bluuebunny/crossref_metadata_2025 huggingface dataset:
New Representative Curves for Gas Lift Optimization
Authors: Salazar-Mendoza R.
Published: December 2007

The typical GLR sensitivity curves for gas-lift design and optimization are obtained for a constant wellhead pressure when the system sensitivity study is for a single well system and for a first-stage separator pressure or fixed pressure when the system sensitivity study is for a complete surface production network modeling.

In this paper a production analysis for a six gas-lifted wells system with a new representative curves for gas-lift optimization is presented. These new representative curves were obtained for the complete surface production network modeling that links the well models with the surface network model. Two cases are analyzed: 1) All the six wells are operating and flowing simultaneously and 2) Only one well is operating and flowing alone. The representative curves for each case analyzed were compared with the typical GLR sensitivity curves. The results show that the representative curves are in a better agreement with the profile of measured data.
Overbalanced Perforating Yields Negative Skin Values in Layered Reservoir
Authors: Pizzolante Italo , Grinham Steve , Xiang Tian , Lian Jihong , Khong Chee Kin , Behrmann L. A. , Mason Steve
Published: December 2007

China National Offshore Oil Corporation (CNOOC), Chevron, and ENI, the field operator, are partners in the development of the HZ oil and gas fields, operating as the CACT Operators Group (CACT) in the South China Sea. The HZ fields are stacked, thin, high-permeability sandstone reservoirs interlayered with low-permeability layers. The shallower layers generally have better permeability and were developed first while the deeper, lower-permeability reservoirs have been developed more recently.

The lower-permeability reservoirs are generally of lower porosity and higher compressive strength. Drilling-mud-filtrate invasion also tends to be deeper. Deep-penetration perforating charges are required to perforate past the damaged zone. Experience indicates that underbalance perforation provides better productivity compared to overbalance perforation.

Although conventional underbalance perforation can be performed using pipe-conveyed or tubing-conveyed perforation (TCP), depth uncertainties and the time requirement for TCP service in thin reservoir zones makes wireline-conveyed perforation an attractive method. However, where multiple zones must be perforated, the conventional wireline approach can only perforate the first zone underbalance (with the completion fluid weighted accordingly) while subsequent zones could only be perforated balanced at best.

A new perforating system, designed to generate a large dynamic underbalance with a static overbalance, was used to perforate new wells for the development project to maximize well productivity per well expenditure.

A multilayer production evaluation of one of the wells perforated with the dynamic underbalance method produced a zero skin value in the 9-md layer and a −0.97 skin value in the 1600-md layer. Conventional underbalanced perforation, employing multiple wireline runs, could not achieve these low skin values over this wide range of permeabilities.
Organically Crosslinked Polymer System for Water Reduction Treatments in Mexico
Authors: Vasquez J. , Jurado I. , Santillan A. , Hernandez R.
Published: December 2007

This paper presents the application of an organically crosslinked polymer (OCP) system, a system widely used in the oil industry for water shutoff applications. The OCP system is based on a copolymer of acrylamide and t-butyl acrylate (PAtBA) crosslinked with polyethyleneimine (PEI). To date, about 100 jobs have been performed with this system in Mexico to address conformance problems such as: Water coning/cresting.High-permeability streaks.Gravel pack isolation.Fracture shutoff.Casing leak repair.

This paper presents an overview of case histories that used OCP in various regions of Mexico for a wide variety of applications. In particular, a case history of an offshore well treated with the OCP is presented. A direct comparison of the application of the OCP with conventional cement squeeze treatments is presented to illustrate the advantage of having a deep matrix penetration for a more efficient water shutoff. In addition, data presented in this paper indicate the development of a retarder that allows the upper placement temperature of the OCP system to be raised to at least 350°F. The upper placement temperature of the system originally was ~260°F.
A Multiple-Continuum Approach for Modeling Multiphase Flow in Naturally Fractured Vuggy Petroleum Reservoirs
Authors: Wu Yu-Shu , Qin Guan , Ewing Richard E. , Efendiev Yalchin , Kang Zhijiang , Ren Yulin
Published: December 2007

The existence of vugs or cavities in naturally fractured reservoirs has long been observed. Even though these vugs can be largely attributed to reserves of oil, natural gas, and groundwater, few investigations of vuggy fractured reservoirs have been conducted. In this paper, a new multiple-continuum conceptual model is developed, based on geological data and observations of core samples from carbonate formations in China, to investigate multiphase flow behavior in such vuggy fractured reservoirs. The conceptual model has been implemented into a three-dimensional, three-phase reservoir simulator with a generalized multiple-continuum modeling approach. The conceptual model considers vuggy fractured rock as a triple- or multiple-continuum medium, consisting of (1) highly permeable fractures, (2) low-permeability rock matrix, and (3) various-sized vugs. The matrix system may contain a large number of small or isolated cavities (of centimeters or millimeters in diameter), whereas vugs are larger cavities, with sizes from centimeters to meters in diameter, indirectly connected to fractures through small fractures or microfractures. Similar to the conventional double-porosity model, the fracture continuum is responsible for the occurrence of global flow, while vuggy and matrix continua, providing storage space, are locally connected to each other (and interacting with globally connecting fractures). For practical application of the multi-continuum concept in reservoir simulation, we propose a novel upscaling method for computing equivalent gridblock permeabilities of coarse blocks containing large isolated vugs, in which the local problems consisting of Darcy and Stokes flows are solved. In addition, we describe an efficient boundary condition for accurate computation of upscaled permeabilities. In the numerical implementation, a control-volume, integral finite-difference method is used for spatial discretization, and a first-order finite-difference scheme is adapted for temporal discretization of governing flow equations in each continuum. The resulting discrete nonlinear equations are solved fully implicitly by Newton iteration. The numerical scheme is verified and applied to simulate water-oil flow through the fractured vuggy reservoirs of the Tahe Oil Field in China.
Percussion Drilling: From Laboratory Tests to Dynamic Modeling
Authors: Han Gang , Bruno Mike
Published: December 2007

Percussion drilling has long been considered an effective approach to breaking rock in the civil and mining industries. A large number of air hammers were introduced to oil and gas industries in the 1980′s. However, limited fundamental understandings of the physical mechanisms involved in percussion drilling hinder its acceptance and applications.

In a 2-year research effort, fundamental rock physics are investigated through a series of lab tests, including single impact tests and full-scale hammer drilling tests. For each impact test, three impacts are sequentially loaded at the same rock location to investigate rock response to repetitive loadings. Besides crater depth and width, the displacement and force in the rod and the force in the rock are recorded at 100K Hz frequency. For hammer drilling tests, an industrial fluid hammer is used to drill Berea sandstone and Mancos shale under both underbalanced and overbalanced conditions. The bottom hole pressure varies from 3.5MPa to 20.7MPa while pore pressure is controlled separately, varying from 0MPa to 24.2MPa. During these tests, Rate of Penetration is recorded continuously from one pressure condition to another. Cuttings are then screened, collected, and analyzed.

The lab data are then used to calibrate a 3D drilling simulator developed specifically for percussion drilling. First a strain-softening rock material model is derived from matching rock stress-strain curves in a series of rock mechanical tests. Then a stress history is specified as loading conditions based on the stress and displacement data recorded in the impact rod. With appropriate material model and boundary conditions, both rock displacement and indentation geometries are well matched. Further, the simulation reveals in detail how rock becomes defragmented when receives impact. These developments improve the fundamental understandings of rock physics involved in hammer drilling. The 3D drilling simulator can also be applied to investigate rock breakage and optimize operations in field.
The Effect of Well Trajectory on Horizontal Well Performance
Authors: Bond A. , Zhu D. , Kamkom R.
Published: December 2007

Horizontal wells provide extended contact with the reservoir, and have unique advantages over vertical wells in many applications. As nominally horizontal wells get longer and follow more complicated trajectories, wellbore hydrodynamics becomes an important issue on well performance. In this paper, we will discuss a problem in horizontal wells - the elevation change in well trajectory and its effect on well performance. In general, a horizontal wellbore is never perfectly horizontal. The inclination angle could be a result of drilling control, or sometimes could be designed on purpose for an extremely anisotropic formation. When vertical permeability is much smaller than horizontal permeability, an undulating wellbore may be favorable to overcome the low vertical permeability. Undulation in wellbore trajectory will change the inflow distribution along the wellbore, and therefore change the wellbore performance. When two-phase flow is involved, especially gas-liquid flow, the pressure distribution in the wellbore may cause flow problems, such as trapping gas because of accumulated liquid at low spots. We use a simple analytical model to examine the flow conditions for inclined or undulated horizontal wells. The reservoir inflow is interactively coupled with the wellbore flow, and the pressure and flow rate distribution are predicted by the model.

The model then is used to analyze the development plan for the Cosmopolitan field in Alaska. The field has stress-dependent permeability, and the vertical permeability is much lower than the horizontal permeability. The results of the model explain the effect of wellbore trajectory on well performance of horizontal wells, and justify the benefits of undulating wellbores in horizontal well development in this low vertical permeability reservoir. The study showed that undulating wells in the Cosmopolitan field can help to improve well productivity.
Lasers: The Next Bit
Authors: Pooniwala Shahvir
Published: December 2007

Since the early twentieth century rotary drilling has revolutionized the procedure of extraction of crude oil replacing conventional methods like cable tool drilling. However with the advent of new technology it is time to look at future alternative, more efficient drilling methods.

This paper acts as an eye opener to the feasibility of using laser drilling over modern currently used drilling techniques.

The design and operation of a new laser-mechanical bit is put forth by the medium of this paper. This innovative bit shows probability of reducing rig time and increasing efficiency in drilling.

The possible changes to be implemented in the present day drill string due to incorporation of this new bit is accounted for and an analysis of the possible advantages and disadvantages of this bit if implemented is also highlighted.
Smart-Well Completion Utilizes Natural Reservoir Energy to Produce High-Water-Cut and Low-Productivity-Index Well in Abqaiq Field
Authors: Al-Otaibi Nashi M. , Al-Gamber Abdulwafi A. , Konopczynski Michael , Jacob Suresh
Published: December 2007

Innovations and smart well technology applications have helped overcome the challenges of complex and mature fields such as the Abqaiq field. This paper presents the application of smart well technology in utilizing "free energy" from an overlying gas cap to produce high water-cut and low productivity wells completed in underlying reservoirs.

The smart well completion was implemented in Abqaiq field to naturally gas lift an intermittent well (a well which cannot continuously flow to the surface), completed in the low permeability Hanifa reservoir. The well is drilled through the gas cap having 40 ft of gas column in the upper section of Arab-D reservoir. In this application, the smart well completion consists of a surface controlled, hydraulically operated downhole choke valve that regulates the gas inflow from the gas cap into the production tubing. This application eliminates the need for artificial lift infrastructure at the surface and operational expenditures. Using gas cap energy basically is providing free energy. This paper discusses selection criteria of smart well application to naturally lift an oil producer by utilizing energy from an overlying gas cap, completion & operation experiences and production optimization. Results show the applicability of natural gas-lift dependent upon standoff (with respect to the initial gas-oil and water-oil contacts) and target production rate. The paper addresses design considerations for natural gas-lift applications and report the operational experience gained in the Abqaiq field with gas-cap gas-lift applications.
Tubing Buckling—The State of the Art
Authors: Mitchell R. F.
Published: December 2007

Almost unique in engineering analysis is the problem of tubing buckling in wellbores. In general, structures loaded above their critical load fail catastrophically. Yet, both tubing and drillstrings are commonly operated above the critical load. These tubing strings do not fail because the wellbore provides the necessary support for "post-buckling" equilibrium.

The two fundamental questions about tubing buckling are:

What is the critical load?

What is the post-buckled configuration?

The critical load tells us if the tubing will buckle. Euler solved the problem for "short" columns, but these results rarely have application in a wellbore, because the pipes are usually very long1. The first stability criterion which considered the stabilizing effect of weight on long pipes in inclined wellbores was developed by Paslay and Dawson2.

The post-buckled configuration tells us about tubing movement, bending stresses, contact forces, and axial load distributions. The original buckling analysis by Lubinski and Woods3 proposed a helical configuration in a vertical wellbore, and used the method of virtual work to determine a specific constant pitch for that helix, as a function of the axial force and bending stiffness.

These two works set the following themes for further analysis of tubing buckling:

What is the critical buckling load in curved, three dimensional wellbores? How does torque affect the critical buckling load? How do tapered strings affect the critical buckling load? What is the buckling configuration in inclined wellbores? How do the boundary conditions affect the configuration? How do tapered strings buckle? How does torque affect the buckling configuration? What effect does friction play in tubing buckling?

Many of these questions have been, at least, partly answered in the three decades since the original papers were published. This paper will examine the technical fundamentals of the tubing buckling problem, summarize the most useful new results from these papers, and discuss the remaining challenges in tubing buckling analysis.
Oil and Gas Industry Partnership With Government to Improve Cybersecurity
Authors: Aubuchon Tom , Susanto Ivan , Peterson Brian T.
Published: December 2007

The Oil & Gas industry faces common challenges in securing its process control systems. These SCADA and DCS systems are critical to the industry because they control the operations of oil fields, pipelines and refineries. These systems are also critical to a nation's infrastructure and are essential to its national security, public safety, economic well-being and way of life. Within a critical infrastructure environment, addressing security is a shared problem that needs to be addressed collaboratively. Until now, little progress had been made to address this issue from an industry-wide standpoint.

Linking Oil & Gas Industry to Improve Cyber Security (LOGIIC) is a partnership of the Oil & Gas industry with the U.S. Department of Homeland Security (DHS). This partnership brings together the best resources from participating industry members, government, and the research community. The LOGIIC correlation project represents the first time a public-private collaborative model has been implemented to address a critical Oil & Gas industry research and development issue in cyber security. This partnership resulted in innovative improvements being made to cyber security on process control networks.

This paper describes the LOGIIC model and explains how industries can work together with government and process control system and security technology vendors to address common challenges. Details of the project are discussed, including: how the testbed was created; what attack scenarios were developed and implemented; and how actual process control activities were simulated in a lab environment. It also describes the lessons learned from the partnership and our future plans to collaborate with government on cyber security issues.

NOTE: Substantial portions of this paper are from various LOGIIC documents and presentations. Some images and portions of this paper have already been presented at LOGIIC meetings and other related conferences, and may be included in future presentations or publications.
Pipeline Corrosion: Its Remote Detection and Corrosion Management
Authors: Sinha Manish Kumar
Published: December 2007

The recent failure of a buried onshore 18C" refinery pipeline coated with FBE recites the ferocious consequences of corrosion problem. Situation will be even worrisome in case of marine environment where the entire aquatic life will be endangered. The critical zone prone to severe corrosion in offshore is transition area between riser thick coatings & atmospheric paint system where accelerated corrosion may occur.

ISO 13623 established by ISO TC 67/SC2 deals with the design, construction, inspection and maintenance of pipelines used in oil industry. Corrosion management includes evaluation of corrosion, corrosion prevention, corrosion monitoring, periodic inspection & re-qualification of the pipeline& tubing.

Intelligent Pigs and Remote Sensing Equipments can be used for estimation of corrosion. Intelligent pigs give the inner profile of the pipeline and run from one end to the other, however are costly affairs and are avoided. Remote sensing equipment essentially consists of infrared camera, video camera, laser spectrometer and global positioning system. Simulation of the readings gives the insight of the pipeline corrosion status and location of leakage. Working principle is temperature diminution, transmittance and thermal contrast of oil spot.
Comparison of Various Approaches to Near-Surface Impact Correction for Seismic Data Obtained in Permafrost Environment
Authors: Kuznetsov V. I.
Published: December 2007

The main gas condensate and oil bearing fields are concentrated within the polar area of Western Siberia. The target depth varies from 900 m for Cenomanian gas deposits up to 4000 m for Upper-Middle Jurassic oil, gas and gas condensate sediments. The target structure is very complex that is why 2 and 3D seismic survey is required to explore the fields. However, seismic survey is complicated by environment.
Efficiency of Bottom-Hole Heaters for Gas Hydrate Dissociation
Authors: Bondarev Edward , Popov Vasili
Published: December 2007

Studies presented in [1] show that during gas production from the fields located in the permafrost regions intensive hydrate formation occurs in the bottom-hole zone. The process begins from the moment of bringing well into production, and approximately in 100 days all free water transforms into a hydrate. As a result, well productivity within this period reduces to about 20%. One of the ways of well productivity recovery is the use of different types of heaters. The paper presents the evaluation of the above method efficiency. To study the dynamics of hydrate formation and dissociation the modified mathematical model proposed in [1] has been used. During the computational experiment the effect of heating intensity, gas well production rate and permeability of gas-bearing reservoir on dynamics of the formation and dissociation of natural gas hydrates has been studied.

The results of calculations for the intensive heating show that regardless of the distance from a well, rate of hydrate saturation growth and its absolute magnitude significantly depend on permeability and production rate and that hydrate formation occurs in a comparatively narrow zone near wells where all pore water transforms into a hydrate. But this hydrate-free zone is stable during successive gas extraction for a long time. If the heater temperature only slightly exceeds the equilibrium temperature of hydrate formation but its active period is much longer, then its influence is more localized than in the first variant. Moreover, here the size of the hydrate-free zone depends both on gas flow rate and bed permeability.
Efficiency Evaluation of Non-Uniform Upgridding Method Based on Streamlines Approach: Western Siberia Field Example
Authors: Kurelenkov Sergey Kh. , Ryazanov Andrey V.
Published: December 2007

In this work we present the comparative analysis of uniform and non-unifrom upgridding techniques in combination with upscaling methods currently included in commercially available software. Also the efficiency of the new Streamlines-based upgridding method1 as one of the non-uniform upgridding technique was estimated. In the context of the project it was realized (coded). The effectiveness of these techniques is evaluated by their application to the revision process of the reservoir model of the part of "Kp" field of Western Siberia, Russia.

Considered reservoir is highly heterogeneous in vertical direction (permeability ranges from 0.01 to 500 mD). The existing geological model has low vertical resolution (about 1.3 m). The simuation model was upscaled by uniform simple (algebraic averaging) method.

The new geological model (finer in vertical direction) was constructed with the resolution closer to well logs. Several simulation models were constructed by the combined application of different upgridding and upscaling techniques. The model which was the most adequate to geocellular one was chosen.

After that the history matching of the chosen model was carried out. As a result of well done upscaling it was done easier and less time consuming in contrast to the previous model.
The Problem of Scaling and Ways to Solve it in the Oilfields of Rosneft Oil Co.
Authors: Ragulin V. V. , Markelov D. V. , Voloshin A. I. , Matyash S. E. , Mikhailov A. G.
Published: December 2007

Rosneft oil production experience indicates that scaling is one of the most significant factors leading to a fall in the well production rate and to a shorter mean-time-between-failures of well pumps. Deposition monitoring indicates that the share of ECP failures due to scale varies from 12 to 25%.

The various intensity of scaling in wells is related to a different saturation of produced waters with scale-forming ions, water-cut of the recovered fluid, and conditions of submersible well pump operation. In Rosneft wells, sulphate (barite) and carbonate (calcite) scales have been observed.

To efficiently develop most oil fields, it is necessary to select scale inhibitors and preventing technologies taking into account peculiarities of individual wells. Analysis of ionic composition of reservoir and produced waters allowed to determine their saturation with scale-forming ions and to draw up recommendations as to the usage of chemicals, the effectiveness of which must be not lower than 90%, from a wide range of scale inhibitors.

Pilot-field testing and a following large-scale application of scale preventing technologies, i.e. adding an inhibitor to the kill mud, permanent chemical feeding into the annular space of wells, application of submersible well feeding containers, and inhibitor injection into the water injected into the formation allowed to overcome the growing tendency of ECP failures due to scaling in the biggest oil production enterprise of Rosneft – OAO "Yuganskneftegas", and to increase the mean-time-between-failures of submersible pumping equipment by more than twice.
Optimization Development of Sugmut Oil Field Using Horizontal Wells
Authors: Gaponova Larisa M. , Karnauhov Michael L.
Published: December 2007

In the given work the estimation of efficiency of practice of wide application of horizontal drilling on Sugmut reservoir, one of the largest in Russia is presented.

The reservoir is in development of 10 years, significant reserves of oil are concentrated in a water-oil zone. At the first stage of drilling, at realization of three-row system of development by vertical wells there was a problem of nonuniform development of reserves with formation of the centers of active movement of fluids and stagnant zones, effects early water cut wells, annulus overflows were showed.
Monitoring and Optimization of Well Performance in Rosneft Oil Company-The Experience of the Unified Model Application for Multiphase Hydraulic Calculations
Authors: Khasanov Mars , Krasnov Vitaly , Pashali Alexander , Khabibullin Rinat
Published: December 2007

This article presents the experience of the application of the unified mechanistic model for multiphase flow hydraulic calculations in the wellbore for the means of monitoring and optimization of producing wells performance in Rosneft Oil Company.
Development of Multiparametric Geophysical Formation Models for Devonian Deposits in the Romashkinskoye Oil Field
Authors: Diyashev R. N. , Khisamov R. S. , Saveliev A. A. , Agliullin M. Ya.
Published: December 2007

In the paper published by us [1] we set forth the methods and results of multivariate formation classification using the data base of geophysical parameters.

Four types of formations have been identified with a 87–94% accuracy presenting non-reservoirs, water saturated and oil saturated reservoirs and one class which we called intermediary or mixed which judging by the results of standard conclusions on well-logging data, includes in various proportions the formations of all the above-mentioned classes. The present paper illustrates the results of classification with identification of other 6 or 8 groups of formations with the purpose of their detailization according to lithology and fluid saturation.

The used data base included 6 geophysical parameters characterizing 14,546 formation intersections in 1,707 wells. The classification method lies in building of a ‘Tree of Classes’ according to the Ward method and appropriate classifying equations of discriminant analysis, and in determining the position of classes on the ordination plot in compliance with canonical equations.

The classification results in the delivery of: –Borders of classes identified implicitly by means of discriminant analysis and described by classifying functions;–Tables with the results of classification quality on the training subsets, including the percentage of correct attribution of the interval to the class;–Statistical description of classes.

Even though interpretation results were not used when making up classifying equations, the comparative analysis of classification results with standard interpretation data points to possibility and practicability of including the generated classifying and canonical equations into the active software for interpretation of well-logging data. This will increase accuracy and unambiguity of issued conclusions on the lithology of formations and their fluid saturation, which is very important for building geological and hydro-dynamic models of oil fields and estimation of reserves and designing of development.
Intraformational Bed Influence on Remaining Oil Distribution and Tapping Potential Technology with Horizontal Well in Extrahigh-Water-Cut Reservoir
Authors: Liu Xiantai , Liu Zhihong
Published: December 2007

The main pay of Guantao Formation in Gudao Field is a large-scale thick positive-rhythm channel sand oil layer. At the extra high water-cut stage, the thick oil layer is waterflooded seriously, but the top remaining oil is still enrichment due to influence of reservoir heterogeneity. The research shows that the development effectiveness of tapping the potential with vertical well is bad and the economic benefit is low [1]. If horizontal well is used, the producing degree and the recovery of the remaining reserve can be improved effectively. Among various factors of affecting development effectiveness of horizontal well, the influence of intraformational bed development is much more important. The development of intraformational bed and its control on remaining oil distribution should be understood first, then the technology policy research of tapping the potential with horizontal well was conducted in order to ensure the good development effectiveness with horizontal well. In this paper, the remaining oil distribution features under the different developmental conditions of intraformational bed are expounded in detail, the intraformational bed was divided into two kinds, developed and undeveloped; according to its developmental conditions, the technology policies of horizontal well were studied respectively, and the commensurate design criteria of horizontal well was proposed. The application of the achievements in tapping the potential of remaining oil in thick positive-rhythm oil layer during the extra-high water cut period has achieved preferable effectiveness, which provides reference for that in the same type of reservoir.
New Technology for Raising the Production in Injecting Steam Well by Using SEPA
Authors: Xie Jianjun , Shi Buqian , Zhou Jianhua , Li Jiang , Liu Guosheng , Yao Yiming
Published: December 2007

High cycle stimulation in Henan heavy oilfield has been suffering the problems such as low formation pressure, much accumulated water which deadly influence the steam thermal efficiency, leading to a bad production recovery. In high temperature, SEPA solution can decompose out gas that can increase the elastic flooding energy, compounding with special surfactant and alkaline, SEPA can develop steam conformance and flooding efficiency. Laboratory tests show that the recovery of non-homogeneity core has been increased by 16.5 percent point. This technology has been used more than 120 wells in Henan oilfield and effective rate reach 92.5percent. It has been proved that the injecting well has a bigger peak daily outputs longer valid period and a significant increment of production.
Efficient Technology Following Cyclic Steam Stimulation for Thick, Massive Heavy-Oil Reservoirs
Authors: Liu Shangqi , Gao Yongrong , Liu Shuangmao
Published: December 2007

With high temperature and high pressure 3-D physical simulation and reservoir numerical modeling, the gravity assisted steam flooding process with the combination of vertical and horizontal wells was investigated, including its production mechanism and feasibility, the influence of key parameters and the process optimization. The results indicated that there are 3 phases: pressure-drive dominance, the combined effects of pressure-drive and gravity drainage, and gravity drainage dominance for this new technology, compared with SAGD process in oil sand. In each phase, the pressure differential and production performance have different character. The heat communication between injection and production wells has great impact on pressure difference. Using this new technology, the recovery factor can increases by 35% with cumulative oil steam ratio of 0.188 after CSS.
SAGD as Follow-Up to Cyclic Steam Stimulation in a Medium Deep and Extraheavy-Oil Reservoir
Authors: Li-qiang Yang , Da-sheng Zhou , Yu-huan Sun
Published: December 2007

Guan-tao oil layer of Shu 1 Block in Liaohe oilfield is a medium deep and extra heavy oil reservoir, which has high porosity and high perm with edge water. In 2001, cyclic steam stimulation was applied with square well pattern and well-space 70m. After 9-10 cycles the stimulation development effect deteriorated and the degree of reserve recovery was only about 15%. To seek development method of extra heavy oil reservoir and improve the entirety recovery ratio of this block, after the feasibility research on SAGD technology in Guan-tao oil layer was finished, horizontal wells were infilled between vertical wells and 4 SAGD pilot test well groups combining vertical wells with horizontal wells were conducted Three cycles of cyclic steam stimulation to preheat the formation and decrease pressure were proceeded and the 4 well groups had produced for 1 year after converted to SAGD. Daily oil production capacity of single horizontal well increased from the initial 20-40t/d to 70-80 t/d after the multiple adjustment of the injection-production parameters. Preferable period effect was accomplished and the test provides good guide for same medium deep and extra heavy oil reservoir to change their development methods.
The Chaos and Its Complexity Degree for Petroleum Price Sequence
Authors: Jian Wang , Guangxue Cui
Published: December 2007

The paper takes Brent oil price as an example to study the nonlinear characteristic of oil price sequence. The original price data is processed first, then the chaos and its complexity degree is studied systematically, based on which the chaos cause of oil price is analyzed. Thus, the variation of oil price sequence is opened out, which can be used to forecast and regulate the oil price.
Research and Application of Reverse Circulation Drilling Technology
Authors: Li Lichang , Ru Dajun , Li Kefu , Yishan Wang
Published: December 2007

The reverse circulation drilling technology is that drilling fluid is pumped down to the annulus, through drill bit and inside of the drilling tool, comes back to the ground. It has many advantages, such as reducing the formation leakage, protecting the oil and gas formation, and cutting sample very clear etc. It includes air lifting, air and pump sucking reverse circulation drilling. Air lifting reverse circulation drilling needs air compressor, air tank, air box, double wall drill tool, air mixer and reverse drilling bit etc. By applying the original drilling rig, these equipments are connected to drill string and carried out the drilling work, after finishing drilling work, these equipments can be removed totally, and have no influence to the normal drilling work. Through testing and on-site application, these equipments are coordinative, drilled 400m in the leaking formation and got a better effect.
Pilot Test of Weak Alkaline System ASP Flooding in Secondary Layer With Small Well Spacing
Authors: Xinde Wan , Mei Huang , Huiyu Yu , Yingzhi Zhang , Weidong Chen , Ershuang Gao
Published: December 2007

ASP flooding is an important EOR technique currently. five pilot tests have been conducted in Daqing oil field, obtaining good results whose incremental recovery is over 20%OOIP higher than water flooding[1,2], strong alkaline system is mostly adopted which is harmful to oil formation, leading to severe scaling and difficulty in treating produced fluid[3]. Taking advantage of weak alkaline ASP system that is developed newly in laboratory, small well space and fast effect show in pilot area, the representative SII12 formation was selected for weak alkaline ASP flooding pilot test in 2004, and evident result has been obtained. In this paper, the dynamic varying regularity of oil and water wells was analyzed systematically, the result and understanding were introduced, and some technical problems were discussed.
Technology of Plugging Long-Interval High-Pressure Channeling Wells by Cement with Overburden Pressure During Curing
Authors: Yan Wang , Demin Wang , Jun Wan , Jiangtao Luo , Ping Zhong , Zengyou Dong , Yingzhi Liu
Published: December 2007

With the prolonged time of development and increased interlayer pressure difference, there is numerous cement channeling problems between isolated zonal intervals in production and injection wells in Daqing Oilfield. The cement channeling problems, especially in long intervals, change the original layers developed and make the interlayer interference more severe. Furthermore, all kinds of chemical treatment methods that are used to remedy channeling cannot meet the needs of plugging long interval channeling wells in the field because of the disadvantages of complex process, high cost, low success rate, safety concerns, high risk and etc. Therefore, a new method has been developed specifically for plugging long interval high pressure channeling wells by cement curing with an overburden pressure and the results are encouraging.
Application and Study of Acid Fracture Technique Using Novel Temperature Control Viscosity Acid in Carbonate Reservoir, Tarim
Authors: Zhou F. , Liu Y. , Zhang F. , Xiong C. , Peng J. , Yang X. , Liu X. , Lian Y. , Qian C. , Yang J. , Chen F.
Published: December 2007

This paper will present the development novel temperature control viscosity acid (TCA) technique that uses for acid fracturing in Ordovician formation in TZ region of TARIM, China. The Ordovician formation in TZ field is extreme heterogeneous carbonate with naturally fractures, that locates in deep underground of 5000-6300m, the reservoir temperature is around 120°C-145°C, and the reservoir close-fracture pressure The above 90Mpa. During the past decade, many acid fracturing techniques (such as gelled acid technique and emulsified acid technique) have been applied, but the results were not satisfactory. Under these difficult circumstances, in order to gain perfect acid fracturing effectiveness, we have succeeded in developing TCA acid fracturing technique.

A new TCA system is presented in this paper that has unique viscosity-temperature characteristic, the TCA viscosity is the same as gelled acid at room temperature, and increase rapidly while under high temperature reservoir conditions, the TCA viscosity can come to over 200mPa.s. It is a preferable retarded and little leakoff acid system, at 120°C, TCA's rock/acid reaction rate is 6.3 times and 2.4 times slower than straight acid and gelled acid respectively.

This paper also provides two TCA acid fracturing cases in the Ordovician formation in TARIM, the results are remarkable. one of the wells (well A), The production was used with choke of 12.7mm after acid fracturing. The tubing pressure was 37MPa. Production was 72.7×104m3/d of gas and 485m3/d of oil. That demonstrates that TCA can generate longer etched fractures in heterogeneous carbonate reservoir.
Application and Its Extension of Autocontrol Management Technology in Oil Production
Authors: Wang Jixin
Published: December 2007

Several auto-controlled oilfields with more than one million tons oil production capacity per year respectively have been build in the deserted area in Junggar basin in Xinjiang, China since 1994. Advanced SCADA (Supervisory Control and Data Acquisition) systems have been used to gather the information (such as pressure, temperature, flow rate etc.) of oil wells, gas wells, and water injection wells, and transmit the data wirelessly to a central control room so as to realize the supervising of the production process and the controlling to some of the device(valves on a metering manifold) or equipment (beam pumping units on site). After the data processing, some kinds of services could be provided such as to print daily production reports, to analyze or inquest the production data and so on. A higher efficiency and lower production cost of oil production in these oilfields have been realized compared with the ones managed with conventional means. With the development of automation technology and petroleum engineering, advanced management and better efficiency could be achieved if some improvement about the auto-control system would be done, including installing some devices to collect the input power of a motor and the producing liquid level of pumping wells, developing the necessary software for the monitoring of the gear net torque, the balance state of unit load and the motor power of pumping units. The running condition of a pumping unit and its energy efficiency (surface, down hole and the whole system efficiency) could be supervised, diagnosed and improved. This paper brings a brief introduction to the application of auto-control technology in Xinjiang oilfield, and from the view of oil production engineering, offer an upswing plan for auto-controll system to pumping wells.
Discussion of Visual Technology of the Big Scene of Virtual Reality on WEB
Authors: Jia ShaoFei , Tian XueSong , Wang Tong , Shan ChunYan , Li ZhuoYi
Published: December 2007

Using virtual reality technology to build the scene of big scope and many scenery, it exist the question of network bottleneck and drawing difficulty when WEB browses.

For this question, according to rules of Virtual Reality Modeling Language, we make the big scene effective division and layered attemper and capability optimization.

The effective division means partition a big scene into several small rectangle scene pieces, every scene piece all can run alone and the easy and smooth operating on WEB, thus realizes that the scene is partitioned effectively. The layered attemper means using the node in the VRML, realized the scenery model in the scene piece delamination load by step. the scene piece Again conformity and whole attemper. The capability optimization means adopting reducing number of subsection, Instances and text compression methods etc. Carrying on the scene capability optimizes. Thus realize that the big scene is run on WEB.

Uses the above technology to have accomplished big scene development work in "virtual history of No.8 Production Plant" system, that is runing. The realization of this technology, for show the large-scale virtual jointly station and oilfield templet engineering on the net in future etc, all have the very important meaning. Establish the technology foundation for forges "Digital Oil Field".
Casing Collapse Strength Reduction Under Lateral Loads From Yielding Shales in the Daqing Oil Field
Authors: Ai Chi , Zhao Wanchun , Guo Boyun
Published: December 2007

Casing failure has been found in nearly 20% of production wells in the Daqing Oilfield after 45 years of oil production history. Plastic failure of casing strings has been recognized in the zones of yielding shales overlaying reservoir pay zones in the field. This type of casing failure is one of the most costly problems in the field. No research has been done to study the resistance of casing string against the lateral loads from the yielding shales. This paper fills the gap.

Assuming a lateral load uniformly distributed along a casing section from a clay zone clamped between an upper and a lower sandstone zone, a mechanistic model was developed in this study. Results of the model indicate that the resistance of casing string to the lateral loads drops sharply in the early stage of development of radial deformation. The resistance of casing string to the lateral loads is not very sensitive to the longitudinal deformation. The remaining strength of casing string also depends on properties of the casing string.

A calculation example is illustrated in this paper. This work provides an analytical tool that can be used for optimizing casing programs against lateral loads from yielding clay zones to minimize casing failure and field operation cost.
Reservoir Management Ingredients for Optimizing the Water-Injection Performance in Small and Medium-Sized Fields
Authors: Tewari Raj Deo , Abd Raub Mohd Razib Bin , Xi Wang Yin , Abdallah Fahmi
Published: December 2007

Greater Unity a multilayered clastic reservoir in Sudan is a conglomeration of number of fault blocks- lacustrine deposits of late cretaceous age. Reservoir characteristics are mostly heterogeneous with varying degree of heterogeneities both vertically and horizontally. Reservoirs are highly undersaturated and have poor aquifer support. Rapid pressure decline was observed in early phase of production, severely affecting the performance of pumps resulting into frequent failures and causing sharp production decline. Water injection in low pressure mode was resorted in some blocks. Failure rates of ESP and PCP reduced significantly as dynamic fluid level (DFL) increased noticeably, provided sufficient submergence, and improvement in efficiency of the pumps.

Significant decline in injectivity in Aradeiba formation compelled to change the strategy of injection. Step rate tests were the guiding factor for selecting the low and high pressure injections and also stimulation. Paper discusses application of diagnostic methods like Hall plot, Jordan plot and other empirical relations using Pressure, injection and production data for understanding and improving the injection process. Profile modification for better conformance control gained early importance in view of smaller sizes of the pools.

Nonparametric statistical method known as Spearman rank analysis has been used to understand and analyze the degree of communication between injectors and producers. This analysis quickly identifies the communication between injectors and producers, or lack of communication and helps in understanding the response of injection. Preferential flow trends are reflected by the correlation in rates between injectors and producers alongwith lead time response of injection on production.

Paper illustrates the important ingredients which can add value to asset and improve the reserves and overall development strategy. Therefore, it is highlighted that success and failure of water injection project depends on why, when, where, what, how and how much to inject, plus what will happen to the formation once the water injection starts.