bluuebunny/crossref_metadata_2025 huggingface dataset:
Rigless Tubing Repair Using Permanent and Retrievable Patches at Prudhoe Bay, Alaska
Authors: Julian J. Y. , Cahalane T. W. , Cismoski D. A. , Burton J. , Savage E. L.
Published: December 2007

In Prudhoe Bay, Alaska, non-rig tubing repairs have become a viable alternative to rig workovers (RWO's) to provide an economic remediation for wells with production tubing by "A" annulus communication. Electricline (EL)-set patches can eliminate tubing communication at a significant cost savings and are particularly attractive in areas where RWO cost is significant, such as offshore, remote, or arctic locations. The advantage of tubing patch repair over a conventional RWO is that there is no need to pull tubing, resulting in the well being returned to service faster. Typical patch deployment costs are less than 5% of the costs for tubing replacement with a RWO. To date, 263 permanent and retrievable tubing patches have been set in 181 wells at Prudhoe Bay.

This paper discusses the history of conventional tubing patches at Prudhoe Bay, recommended pre-patch diagnostics, and the use of 3-D advanced caliper viewing software. The paper also provides a systematic approach for the design and deployment of conventional tubing patches.
On a Well-Test Pressure Theory of Analysis for Naturally Fractured Reservoirs, Considering Transient Interporosity Matrix, Microfractures, Vugs, and Fractures Flow
Authors: Pulido H. , Samaniego V. F. , Rivera J. , Díaz F. , Galicia G.
Published: December 2007

Constant flow, rate solutions are presented for a fractured reservoir with transient interporosity flow in a convolution form, considering matrix, microfractures, vugs and fractures flow.

New solutions are presented for two cases, where there is no primary flow through the microfractures and where the compressive and distensive strength process has created an interconnected system of microfractures. In both cases there is an interaction between matrix, microfractures, and fracture systems.

The numerical inversion was carried out with Stehfest's algorithm. In addition, approximate analytical solution for short and long dimensionless time are obtained and compared with the solution calculated by numerical inversion, providing satisfactory results. The values of the numerical inversion were used to generate the results, presented in terms of the dimensionless groups derived from the approximate analytical solution.
A Multifunctional Gel System To Mitigate Deepwater Drilling Challenges
Authors: Amanullah M. , Boyle Richard
Published: December 2007

Deep water drilling generally encounters additional drilling challenges due to the presence of a suite of drilling hazards such as SWF, gas kicks and blowouts, presence of unconsolidated sand formations, shallow gas and gas hydrate problems, lost circulation problems, sea floor washout and erosion, etc. All these drilling hazards cause a significant increase in total drilling cost. Hence, mitigation of the scope of these deep water drilling hazards is very important for safe and economic completion of deep water wells.

The presence of geologically young, mechanically weak and physically loose unconsolidated formations with high pore pressures, porosity and permeability below the ocean bottom is one of the major causes of deep water drilling hazards. Hence, treatment of such formations while drilling or immediately after drilling by incorporating a multifunctional gel, a chemical and/or a polymer either alone or as an integral part of a drilling mud can reduce the deep water drilling hazards significantly. This paper describes a multi-functional and environment friendly gel system to mitigate some of the deep water drilling challenges.

The newly identified multi-functional gel shows excellent compatibility with fresh, sea and salt water. A 16/30 sand pack was used to represent unconsolidated sand formation encountered below the Ocean bed. Experimental results indicate excellent sealing and reasonable strengthening capability of the additive. Permeability measured before and after treatment of the sandpack indicates more than 95% decrease in permeability compared to the original sandpack permeability. The gel also caused more than 50% increase in the penetration resistance of the sand pack i.e. enhanced the strength characteristics of the sandpack.
Use of Surfactants in High-Salinity Atmosphere: A Nonconfigurational Approach
Authors: Siddiqui M. A. , Al-Dossary K. A. , Bataweel M. A.
Published: December 2007

Commonly used surfactants exhibit cloud point or salting out phenomena in a high ionic environment. These phenomena were interpreted in the literature with configurational aspects of surfactant molecules such as functional groups and ionic nature. This paper presents a non-configurational interpretation of this behavior of surfactants and set a parameter for their selection to be used in that environment to avoid treatment failure, previously not reported in the literature.

The power water injectors in carbonate reservoir in field Q were left stable after drilling using a diesel based completion fluid. The flowback of the completion fluid was not allowed due to presence of hydrogen sulfide gas in high concentrations. Formation damage was expected due to injection of the completion fluid into the formation.

These injectors were planned to be treated by using surfactants that are compatible with high salinity formation and injection waters. Thorough lab investigations were conducted on the formation damage induced by the completion fluid by conducting return permeability tests on reservoir cores and compatibility tests. Various treatment fluids containing surfactants and mutual solvents and combinations of these were prepared. Use of surfactants with low electrochemical properties resulted into sudden precipitation of salts. This behavior of surfactants has been discussed in detail in this paper.
Openhole Cleanup of Deep, High-Temperature Horizontal Wells With a Chelant-Based Acid System—Case Histories From Indonesia
Authors: Wibisono Kunto , Burton Robert C. , Hodge Richard M. , Wijaya Rio , Nieuwland Bastiaan , Cassidy Juanita
Published: December 2007

ConocoPhillips Indonesia Inc. Ltd. is producing oil and gas in various locations in Indonesia, both on and offshore. This paper covers work performed in the Belanak field offshore Indonesia. The field is located in Natuna Sea, north of Indonesia, near the border between Indonesia and Malaysia. The gas produced by the Belanak field is transported to Singapore and Malaysia.

Belanak wells which are drilled in the Gabus Massive reservoir have a bottom hole static temperature of 315°F (157°C). The wells are typically long horizontals (2,300–3,400 ft) with openhole completions utilizing stand-alone screens through the producing interval. The reservoir section is drilled with a water-based Drill-in-Fluid (DIF) consisting of polymer and CaCO3 particles and displaced to a solids-free, DIF prior to running the screens.

Typically, acid is used to degrade water-based DIF filtercake and remove CaCO3 contained in the filtercake. The use of a common acid was not an option for this development because of the high reservoir temperature (>300°F). The combination of high reservoir temperature and long shut-in times after acid treatment lead to a high probability of severe corrosion of the sand control screens. In addition to the corrosion concerns with common acids, the rapid removal of the filtercake with acid could create localized, high leak-off of the treating fluid resulting in an uneven distribution of acid across the horizontal open-hole section.

To overcome these problems, a slow reacting alternative chemical solution was required allowing the stimulation fluid to be placed across the entire horizontal open-hole section before the CaCO3 filter cake was dissolved and before major losses started to occur. The solution was found in the application of a Chelant Based Acid System.

This paper details the application of the Chelant Based Acid System as a means to remove CaCO3 filter cakes in 10 Belanak wells, post treatment well performance, best practices, and lessons learned.
Design of Drill-in Fluids by Optimizing Selection of Bridging Particles
Authors: Jienian Yan , Wenqiang Feng
Published: December 2007

To select bridging agents properly is a critical factor in designing the no-damaging or low-damaging drill-in fluids. Historically, the Abrams's rule has been used for this purpose. According to this rule, the median particle size of a bridging agent should be equal to or slightly greater than 1/3 of the mean pore size for a given target formation. However, Abrams' rule only addresses the size of particle required to initiate a bridge. The rule does not give optimum size or address an ideal packing sequence for minimizing fluid invasion and optimizing sealing.

This paper elaborates an ideal packing approach to solve the sealing problem, with the aim being to minimize formation damage by sealing pores with different size, especially those large pores which usually make dominant contribution to permeability and thereby preventing the solids and filtrate of drill-in fluids from invading into formations more effectively, compared with the conventionally used techniques.

A practical software has been developed to optimize the blending proportion of several bridging agents, so as to achieve ideal packing effectiveness. It is very convenient for use in the field only by inputting some data of formation, such as the maximum pore size or permeability.

It has been confirmed from numerous experimental results that the core sample contaminated by the drill-in fluid designed following ideal packing approach can acquire higher return permeabilities, and have a shallower invading depth, a lower breakthrough pressure as well as a lower dynamic filtration rate than cores contaminated by the drill-in fluid designed applying the Abrams's rule.

The method and its use in selecting the best blending proportion of several bridging agents, focusing on an ideal packing sequence for minimizing fluid invasion, are also discussed in this paper. A carefully designed drill-in fluid using the ideal paking technique (named the IPT fluid) for offshore drilling operations at the Weizhou oilfield located in the west of South China Sea is presented. The near 100% return permeabilities from the dynamic damage tests using reservoir cores prove the excellent bridging effect can be provided by this drill-in fluid.
Leak Detection for Gas and Liquid Pipelines by Transient Modeling
Authors: Wang Shouxi , Carroll John J.
Published: December 2007

The leakage of hydrocarbon products from a pipeline represents not only the loss of natural resources, but also is a serious and dangerous environment pollution and potential fire disaster. So quick awareness and accurately location of the leak event are important to cut down the losses and avoid the disasters.

A leak detection method using transient modeling is introduced in this paper. This method is suitable for both gas and liquid pipelines with comprehensive consideration of the transient flow features of compressible flows and stochastic processing and noise filtering of the meter readings. The correlations for diagnosing the leak location and amount are derived based on the online real time observation and the readings of pressure, temperature, and flow rate at both ends of the pipeline. As an online real time system, great efforts have been paid to the stochastic processing and noise filtering of the meter readings and the models to reduce the impact of signal noise. It is essential too for the robust real time pipeline observer to have the self study and adjustment abilities in response to the large varieties of pipeline configuration, pipeline operation conditions, and fluid properties.

Real application cases are presented here to demonstrate this leak detection method. For example, in the leak detection of a crude oil pipeline of 34.5 km and Φ219mm, this method located the leak at 16.6 km from the pipeline upstream end which is only 0.6 km away from the actual leak location.
Advanced Production Monitoring
Authors: Hooimeijer Martijn , Azmi Mohamad
Published: December 2007

An effective and comprehensive integrated production-system monitoring framework plays an important role in the Smart Fields philosophy to turn data into actionable information and therefore value.

This has been demonstrated by implementing some of the principal requirements for such a framework in the application called Data Broker in Shell.

The Data Broker infrastructure has allowed Shell Engineers to perform exception-based surveillance. Used together with other Smart Fields applications such as FieldWare Production Universe, FieldWare Well Test, IPM and Energy Components, automated event recognition and workflows has freed up engineer's time to do more value added work, such as technical analysis and decision-making – time that would otherwise be spent looking for and validating data from many different sources. The system allows for a more efficient handling of data in terms of efficiency, quality and timeliness in reporting to end-users.

The advent of real-time algorithms, monitoring tools, better integration software, event and workflow application tools allows the above infrastructure to be realised.
Application-Appropriate Drilling Technologies Excel in Managed-Cost Mature-Asset Environments
Authors: Corson C. S. , Madarapu R. , Cerkovnik J. , Walters D. , Walton D.
Published: December 2007

Production in most wells follows a predictable pattern dictated by the decline curve. Initially high production is quickly followed by a long, measured decline. This potentially long decline in production, together with an ever-increasing demand for energy, has resulted in many mature, low production fields. To stem the decline in production in these wells and extend the viable economic life of these assets, operators are increasingly turning to advances in technology. Technologies such as improved slimhole re-entry drilling bottomhole assemblies (BHAs), enhanced reservoir navigation systems, and improved conventional drilling techniques are successfully meeting the challenges of developing mature fields in established oil and gas basins around the world. This combination of techniques and technologies is being used in the Williston Basin to increase the recoverable reserves and improve the present economic value of each asset.

Production from the Williston Basin declined from the time of its initial discovery through the early 1990s. The introduction of horizontal re-entry drilling technologies then revitalized this region.

Targeting these thin beds typically requires extending 4½-in laterals from existing or new vertical 7-in. cased wells. In the recent past, re-entry performance was confined by well placement restrictions, water and salt zones, and available drilling technologies. These requirements restricted the wellpath to relatively tight radius build sections. Together with the drilling difficulties associated with slimhole tubulars, these tight builds often resulted in high drag in the hole, limiting the lateral section to 3,000 to 4,000 ft due to weight transfer and drag constraints. However, in recent applications that did not suffer from such restrictions or the consequences of the water/salt formation hole instability issues, larger radius curves could be incorporated into the wellplan. This increased radius reduced drag in the well program, which together with improved motor technologies and experienced wellsite execution, allowed the 4½-in. re-entry section to achieve world record open slimhole multilaterals. The successful completion of such multilateral wells provide for over 10,000 ft of potential reservoir exposure in this thin bed.
Transport of Small Cuttings in Extended Reach Drilling
Authors: Duan Mingqin , Miska Stefan , Yu Mengjiao , Takach Nicholas , Ahmed Ramadan , Zettner Claudia
Published: December 2007

Field experience has shown that inefficient transport of small cuttings is a main factor for excessive drag and torque during extended reach drilling; however, very little is known about the transport behavior of small cuttings. In this study, extensive experiments with three sizes of cuttings (0.45 mm-3.3 mm) were conducted in a field-scale flow loop (8 in. × 4.5 in., 100-ft long) to identify the main factors affecting small cuttings transport. The effects of cuttings size, drill pipe rotation, fluid rheology, flow rate and hole inclination were investigated.

The results show significant differences in cuttings transport based on cuttings size. Smaller cuttings result in a higher cuttings concentration than larger cuttings in a horizontal annulus when tested with water. However, a lower concentration was achieved for smaller cuttings when 0.25 ppb Polyanionic Cellulose (PAC) solutions were used. Unlike the transport of large cuttings, which is mainly dominated by fluid flow rate, the key factors controlling small cuttings transport were found to be pipe rotation and fluid rheology. Improvement by pipe rotation in the transport efficiency of small cuttings is up to twice as large as the improvement in large cuttings transport. Compared with water, PAC solutions significantly improve smaller cuttings transport, while the transport of larger cuttings is only slightly enhanced.

Mathematical modeling was performed to develop correlations for cuttings concentration and bed height in an annulus for field applications. Predictions from a three-layer model previously developed for larger cuttings were also compared with experimental results. Differences (up to 80%) indicate the need for improving the frequently used three-layer model by including correlations specifically developed for small cuttings to get a better design of extended reach drilling. This study is also useful for horizontal or high-angle well drilling and completion through sand reservoirs.
Streamline Assisted Ensemble Kalman Filter for Rapid and Continuous Reservoir Model Updating
Authors: Arroyo-Negrete Elkin , Devegowda Deepak , Datta-Gupta Akhil , Choe J.
Published: December 2007

The use of the ensemble Kalman filter (EnKF) appears to be a promising approach for data assimilation and assessment of uncertainties during reservoir characterization and performance forecasting. It provides a relatively straightforward approach to incorporating diverse data types including production and/or time-lapse seismic data. Unlike traditional sensitivity-based history matching methods, the EnKF relies on a cross-covariance matrix computed from an ensemble of reservoir models to relate reservoir properties to production data. For practical field applications, we need to keep the ensemble size small for computational efficiency. However, this leads to poor approximations of the cross-covariance matrix and loss of geologic realism through parameter overshoots, in particular by introducing localized patches of low and high permeabilities. This difficulty is compounded by the strong non-linearity of the multiphase history matching problem. Specifically, the updated parameter distribution tends to become Gaussian with a loss of connectivities of extreme values such as high permeability channels and low permeability barriers which are of special significance during reservoir characterization.

We propose a novel approach to overcome these limitations by conditioning the cross-covariance matrix using information gleaned from streamline trajectories. Our streamline-assisted EnKF is analogous to the conventional assisted history matching whereby the streamline trajectories are used to identify grid blocks contributing to the production response of a specific well. We then use these grid blocks only to compute the cross-covariance matrix and eliminate the influence of unrelated or distant observations and noisy calculations. We show that the streamline-assisted EnKF is an efficient and robust approach for history matching and continuous reservoir model updating. Our approach is general, suitable for non-Gaussian distribution and avoids much of the problems in traditional EnKF associated with instabilities, overshooting and the loss of geologic continuity during model updating. We illustrate the power and utility of our approach using both synthetic and field applications.
Study on Reorientation Mechanism of Refracturing in Ordos Basin—A Case Study: Chang 6 Formation, Yanchang Group, Triassic System in Wangyao Section of Ansai Oil Field
Authors: Li Peichao , Song Zhenyun , Wu Zengzhi
Published: December 2007

The essence of fracture reorientation of refracturing is rock failures. Therefore, the study on reorientation mechanism should be started from studying rock failures, taking the influences of objective and subjective factors such as reservoir microfracture distribution, geostress field, rock mechanics characteristics, physical properties and the methods of well-completion, injection/production, hydraulic fracturing technology upon fracture reorientation into account.

As a result, the conditions that rock failures occur were analyzed, thus the theory criteria for fracture reorientation was given, namely the critical bottomhole pressure required and the conditions which the geostress field and rock mechanics parameters should have. The new fractures are divided into shear fractures and tensile fractures, which correspond respectively to the two kinds of rock basic failure mechanisms-shear failure and tensile failure. The azimuths of these two kinds of fractures are both different from the initial hydraulic fracture (abbr.IHF), and the critical pressure is the function of the geostress field and rock mechanics parameters. Based on the above criteria, utilizing the refracturing data of Chang 6 formation, the feasibility of fracture reorientation for Wangyao section was investigated. And three typical wells were analyzed in details, which show the refracture characteristics we predict accord with that of microseismic monitoring or the curve of the treating pressure.

It indicates that even if the geostress field keeps unchanged, fracture reorientations can be achieved by other ways.

In the certain range of parameters for reservoir physical properties, if a proper fracturing technology, such as TSO (i.e. Tip Screen Out) with temporarily blocking treatment (abbr.TBT), can be applied so as to create the treating conditions that meet the demand of the above criteria, the refracturing can produce new fractures in Wangyao.

And for refracturing treatments, with the shot holes along the IHF azimuth blocked effectively, multi-fractures and new fractures can be achieved by oriented perforations.
Steerable Motors Hold Out Against Rotary Steerables
Authors: Warren T.
Published: December 2007

A decade after field testing the first modern rotary steerable systems, steerable motors still command more than 80% of the directional drilling market. While rotary steerable systems offer a significant technical advantage over steerable motors and provide an enabling technology for many wells, economic forces may moderate their current high growth rate. The realities of balancing system performance, directional program complexity, cost, and risks often dictate bypassing this "latest and greatest" technology.

Evolutionary improvements in steerable motor power, reliability, and operational techniques have allowed them to maintain a healthy competition with the more capable, but more expensive, rotary steerable systems. Operators encourage service companies to provide less costly rotary steerable solutions, but for the short term, the best solution for many wells is still to use the old tried and true steerable motors.
Guidelines to Successful Dewatering of CBM Wells
Authors: Bassett L.
Published: December 2007

Introduction

Pumping water from a well is a straight forward effort that has been done for centuries. Pumping fluid from relatively shallow wells should be an easy task. Normally a pump is installed in a well, started and then forgotten. This premise does not hold true in CBM wells. In CBM wells, this pumping process can be complicated by many issues unless precautions are taken. This paper is designed to address the basic precautions that can be taken to improve de-watering of CBM wells. These precautionary steps can save the operator money by reducing the month to month maintenance associated with CBM wells. Although we cannot cover every potential pitfall to de-watering operation, the basic steps discussed will identify potential problems and offer ideas to address them.

Well Planning for Artificial Lift

The successful de-watering of CBM wells, especially Coal Bed Methane (CBM) wells takes some planning before the first well is dilled. Many factors should be taken into consideration so that the operation can be economical for the entire life of the well. Unconventional gas has gone from an experiment to a logical and viable energy source. Pre-planning can and will reduce the overall cost of operation over the life of a CBM well. Short cutting the pre-planning stage can often take perceived savings in well drilling costs and transfer these costs to much higher day to day maintenance costs and lower gas production, thus decreasing the economics of the play. The learning curve has been steep for operators and suppliers as well as we all try to find solutions to the many challenges that face the industry.

The first step is to identify the type of coals to be de-watered by asking these questions. Are the cleats in the coals easily fractured? How thick are the coals? Do the coals contain sand, clay or other solids that could interfere with pump operations? Are their multiple coal zones and what kind of material separates the zones? Are their other CBM wells producing from the same formations and what problems have they encountered? Pre-planning will reap benefits in lower operating costs and maintenance and higher profitability for the operator.
KPIM of Gas/Condensate Productivity: Prediction of Condensate/Gas Ratio (CGR) Using Reservoir Volumetric Balance
Authors: Olaberinjo A. F. , Oyewola M. O. , Adeyanju O. A. , Alli O. A. , Obiyemi A. D. , Ajala S. O.
Published: December 2007

Accurate forecasting of condensate well deliverability usually requires good knowledge of the gas condensate vapor – liquid properties. Condensate well deliverability is particularly important as it impacts downstream issues such as the number of wells required, surface gas handling facilities, drilling schedules and income from gas sales contracts.

A new approach for forecasting viability of gas condensate wells and calculating condensate gas ratio (CGR), using simpler techniques is presented. The calculation uses a volumetric balance model for reservoir system, standardized and modified correlations, equation of state and a vapor-liquid equilibrium technique. The technique has been extended to include mass transfer and also to allow for the changes in produced fluid composition due to the formation of the condensate bank.

The approach will provide a useful tool for rapid forecasts of condensate well performance, for examining the effects of condensate blockage in different well types or for studying sensitivities. It is also valuable where simple models of condensate reservoir performance are required for use in integrated studies.
An Applied Mathematics Method of Formalizing the Comprehensive Approach to the Evaluation of Reservoir and Well Completion Characteristics
Authors: Spivak S. I. , Yulmukhametov D. R.
Published: December 2007

The determination of petrophysical properties of oil reservoirs is complicated by the limited volume of investigation of the heterogeneous object under study (about 10−6 of the total volume) and the indirect nature of the information obtained. For each property several ways of determination exist, giving values differing sometimes by 1–2 orders of magnitude. One of the principal causes of such discrepancy is the that the problems of property determination using conventional methods are ill-set.

The issues of solving ill-set problems are investigated in the special mathematical theory, which has a lot of applications in natural science generally and in petroleum science in particular. Many problems of reservoir characterization and simulation are ill-set as well; a priori information and multicriterial approach are used in there solution. These are very complex problems, for example, flow model history matching and seismic interpretation. However, the formal multicriterial approach is not well developed with respect to relatively simple tasks of geology, petrophysics and reservoir engineering, such as permeability determination from well logging data, and others. The purpose of this work is the formalization of comprehensive approach to the solution of such problems.

The problem of determining the well permeability profiles from well logging data using statistical relationships based upon core analysis data with a priori information incorporation is investigated in detail. The additional criteria options and ways of their application are considered. The setting and solution of a two-criterial problem of determining permeability from well logging data, care analysis data and well test data on a real West-Siberian filed is provided.
System Approach to Hydraulic Fracturing Optimization in Rosneft Oilfields
Authors: Timonov Alexey V. , Zagurenko Alexey G. , Hasanov Mars M. , Pasynkov Andrey G. , Afanasiev Igor S.
Published: December 2007

Nowadays hydraulic fracturing is the most successful well simulation technique, which provides a multiple increase in production and increase in effectiveness of low-permeability reservoirs development. In connection with the significant potential and, at the same time, the complexity of this type of stimulation treatment, creation of the integrated system of planning and optimization of hydraulic fracturing business-process is necessary.

The optimization of fracturing treatment design is one of the highest priority directions of integrated system. The significant number of scientific works about optimization of fracturing design is mainly dedicated to optimization of fracture parameters for creating minimum skin - factor with the defined proppant mass. At the same time, while selecting an optimum proppant mass, until now they most frequently rely only on the old proven trial-and-error method, and the diversity of specialists' opinions varies in the very broad range - from the conservative designs with the minimum volume of proppant to the aggressive designs on the possibility frontier of contemporary technology.

At the same time, the new level of technology development makes possible conducting large-volume hydraulic fracturing treatment, for successful realization of which the more careful study of the effect from different characteristics is required, including technological risks. For example, even now inside the Company there is an experience of conducting fracturing jobs up to 400 tons of proppant.

Analysis of fracturing treatments, carried out by different service companies, confirms that with a notable increase in the proppant mass absence of integral approach leads to reduction in the fracturing treatment effectiveness. First of all, this is caused by the ineffective use of a substantial part of injected proppant while conducting large-volume hydraulic fracturing.

Therefore, the need for solution of the following multiparameter problem is obvious: optimization of the mass of proppant under maximization of economic effectiveness and consideration of technological and geological risks.

The article shows the solution of this problem on the basis of integral approach using integrated technical and economic optimization of hydraulic fracturing design in Rosneft. Also the integrated system of hydraulic fracturing planning and conducting is presented. It made possible to increase considerably the effectiveness of hydraulic fracturing in the company.
A System Approach to Vankorskoye Oilfield Development Planning
Authors: Antonenko D. A. , Islamov R. A. , Stavinsky P. V. , Yatsenko V. M.
Published: December 2007

Rosneft Oil Company actively develops its resource base and increases oil production. Therefore, great attention is focused on the development of geologically complicated oilfields. The Vankorskoye project that has major priority for Rosneft is a striking example of such fields.

To increase efficiency of oilfields development within Rosneft Oil Company a unified design system including all stages of development – from development prospects to development monitoring – has been created. Within the system a multidiscipline workgroup has been created for designing Vankorskoye oilfield development, which is able to react actively on new information and to adapt flexibly design solutions to the new conditions. Main results of this group are design solutions considering the application of new technologies and increasing sufficiently the development efficiency.

New technologies of field prospecting and modeling are widely applied in development of the Vankorskoye oilfield that allows designing field development and decreasing risks. An application of spectrum-velocity forecasting technology at the stage of seismic data interpretation allows defining exactly reservoir properties with a small number of exploration wells. Techniques of geo-stochastic modeling reflecting heterogeneity of reservoir properties are used in geological model building.

New technologies allowing increasing oil recovery, optimizing oil production rates and decreasing field development costs are used in project design. Use of gas reinjection provides decrease of environmental damage, maintenance of reservoir pressure and increase of oil recovery. Modern techniques of well construction and operation (horizontal wells with long horizontal length and intelligent completions) significantly increase field development effectiveness.

The article below describes base elements of the Vankorskoye oilfield design system, as well as the work results and prospective of sharing experience for other Company's field development.
Re-activation of Multilayer Oil Field Development at the Late Stage of Production
Authors: Diyashev R. N. , Nurislamov N. B. , Voronovsky V. R. , Senochkin P. D. , Khussainov V. M. , Vildanov A. A.
Published: December 2007

Majority of the largest Russian oil fields are at the stage of depleting active resources. A problem of reactivating development of the marginally profitable old oil fields is becoming increasingly vital due to decrease in discovering of new large oil deposits. This is also witnessed by the worldwide experience of the oil industry development.

One of the major problems of the late stage development of the multilayer oil fields is a task of identifying accumulations of residual oil deposits and substantiation of geological and technical activities for the purpose of their maximal recovery.

The example of horizon D1 productive sediments in Block III of Romashkiskoe oil field Pavlovskaya area has served as a basis for implementing a set of activities to increase the effectiveness of developing a multilayer oil field at the late stage of operation, including re-interpretation of the primary geophysical data, re-appraizal of the initial oil in place, analysis of the development status, identification of areas containing residual oil reserves and justification of activities aiming to involve such reserves into the drainage process as well as analysis of all the works performed effectiveness.

The results of the works performed allowed adding recoverable oil reserves by 3.89 %, optimizing the formation and the bottomhole pressure values through water injection and product withdrawal and during the five year period allowed to additionally produce 599.1 thousand tons of oil accounting for 55.5% of the total oil production within the block during the period under consideration.

By the beginning of the re-activating activities implementation the production watercut amounted to 88.6 % with the current oil recovery factor amounting to 44.3 %.
Successful PDC/RSS Vibration Management Using Innovative Depth-of-Cut Control Technology: Panna Field, Offshore India
Authors: Jaggi Anil , Upadhaya Sunil , Chowdhury Ashabikash Roy
Published: December 2007

The operator has been active in Panna field for several years drilling a main horizontal and two laterals through a window milled in pre-existing 9-5/8" casing. The laterals vary in length between 800m to 1600m, depending on the carbonate reservoir's constraints. However, interbedded formations with contrasting hardness had the potential to cause stick-slip and lateral vibration.

Initially, the operator utilized RSS/MWD to geosteer the BHA within the target formation. However, previously chosen PDC bits caused severe lateral vibrations, stick slip and BHA whirl that resulted in multiple downhole tool failures. It appeared new PDC technology was required. An in-depth study revealed the BHA was exposed to severe stick-slip and lateral vibrations. There were also regular instances of BHA whirl and severe acceleration and deceleration caused by stick-slip.

To enhance overall bit/BHA stability, a new-style 8-1/2" PDC was implemented with innovative depth-of-cut control (DOCC) technology and enhanced stability features. BHA design was also reviewed and minor changes were implemented. The result was a significant reduction in stickslip, lateral vibration and BHA whirl. The new PDC/RSS set a new national Indian record for the longest 8-1/2" offshore section making 3956m of hole in a single run. The bit has since successfully drilled several multilateral drainholes in a single run proving the reliability of the new PDC design and enabling technology. The authors will present the vibration signature of a standard PDC versus the new one with DOCC. The authors will discuss proper RSS/PDC bit selection and demonstrate the benefit of DOCC/PDC on RSS when applied in high angle/horizontal wells.
Using the Technology of Intercepting To Take Precautions Against the Spread of the Worms in Intranet
Authors: Huifeng Tian , Jingxin Xu , Shubo Cai
Published: December 2007

With the wide application of the network the traditional virus spreading through the file has already left the leading post and the worms spreading automatically through the network suddenly become the mainstream of the virus. The worms spread all over the whole world within less than one day by utilizing hole of the operating system or application software what cause the network to slacken even paralysed. Because there are many nodes of networks in the intranet, and most users are not the professional personnel of the computer, it is no doubt important to train users their network security consciousness; but if we can find and isolate the computer which propagate the worm in time, we'll ensure the normal running of the network. The article recommended a method using the network interception technology to detect the worms according to the spread mechanism of the worms.
Drilling in High-Density and Thin-Pressure-Windows Complex Formation
Authors: Jia Guoyu , Zhang Lisheng , Duan Yongxian
Published: December 2007

Super-high pressure gas fields in Tarim Oilfield mostly lie in the area of Tianshan mountains. the upper cap rock of these gas fields is salt gypsum formation which is deeply imbedded, this salt gypsum formation contains not only many different pressure systems but also soft mudstone and salt-water bed with super-high pressure, 80 percent of all accidents and complex situations take place in this section. Tarim Oilfield arranges well Dina-11 in Dina structure in order to change this adverse situation; all results and achievements during drilling operation are as follows:

Drill through salt gypsum formation about more than 1,000 m, and salt-water bed with super-high pressure Drill through two low pressure formation with under balanced drilling technology Perform 16 times of blocking leakages operation with high density drilling fluid successfully Perfect well control technology for super-high pressure gas reservoir Find Dina gas field finally

Consummate the drilling technology for Shanqian structure and reduce the possibility of accidents and complex situations, quicken the speeds of exploration and development through drilling operation in well Dina-11
Study on Forming Conditions of Condensate Gas Reservoir in Deep-Seated Formation in Dongying Sag
Authors: Fenggui Sui , Guozhen Chang , Wenlin Wang
Published: December 2007

By the analysis of the composition, the phase and the carbon isotope characteristics of the natural gas, It reached that the natural gas reservoir of Fengshen 1 of the lower section of the forth strata of Shahejie Formation, buried underground 4300m approximately, is a secondary condensate gas reservoir, as well as an indigenously generating and accumulating gas reservoir which source rock is the dark mudstone within the salt-layer of the lower section of the forth strata of Shahejie Formation. The synchronous conglomerate fan-body and the abnormal high-pressure zone, which occur in their hanging walls of the major faults in the north of Dongying Sag, are the favorable conditions for petroleum accumulation and preservation. The thick rock gypsum deposited on the conglomerate fan-body is the best cap rock. The appropriate pressure and temperature condition determinate the formation and the preservation of the condensate gas reservoir. In Dongying period, the source rock of the lower section of the forth strata of Shahejie Formation stepped into mature stage and a great quantity of petroleum was generated and migrated laterally into the conglomerate fan-body and accumulated as a pool finally. In Quaternary Period, the petroleum in the pool was cracked into condensate gas because of the rising of pressure and temperature. In one word, the deep strata of Dongying Sag, even Jiyang Depression will be the most important domain of condensate gas reservoir exploration of Shengli Oilfield.
Studies and Application of Slag-Blocking Agent for Steam-Injection Reservoir
Authors: Pan Jingjun , Weibin Deng , Zhuofei Wang
Published: December 2007

With the technique of steam flooding widely used in heavy oil recovery in Xinjiang Oilfield, a noticeable steam channeling mainly caused by the heterogeneity of the reservoir and the steam overlay has been observed, which in most cases can result in a rapid increase of water cut and even in a direct production of steam in the wells. To enhance the utilization of the steam and heavy oil recovery, this work puts forward the technique of slag blocking agent for steam injection reservoir.

Based on the compositions and properties of industrial slag with silicate as the main component, the activation system, the high temperature retardant and the suspension system have been developed accordingly. The systematic investigations have been carried out on such properties of blocking agent as suspension stability, injection characteristic, initial setting time, thickening process and setting strength. The high-temperature blocking agent developed is of characteristics of better stability, easy preparation, low cost, controllable setting time and convenient in-situ operation. The field experiments were further conducted by applying the blocking agent to the selected 4 wells with observable occurrence of steam channeling in the steam injection heavy oil reservoir. The results show that the blocking agent has an excellent ability to plug the gas-channeling path, thus mitigating the steam channeling and expanding the sweep of injection steam. The good results of an increase of 3,776t oil production and a reduction of 1.5×104m3 water production have been obtained eventually.
A New Methodology on Reservoir Modeling in the Fracture-Cavity Carbonate Rock of Tahe Oilfield
Authors: Liu Xueli , Yang Jian , Li Zongyu , Wang Yang
Published: December 2007

Tahe, one of the largest scale oilfields which are discovered in western China recently, in which Ordovician carbonate as the main storage, characterized with deeply embedding and various storage type, mainly are cavities and fractures. It is difficult to describe as its serious heterogeneity and there is rare technical reference regarding the reservoir modeling methodology.

Commonly, the geology modeling is based on well logging and seismic data, and the stochastic method is reasonable applied. However, Tahe oilfield has very limited seismic data and poor well logging interpretations, especially for the fracture-cavern section. Furthermore, as it is controlled by paleukarst, the stochastic geological method, which is widely used in the ordinary sedimentary, is unacceptable to Tahe. The volumetric reserves calculation, which is suitable to sandstone but is not applicable to the fracture-cavity reservoir either, as it can not be proved in the severe anisotropy fracture-cavity carbonate formation. Furthermore, the concept of porosity and saturation is less meaningful in this kind of reserves. As a result, there is no applicable modeling method to describe the geological characters of the Tahe carbonate reservoir.

A new methodology which is characterized by the fracture-cavity volume is presented in this paper. Accordingly, a new reservoir modeling and a new reserve calculation is built up. Mainly from geology, combined with static and dynamic data, a quantified 3-D reservoir model of Ordovician reservoir is formed, and this modeling methodology is proved practically by the results of history match from the streamline numerical simulation. The result will technically support the exploitation of Tahe oilfield.
The Study and Application of Hydraulic Fracturing and Acidizing in Exploration Wells in China
Authors: Lei Qun , Ding Yunhong , Jiang Tingxue , Xu Yun , Song Shemin , Liu Yanxue , Liu Yincang , Cai Bo , Duan Yaoyao
Published: December 2007

The characteristics of exploration zones in China in recent years are summarized as: 1) Special lithology such as volcano and clay-carbonate, etc. 2) low porosity and ultra-low permeability; 3) Complex storage types and fluid flow mechanics as a result of natural fractures distributed stochastically; 4) Special in-situ stress and loss characteristics; 5) complex rock mechanics and elastic-plastic traits; 6) Undetermined fracture height growth; 7) complex stress sensitivity. Therefore, a systematic technologies are put forward in the paper, the highlights are: 1) Systematic formation fine evaluation which contains Nuclear Magnetic Resonance, Constant Rate Mercury Injection and so on; 2) Low damage fracturing fluids such as super grade Guar fracturing fluid and its combination with liquid nitrogen, low cost VES(less than 300 RMB below 90 ° C), low polymer concentration fracturing fluid and linear gel, and variable viscosity is utilized in different treatment stage; 3) Different type and diameter proppants are used in one treatment job, and the combined ratio is optimized; 4) A new method of multiple stage optimization is put forward to ensure not only the success of stimulation treatment but also the maximal post-treatment performance; 5) Counter measures are applied systematically such as two combinations of pumping rate and viscosity to control loss and multiple fractures, fracture height control, systematic quality control and post-treatment management, etc. What's more, above technologies have been put in to field applications in more than 39 wells in the year of 2005, and the result is satisfied with the newly increased oil reserves being greater than 1×108 t, gas reserves greater than 800 × 108 m3. Consequently, it has a great significance in China's main exploration zones, in the mean time, it also has a great benefit of economy and hydraulic fracturing and acidizing themselves.
The Reservoir Simulation Research and Extending Application About Cyclic Water Injection
Authors: Yaozhong Yang , Tao Dai , Chengfeng Wang
Published: December 2007

In this paper, reservoir simulation model is built so that the geological characteristics of West region in Gudao oilfield, which has entered into very high watercut development period, are described finely. Then, the production history of about 20 years was matched. Base on the exact geological model built through history match, the remaining oil distribution and cyclic waterflooding mechanism was studied systematically. The research achievements can be taken as reference for the similar reservoirs which have entered into high or very high watercut development period and have improved development effects of different types of reservoirs after field application.