and the base metal in the appropriate flow regime is described. A description of other compatibility requirements is also given.
Performance Improvements from Chemical Drag Reducers
Authors: Campbell Samuel E. , Jovancicevic Vladimir
Published: December 2007

For over 20 years, high molecular weight polymers and surfactants have been used to reduce pressure drop and enhance flow in oil and aqueous systems from production pipelines to water injection systems. The mode of action has been attributed to a reduction in energy loss by a suppression of turbulent fluctuations. However, surface modifications also play a role gas transmission systems. As will be shown with laboratory and field data, the alteration either in the surface or in the fluid flow properties can also improve other aspects of oilfield production. Such as in this paper, four particular instances of drag reduction will be related to corrosion performance. In a first case, two model surfactant corrosion inhibitors, cetyltrimethylammonium chloride (CTAC) and cetylpyridinium chloride (CPC) were chemically modified to drag reducing agents by exchange of the chloride with salycilate counterion. The modified surfactants (cation exchanged) and the corresponding halides were compared in a corrosion test under conditions were drag reduction occurred. Drag reduction promoted corrosion inhibition in a standard corrosion test. In a second case, the introduction of a low foam surfactant into a brine system resulted in a reduction in the corrosion rate as shown by laboratory data. In a third case, utilizing a cleaner/antifoulant surfactant, the pressure drop was reduced and the production increased in a gas gathering system. As a side benefit of the removal of solid deposits, the uninhibited corrosion rate was decreased by a factor of seven. In a final case, a foaming surfactant was utilized to remove liquid hold-up in a production well. By removing the liquid hold-up, the corrosion rate was decreased. Utilizing a drag reduction chemical in an oil or gas production system can lead to additional performance enhancements as demonstrated for the case of corrosion control.
A Summary of Successful Field Applications of A Kinetic Hydrate Inhibitor
Authors: Fu S. B. , Cenegy L. M. , Neff C. S.
Published: December 2007

A kinetic hydrate inhibitor based on a copolymer of vinylcaprolactam and vinylmethylacetamide has been successfully deployed in a number of fields, including both inland and offshore applications. The inhibitor has a low toxicity and manages a high degree of subcooling, up to 20°F. The effective dosage ranges from 550 ppm to 3000 ppm, depending upon the severity of the operating condition in each field. The performance of this inhibitor, the field conditions in which it was applied, and the benefits are discussed in this paper. These field cases helped establish the application technology for proper deployment of kinetic hydrate inhibitors. The success of these programs has confirmed the viability of using kinetic inhibitors as an effective hydrate control method. This kinetic inhibition technology not only provides an attractive cost-saving alternative to thermodynamic inhibitors; it also improves the safety of operation while lowering the environmental impact.
Evaluation of Retarded HF Acid Systems
Authors: Al-Dahlan M. N. , Nasr-El-Din H. A. , Al-Qahtani A. A.
Published: December 2007

Stimulation of sandstone reservoirs usually involves the use of a hydrofluoric-based acid (HF). Hydrofluoric acid reacts rapidly with clay minerals and slowly with sand particles. Stimulation of sandstone formations is a challenging task because it involves several chemical and physical interactions of the acid with the formation. Some of these reactions may result in formation damage. Retarded HF (RHF) acids are less reactive with the rock and normally result in deep acid penetration into the formation.

Three RHF acids that are based on boric acid (H3BO3), aluminum chloride (AlCl3), and a phosphonic acid were examined. Several tests were conducted to evaluate interactions between RHF acids and sandstone rocks. Static solubility tests were performed using sand particles and clay minerals at 25 and 75°C. Chemical analysis of spent acids was extensively used in this study.

Acidizing sandstone reservoirs using mud acid is a complex process where dissolution and precipitation occur simultaneously. The process is even more complicated when RHF acids are used. The results of this study indicate that the composition of spent acid strongly depends on the retarded system used. Dissolution of clays is generally reduced when a form of RHF is employed. However, increasing the soaking time caused precipitation in all RHF acids examined. Some of the RHF acids precipitate materials that are not encountered when regular mud acid is used. This paper addresses several chemical interactions that have not been addressed previously in the literature.
Development of New "green" Demulsifiers for Oil Production
Authors: Dalmazzone Christine , Noïk Christine
Published: December 2007

There is an increasing need in the oil production to limit the use of chemicals and to search for safer products, mainly due to more severe environmental constraints. Demulsifiers performance has to be therefore improved, from the application as well as from the environmental point of view. New formulations must be less toxic and at least as efficient as classical chemical families, which contain toxic molecules like phenol groups. A methodology was developed to screen the main chemical families used as demulsifiers. Effective separation ability of different surfactants was first evaluated according to the classical " bottle test". From this preliminary screening, some silicone derivatives appeared to be efficient on several crude oil emulsion types and were therefore studied more intensively. A specific methodology was used, including turbidimetric measurements with a vertical scanner to quantify water and oil separation kinetics and also the quality of the separated water. Finally, silicone chemicals were found to exhibit very interesting performances and could be used as "green" demulsifiers in oil production.
Steering of Horizontal Wells with 3D High Resolution Seismic Model
Authors: Lanfranchi Pierre
Published: December 2007

Until recently, seismic data failed to be used for qualitative reservoir characterization for two main reasons:

the vertical resolution is not good enough to describe the subtle stratigraphic feature at the reservoir scale there is no direct relationship between seismic amplitudes and reservoir related parameters (porosity, permeability, …), fluid content and lithology.

In this paper, we first present an optimized method allowing us to overcome the two drawbacks given above. Then, we will show examples where this technique is successfully applied to steer horizontal drain in order to optimize production performance.
SWAG Injection on the Siri Field - An Optimized Injection System for Less Cost
Authors: Quale Eileen A. , Crapez Bénédicte , Stensen Jan A. , Berge Lars Inge
Published: December 2007

Simultaneous Water And Gas (SWAG) injection has been implemented on the Siri Field on the Danish Continental Shelf and represents the first reported full field application of its kind in the North Sea. The associated produced gas is mixed with injection water at the wellhead, and injected as a two-phase mixture. The required total injection volume for voidage replacement is thus achieved with a simplified injection system, fewer wells and reduced gas recompression pressure requirements.

Injection per well has typically been in the range 4,000–8,000 Sm3/day (25,000–50,000 bpd) water and 200,000 – 400,000 Sm3/day (7 −14 Mscf/d) gas.

Evaluation of alternative injection schemes identified SWAG as the optimum scenario for Siri. The choice reflects that:

There is no established gas export infrastructure in the immediate area, Siri gas volumes alone are too small to warrant establishment of a system, and routine gas flaring is unacceptable. Reinjection is therefore required. Reservoir simulation studies indicate improved oil recovery (IOR) with combined gas and water injection as compared to pure water injection, apparently related to attic oil displacement, reduced residual oil saturation and better sweep efficiency. Continuous water injection from both injectors is required to maintain reservoir pressure.

The SWAG concept fulfills all these requirements, representing a safe, economic and environmentally-friendly development solution.
Production Gains from Re-Fracturing Treatments in Hassi Messaoud, Algeria
Authors: Marquardt Michael B. , van Batenburg Diederik , Belhaouas Rafik
Published: December 2007

Since 1990, over 200 hydraulic fracturing treatments have been performed in the Hassi Messaoud field in northeast central Algeria resulting in an average production increase of 5 m3/hr (750 bopd). The success of the stimulation program in this Cambrian age sandstone formation resulted from improved field practices of treating open-hole and slotted liner completions, and from the use of state-of-the-art fracturing equipment and engineering tools.

After several years of production, the production rates of some fractured wells have declined due to several reasons: reservoir depletion, salt precipitation from formation water breakthrough or injection water breakthrough, and fracture conductivity damage due to barium sulfate scale and asphaltene deposition. Since 1996, re-fracturing treatments have been conducted on nine wells in order to restore production by placing another propped hydraulic fracture in the same target drain.

The three case histories presented show exceptional, normal and marginal responses to the re-fracturing treatments. Explanations for the observed responses are presented and recommendations for the selection of new re-fracturing candidates in the Hassi Messaoud field are presented.
Present Status and Development Prospect of Oilfield Chemicals in China
Authors: Ji-de Liu , Ya-bin Niu , Da-ming Zhang
Published: December 2007

This paper presents the production and applications of a five classes of oilfield chemicals according to "standard of the kind and code of oilfield chemicals" issued by CNPC, and the results gained in oilfield application. Some key oilfield chemicals and oilfield chemicals given priority to development in the near future were pointed out.
Application of Drilling Fluid chemicals in China
Authors: Zhang Daming , Niu Yabin , Liu Jide
Published: December 2007

This paper present the sixteen types of drilling fluid chemicals manufactured in china and describe some important chemicals in detail. The consumption of drilling fluid chemicals is listed on different types for each year. The tendency of consumption of chemicals is analyzed. According to API Classification of drilling fluid and characteristics of Chinese drilling fluid application, drilling fluids are classed in nine types. Explanation and formulations of nine types of drilling fluid are presented in this paper. The recent development of drilling fluids is presented in this paper. The recent development of drilling fluid chemicals and drilling fluid systems is analyzed. The mechanism and formulation of these new drilling fluids are presented. Nowadays, drilling fluid chemicals manufactured in china can satisfy the native market, some of them are exported to abroad market.
Emulsification and Stabilization of ASP Flooding Produced Liquid
Authors: Di Wu , Xiangchun Meng , Fengling Zhao , Ruiquan Zhang , Yan Chen , Qingsheng Wang , Huicheng Liang
Published: December 2007

Emulsification and stabilization of o/w ASP flooding produced liquid in Daqing Oilfield were studied on artificial produced liquid and oily water. The influences of alkaline (NaOH), surfactant and polymer (partially hydrolyzed polyacrylamide HPAM) on the stability of ASP flooding produced liquid and oily water were tested. Bulk phase rheology and interfacial properties such as interfacial tension, oil droplet Zeta potential and interfacial rheology were tested to reveal the mechanisms of the emulsification and stabilization of ASP flooding produced liquid. The experimental results showed that residual alkaline, surfactant and polymer in ASP flooding produced liquid all tend to increase the stability of o/w ASP flooding produced liquid; The emulsification of ASP flooding produced liquid is mainly caused by the reduction of dynamic oil-water interfacial tension by residual alkaline and surfactant, the increase of water-phase viscosity by residual polymer, and the mechanical shear experienced by ASP flooding produced liquid during production; The stabilization of ASP flooding produced liquid by residual alkaline, surfactant and polymer lies in the enhanced emulsification of produced liquid in which smaller oil droplets are produced, the increase of water phase viscosity by polymer which decreases the rising velocity of oil droplet and the hindrance of alkaline and surfactant on oil droplet coalescence.
Remotely Acidizing Satellite Wells
Authors: Da Motta E. P. , Branco C. C. M. , Shecaira F. S.
Published: December 2007

Matrix acidizing of satellite wells in deepwater fields depends on the use of a dynamic position vessel (DPV), what makes it a very expensive operation. Moreover, the availability of DPVs for stimulation treatments can be a limiting factor for deep water and even for ultradeep water fields. For some shallow water fields with particular characteristics, the use of DPVs is also mandatory. While the acid treatments of several satellite wells in the Campos Basin, offshore Brazil, are not performed due to cost restrictions and/or DPV availability, injectivities and productivities of those wells are decreasing. If not properly controlled, these declines could jeopardize the profitability of some fields. One solution for this problem, devised by Petrobras R&D Center (CENPES), consists of anchoring the stimulation boat to the production rig and pumping the acid treatment through the flexible pipelines, which may extend for several kilometers. The main difficulty for performing such a treatment is controlling the corrosion of metallic parts of the pipelines, as well of the Christmas tree and tubing. This paper presents the results of the remote acidizing of an offshore well of the Campos Basin, producing oil from a carbonate reservoir. The paper also describes in detail the laboratory tests required for the field test.