bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study and Application of Snubbing Technology for Low Pressure Gas Well
Authors: Han Weiye , Li Tao , Wang Dabiao , Ming Eryang , Huang Shouzhi 
Published: October 2017

Abstract
With the further development of natural gas, the quantity of gas well has been increasing year by yearin China, the demands for well completion and workover are growing. At present, more than 70% of gas wells are low yield and low pressurein China, in order to protect the reservoir and make the production stably, it's an urgent need to use snubbing technology for low pressure gas well.
Snubbing technology faces several challenges for low pressure gas well, such as high risk, complex downhole conditions, high cost, low operation efficiency, etc. High efficiency, low cost and low risk are crucial targets for gas well snubbing. To achieve this target, we developed a set of snubbing wellhead for low pressure gas well which operation pressure is less than 14MPa. Some key technologies are formed, such as airtight makeup and breakout device, gas sealing system, rotating slips etc. The unit can realize pipe tripping and rotating operation with high efficiency and low risk in low pressure gas well, it's composed of lifting system, gas sealing system, working BOP stacks, airtight makeup and breakout device, security BOP stacks. The main working principle is adopted liquid to seal gas, the gas sealing system is composed of two sets of annular preventers, and a length of liquid which has 3-4MPa pressure is sealed between them. When it comes to begin snubbing operation, the gas sealing system can realize effective sealing within the wellbore pressure and also achieve the purpose of tubing lubrication, the safety and reliability can be well guaranteed when it works with BOP stacks. The airtight makeup and breakout device is equipped between the working BOP stacks and security BOP stacks, cooperate with the rotating slips, tubing joints can be screwed on and off at the bottom of the snubbing wellhead when it meets special snubbing work conditions, such as no tubing plug or tubing leakage.
The pilot test of this technology is carried out in Jilin oilfield, operation cost is reduced about 50%, and it makes the production development more effectively and economically.
The annual demands of snubbing operation for low pressure gas wellare probably more than2000 wells each year in China, This technology has the advantages of high efficiency, low risk and low cost, the application prospectis broad.
History Match to Support Interpretation of Surfactant Flooding Pilot Test in Tanjung Field
Authors: Aslam B. M. , Ulitha D. , Swadesi B. , Fauzi I. , Marhaendrajana T. , Purba F. I. , Wardhana A. I. , Buhari A. , Hakim R. , Hasibuan R. 
Published: October 2017

Abstract
Tanjung Field is a brown field which pressure has already depleted and been supported by waterflooding for over a decade. To improve production, surfactant injection, is being studied to be employed in the field. The main objective of this study is to identify parameters that affect oil production increase. History match of the pilot test was carried out to improve the reliability of the reservoir model, hence improving the prediction result of surfactant injection forecast.
History match of the pilot test has been carried out using CMG STARS commercial simulator by considering mechanism inferred from laboratory evaluation such as wettability alteration, surfactant retention, interfacial tension reduction and improvement of mobility control due to lower oil-surfactant emulsion viscosity. These parameters are initially perceived from laboratory result, upscaling and adjustment is applied to field model to further on do sensitivity study. Sensitivity analysis of every parameter is provided to better understand the effect of each mechanism that contributes to the oil incremental result.
Stratigraphically, Tanjung Structure has 7 productive zones: Zone A, B, C, D, E, F and P. Reservoir Zone A has total estimated reserve of 193,732 MMSTB, with recovery factor of 16.3%. The zone consists of conglomerate sandstones with porosity of 21% and permeability ranging from 10 to 100 mD. The field produces light oil within 40 °API, 30% wax content and 1.14 cP of viscosity. T-119 is the well chosen to be injected due to its structural position that ease flow by gravity force to producer wells.
Forecast simulation based on coreflood result has been conducted for pilot test. However, the result was very pessimistic in predicting incremental oil gain and breakthrough time after compared to pilot result. An attempt to history match the surfactant flood pilot is presented by considering phenomena that is not included in the forecast based on additional lab and field data.
ICDs for Uncertainty and Heterogeneity Mitigation: Evaluation of Best Practice Design Strategies for Inflow Control Devices
Authors: Lim Michelle 
Published: October 2017

Abstract
Inflow Control Devices (ICDs) are an advanced well completion device used primarily in horizontal wells to enable more efficient reservoir flow performance and to mitigate common production issues by applying an additional pressure drop to choke high productivity zones. This study aims to identify design philosophies that provide for the most robust ICD design, and to determine if ICDs can be implemented for subsurface uncertainty mitigation. As there is no ability to adjust ICD settings once installed without major recompletion, a completion design that is robust to reservoir uncertainty at and away from the wellbore is critical. While ICD design follows a basic set of guidelines, several different approaches exist for each step within this workflow. A major design aspect relates to the design of target inflow profiles (equal inflow or U-shaped inflow). The U-shaped target inflow profile hypothesis was initially proposed for homogenous wells. This study proposes a modification to the existing design philosophy to cater to heterogeneous reservoirs. There is evidence supporting the use of the less conventional U-shaped target inflow profile in ICD design over the more commonly used equal inflow profile method. Sensitivity and robustness under reservoir uncertainty and heterogeneity for each ICD design methodology was assessed using 3-dimensional numerical reservoir simulation of layered and non-layered heterogeneous block models, followed by extensive uncertainty analysis. It was found that ICD completions may be unsuitable as a method for uncertainty mitigation and use of ICDs for this reason must be thoroughly investigated using full uncertainty analysis in dynamic simulation.
Screening of Chemicals for Low Cost Heavy Oil Recovery through Microemulsion Stability Tests
Authors: Lee Jungin , Babadagli Tayfun 
Published: October 2017

Abstract
This paper reports the results of laboratory scale screening of different chemicals for their microeumlsion generation capabilities to be eventually recommended for non-thermal heavy oil recovery (chemical flooding). The study was performed through visualization of microemulsions generated using vials and microscopic images. The impact of salinities of brine on the emulsification was studied thoroughly in order to identify the synergy between the selected chemicals and the heavy oil. An alcohol propoxy sulfate surfactant from the Alfoterra series, Alfoterra S23-7S-90, a nonionic surfactant HORA-W10, gave good emulsion formation results at low salinity conditions (2.5 wt. %, 3.8 wt. %). Polysorbate-type nonionic surfactant Tween 20 gave good emulsion formation at high salinity conditions (6.35 wt. %, 7.6 wt.%). Their emulsion formation performance with a crude heavy oil of viscosity 4,812cP and 11.74 °API helped create an initial correlation of performance with the composition of crude oil and synthetic brine samples of various salinities. Attempts were also made to stabilize oil-in-water emulsions formed with Alfoterra S23-7S-90, HORA-W10, Tween 20 using nanofluids (metal oxides), sodium carbonate, and an anionic polyacrylamide-based polymer (PolyFlood MAX-165). Emulsions were visualized under the Axiostar plus transmitted-light microscope and their stability was studied in order to screen the most optimal chemical (or chemical combinations) available for low cost heavy oil recovery.
Study on Remaining Oil Distribution Characteristics and Water Flooding Efficiency Improvement Technology after Polymer Flooding
Authors: Deli Jia , Xiaohong Tang , Fuchao Sun , Tie Chen , Yongzhi Zhu , Tong Guo 
Published: October 2017

Abstract
It has become a focus of concern for polymer flooded oilfields to further produce remaining oil after polymer flooding at the subsequent water flooding stage. Based on the basic theory of hydrodynamic flow field distribution, a method to produce remaining oil at the diversion lines was proposed in this paper, which controls the increase rate of water cut by developing rational fluid control and water flooding efficiency improvement measures according to remaining oil saturation and the polymer injection rate at the diversion lines. A pilot test block has been selected and it has entered into the subsequent water flooding stage after polymer flooding. The distribution of remaining oil in the pilot test block is more complicated than that before polymer flooding, and the water cut is as high as 97.9%. Both the fluid production rate and injection rate are high among similar blocks. Low efficiency or invalid circulation is very serious, and development problems are becoming worse. This paper systematically analyzed the distribution characteristics of remaining oil. At the subsequent water flooding stage, the distribution of remaining oil is more scattered, most of it distributes near the faults and at the fringes of blocks, and remaining oil at the top of thick layers is produced by shutting in some water injectors and executing fracturing. By identifying preferential flow pathways, stopping water injection, increasing or decreasing the injection rate, water injection is rationalized. After one year of application in the pilot test block, the fluid production has been reduced by 146,000t, and 722,900t of water has been conserved due to properly controlled water injection.
Microbial Huff and Puff Project at Mangunjaya Field Wells: The First in Indonesia Towards Successful MEOR Implementation
Authors: Ariadji T. , Astuti D. I. , Aditiawati P. , Purwasena I. A. , Persada G. P. , Soeparmono M. R. , Amirudin N. H. , Ananggadipa A. A. , Sasongko S. Y. , Abqory M. H. , Ardianto R. N. , Subiantoro E. , Aditya G. H. 
Published: October 2017

Abstract
This multidisciplinary paper presents microbial Huff and Puff project results with objectives: 1) to understand the mechanisms through relating laboratory work results, field implementations and a history matching process during reservoir simulation (2) to seek reliability of the microbial Huff &Puff based on improvements of the production performance parameters. After a thorough screening work was done, detail laboratory works produced fluid samples from selected wells was conducted, implementation programs were designed, and a set of equipment consisting of a cultivation tank, a mobile laboratory, and other supporting facilities was installed at the field. The implementation basically involves three stages: (1) preflush, cultivation solution, and post flush (2) injection of cultivation solution and post flush, and (3) injection post flush. Finally, this project conducted a 6-month monitoring program of microbe population and compositional analysis of the produced fluid samples, and production performance analysis of wells production data. The overall growth of bacteria had increased from 2×103 CFU / mL to 5×106 for 176 days in Well MJ122, on the other hand, Well MJ-125 can reach much higher up to 500×106 bacteria (CFU/ml) in 122 days. Using the GC/MS composition analysis for semi-quantitative analysis with standards internal reference marker ratio of Pr/Ph shows monthly biodegradation samples percentage before and after application up to about 34% at the 3rd month of monitoring. The well MJ-125 Structure Analysis of Bacteria Community resulted from Single Strand Conformation Polymorphism (SSCP) Method indicated that the number of Operational Taxonomy Unit (OTU) change during the production was relatively stable and this correspond to their Sorensen Index values. But, MJ-122 well indicated unstable community structure, however, the interaction between microbes which were injected with indigenous microbes was not competitive. The wells water cut versus gross rate profiles show that the MJ-122 water cut drop occurs at low production rate, whereas, the MJ-125 water cut drop occurs drastically both in low and high production rates. The well MJ-125 average oil rate gain is about 20%. However, both wells show peculiar production profiles by depicting a cycle of "a valley of low values". Finally, a history matching process supports understanding of the mechanisms.
Extending Life of Liquid Loaded Gas Wells Using Velocity String Application: Case Study & Candidate Selection
Authors: Andrianata Satria , Allo Keken Rante , Lukman Ade , Kramadibrata Ari Taufiq 
Published: October 2017

Abstract
Depletion of the reservoir leads to a decrease in production rate and continuously drops below its minimum critical velocity. At this point, the liquid which flows vertically upward with gas begins to fall back into the wellbore. Liquids accumulation in the tubing creates additional pressure drop and gives more flow restriction to surface. Smaller diameter tubing string (so-called, velocity string) installation is a simple yet successful methods applied in Semberah field to overcome liquid accumulation in wellbore of low production critical gas wells. This paper discussed case studies and screening improvement of velocity strings installation in the observed field. The project delivered an improvement of candidate screening and design to achieve the continuously flow after installation. Case studies were introduced in this paper as example of success and non-success application. Screening improvement was delivered based on post-mortem analysis. Selection candidate included identification of liquid loading symptom by well behavior, critical rate analysis on each wellbore section, and flow regime analysis. Pressure and temperature bottom-hole survey, either at static or flowing condition had to be provided and matched with velocity string model. Evaluation of new critical rate each wellbore section and new flow regime after installation must be calculated. This applied method was proven to extend production life and increase gas cumulative production in observed field. Better understanding of comprehensive well screening is an important factor to enhance success ratio of velocity string installation project. The improved screening based on field experiences can be used as a reference of velocity string selection candidate and design in other liquid loaded gas field. This paper also discussed further opportunities of un-success cases, which apply a tandem de-liquefaction technology: velocity string and wellhead compressor or gas lifted injection for gas well.
Integrated Stress Calibration by Utilizing Advanced Acoustic Information - A Case Study from Deepwater Malaysia
Authors: Heidari Babak , Millot Pascal , Chujo Kota , Watanabe Yoshiaki , Yoshiyama Tomoyuki 
Published: October 2017

Abstract
"Block X," located in offshore Sabah is operated by JX Nippon Oil & Gas Exploration (Deepwater Sabah) Limited., which had drilled several exploration wells and acquired extensive wireline and LWD information to evaluate the block for further exploration and future development. Drilling exploration wells in a deepwater environment can lead to drilling difficulties. For example, a very narrow safe mud weight window was encountered in the discovery Well X and subsequent drilling difficulties delayed the well delivery. In orderto minimize the drilling risk for upcoming prospects, detailed petrophysical, geological and geomechanical studies have been conducted based on extensive evaluation of wireline and LWD data.
Determination of horizontal stress directions and magnitudes are an important part of building the 1D mechanical earth model, which allows optimizing perforation and completion design, and production planning. Knowledge of the stress directions also helps to optimize well trajectory design so that wellbore instability can be minimized. Several methods for identifying stress directions are available and investigated, including borehole breakout orientation and shear sonic anisotropy information. For complementing the existing drilling data (leak-off and formation integrity tests), the horizontal stress magnitudes are determined using the dipole radial profiles and the sonic anisotropy using acoustoelasticity theory.
The variation in shear sonic slowness within the elastic region of the rock is compared to the stress distribution caused by the presence of the wellbore. The relationship between shear slowness (modulus) and stress is then established to provide the acoustoelastic coefficient and horizontal stress magnitudes (both minimum and maximum) are then determined. These results were used to reduce uncertainty in the state of stress, and used in optimizing the wellbore trajectories for future development wells.
In the current study, besides conventional stress calibration data such as LOT/FIT and calliper information, advanced sonic information helped to calibrate further the stress profile, which resulted in a comprehensive understanding of the stress regime of the study area. These results are utilized to better design the mud weight program for the drilling of future Deepwater prospects in Block X.
Reservoir Rock Typing for Sweet Spot Identification within Complex Clastic Reservoir: A Success-Story from Northwest China
Authors: Wan B. , Jiang B. , Meng X. , Li S. , Yang Y. , Gong H. , Zhao H. , Wang W. , Wei G. , Zhuang X. 
Published: October 2017

Abstract
The studied reservoir is represented by complex clastic deposits located in northwest of China. From the core description, there are 15 rock types and five oil bearing gradesvarying from no oily to oil immersion. So the reservoir is very heterogeneous and it is very challenging to identify the best zones for fracturing. To mitigate this challenge, it is of utmost important to understand and evaluate the relationship between reservoir heterogeneity and oil saturation level to find out the best reservoir rock type for further completion work.
At the beginning of the work, detailed analysis have been done and a very strong relationship is observed between core grain sizes and oil bearing grade. In the current study area, high resolution borehole image logs are acquired but core data is available only for short intervals. Consequently, borehole image based methodology has been developed to characterize relationship among grain size, sorting and oil saturation. Also, Reservoir Rock Type (RRT) has been computed using integrated result from shale content, effective porosity and image derived advance outputs to identify sweet zone for hydraulic fracturing.
The study shows very interesting results from integrated image analysis within sandy interval, with decreasing grain size the oil bearing grade is increasing and the oil bearing grade is maximum in the medium grain sized pebbly zone. Four main reservoir rock type has been computed from clay content, effective porosity curves and image derived sorting index data. RRT result shows very good relationship with the oil bearing grade. Good RRT is dominated with oil immersion, Good to Moderate RRT is dominated with oil spot, Moderate RRT is dominated with oil stains and Poor RRT is dominated with no oily.
This RRT computation method from image derived high resolution data provides very valuable information for proper evaluation of this complex reservoir and sweet spot identification. This workflow has been established as a standard workflow to be applied in other parts of the study area. Also, this work can be a very good example to follow in similar complex clastic reservoirs from any part of the world.
Corrosion Under Insulation CUI Management on Idle LNG Process Train
Authors: Haga Gren 
Published: October 2017

Abstract
Badak LNG was capable to operate eight LNG Process Trains to produce LNG with maximum annual capacity of 22.5 MTPA. However, Badak LNG is currently entering idle phase for several of process trains due to declining of feed gas supply. Long Term Idle (LTI) preservation program has been developed to maintain the condition of all plants including insulation removal for all insulated lines and equipment. Insulation removal program is intended to reduce risk of Corrosion Under Insulation (CUI) that may attack all insulated lines and equipment.
Unfortunately, due to cost effectiveness program, insulation removal has been postponed and evaluation was needed to understand the severity of CUI and its effect to material integrity and cost benefit that maybe generated from this postponement. Therefore, evaluation of CUI severity was conducted during 5 years of idle period by using visual observation on selected inspection windows to determine the severity. Thickness measurement for the worst CUI grade items was also performed in the end of idle period to find out the effect of CUI degradation to integrity of material.
The evaluation reveals that about 21 percents of all inspected pipings and equipment were actually degraded in term of corrosion grade after 5 years in idlecondition. However, no degradation into grade D (worst grade) from grade A and B items was observed. Thickness measurement on worst grade items shows that the degradation of CUI is not affecting the material integrity significantly. Recommendation might be given in the future to exclude better condition, such as grade A and grade Bfindings from insulation removal programwhile removal still has to be conducted for worse grade items (grade C and grade D).
WAG Cycle Dependent Hysteresis Modelling through an Integrated Approach from Laboratory to Field Scale, Malaysia Oil Fields
Authors: Belazreg Lazreg , Raub M Razib , Hanifah M Azri , Ghadami Nader 
Published: October 2017

Abstract
With the increasing demand in domestic energy requirement and with declining production rates from mature fields of offshore Malaysia, PETRONAS has embarked on an aggressive campaign to address the decline in rates as well as increase the reserves through proven Enhanced Oil Recovery (EOR) application. An immiscible Water Alternating Gas (WAG) process is found to be the most favorable EOR method due to gas supply availability, proven world-wide application, and promising results in improving injection fluid sweep efficiency and reducing residual oil saturation.
To reduce the uncertainty of EOR technical studies under low oil price, a comprehensive integrated procedure is required to study WAG performance and define key factors that impact flow efficiency under three-phase flow conditions for a more representative full-field reservoir simulation study results.
This procedure involves a detailed comprehensive parametric study of the cycle dependent hysteresis starting from extensive literature review, followed by laboratory experiments and extracting pertinent WAG parameters from coreflood history matching and finally applying these parameters in full-field reservoir simulation study. This study demonstrated that the WAG cycle dependency of relative permeability during WAG process is one of the key factors that has significant impact on WAG performance and recovery factor. This feature cannot be captured by conventional three-phase flow models used by reservoir simulators. The study indicates additional recovery factor of about 1%-2% compared to the base-case WAG model without WAG hysteresis.