bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrogen Storage Characteristics and Corrosion Behavior of V-rich Ti-V-Cr-Fe Alloy
Authors: Abdul Jimoh Mohammed , Chown Lesley Hearth , Odusote Jamiu K. , Nei Jean , Young Kwo-Hsiung , Olayinka Woli Taiye
Published: April 2017

In this work, we investigated the effects of heat treatment on the microstructure, hydrogen storage characteristics and corrosion rate of a Ti34V40Cr24Fe2 alloy. The arc melted alloy was divided into three samples, two of which were separately quartz-sealed under vacuum and heated to 1000 °C for 1 h; one of these samples was quenched and the other furnace cooled to ambient temperature. The crystal structures of the samples were studied via X-ray diffractometry and scanning electron microscopy. Absorption/desorption characteristics were investigated using a Sievert apparatus. Potentiostat corrosion tests on the alloys were performed using an AutoLab® corrosion test apparatus and electrochemical cell. All samples exhibited a mixture of body-center-cubic (BCC) and Laves phase structures. The corrosion rate, maximum absorption, and useful capacities increased after both heat treatments. The annealed sample had the highest absorption and reversible capacity. The plateau pressure of the as-cast alloy increased after quenching. The corrosion rate increased from 0.0004 mm/y in as-cast sample to 0.0009 mm/y after annealing and 0.0017 mm/y after quenching, due to a decrease in the Cr-content of the C14 phase.
Water Quality Dynamics of Urban Water Bodies During Flooding in Can Tho City, Vietnam
Authors: Nguyen Hong Quan , Radhakrishnan Mohanasundar , Huynh Thi Thao Nguyen , Baino-Salingay Maria Luisa , Ho Long Phi , Van der Steen Peter , Pathirana Assela
Published: April 2017

Water pollution associated with flooding is one of the major problems in cities in the global South. However, studies of water quality dynamics during flood events are not often reported in literature, probably due to difficult conditions for sampling during flood events. Water quality parameters in open water (canals, rivers, and lakes), floodwater on roads and water in sewers have been monitored during the extreme fluvial flood event on 7 October 2013 in Can Tho city, Vietnam. This is the pioneering study of urban flood water pollution in real time in Vietnam. The results showed that water quality is very dynamic during flooding, especially at the beginning of the event. In addition, it was observed that the pathogen and contaminant levels in the floodwater are almost as high as in sewers. The findings show that population exposed to flood water runs a health risk that is nearly equal to that of being in contact with sewer water. Therefore the people of Can Tho not only face physical risk due to flooding, but also exposed to health risk.
China's Copper Demand Forecasting Based on System Dynamics Model
Authors: Yang Jianbo , Li Xin , Liu Qunyi
Published: April 2017

Copper demand for a country's copper industry has a greater pull effect. China's copper consumption in 2015 has accounted for 50% of the world. The scientific forecast of China's copper demands trend is also an important basis for analyzing its future environmental impact. This paper assumes that China's economy will be developing high, medium and low scenarios, and forecasts economic and social indicators such as total GDP, population and per capita GDP in China from 2016 to 2030. Then, predicted the demand of copper resources in China from 2016 to 2030 by the combination of system dynamics model, vector autoregressive moving average model and inverted U-type empirical model. The results show that: (1) in 2020, 2025 and 2030, China's refined copper demand will be 13 Mt, 15 Mt and 15.5 Mt. (2) China's copper demand growth slowed down significantly from 2016-2030. (3) 2025-2030, China's copper resource demand is stable, into the platform of demand growth, the highest peak value in 2027 will be 15.5 Mt. (4) 2030 years later, China's copper resource demand will enter a slow decline.
Optimization Simulation of the Light Aircraft’s Cockpit Made of Carbon Fiber Reinforced Composites
Authors: Chen Pu-Woei , Liu Chia-Hung
Published: April 2017

Due to the demands of personal travels and entertainments, light airplanes and small business aircrafts are developing rapidly. Light airplane structure is simple; however, it lacks crashworthiness design, especially the considerations on the impact of energy absorption. Therefore, in an event of accident, significant damage to passengers will be usually incurred. Airplanes made of composite materials structurally have high specific strength and good aerodynamic configuration. These materials have become the primary choice for new airplane development. This study mainly explores the topology optimization analysis of the light aircraft’s cockpit made of carbon fiber reinforced composites. This paper compares the compression amounts in the original models of composite material and aluminum alloy fuselages with the models after optimization during the crash-landing, in order to investigate the safety of fuselages made of different materials after structural optimization under the dynamic crashing. This study found that the energy absorbed by the aluminum alloy fuselage during crash-landing is still higher than that by the carbon fiber reinforced composites fuselage. On the other hand, the aluminum alloy fuselage after topology optimization could have an energy absorption capability enhanced by 40%, as compared to the that of the original model of aluminum alloy fuselage.
Non-Markov Stateful Evolutionary Games
Authors: Burgess Mark
Published: April 2017

A new evolutionary game is introduced which incorporates states and actions into the strategies of the organisms of the evolving populations. The game centrally features actions that result in demographic flow between states that may not conserve organism numbers. It is by this feature that the game encapsulate a range of other evolutionary games, and can encode almost very complex interactions between organisms, species and populations. The game's formalism is expounded and the nature of the game's equilibrium is discussed. This discussion leads to an algorithm for numerically determining the stable equilibrium points which is exemplified in the context of a modified Hawk-Dove game. The game's flexibility for modeling population dynamics is evaluated and compared with other evolutionary games.
Social Determinants of Health and Epigenetics: A New Tool for Health Policy
Authors: Sehgal Hitakshi , Toscano William
Published: April 2017

Globally, humans are struggling with the double threat of communicable and non-communicable diseases, which are presenting new challenges to public health. Public health problems are generally studied and addressed at primary, secondary and tertiary levels. Most effective results are seen with primary interventions. Public health is becoming more aware of the importance of environment-gene interactions in the ontology of health and disease using epigenetics. Epigenetics is the study of altered gene expression without change in base pairs. Be it physical, social, behavioral, or economic factors; they all influence quality of life and health of individuals and populations. That environments are changing the human health phenotype and these changed phenotypes are heritable is of concern for the future of the human race. Knowing the causes of non-communicable human diseases using epigenetics will contribute to the development of new policies to encourage prevention using primary public health initiatives. Research and application of epigenetics shows great promise for improving population health. Continued advances in epigenetics will enhance how we understand and address the way environments are affecting the human health phenotype. For some time, health systems have been and continue to be tertiary in nature. Epigenetic changes can provide information necessary to better understand how social determinants of health can be used to build societies focused on equitable health for all people, rather than continuing to focus on treatment of diseases in the tertiary phase that leads to health disparities. Understanding mechanisms of social determinants of disease, will allow society to evolve in a health-oriented rather than a disease-oriented world. For this reason, we must enhance and apply epigenetics (physical, social, behavioral, economic) research to policy development. We will discuss how bringing social determinants together with biology can be used as new tools for public health policy.
Hypoxia and Inflammation in Cancer, Focus on HIF and NF-кB
Authors: D'Ignazio Laura , Batie Michael , Rocha Sonia
Published: April 2017

Cancer is often characterised by the presence of hypoxia and inflammation. Paramount to the mechanisms controlling cellular responses under such stress stimuli, are the transcription factor families of Hypoxia Inducible Factor (HIF) and Nuclear Factor of kappa-light-chain-enhancer of activated B cells (NF-кB). Although, a detailed understating of how these transcription factors respond to their cognate stimulus is well established, it is now appreciated that HIF and NF-кB undergo extensive crosstalk, in particular in pathological situations such as cancer. Here, we focus on the current knowledge on how HIF is activated by inflammation and how NF-кB is modulated by hypoxia. We summarise the evidence for the possible mechanism behind this activation and how HIF and NF-кB function impacts cancer, focusing on colorectal, breast and lung cancer. We discuss possible new points of therapeutic intervention aiming to harness the current understanding of the HIF-NF-кB crosstalk.
Pengenalan Atas Takhrij Hadis
Authors: Rahman Andi
Published: April 2017

Untuk meneliti keshahihan sebuah hadis, kita perlu meneliti kualitas sanad dan matannya. Langkah awal dari penelitian hadis adalah takhrij hadis, yaitu penelusuran letak hadis pada kitab-kitab primer (mashadir ashliyah) yang mencantumkan hadis secara lengkap dengan sanadnya.
Tulisan ini mengulas pentingnya takhrij hadis, sejarah dan dan perkembangan takhrij hadis, delapan metode takhrij yang lima di antaranya dipaparkan oleh Mahmud al-Thahhan dalam kitab Ushûl al-Takhrîj wa Dirâsah al-Asânid, prinsip-prinsip dan manfaat takhrij hadis.
Menyoal Kritik Sanad Joseph Schacht
Authors: Suadi Hasan
Published: April 2017

Secara umum, orientalis mengkaji Ilmu-ilmu keislaman dimulai sejak abad 17 M dan mencapai puncaknya pada pertengahan abad 19 M. Hal ini dimulai semenjak negara-negara Islam di bawah cengkraman kolonialis barat. Trend kajian orientalis terhadap hadits dapat dikelompokkan kepada 4 periode, yaitu pertama, periode  permulaan. Kedua, periode Ignaz Goldziher (1850-1921), ketiga periode Joseph Schacht (1902-1969), keempat periode Pasca Joseph Schacht.  Dari keempat periode tersebut, secara umum dalam kajian hadits, orientalis terbagi menjadi tiga (3) kelompok, yaitu Skeptisisme (ragu atau meniadakan sama sekali kebenaran hadits), Middle Ground (pertengahan antara Skeptis dan Non Skeptis) dan Non Skeptisisme.
PEMAHAMAN HADIS ALI MUSTAFA YAQUB Studi atas Fatwa Pengharaman Serban dalam Konteks Indonesia
Authors: M MISKI M
Published: April 2017

Artikel ini berangkat dari paparan yang dikemukakan oleh Ali Mustafa Yaqub –seorang pakar hadis– bahwa mengenakan serban untuk konteks Indonesia hukumnya haram. Artikel ini mencoba melakukan eksplorasi lebih jauh tentang pemikiran dan pemahaman hadis Ali Mustafa Yaqub khususnya dalam konteks ke-Indonesia-an dan lebih spesifik lagi yang berkaitan dengan persoalan serban. Sebagai hasilnya, didapati kesimpulan bahwa alasan sederhana pengharaman serban adalah karena ia termasuk pakaian syuhrah dan tidak termasuk pakaian yang biasa dikenakan oleh masyarakat umum. Ali Mustafa tidak menafikan hadis yang menyebutkan bahwa Nabi mengenakan serban, tetapi hadis tersebut dipahami secara kontekstual yang berarti tidak ada muatan hukum harus diterapkan dalam segalam situasi dan kondisi. Dengan demikian, pemahaman hadis ala Ali Mustafa ini lebih mirip dengan pemahaman Yu>suf al-Qarad}a>wi> dan Muh}ammad al-Gazali>.
Issues and Challenges With Controlling Large Drawdown in the First Offshore Methane-Hydrate Production Test
Authors: Sakurai S.. , Nishioka I.. , Matsuzawa M.. , Matzain B.. , Goto A.. , Lee J. E.
Published: April 2017

The first offshore methane-hydrate production test was conducted in the Eastern Nankai Trough area of Japan in 2013, subjecting a gas-hydrates reservoir to large drawdowns by reducing bottomhole pressure (BHP) for in-situ dissociation of gas hydrates. This pioneering test has proved the feasibility of the depressurization method through demonstration of gas production from a deepwater gas-hydrates reservoir. Approximately 119 500 std m3 of gas was produced during a continuous flow period of 6 days. However, reservoir response to a range of drawdown conditions was not attainable, which is important for reservoir evaluation, because drawdown became uncontrollable after unintended water production through the gas line occurred.

Gas and water released from the dissociation of gas hydrates were separated by use of a downhole gas-separation system. The separated gas and water were produced to surface by means of two dedicated gas and water lines. Drawdown was executed by pumping out water into the water line by use of an electrical submersible pump (ESP). Drawdown control was designed to regulate the liquid level (or hydrostatic pressure) in the gas line by controlling the ESP frequency and the water-line surface backpressure.

Analysis of production data supported by flow simulations indicated that continuous water production through the gas line was the main reason for the loss of drawdown control. The trigger of the water production was that the water column in the gas line reached surface because of the rising water level resulting from the produced gas, which also lightened the water column and lowered the BHP. Consequently, the continuous water production made it difficult to regulate the drawdown as intended.

The analysis concluded that the risk of water production through the gas line could be significantly lowered if a choke valve was installed at the surface gas line and/or the ESP had high tolerance to the presence of free gas. This first field trial has provided valuable information in understanding the methane-hydrate production system to further improve/develop strategies in controlling large drawdown in the system.
Temperature Correction in NMR Logging While Drilling
Authors: Coman Radu , Tietjen Holger
Published: April 2017

The formation temperature affects numerous logging measurements including nuclear magnetic resonance (NMR) data. Obtaining NMR porosity requires the multiplication of the raw NMR signal by a factor that includes the temperature in the sensitive volume. Typically, the temperature of the mud is used as a proxy for the temperature in the sensitive volume. However, if the two temperatures are not equal, the temperature effect reduces the accuracy of the NMR porosities. In some environments (e.g., NMR logging while drilling in deep wells) the NMR temperature effect might as large as 10% of the total NMR porosity.

The main challenge in correcting the NMR porosity for temperature effect is the estimation of the temperature in the sensitive volume. By assuming that heat conduction is the main heat transfer mechanism, the formation temperature can be estimated by solving the heat equation in the proximity of the borehole. To reduce the computational time, a level-based approach is used, whereby the size of the model is controlled by the borehole size. Moreover, by assuming that the temperature in the axial direction is constant within the sensitive volume, the 3-D temperature distribution is reduced to a 1-D distribution (in the radial direction) that can be numerically computed by a finite-difference (FD) scheme.

The temperature distribution around the borehole depends on several parameters including the undisturbed temperature of the formation, the borehole size, the thermal diffusivity of the formation, the time since drilled, and the whole history of drilling mud temperatures. A level-by-level FD computation of the formation temperature is too slow for practical use. Fortunately, the FD computation can be fully replaced by a fast analytical computation based on two pre-computed maps. The maps contain dimensionless formation temperature as function of dimensionless time and dimensionless radius. The first map is for the continuous cooling case (mud temperature is constant and lower than formation temperature), while the second map is for a so-called impulse cooling case.

This paper presents the theoretical background of the NMR temperature correction, several FD schemes and the quasi-analytical approach used for the computation of the formation temperature, numerical examples illustrating the computation of the formation temperature for several cases (e.g., a logging-while-drilling run and a logging-after-drilling run), and a temperature correction workflow for NMR logging data.
Development of Inhibitive Water Based Drilling Fluid System with Synthesized Graft Copolymer for Reactive Indian Shale Formation
Authors: Kumar Saket , Jain Rajat , Chaudhary Pulkit , Mahto Vikas
Published: April 2017

Wellbore instability in shale formations is one of the major problems with water based drilling fluids. The wellbore instability may escalate drilling costs and time. The swelling and dispersion of shale inside the wellbore may lead to high torque, drag, pipe sticking, and additional reaming and borehole enlargement problems. The synthesized graft copolymer is characterized by FTIR, and FESEM techniques. The graft copolymer exhibited superior rheological and filtration properties in the developed drilling fluid system due to increased hydrogen bonding and synergistic effects. The graft copolymer based drilling fluid system has excellent shale inhibition property as compared to PHPA polymer. The shale recovery and slake durability index of graft copolymer based system is higher than PHPA system. This is achieved due to formation of a film-like barrier on the shale surface in presence of graft copolymer, thus restricting the entry of water molecules and solid particles into the shale. The developed system has low reactivity with the core sample as revealed by core flooding studies.
Effect of Varying Permeability on Inflow Performance Curve of Gas Reservoirs
Authors: Kommineni M. , Kavanamani R. , Kurupati A. , Cherian T. T. , Aborig A. M. , Hossain M. , Huque M. M. , Miah M. I.
Published: April 2017

An inflow performance relationship (IPR) curve is a mathematical tool used to predict the production of the well throughout its lifetime. This curve is plotted for bottom hole flowing pressure against production rate. An inflow performance curve is presented considering the gas reservoirs where permeability alteration due to pressure is introduced. Results are compared with conventional curves which are based on constant permeability. The new approach considers the permeability of the reservoir as a function of pressure. In addition, modified Kozeny-Carman equation is employed to take care of the variation in porosity, Cementation factor, Shape factor, Lithology factor. The proposed approach considers the porosity and cementation factor as a function of pressure based on compressibility of the rock matrix. The numerical solution shows the over prediction of the gas flow rate with reducing bottom hole pressure, by conventional IPR based on constant permeability. The pseudo pressure equation is considered and the conventional IPR curves are compared with the two proposed models. The first model considers only the porosity as a function of pore pressure whereas the second model considers both porosity and cementation factor as a function of pore pressure. For validation, two field case studies are presented for vertical wells in a gas reservoir. Gas flow rates predicted by suggested models are same as that of conventional IPR at average reservoir pressure. On contrary, the IPR curves for both models shifted left due to the low gas flow rates obtained. The most significant finding is that porosity has a greater effect on permeability compared to the cementation factor and thus on IPR curve. The first model considers only the effect of porosity on pressure, shows significant deviation in IPR curve due to a decrease in flowing bottom hole pressure resulted due to production from the gas reservoir. The second model considers both porosity and cementation factor as a function of pressure is more accurate and recommended for inflow performance predictions.
A Study of Drilling Jar Utilization and Effectiveness in the Kingdom of Saudi Arabia
Authors: Oliveira V. C. , Martinez M. A. , Zahrani B. S. , Abouelnaaj K. K.
Published: April 2017

In the present paper, numerous stuck pipe events were carefully studied in wells drilled in the Kingdom of Saudi Arabia between 2013 and 2014. Stuck pipe events were analyzed per different hole sections (from 34 in. to 5 7/8 in.) and it was noted that overall the number of stuck pipe events were less for the top hole sections. Therefore, the focus of the study was to evaluate the utilization and effectiveness of Drilling Jars in the top hole sections 34″, 28″ and 22″ during stuck pipe events.

The data was collected from Saudi Aramco Stuck Pipe database and limited to new wells, a total of 42 fields and 1026 wells were reviewed. After that, each stuck pipe event was classified according to field name and to the respective hole size where the incidents occurred. A detailed and comprehensive study was conducted for each stuck pipe incident independently, reviewed daily drilling reports and determined the utilization of the Drilling Jars as well as the effectiveness to free the drill string during the stuck pipe incidents.

Classifying the stuck pipe events and analyzing the results, showed that the effectiveness of Drilling Jars in the top hole sections was uncertain. For the 34″ and 28″ hole sections, the effectiveness of Drilling Jars was minimal. For the 22″ hole sections, it showed higher number of utilization and effectiveness. The study concluded that the use of Drilling Jars in the 34″ and 28″ hole sections were ineffective, therefore it was recommended to eliminate the use of Drilling Jars for the respective hole sections across drilling operations in KSA. This decision will result in significant savings, and help to free up service provider resources for use in other hole sizes.

The research became a useful reference in defining the utilization and effectiveness of Drilling Jars across Saudi Aramco Operations. Drilling Engineers are encouraged to optimize the use of drilling equipment in the bottom-hole assembly, to improve efficiency and reduce drilling costs.
A Successful Water Shut Off Treatment in Gas Well of Bassein Field by Polymeric Gel System
Authors: Mattey Padmaja , Varshney Meenu , Daksh Pd. Vikrant , Kumar Aditya
Published: April 2017

Worldwide excessive water production in gas reservoirs has always been regarded as one of the most formidable problems, which hampers the productivity of the well to any extent and in the extreme cases may lead to ceasure of the well due to water loading although the reservoir contains sufficient amount of recoverable reserves. The source of water production can be a channel behind casing due to poor cementation, casing leaks, coning, encroachment, water breakthrough and flow through natural and induced fractures. In the process of shutting off /mitigation of unwanted water production, the identification of source of water inflow in the well is the most important step for choosing a correct technique. However, the problem becomes even more complex if multiple mechanisms of water invasion are simultaneously active in the well.

There are various mechanical and chemical techniques to deal with excessive water production. The mechanical means provide a seal in the near-wellbore openings. However, most of the time, it is desirable to achieve matrix or small fissure penetration of the sealing material. Among the chemical methods, polymer gels are considered as one of the most commonly applied technique on account of relatively low cost, ease of pumping and ability to penetrate deeper into the reservoir.

Bassein is a major gas field in the western offshore basin of India and is producing gas since 1988. The entire structure of the field is a gas cap gas reservoir, which is underlain by very thin oil column and large aquifer and producing gas under partial aquifer drive. The field recovery has crossed 60% of GIIP and presently most of the wells of BC and BE platforms are either producing large amount of water or have ceased to flow due to water loading leading to huge loss of well productivity and making them suitable candidates for water-shut-off treatments. The well BC-2, which was/ had ceased to flow due to water loading, but could not be brought back on production even after mechanical water shut off method was chosen as a pilot well for treatment with deep penetrating high temperature resistant gel system. After gel treatment, the well was put on sustained production along with reduction in water production by 90%.

This paper discusses the laboratory studies for polymeric gel optimization, methodology of job design with operation sequence and results obtained from the field.
Multistage Up-Dip Well (>94 Deg) Fracturing using Plug & Perf Technology through Coiled Tubing - A Case Study
Authors: Gupta Anand , Gupta Vaibhav , Okeke Ugochukwu , Jerath Shweta
Published: April 2017

Unconventional Horizontal Multistage Fracture Completions have a vast acceptance worldwide and is proven in various Geographical and Geological setups in producing the Initial Oil and Gas in Place. The most immense method of conducting the Multistage Horizontal Fracturing operations is through the "Plug and Perf" method. This technique is one of the most practiced way of conducting the operations in a time effective and a safe manner. This usually entails a conveyance method with threaded joints or Coiled Tubing. Other conveyance methods can also be Electric Line, however Coiled Tubing/Threaded Joint is needed for the later part of operations to bring the well online for production. The Coiled Tubing is a fast and effective way to complete the operations necessary for achieving the well design targets.

Currently most of the operations are done in the same fashion, where most of the operational problems are not counted in while planning initially. This paper will give an insight on the optimization of such operations in Horizontal Wells and especially wells with an angle more than 90°.

This paper will describe the optimizations done to make the operations much more time effective and efficient in terms of equipment and resources through field experience and published data. These optimizations can be utilized for pre-job designs, Well Bore Clean Outs (WBCU), CP Setting, Motor Design, Mill Design, Milling parameters, Extended Reach Issues and Post Milling Practices.
Exploiting the Thick Tight Gas Sandstone Formation of Periyakudi Field of India through Fracturing Stimulation - A Challenging Experience
Authors: Mahawar Dheeraj , Kumar Rajesh , Das Santanu , Rajendra K , Nainwal S P
Published: April 2017

This paper discusses the Hydraulic Fracturing (HF) treatment of the Andimadam Sandstone formation of Periyakudi field of India. The Andimadam sandstone is a hydrocarbon bearing formation, with estimated in-place reserves of 47.43 MMt (O+OEG) which was prognosticated after drilling and established hydrocarbon potential. Well PD#A was drilled in Andimadam Sandstone and HF in this well was attempted in order to develop and exploit the full potential of the oil and gas reserves of the field.

The fracturing treatment of the tight gas reservoir in one of the deep well in Periyakudi field was performed eld. It was a challenge to carry out HF in well PD#A at such deeper depth formation. There was no previous information available to understand the formation and to predict its behaviour during HF treatment.

HF treatment in tight gas Sandstone laid so many challenges. Formation breakdown, succeeding minimum rate required for fracturing and attaining high proppant concentration during job with crosslinking gel under extremely strenuous operational conditions and pressure limitations were some of the major challenges. Delayed cross-linked gel was used to minimize tubing friction pressure. Managing the pumping rate with pressure limitations during HF treatment was one of the major challenges. Execution of the treatment with low pumping rate results in stimulation of small volume of rock comparatively. All these limitations were overcomed by proper job designing, optimization of fracturing fluid and analysis of pre-frac treatments. A substantial amount of fracturing fluid and proppant placed into the formation maintaining all safety standards. Satisfactory flow back of frac fluid with gas was observed and high flow back pressure at surface was noted.

This paper discusses challenges to execute hydraulic fracturing treatment in well PD#A and the lessons learned during the execution. In addition, it was the deep well (drilled upto 4945 m) in Periyakudi field with low permeability reservoir. Post analysis of pre-frac treatments done to obtain the reservoir properties and to design the main frac treatment. The results of fracturing treatment are also discussed. The promising hydrocarbon potential of the Andimadam sandstone which are based on post fracturing analysis, encourages further future development of the Periyakudi field, Cauvery Basin, India.
Pressure Build up Study with Echo Meter Data - A Case Study of NE Field
Authors: Kumar Vineet , Vema Saurabh Kumar , Bhatnagar Anil Kumar
Published: April 2017

The NE field is located in Barmer Basin, Rajasthan, India. The field is on production with two wells since March 2015 and is currently producing about 1100 bopd. Both the wells are completed with progressive cavity pumps (PCPs). Production is being carried through a small production facility (QPF). The presence of pumps in the well makes the acquisition of pressure build up (PBU) data complex. However, gathering a PBU was considered an important part of gauging reservoir performance. This paper details how an echo-meter was used in one of the wells for acquiring Pressure Build Up data. The echo-meter was used to measure dynamic fluid levels in the casing-tubing annulus; these were used to estimate reservoir pressure and other properties in a cost effective manner. The paper discusses a systematic approach in echo-meter based well test design, execution challenges and the PTA of the acquired data.

The well was flowing with a drawdown of about 100 psi and the liquid level in the annulus was about 100m from the top. The direct collection of PBU data would have required a work-over to remove the pump to place the gauge. This would need to be repeated to retrieve the gauge. A novel & cost effective approach was required to acquire pressure build up data. An alternate option was acquiring the pressure data indirectly by measuring the continuous dynamic level in the annulus using an echo-meter. Although this option had its own challenges, it was economically justified. The required number of echo-meter shots and frequency of the shots was selected based on well test design. The test design provided guidance on the pressure build up rate required for damaged (skin) and non-damaged conditions, permitting us to identify the pressure build up duration and the optimum frequency of the echometer shots. One challenge was concern over annulus liquid level rise in the wellbore. This was addressed prior to the build-up by injecting nitrogen into the annulus to reduce the liquid level in the annulus. This mitigated the possibility of liquid level rise in the annulus to the wellhead.

The quality of the pressure data acquired through echometer shots was good enough for carrying out pressure transient analysis. The pressure derivative plot was constructed and information on skin & permeability was obtained. Radial flow signature was clearly observed. The average reservoir pressure value as well as the permeability agreed with expectations. The impact of uncertainties on the final interpretation was evaluated and found to be in acceptable range.

In current oil price environment and in marginal fields like NE, where there is always a constraint on economics, this low cost technique can be a vital tool for effective reservoir management.
A More Holistic Approach to Determine Economics of Using Synthetic Oil Based Mud over Water Based Mud System in Onshore Development Drilling
Authors: Sinha Pankaj , Kumar Varun , Prabhakaran Tushar , Katre Anurag , Patel Maulik , Doodraj Sunil
Published: April 2017

This paper presents a more holistic approach to compare the drilling economics of Synthetic Oil Based Mud (SOBM or SBM) versus Water Based Mud (WBM) in onshore development drilling in India. Here, a key parameter which has been incorporated in the economics is the mud re-use and overall consumption trend of SBM versus WBM, which has been analyzed from statistical data across 200+ wells and quantified into overall cost savings with SBM estimated across roughly 500 development wells drilled.

The surface holes in all the development wells were drilled with WBM instead of SBM to avoid contamination of shallow water aquifers. Hence, the performance evaluation of SBM was limited to intermediate and production holes only, which were drilled with SBM. Also, past exploration and appraisal wells had used WBM for drilling these hole sections. A key parameter calculated from statistical data was average mud consumption (barrels per meter drilled) for SBM and WBM. The mud consumption of SBM and WBM is expected to differ because theoretically SBM can be re-used across greater number of wells compared to WBM. The average mud consumption was separately calculated for different hole sizes to better analyze the effect of hole size on mud consumption. The actual cost incurred with SBM application in development wells was calculated. Next, cost for drilling these wells with WBM was estimated using mud consumption (barrel per meter) data obtained from exploration/development wells. These two cost scenarios were compared to arrive at the net cost savings with SBM compared to WBM.

A maximum cost savings upto ~10 MMUSD (for various sensitivities especially SBM cost per barrel) is estimated across 500 wells in spite of the higher contracted costs of SBM (cost per barrel) when compared to WBM. The maximum cost saving of ~10 MMUSD corresponds to anticipated reduction in base oil cost in the current crude market. The savings with SBM are mainly attributed to the fact that SBM can be theoretically re-used infinitely moving from one well to the other while the WBM can be re-used for a limited number of wells. This cost model excludes any savings on part of SBM due to improved hole conditions and resultant reduction in drilling non-productive time.

SBM system minimizes drilling problems due to good clay inhibition, enhanced hole cleaning, lubricity additionally SBM is least effected by contamination. However, the higher cost per barrel of SBM and associated environmental concerns normally act as deterrents for operators to choose SBM for planning their wells. This paper provides clarity on the perception "SBM is costlier to WBM" and reinforces the recommendation to use SBM for drilling operations from an overall cost perspective.
A New Approach for Productivity Enhancement in Mature Sand Prone Fields Having Nearby Water Contact Through Slick Water FracPack: A Case Study
Authors: Mishra Nirmal Kumar , Singh Amar , Rakundal Snehal , Rajendra KWS , Nainwal S. P.
Published: April 2017

Due to nearby water contact, conventionally cased hole gravel pack (CHGP) was preferred completion techniques for sand prone reservoirs in western onshore basin and KG basin of India. However, these completions had often performed poorly both in terms of productivity and longevity. This paper describes the detailed case studies for new completion approach (i.e. Slick Water Frac Packing) adopted to alleviate the productivity decline including favourable modification in completion procedure & job treatment.

Since inception, Cased-hole Frac Packing (CHFP) was avoided owing to incompetent shale barriers and nearby water contact. Later on, Horizontal Open-hole gravel packing and Standalone screen completion techniques were adopted but result was not encouraging. The productivity decline was further aggravated with "water-shut off" treatment prior to cased-hole gravel packing.

The existing completion strategy was reviewed to identify the shortcomings & a new completion strategy of Slick Water Frac packing(SWFP) adopted for these fields, which was further customized to suit the specific well conditions. When these customized SWFP were implemented, significant improvement in well performance was seen, in form of hydrocarbon production.

Till date more than thirty wells have been completed with SWFP. Among them, many wells were already producing water beyond the acceptable limit while some wells have very near water contact (< 2.5 m) without competent barriers. Apart from this, one well had long history of fines production and CHGP / standalone screen (SAS) completion applied did not give good result. The execution of customized SWFP was successful in almost all wells and amount of proppant placed in the formation was the range of 300-1000 lbm /feet of perforation.

These completions have achieved the objective of productivity enhancement with average incremental oil gain of about 22 barrel per well apart from formation sand retention.

Although some SPE papers have described the CHFP application in wells having near water contact, but the combination of WSO treatment and Frac packing treatment for wells already producing high water cut, is unprecedented as per author's knowledge. The information provided in this paper can be used to enhance hydrocarbon production without increasing significant water production in similar fields.
Optimizing Cost and Effectiveness of Well Interventions: An Holistic Approach
Authors: Gosain Sonali , Dhiman Mansi , Kothiyal Manish Dutt , Upadhyaya Akhilesh , Jetley Shailendra , Jain Sachin , Jain Akanksha , Patel Nilay , Hammond Paul
Published: April 2017

Cairn India Limited operates over 600 wells in the Barmer basin in Rajasthan with over 30 well intervention (rig and rigless) units deployed on an average to perform over 5000 interventions per year. Maintaining the quality of interventions and analyzing the performance of such a scale of operations is a major challenge. This paper describes "An holistic approach" for evaluating well intervention campaigns, reviewing candidate selection, intervention techniques and technologies utilizing an intensive data warehouse and the techno-economical tool, "Scorpion Plot" to optimize intervention costs and rewards.

The performance of all Well & Reservoir Management (WRM) activities are analyzed in terms of cost and associated gain. The data gathered is categorized into four types namely Well Surveillance, Production Enhancement, Restoration, Well Integrity and Support. The expenditure on non-oil and gas gain generating interventions (Well Surveillance, Restoration, Well Integrity & Support) plotted on cumulative cost basis gave an overall idea of the health of the well stock and understanding of the value of information from data gathering. The Production Enhancement activities, sorted in increasing order of cost per barrel gained were plotted on a cumulative cost vs cumulative gain curve termed as "Scorpion Plot" because the shape always largely resembles a "scorpion tail" with low cost-high gain jobs lying in the bottom left part of curve and high cost and negative value interventions forming the "tail" of the scorpion to the top right. The analysis of the type of jobs falling in the different tranches of the plot on the basis of $ spent per barrel gained, helps in identifying the areas for optimizing the process of candidate selection and job execution.

The objective is to remove negative gain and reduce high cost low gain activities (the tail of the "scorpion plot") and shift the curve towards the bottom left to improve oil realization while reducing cost. After Action Reviews are carried out for all the negative and lower value activities and the lessons learnt are fed back into the intervention management system to enhance future intervention campaign results. Production enhancement activities such as ‘Well Stimulation’ positioned in the negative value group were further analyzed based on the selection criteria, technique of stimulation, chemical recipes/volumes were benchmarked against the high value interventions. Case studies showing how the analysis helped in better candidate selection and best technique for interventions are discussed.

This paper also describes how the process of candidate selection, cost, resource allocation and job impact assessment is automated ensuring engineering focus on job planning and after action review.
Characterisation and Modelling of Fractured Basement Reservoirs: A Case Study
Authors: Nautiyal D. K. , Goswami Sandeep , Dutt Ankit
Published: April 2017

Padra field, discovered in 1977, is located in the eastern margin of Ankleshwar-Broach tectonic block of Cambay basin. Padra basement is overlain by thick sedimentary succession of clastic reservoir rocks and shale barriers including Cambay shale (major source rock). The characterization, modelling and flow simulation of fractured basements is complex and entirely different from conventional reservoirs. The paper aims to introduce a unique approach for study of basement reservoirs.

A Discrete Fracture Network (DFN) model is made to represent two fracture set explicitly, based on spatial and non-spatial parameters. Fracture orientation is distributed using statistical model of Fisher. Simulation exercises are carried out wherein; fractures are not explicitly represented but an equivalent virtual medium is created with effective properties (porosity and permeability) representing the dynamic properties of the flowing domain (fractures). Being a type I basement reservoirs, single medium model (single porosity and permeability) is used for flow simulation with effective properties calculated by Oda's method of numerical flow.

This work paves the way to establish workflows that benefit from the merits of complementary methods, which will allow us to characterise the uncertainty in naturally fractured reservoirs more accurately. The case study elucidates the experiences gathered during simulation study of 112 wells, out of which 48 wells have been found to be hydrocarbon bearing. Pressure and water cut trend indicate active aquifer support. Early cessation of structurally higher wells in same as well as different fault blocks has been found to be a prominent anomaly. Also, strong contrast in reservoir performance of nearby wells has been found in a few cases. This indicates a great level of heterogeneity in fracture distribution in reservoir. Ten zones of alternate high and low fracture intensity have been created based on interpretation of 6 FMI logs. The fracture counts (P10, count per length) in wells with FMI should have been used as indicator for fracture intensity (fractures area in a unit volume). Sensitivities on interaction forces and roughness of fracture planes is carried out as a key part of dynamic modeling. The DFN approach allows us to generate multiple realisations of fracture models and condition these to the field observations.

Characterizing fractured reservoirs using borehole core and image logs provides the static description of fracture properties. However, some fracture properties (3D fracture-density) are highly uncertain when they are evaluated using static characterization methods only. Hence, dynamic calibration methods are required to condition geological fracture models and to increase confidence in the adopted conceptual model. Pressure transient analysis integrated with log/core information must be used to characterize the reservoir's flow capacity and for the dynamic calibration.
Best out of Waste - Waste Water Management for Sustenance of Well Intervention Activities
Authors: Gupta Abhishek , Sharma Vedant , Parasher Arunabh , Thummar Dinesh , Satyarthi Rajesh S. , Rao Eshwar , Tiwari Shobhit
Published: April 2017

Drilling, Completion and Well Intervention operations generate waste water. With the increasing volume of well fluids being flowed back due to aggressive Well Intervention activities, there was a need to handle and dispose the waste water efficiently. This was required to maintain continuity of well flow back and stimulation operations in an efficient and sustainable manner without incurring additional cost keeping in mind the current Oil and Gas market scenario.

This paper presents the "Best out of Waste" methodology adopted by the Well Services Department of Cairn India Limited to manage the huge waste water volumes by pooling in-house resources for developing Waste Water Treatment Project.

This project as it stands today was brought together by first, evaluating various treatment methods such as EC (Electro Coagulation) unit, Chemical methods, Particle settling and Disposal methods such as natural evaporation, evaporators (Mechanical and Solar) and injection and further combining features of the above stated methods to gain maximum benefit. These evaluations led to selection of EC Unit combined with the effectiveness of Mechanical evaporators and Natural evaporation for decreasing the waste water footprint.

Second, identifying a disposal well for treated water injection, established by various integrity and injectivity tests to confirm that the well was ready to accept the water with parameters and properties similar to that of EC unit output. The encouraging results in the injectivity tests proved to be the kick-off point of the project. Continuous monitoring of the treated water was also done to ensure the TSS and oil in water remained within the acceptable limits for injection, as per prevailing norms.

Third, developing disposal pits and tank farm to facilitate the treatment and dumping of the treated waste water. Lastly, decreasing current waste water inventory along with reducing the OPEX involved with handling, transportation and disposal of the waste water.

The key feature of this project was the utilization of above mentioned equipment's from internal resources of the company, which were either working stand-alone or were nonfunctional. Thus, the CAPEX for the project was brought to a bare minimum.

The objective of this paper is to present the various technical, administrative and commercial aspects associated with this project and conclude with plans of further utilizing the treated water for future Fracturing, Stimulation and even completion jobs.
One-particle density matrix of trapped one-dimensional impenetrable bosons from conformal invariance
Authors: Brun Yannis , Dubail Jerome
Published: April 2017

The one-particle density matrix of the one-dimensional
Tonks-Girardeau gas with inhomogeneous density profile is calculated,
thanks to a recent observation that relates this system to a
two-dimensional conformal field theory in curved space. The result is
asymptotically exact in the limit of large particle density and small
density variation, and holds for arbitrary trapping potentials. In the
particular case of a harmonic trap, we recover a formula obtained by
Forrester et al. from a different method.