bluuebunny/crossref_metadata_2025 huggingface dataset:
Recovering Well Productivity in Banyu Urip Field
Authors: Putra Ardian P. , Barrow Jonathan M. , Susanto Edward , Hutauruk Leonardo E. , Daud Munir M.
Published: October 2013

Banyu Urip Field is a newly developed oil reservoir located in between Central and East Java provinces, Indonesia. The field is currently producing in an early development phase. There are 4 producer wells, 1 gas injector and 1 water injector. The six wells are located on one well pad and production flows to temporary facilities operated by another party.

Two years after starting production, inflow capacity began to rapidly deteriorate in one of the producers; resulting in a decline in overall field deliverability. The declining well is a deviated well which had experienced massive lost circulation while being drilled. The well initially produced at the highest rate among the 4 producers. However after the rapid production decline it produced at the lowest rate of the four producers.

This paper describes steps taken in evaluating the root causes of the decline in well productivity. Research and screening mitigation options are also discussed in this paper. Lost circulation materials, plugging, and scale/wax build-up are suspected as potential root causes of the decline in productivity. Acid stimulation, coiled-tubing cleanup, and re-perforating were identified as possible mitigations. The workover was divided into 2 phases; phase-1 was conducted for data acquisition and phase-2 for execution. Furthermore, this paper continues with describing the well work execution and challenges.
Zonal Isolation Remedial Solutions in Mature Fields Using Sealant Polymer and Straddle Assembly
Authors: Nziembo Cyr Rodrigue , Martocchia Francesco , Okassa Fabrice , Quero Philippe , Santin Yoann
Published: October 2013

Water and gas management in mature fields is a daily challenge. It is even more critical when re-development is required using existing assets to be side tracked. The severe depletion of the oil zones creates significant pressure contrast with water and gas layers that need to be properly isolated.

Failure to correctly cement the casings or liners generally ends up by generating cross flows, not only affecting the current well but also other wells producing from same levels.

The paper is based on a successful case history, performed in Congo for a major, where the restoration of the zonal isolation on highly deviated wells was required.

The objective of the paper is to describe the methodology process to determine the source of water in a well, the merge of oil field competencies to engineer a chemical and mechanic solution, the fluid design and the full operational deployment on location to cure the problem.

The combination of several specialties provided an innovative solution that gave the following benefits: -Minimize the number of runs, with only two trips required to perforate the liner to access the cross flow area and to set a straddle assembly-Minimize well restrictions and still give access to the lower completion-Minimize risks of getting stuck using sealant polymer instead of cement-Provide complete annular isolation and restore casing integrity in a same run-Evaluation and control of the cross flow before sealing operation-Protect the lower oil producing zone during the entire remedial operation

At the end, the objective of the paper is to give best practices to perform remedial cement operations in similar well architectures.
Low Salinity Cyclic Water Floods for Enhanced Oil Recovery on Alaska North Slope
Authors: Kulathu S. , Dandekar A. Y. , Patil S. , Khataniar S.
Published: October 2013

With low salinity waterflooding already implemented, cyclic waterflooding is under extensive research for increased oil recovery than conventional waterflooding. Low salinity cyclic water injection (CWI) is an interesting combination that offers the effects of both, with notably high oil recovery and less usage of water. Careful evaluation might promote the application of cyclic injection in the fields, especially on Alaska North Slope (ANS).

Two phase flow experiments were conducted on representative sandstone cores. After establishing initial water saturation, Amott-Harvey Wettability tests were performed with spontaneous and forced displacement of the fluids by one another. Cyclic water floods were conducted to calculate oil recovery from the volume of produced fluids. Pulsed cyclic floods were programmed in the injection pump. The experiments were repeated with cores of different permeability and lab reconstituted brines of 22000, 11000 and 5500 ppm salinity. Results were compared with available data from continuous injection performed on the same cores. Cyclic floods were also tested for two symmetric on-off time intervals.

With the dead oil experiments, it is observed that residual oil saturation (Sor) is achieved as early as 3-4 pore volumes (PV) of injected water in cyclic injection as compared to 6-7 PV’s in continuous injection. Additional oil recovery is observed in cyclic injection’s idle time, when the already flooded water spreads smoothly within the pores to displace oil out of the core. Better recovery was obtained with lower salinity brines. Within cyclic injection, shorter pulse intervals yielded better results. To conclude, low salinity CWI with shorter pulse intervals yield better oil recovery and early Sor. This is an attractive option for ANS operators.
An Overview of Polymer Broken Down for Increasing Injectability in Polymer Flooding
Authors: Liu He , Yang Gao , Fangchao Liu
Published: October 2013

There are many reasons for the low fluid volume of oil wells and decreasing injectability of the polymer injection wells, such as the unreasonable process, the variations of the formation conditions, imperfect injection-production pattern, and improper production management, etc., and moreover, another important factor is the injected polymer and cross-linked polymer jamming in the near wellbore area and deep oil reservoir. According to the Statistical analysis of the 289 wells in Daqing Oilfield, there are two situations existing in polymer jamming which caused decreasing injectability, one is the shallow blocking, blockage radius within 3 meters, mainly caused by the polymer micelles, polymer floc, mechanical impurities, salt scale and iron sulfide, etc.; the second is the deep formation block, blockage radius around 10 meters, there are two factors resulting in this situation, which are, high viscosity caused near wellbore area jamming and polymer retention and adsorption in far wellbore zone. Aiming at these two situations, we have developed the polymer blockage remover and its supporting technology, which can efficiently remove blockage from polymer / cross-linked polymer, through this technology, the injection stop or under-injection can be solved to some extent, and the development effects of the polymer injection area have been improved.
Reducing Target Uncertainties and Guiding Drilling Using Seismic While Drilling Technology, a Novel Approach in Andaman Sea Deepwater
Authors: Chandrasekhar S. , Dotiwala F. , Lim T. K , Khaitan M. L. , Kumar R.
Published: October 2013

Seismic while drilling (SWD) technology was first time being used by Oil and Natural Gas Corporation, ONGC recently, on their Andaman Seas deepwater drilling campaign. Numerous publications have been made by the industry experts over the past 10 year on SWD technology In this case study we demonstrate the practical applications of SWD technology that help to guide the real-time drilling process with effective cost and time in acquiring checkshot data.

ONGC has started exploration campaign in Andaman deep water area recently in 2011. The drilling was commenced with very limited information available from surface seismic, because of no well control in the area. By virtue of surface seismic technique, uncertainties are always associated with it. Uncertainties in seismic impacts the well plan and safety, which effectively impacts the well cost. Any technology which can reduce the seismic uncertainties and risks can be useful to reduce the cost and enhance safety.

In this paper a case example is presented, where real time checkshot was acquired without disturbing the normal drilling operation. The real-time checkshot was recorded at every drill string stand and recorded waveform was transmitted uphole through mud telemetry system. The computed time-depth function was used to refine pre-drill velocity model and this was subsequently used to update the drilling target prognosis depths and geomechanics model. Real-time checkshot also confirmed the drill bit position on the surface seismic section. Updated seismic lookahead give confidence to ONGC to continue drill ahead with single 12.25" hole to reach their final TD at 3700m. All targets were reached within a few meters errors of the prediction. This case study demonstrated that SWD technique added considerable values in helping eliminating drilling 17.5" enlarge hole and 13 3/8" casing run.
Predicting Drilling Target Ahead of Bit Using VSP Lookahead Technique that Help Mitigate Drilling Risk in Over Pressure Zone, a Case Example from South China Sea
Authors: Yang H , Cai J. , Guo S. , Gao Y. , Yanhua Y. Li , Lim T K
Published: October 2013

Yinggehai basin is located in South China Sea; it is characterized with high geothermal gradient and high overpressure. Numerous pore pressure predictions with VSP look-ahead have been conducted in this area. As pore pressure prediction with this approach is very sensitive to the inverted VSP velocity, based on our post drill analysis of pore pressure prediction results with VSP look-ahead data, it has been demonstrated that undercompaction is not the only overpressure mechanism in this study area, unloading may also have contributed to the overpressure. Both Bowers and Eaton models can be applied to predict pore pressure ahead-of-bit for the overpressure mechanisms in the area. An error of 5% in VSP-inverted velocity could generate the error in predicted pore pressure approximately 0.16SG based on Bowers model. Therefore, with experiences gained from VSP velocity inversion part, determining the top depth of the high pressure target with the inverted VSP velocity curve is proposed in this study block to allow for an optimal setting depth of the casing shoe. A case study with this approach is presented in this paper.
Cased Hole Formation Connectivity Investigation Aids in Completion and Production Optimization: Offshore Malaysia Field
Authors: Hanalim L. , Kyi K. , Haddad S. S. , Hooi Yee K. , Wa W. , Lim L.
Published: October 2013

Reservoir pressure is one of the key properties needed in formation characterization. In addition to reservoir fluid identification through pressure gradient, reservoir pressure measurement plays a vital role in evaluating reservoir connectivity. This understanding of reservoir connectivity will subsequently aid in reservoir management planning, including completion design optimization. Formation connectivity investigation is especially challenging in a cased-hole environment where unfavorable wellbore conditions prevented open-hole evaluations.

This paper presents a case study in a Malaysia offshore field where formation pressure measurements behind casing were carried out to allow the investigation of formation connectivity which is required for completion design, production planning, and potential cross-flow for zone commingling strategies. Cased-hole formation tester was used to evaluate formation pressure in the target zones where two wells were drilled in the same field. The formation pressure acquired was subsequently utilized in completion design and perforation planning based on reservoir connectivity.

The pertinent questions about this field have been answered and helped in making the best possible connection between the wellbore and production optimization. This application of formation pressure measurement behind casing has been proven to add value to the completion design optimization process. Lessons learned supported by field data will be presented along with recommended cased-hole reservoir connectivity investigation techniques and strategy.
Redesign of ICCP System for Ladinda FSO for Effective Corrosion Protection
Authors: Gangsar Agus , Purwanto Sugeng , Antono Ari
Published: October 2013

The Impressed Current Cathodic Protection (ICCP) System is a corrosion control method where there is a flow of electrons to a metal structure, thus protecting it. As a ship owner, the EMP Malacca Strait SA used a coating method combined with the ICCP system to control corrosion on the Ladinda FSO. However, nowadays, the Ladinda FSO is known to carry a decreased volume of oil cargo due to declining oil production. This results in a change in the wetted area on the tanker’s hull in the design conditions of the ICCP system from early 1983 to the current conditions (2010) that affect the current magnitude of the protection given. This leads to an over- protection that destroys the coating layer.

To avoid over-protection on the hull of the Ladinda FSO, an analysis and redesign of the ICCP system has been conducted. In the redesign of the cathodic protection system on the Ladinda FSO, the NACE Standard RP 0176- 2003 "Corrosion Control of Steel Fixed Offshore Structures Associated with Petroleum Production" was used as a basic reference in the design. The first step was to make the initial ICCP system design and then rebuild the initial ICCP system design for cathodic protection according to recent conditions. Next, the new design was analyzed and the results are the recommendations. The monitoring system was also redesigned to maintain proper control at a range of–1100 mV to–800 mV vs. Ag/AgCl/seawater.

The new design will needs two transformer rectifier units as the power supply, which will give sufficient voltage to drive six titanium anodes coated with mixed metal oxide (MMO). The capacity of each transformer rectifier is 236.25 kV.A with a DC current of 21 A and DC voltage of 9 V. Four potential test boxes featuring Ag/AgCl reference electrodes and the "Protection Current Control Program" as the control system and monitoring system are added in this new ICCP system design.
A Numerical Study on Long-Term Water Injection Procedure and the Corresponding Formation Property Variation
Authors: Liu He , Wang Han , Wu Heng'An , Wang Xiu'Xi
Published: October 2013

The technique of water injection is a commonly used technology for enhancing oil recovery. We establish finite element models (2D axial symmetric model and 3D model) to simulate the procedure of long-term water injection. In the models, fluid- solid coupling is considered. The primary equations include stress equilibrium, Darcy’s law, the effective stress principle, formation damage and so on.

The basic mechanism of water injection is discussed with the 2D axial symmetric model. The results show that water injection may lead to increase of the pore pressure evidently and enlargement of the influenced area gradually in the duration of injection, and thus the main purpose of water injection is achieved. However, the stress field redistributes. The stress distribution near wellbore is more complicated and results in stress concentration. Consequently the formation is damaged and the permeability changes obviously. The effect of original formation heterogeneity on water injection is also studied. The original formation property obeys Weibull distribution. The results indicate that the more inhomogeneous the formation is, the larger the damaged area will be.

The influence of different helical perforation densities on water injection procedure is discussed with the 3D model. The results show that high perforation density may lead the formation damaged more seriously. Since perforation is a kind of artificial defect in the formation, more perforations make the stress concentration near wellbore more serious. As a result, the damaged formation area is larger.

Our work can provide an understanding of formation property variation due to water injection, and the petroleum engineering practice will benefit.
Flng Lean – A Natural Development
Authors: van Dongen Marc , van der Velde Harry
Published: October 2013

Construction of the Shell Prelude FLNG facility is currently well underway. When completed, the facility is expected to export LNG, LPG and condensate from a rich gas stream. Developments with rich gas streams, using similar facilities, may also benefit from the considerable amount of revenue possible from condensate and LPG sales. However, some fields contain gas that is significantly leaner, and will not have the benefit of condensateand LPG revenue streams. Recognising that the world has lots of low liquid content gas, so called ‘lean gas’, Shell saw a strategic opportunity and is developing FLNG Lean.

FLNG Lean is an FLNG concept with a nominal LNG production capacity of 6 million tonnes per annum and reduced functionality for other liquids. FLNG Lean is a natural development within the Shell standardised FLNG design approach and it is designed to expand our LNG capabilities. We anticipate it to be cost-competitive for larger, lean gas fields. FLNG Lean has many similarities when compared to the standard FLNG design. We continue to focus on standardisation, with modifications only as required. The substructure design with its utilities, the accommodation, the operating and the safety philosophies, the flare and blow-down system, the LNG containment systems, and the LNG off loading system are all the same thereby enabling repeatability gains. Lessons learnt and the latest technology developments have also been implemented. Some utilities are relocated to the substructure to create sufficient deck space for the liquefaction trains and process equipment. High capacity modern aero-derivative gas turbines will drive the liquefaction compressors and power generators. Process heating requirements will be largely met by waste heat recovery units.

This paper will describe the FLNG Lean design and its potential application area. We will highlight the approach followed, explain the main features of FLNG Lean, and compare it with the generic Prelude FLNG design.
Planning, Organization And Success Of A Wide, Detailed Geophysical Survey Offshore Makassar Strait
Authors: Coral Juan Carlos , Paone Francesco , Marceglia Andrea
Published: October 2013

The Oil & Gas industry has seen recently a strong push towards high end goals required by the tight bond between economics, the time for the development of an investment, planning and finally construction and service of plants. This is the specific case of the Jangkrik field development. As part of the POD (Plan of Development) approval by the Government of Indonesia, eni Indonesia committed to a "fast track" strategy in which the field would come into production in 2016 and consequently directed all efforts towards early development of the engineering design for the production facilities. Thanks to the execution of the geophysical site investigations during the early project design stages, several elements were discovered, which quality allowed a much clearer picture of several morphologic elements affecting the field design. Among the most important decisions that were taken during this design phase, we can consider the one to relocate the FPU in a shallower water depth (100mt WD on the continental shelf) with respect to the preliminary design (about 320mt WD along the escarpment). Such decision, if not taken on time, would have created major reworks during the execution phase, together with a potential big delay in the project and potentially jeopardizing the possibility of the Jangkrik North East integration. Another important decision was the one relevant to the use of rigid versus flexible flow lines. This is also critical for the procurement activities to be progressed on time and also for the flow assurance studies. This type of decisions, taken during this phase of the project, in the long term will lead to better design, minimize re-works, reduce costs and time and ensure project integrity.
Drilling Statically Underbalanced Gas Well with Managed-Pressure Drilling to Target Depth Safely and Efficiently
Authors: Krisboa Agustinus , Iskandar Yoshua P. , Irawan Fikri , Karnugroho Ardia , Toralde Julmar Shaun
Published: October 2013

Drilling a statically underbalanced well means that the hydrostatic head exerted by the fluid used for drilling is lower than the formation pressure. However, by utilizing Managed Pressure Drilling (MPD) equipment, such as a Rotating Control Device (RCD), an automated MPD choke manifold, and a downhole isolation valve (DIV), and employing MPD techniques, such as Constant Bottomhole Pressure (CBHP) and Pressurized Mud Cap Drilling PMCD), surface backpressure can be exerted during drilling and a dynamically overbalanced condition can be established during the operation, thereby preventing the constant flow of reservoir fluids to surface.

The CBHP variant of MPD was initially deployed with statically underbalanced drilling fluid to minimize damage to the reservoir until severe circulation losses were encountered, once the high permeability areas being targeted for the big-bore gas wells were penetrated. Thereafter, the same drilling fluid was to be utilized to make the transition to another MPD variant, PMCD, faster and easier. PMCD was utilized in order to continue drilling the well to target depth without needing to restore circulation and pump lost circulation material (LCM) and cement, which will also impair the productivity of the gas reservoir.

This paper focuses on how these combinations of MPD techniques were successfully utilized in order to drill high-rate gas wells in South Sumatra safely and efficiently. Details of how the system was safely and efficiently installed and subsequently deployed, as well as the set-up and procedures utilized will be elaborated. Further improvements to the system and to the operation are also discussed for future applications. Finally, the evolution of MPD methods used in drilling the gas reservoir is also described in relation to the changes that have occurred to the reservoir after it has already been put in production for a number of years.
Study on Enhanced Oil Recovery Technology in Low Permeability Heterogeneous Reservoir by Water-Alternate-Gas of CO2 Flooding
Authors: Chang-lin Liao , Xin-wei Liao , Xiao-liang Zhao , Ning Lu , Hong-na Ding , Huan Wang , Yong-ge Liu
Published: October 2013

The common problems that water injection come across in low permeability heterogeneous oil reservoir are poor injectability, low production, high water cut and low oil recovery. The previous studies showed that Water-Alternate-Gas (WAG) of CO2 flooding could enhance oil recovery in low permeability oil reservoir effectively. However, the way to use effective technology to enhance oil recovery and net present value (NPV) in low permeability heterogeneous oil reservoir became a difficult point in WAG flooding. This paper introduces allocation of injection rates (AOIR), tapered Water-Alternate-Gas (TWAG) and AOIR-TWAG to study the feasibility of the technologies in enhancing oil recovery with numerical reservoir simulation base on the previous studies. The development effects of constant WAG in the reservoirs with different variation coefficients were contrasted. And the feasibility of the three technologies to enhance oil recovery was studied. The results show that the development effect of constant WAG flooding is better than that of continuous gas injection with the increasing of the variation coefficient. And the oil recoveries of the three technologies are better than that of the constant WAG flooding. However, only the NPV of the AOIR and AOIR-TWAG are better than that of constant WAG flooding. An actual oil reservoir model of Xinjiang oil field in China was used to check the feasibility of the two technologies. The results show that the oil recoveries and NPVs of the two technologies are better than that of constant WAG flooding. This result proves that the conclution of the reservoir conceptual model is reliable, and the technology could be suitable for other similar low permeability heterogeneous oil reservoirs.
Organic Deposition: From Detection and Laboratory Analysis to Treatment and Removal
Authors: Alian Sima Sheykh , Singh Kulwant , Saidu Mohamed Anwarudin , Ismail M. Zaki , Anwar Mona Liza
Published: October 2013

Organic deposition predominantly in the near well bore and in production tubing can create serious oilfield problems such as flow restrictions, near wellbore damage, efficiency of crude processing units and etc. As the reservoir depleted over the time, the solid deposition can lead to a steep decline in productivity of wells. The deposition of organic solids is one of many flow assurance problems faced by operators in Malaysia. It has been observed that, after years of production, many fields in Malaysia are suffering from organic solid deposition problem. This phenomenon is predominantly caused by changes in temperature, pressure and composition/morphology of the crude oil over time. To perform organic deposit removal treatment and prevention in the well, the nature of the solid should be characterized. If the deposit sample is organic mainly, it is important to quantify the various organic fractions of the solid sample collected from the production facilities. This paper explains how SARA analysis was modified to detect not only Macro-crystalline waxes (Saturates), asphaltene, aromatics and resins but also micro-crystalline wax and naphthenates. The content of each of above component will affect the method of treatment and the chemical formulation to treat the well. By knowing the composition of the solid sample along with Crude’s Colloidal instability index (CII), Pour point and Wax Appearance Temperature (WAT), a customized chemical formulation can be designed. Lab studies were performed on solid samples collected from several wells to detect the flow assurance related issues prior to design of chemical formulation. With the analysis of the production data, history matching, and etc, a customized chemical formulation was developed to treat the wells. The proposed chemical formulation consists of 2 specially designed pills which would be simultaneously injected to the wellbore, which generates heat and ester once comingles. The heat melts the deposits while the ester disperses the melted solid. The initial studies of the treatment showed promising results; moreover the field implementation was very successful and proven significant increase in production rate. This novel system that combines both thermal and physical energy, evidenced to work effectively for wide range of organic compositions. Implementation of this system made it possible to restart the production from those wells which were idle due to extensive organic deposits. This technique was also often used to rejuvenate the old wells with low production rate. This paper discusses the diagnostic process and successful implementation of the proposed treatment in several oil wells in Malaysia.
Field and Numerical Simulation Study on Stereoscopic Network Development at Later Cyclic Steam at Thick Heavy-Oil Reservoir
Authors: Lu Sun , Liu Yuetian , Chen Minfeng , Li Xiaofeng , Zhang Hairu , Guo Zhengliang , Ge Taotao
Published: October 2013

Heavy-oil occurring in thick reservoir is an important resource world-wide. Heavy-oil recovery from such reservoir using cyclic steam is an efficient solution due to very high oil viscosity. However heavy oil recovery at later cyclic steam soaking is a real challenge, yet no direct analogues exists as an efficient solution.

We proposed a new method called stereoscopic network development and needed for efficient heavy-oil recovery from thick reservoir, consisting of ten vertical wells and two horizontal wells in the following manner:

1. Stereoscopic network: adding two superposed horizontal wells between vertical wells in rectangular pattern.

2. Operation: steam injection through the upper horizontal well and production through the lower and all vertical wells.

Field practices of managing a steam flood with stereoscopic network in thick reservoir has shown that oil production and oil-steam ratio increased obviously, and water cut decreased sharply.

In this work, the field results obtained early and parameters were needed for field scale simulation. The numerical model has been developed by CMG simulation software and was validated with field data. Using field results and numerical simulations study on stereoscopic network development, the mechanism of stereoscopic network to enhanced heavy-oil recovery in thick reservoir has been studied theoretically and with field test results. And field scale simulations were performed to identify the efficiency of the new method and the optimal injection/production schemes. Specific conclusions as to how to apply the method in thick reservoir considering the effect of the method were reported.
Innovative Modeling System Develops New PDC Bit Technology: Saves Operator 55% Drilling Time in First Deep Jurassic Slimhole Development Well, Kuwait
Authors: Al-Enezi Dakhel , Al-Khaldy Ali , Al-Mutawa Faisal , Al-Mkhyal Abdullah , Maliekkal Harish , Ghoneim Osama , Saleh Mustafa
Published: October 2013

The North Kuwait Development Project requires a large-hole casing design to isolate problematic formations and enable the operator to reach deep HPHT target zones with maximum hole size. The most difficult section is Zubair to Hith traditionally drilled with 16" bits. These formations consist of abrasive/pyritic sandstone, reactive shale and carbonates with UCS between 5-30kpsi. Historically, to complete the 3900ft section required more than three PDCs or a combination of 4-5 PDC/TCI.

To reduce costs, the first slimhole development well plan and string design was developed for Northern Kuwait fields. The objective would be to downsize the hole section from Zubair to Hith to 9¼" and drill to section TD with three PDCs. The production casing would be run from surface to TD instead of the conventional liner tie-back.

To accomplish the objective, the team decided to develop two different 9¼" PDCs: 1) one for Zubair to Ratawi shale; 2) a second for drilling the remaining carbonates from Ratawi to Hith. To avoid costly field trials, an FEA-based modeling system was used to fully understand how iterative bit design changes would affect performance and drilling efficiency. Based on modeling, two PDC bits were implemented: a M819 with back-up cutters to achieve maximum durability and ROP through Zubair and push deep into Ratawi; a M616 to drill the remaining section from Ratawi to Hith. The bits were equipped with the latest HTHP cutters to enhance durability/ROP.

The section was completed on a motor BHA in two bit runs saving 55% drilling time and the expense of a third bit. The operation set a new Kuwaiti record for the single longest 7¾" production casing string (13,625ft) and cementing back to surface. The downsizing strategy and increased drilling efficiency saved the operator $1 million USD compared to project estimates and a standard liner-string design.
Adding System Optimisation of Corrosion Inhibitor in Oil Producer in CoFlooding Field Test
Authors: Feng Wang , Changyu Liu , Feng Ma , Tianjie Huang , Weiran Dong
Published: October 2013

CO2 corrosion is one of the key factors that restrain CO2 flooding. Corrosion damage by CO2 breakthrough and water content increase has greatly influence the regular production of oil field. To protect the casing pipe, tubing, sucker rod and deep well pump entirely, inhibitor control technology which uses chemical method as the principal method is needed.

At present, filling inhibitor into the casing-tubing annular is used for anti-corrosion, however, adding rests can be influenced by many factors. According to varied environment of CO2 flooding oil field and the study of inhibitor property and residual concentration, a weak-absorption film former inhibitor used in the CO2 flooding well has been chosen by the lab test evaluation and field experience; dosing concentration, dosing circle and dosing method also have been optimized. All of these works help establish a reasonable inhibitor filling system, as well as improve the dosing efficiency and the pertinence of anti-CO2 corrosion.

After being injected in the CO2 flooding well, the inhibitor caused effect of decreasing corrosion damage, as well as reducing the cost. According to the corrosion monitoring and residual concentration test, when the corrosion ratio is lower than 0.076mm/a, there will be no corrosion in the well bore and the downhole tools. This comprehensive anti-corrosion method can meet the field needs.

Keywords: anti-CO2 corrosion, inhibitor, dosing method, dosing circle
Multi-stage Horizontal Fracturing in Casing for Low Permeability Reservoirs
Authors: Qinghai Yang , He Liu , Jianwen Yan , Gao Yang
Published: October 2013

In recent years, the low permeability reserves account for over 70% of the annual new reserves of PetroChina. In 2009, the annual producing reserves and the new drilled wells of the low permeability reservoirs accounted for 70% of the total number, respectively. The low permeability and non-conventional reservoirs are characterized by high percolation resistance and poor connectivity, and may yield commercial value only after acidizing or fracturing. However, the production of acidized or fractured vertical wells is still low and the benefit is poor. The horizontal wells have the advantages of large drainage area and low pressure drop, which make the multi-stage horizontal fracturing an effective technology for the development of low permeability and non-conventional reservoirs. Most of the horizontal wells of PetroChina low permeability reservoirs are completed with casings to meet the requirement of water injection, thus the technology of horizontal fracturing in casing is crucial for improving recovery efficiency. Three principal techniques of multi-stage fracturing were developed, i.e., double-packer single-slip, packer-sliding sleeve, and hydraulic sandblast, together with four matching techniques such as multi-stage stimulation with chemical temporary-blocking gel plug, high efficiency self- diverting acidizing or acid-fracturing technique of carbonate reservoir, hydraulic fracture monitoring and evaluation, and horizontal well workover. In addition, an optimization method of fracture and well pattern was also proposed. The 3 principal techniques, 4 matching techniques, and the optimization method, effectively promoted the industrial application of horizontal wells in low permeability reservoirs.
Economic Evaluation of Volcanic Gas Production Project in Songliao Basin
Authors: qing Xu , zhisheng Yang , fuli Chen , shuyun Liu , shuqin Chen , min Zhong
Published: October 2013

Large amount of nature gas reserve has been found in the deep formations of volcanic gas reservoir in recent years in Songliao Basin, north-east of China. Because of its complicated geological condition, reservoir characteristics and obscurity of knowledge of the people, economic evaluation becomes a crucial measurement in order to insure the feasibility of the gas production projects. Take Changshen area of Jilin gas field as an illustration, discounted cash flow (DCF) model was used, net present value, interior rate of return and payout time was selected as economic indicator. The CAPEX and OPEX were assessed based on engineering schedules. The operating conditions and production profile were optimized by using reservoir engineering numerical simulation. Other parameters, such as gas price, tax rate, discount rate etc. were coming from the rules and regulations of the government. The results indicate that the economic benefit of the project is marginal. Project feasibility, as expected, was found to be very sensitive to gas price, gas production, and CAPEX. Project financial analysis indicates a couple of key points which may affect the development of volcanic gas reserve, (1) a significant increase of CAPEX and OPEX was found, which are obviously higher than the ordinary reserve’s, (2) CO2 may be used as a byproduct and increase the project’s income only it has its commercial purpose, (3) no preferential policy of carbon emission reduction in China, and (4) local gas price is on the low side. Finally, several suggestions are presented in this paper (1) formulate the various terms of the tax credit policy, (2) enact relevant rules and regulations of carbon emissions trade, (3) foster the local industrial gas market to increase the gas price, and (4) increase the financial input into the critical research of the development technique of volcanic gas reserve.
Efficacy and Safety of Rituximab in Biologic-Naive Patients with Rheumatoid Arthritis vs Anti-Tnf Therapy Failure
Authors: Gutierrez-Gonzalez Luis Arturo , Gudiño Marco Antonio Rivera , Ceija Ibell Oropeza , Leonet Marialina Marin , Noguera Zair Tovar
Published: October 2013

Objectives:

Our aim was to compare an AntiCD20 therapy (rituximab) for rheumatoid arthritis in two patient populations (Group 1), anti-TNFα naïve patients and inadequate responders to Anti-TNFα therapy (Group 2).

Methods:

We analyzed the efficacy of the drug Rituximab (RTX) in RA patients who failed methotrexate (MTX) or had a relative or absolute contraindication to receive anti-TNFα therapy.

Results:

25 patients were identified according to the above criteria and followed up for a mean period of 6 months. Thirteen patients were biologic naïve and twelve patients had already failed anti-TNFα therapy. Group 1 used 2> DMARDs (32%vs20%, p<0.005), group 2 had more years of disease progression (5±1.89v s4.10±3.92, p<0.001). The remission as measured by the DAS28 reached faster in group 1 (1.25±0.12vs2.15±1.64, p<0,001). Severe infections especially by herpes viruses were more frequent in group 2.

Conclusions:

Comparing clinical improvement in both groups the decrease of acute phase reactants and the clinical remission measured by DAS28 was reached in both groups, however it was reached more belatedly in group 2 (at 6 months), this is due to the fact that they have more years of the disease evolution and a higher HAQ.
An investigation into bisphenol-A leaching from orthodontic materials
Authors: Kotyk Matthew W. , Wiltshire William A.
Published: October 2013

Objective:

To quantitatively determine the bisphenol-A (BPA) leached from orthodontic materials during simulated intraoral exposure.

Materials and Methods:

Samples of orthodontic materials were subjected to simulated abrasion, immersion in artificial saliva, thermal shock via temperature cycling, and simulated intraoral exposure. Sample aliquots were collected for up to 2 weeks after artificial saliva immersion, derivatized, then analyzed for BPA by gas chromatography/mass spectroscopy.

Results:

Quantifiable amounts of leached BPA were observed from a thermoformed orthodontic retainer material (7.63 µg/g of material) and an orthodontic adhesive (2.75 µg/g of material). BPA leaching was only observed within the first 3 days of artificial saliva immersion.

Conclusions:

Under the test conditions, BPA was observed to leach from two orthodontic materials. While the quantities of leached BPA were below the reference dose for daily intake, existing data of low-dose effects and medical disorders associated with elevated urinary BPA levels suggest that BPA exposure, and thus the use of the leaching materials identified in this study, should be reduced or eliminated.
Polymerization Shrinkage of Different Types of Composite Resins and Microleakage With and Without Liner in Class II Cavities
Authors: Karaman E , Ozgunaltay G
Published: October 2013

Aim

To determine the volumetric polymerization shrinkage of four different types of composite resin and to evaluate microleakage of these materials in class II (MOD) cavities with and without a resin-modified glass ionomer cement (RMGIC) liner, in vitro.

Materials and Methods

One hundred twenty-eight extracted human upper premolar teeth were used. After the teeth were divided into eight groups (n=16), standardized MOD cavities were prepared. Then the teeth were restored with different resin composites (Filtek Supreme XT, Filtek P 60, Filtek Silorane, Filtek Z 250) with and without a RMGIC liner (Vitrebond). The restorations were finished and polished after 24 hours. Following thermocycling, the teeth were immersed in 0.5% basic fuchsin for 24 hours, then midsagitally sectioned in a mesiodistal plane and examined for microleakage using a stereomicroscope. The volumetric polymerization shrinkage of materials was measured using a video imaging device (Acuvol, Bisco, Inc). Data were statistically analyzed with Kruskal-Wallis and Mann-Whitney U-tests.

Results

All teeth showed microleakage, but placement of RMGIC liner reduced microleakage. No statistically significant differences were found in microleakage between the teeth restored without RMGIC liner (p>0.05). Filtek Silorane showed significantly less volumetric polymerization shrinkage than the methacrylate-based composite resins (p<0.05).

Conclusion

The use of RMGIC liner with both silorane- and methacrylate-based composite resin restorations resulted in reduced microleakage. The volumetric polymerization shrinkage was least with the silorane-based composite.
Effective protocol for preparation of three-atom Greenberger-Horne-Zeilinger state and W state with the help of cross-Kerr nonlinearity
Authors: Kang Yi-Hao , Xia Yan , Lu Pei-Min
Published: October 2013

We propose a protocol to generate a Greenberger-Horne-Zeilinger (GHZ) state andWstate by using simple linear elements and quantum nondemolition detectors (QNDs). With the help of cross-Kerr nonlinearity, our protocol can generate the intended states with only one setup, and the probability of getting a W state is greatly increased when compared with previous schemes [Phys. Rev. A 75 (2007) 044301]. Also, our proposed protocol is realizable in experiments.
Scattering of longitudinal waves (sound) by defects in fluids. Rough surface
Authors: Apostol Bogdan
Published: October 2013

The classical theory of scattering of longitudinal waves (sound) by small inhomogeneities (scatterers) in an ideal fluid is generalized to a distribution of scatterers and such as to include the effect of the inhomogeneities on the elastic properties of the fluid. The results are obtained by a new method of solving the wave equation with spatial restrictions (caused by the presence of the scatterers), which can also be applied to other types of inhomogeneities (like surface roughness, for instance). A coherent forward scattering is identified for a uniform distribution of scatterers (practically equivalent with a mean-field approach), which is due to the fact that our treatment does not include multiple scattering. The reflected wave is obtained for a half-space (semi-infinite fluid) of uniformly distributed scatterers, as well as the field diffracted by a perfect lattice of scatterers. The same method is applied to a (inhomogeneous) rough surface of a semi-infinite ideal fluid. A perturbation-theoretical scheme is devised, with the roughness function as a perturbation parameter, for computing the waves scattered by the surface roughness. The waves scattered by the rough surface are both waves localized (and propagating only) on the surface (two-dimensional waves) and waves reflected back in the fluid. They exhibit directional effects, slowness, attenuation or resonance phenomena, depending on the spatial characteristics of the roughness function. The reflection coefficients and the energy carried on by these waves are calculated both for fixed and free surfaces. In some cases, the surface roughness may generate waves confined to the surface (damped, rough-surface waves).
Evaluation of a Smart Parking System
Authors: Fabusuyi Tayo , Hampshire Robert C. , Hill Victoria
Published: October 2013

This paper documents the methodological approach and findings of an evaluation process for a smart parking application that provides realtime information on parking availability. The initiative is in response to the increased demand for parking spaces in the Pittsburgh, Pennsylvania, Cultural District and the desire to improve patrons’ parking experiences. Primary data, obtained through semistructured interviews and in-person and online surveys of patrons, were utilized for the stakeholder analysis, baseline data, process evaluation, and outcome evaluation phases. Secondary data that utilized count data obtained from website usage logs were employed for the output evaluation phase. The contributions of the evaluation framework are the insights it provides on how the key challenges created by the unique environment within which the system was deployed were addressed. The framework could also be employed to tackle response-shift bias through a binary system approach that uniquely identifies distinct cohorts of respondents. The report is especially timely given the prohibitive cost of employing a supply-side approach to address parking problems in cities, the ease of replicating the evaluation framework and the product design, and the wealth of information the study provides to the body of knowledge about the evaluation of technological products.
Residential On-Site Carsharing and Off-Street Parking in the San Francisco Bay Area, California
Authors: Rivasplata Charles , Guo Zhan , Lee Richard W. , Keyon David
Published: October 2013

This research explores the recent practice of connecting on-site car-sharing service with off-street parking standards in multifamily developments; the San Francisco Bay Area, California, is used as a case study. If implemented well, such a policy could help boost the carsharing industry and reduce off-street parking, which is often criticized as being over-supplied as a result of excessive off-street parking standards. In 2011, the authors surveyed all carsharing sites in the Bay Area and all new residential developments (completed after 2000) with on-site carsharing spaces. The results showed that a significant number of carsharing spaces were located on residential properties, but 70% of the spaces had been retrofitted into existing buildings. For the new developments, on-site carsharing did not result in a reduction in the amount of regular off-street parking. Interviews with 15 professionals from three stakeholder groups (planners, developers, and service providers) revealed that even though all the stakeholders were in favor of on-site carsharing at residential developments, three major barriers existed: a lack of incentives, the complexity of access design, and high transaction costs.