Study of the Cause of Lost Circulation while Drilling Fractured Carbonates

2021 ◽  
Author(s):  
Alexey Ruzhnikov
Keyword(s):  
Success Rate ◽  
Drilling Fluid ◽  
Circulation Zone ◽  
Lost Circulation ◽  
Carbonate Formation ◽  
New Information ◽  
Fractured Carbonate ◽  
Long Time ◽  
The Difference ◽  
Fractured Carbonates

Abstract Fractured carbonate formations are prone to lost circulation, which affects the well construction process and has longtime effect on well integrity. Depending on the nature of losses (either induced or related to local dissolutions) the success rate is different when the induced losses can be cured with a high chance, and the one related to dissolutions may take a long time, and despite multiple attempts, the success rate is normally low. To have a better understanding of the complete losses across the fractured carbonates, a series of studies were initiated. First, to understand the strength of the loss zone, the fracture closing pressure was evaluated studying the fluid level in the annulus and back-calculating the effect of drilling fluid density. Second, the formation properties across the loss circulation zones were studied using microresistivity images, dip data, and imaging of fluid-saturated porous media. The results of the studies brought a lot of new information and explained some previous mysteries. The formation strength across the lost circulation zone was measured, and it was confirmed that it remains constant despite other changes of the well construction parameters. Additionally, it was confirmed that the carbonates are naturally highly fractured, having over 900 fractures along the wellbore. The loss circulation zone was characterized, and it was confirmed that the losses are not related to the fractures but rather to the karst, dissolution, and megafractures. The size and dip of the fractures were identified, and it was proven the possibility to treat them with conventional materials. However, the size of identified megafractures and karst zones exceeding the fractures by 10 times in true vertical depth, and in horizontal wells the difference is even higher due to measured depth. This new information helps to explain the previous unsuccessful attempts with the conventional lost circulation materials. The manuscript provides new information on the fractured carbonate formation characterization not available previously in the literature. It allows to align the subsurface and drilling visions regarding the nature of the losses and further develop the curing mechanisms.

Quantification of the Loss Conduit Aperture During Lost Circulation in Fractured Carbonates

2021 ◽  
Author(s):  
Alexey Ruzhnikov ◽  
Ashley Johnson
Keyword(s):  
Drilling Fluid ◽  
Rock Properties ◽  
Circulation Zone ◽  
Lost Circulation ◽  
New Information ◽  
Fractured Carbonate ◽  
The Difference ◽  
New Vision ◽  
Carbonate Formations ◽  
Fractured Carbonates

Abstract Fractured carbonate formations around the world are prone to lost circulation that not only affects the well construction process but creating a longtime effect on the wellbore integrity. Despite multiple attempts to cure them the success rate is usually low. This manuscript is aiming to provide a new vision on the reason of lost circulation across carbonates. To have better understanding of the complete losses across the fractured carbonates the series of studies were initiated. At first to understand the strength of the loss zone the fracture closing pressure was evaluated via study of the fluid level in the annulus and back-calculation of the drilling fluid density effect on it. Secondary, the rock properties across the loss circulation zones were studied by using the microresistivity images, dip data, and imaging of fluid-saturated porous media. At last, the trial tests with different treatment materials were performed to evaluate the effect of it on curing the losses. The results of the studies brought new information and explained some previous unknowns. The formation strength across lost circulation zone was measured and it was confirmed to remain constant despite other changes of the well conduction parameters. It was also confirmed that the carbonates are naturally highly fractured having over 900 fractures along the wellbore. The lost circulation zone was characterized, and it was confirmed that the losses were not related to the fractures but rather to the karst, dissolution and to mega-fractures. The size and dip of the fractures were identified, and it was proven the possibility to treat them with conventional materials. However, the size of identified mega-fractures and karst zones exceed the fractures by 100 times in true vertical depth, and in horizontal wells the difference is thousands times due to measured depth. This new information explains the previous unsuccessful attempts with the conventional lost circulation materials. Further based on the newly available information the mathematic description of the lost circulation zones was provided.

Study on the Construction and Performance of Completion Fluid System in Fractured Carbonate Reservoir

2020 ◽  
Vol 861 ◽  
pp. 388-394
Author(s):  
Cong Bing Chang ◽  
Man Shu ◽  
Yin Fu Han ◽  
Yi Hang Zhang ◽  
Jin Tian ◽  
...  
Keyword(s):  
Early Stage ◽  
Drilling Fluid ◽  
Research Work ◽  
Influence Factors ◽  
Carbonate Reservoir ◽  
Salt Crystallization ◽  
Fluid System ◽  
Carbonate Formation ◽  
Fractured Carbonate ◽  
And Performance

There are microfractures and fractures in the carbonate formation of M oilfield, which are easy to cause collapse and borehole instability. On the basis of the liquefiable cleanflo drilling fluid system for open hole completion of horizontal wells designed in the early stage, this paper has carried out the research work of matching acidizing completion fluid system. In this paper, the influence factors, cleaning ability, compatibility, acidizing situation and protection effect of acidizing completion fluid system are evaluated in laboratory. The way of density adjustment and specific dosage of NaCl and hcoona were established to inhibit the formation of salt crystallization. HTA solid acid and JCI are used to counteract each other to reduce the corrosion of casing steel. The core displacement results show that the permeability recovery value of carbonate core after completion fluid treatment can reach 97.54%, and that of sandstone core after treatment can reach 114.7%. Moreover, the completion fluid system also has a certain acidizing effect, which can not only clean and remove the plugging, but also serve as the early induction of acidizing and stimulation.

Wellbore Cleanness Under Total Losses in Horizontal Wells: The Field Study

2021 ◽  
Author(s):  
Alexey Ruzhnikov ◽  
Edgar Echevarria
Keyword(s):  
High Risk ◽  
Middle East ◽  
Field Study ◽  
Drilling Fluid ◽  
Horizontal Wells ◽  
Circulation Zone ◽  
Hole Cleaning ◽  
Lost Circulation ◽  
Cleaning Behavior

Abstract In the Middle East many of the matured fields have fractured or vugular formations where the drilling is continued without return to a surface. This situation has been commonly interpreted as lack of hole cleaning and high risk of stuck pipe. The manuscript describes a study performed to analyze the hole cleaning while blind drilling horizontal sections. Most of the losses while drilling across fractured or vugular formations happen sudden, and this represents a risk of formation instability and stuck pipe. Additionally, the cuttings accumulation may lead to a potential pack off. To understand the hole cleaning the annular pressure while drilling was introduced in different sections, what via change of the equivalent static and dynamic densities describes the cutting and cavings accumulation in the annulus. Additionally, the hole cleaning behavior with different fluids pumped through the drillstring (i.e. drilling fluid, water, water with sweeps) was studied. The proposed study was performed in 4 different fields, 9 wells, across horizontal 6⅛-in. sections with total lost circulation. It was identified that while drilling with full returns ECD vs ESD variations are within 1.5 ppg, those variations are matching with the modeling of hydraulics. Once total losses encountered the variations between ECD and ESD are very low - within 0.2 ppg - indicating that annular friction losses below the loss circulation zone are minimal. This support the theory that all the drilled cuttings are properly lifted from bottom and carried to the karst into the loss circulation zone and not fluctuating above the loss zone. Additionally, minor to no relation found in hole cleaning while drilling with mud or a water with sweeps. This finding also is aligned with the stuck pipe statistics that shows higher incidents of stuck pipe while drilling the with full circulation due to pack off. The manuscript confirms the theory of the hole cleaning in total lost circulation and application of different hole cleaning practices to improve it. The results of the study can be implemented in any project worldwide.

scholarly journals A Chemical Lost Circulation Agent for Severe Leakage in Drilling

2013 ◽  
Vol 6 (1) ◽  
pp. 48-54 ◽  
Author(s):  
Kaihe Lv ◽  
Hanyi Zhong ◽  
Guanlong Ren
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Significant Influence ◽  
Drilling Fluid ◽  
Drilling Process ◽  
Circulation Zone ◽  
Reaction Products ◽  
Lost Circulation ◽  
Granular Solid ◽  
Reaction With Water

This study presents a chemical lost circulation agent with some distinct advantages that make it suitable for use in controlling severe leakage during drilling process. It is a granular solid with irregular shape and able to bridge or fill the cracks and other porous or faulty formations into where the drilling fluid is lost. Then this agent will undergo a chemical reaction with water, and the reaction products fill between particles and bind tightly lost circulation agent particles to each others or to the rocks at the lost circulation zone, thus effectively enhance the compressive strength of the cementing body formed by the agent and prevent lost circulation. Temperature, particle size, and additives added have been shown to have a significant influence on the consolidating rate and compressive strength of the cementing body. In addition, the cementing body has certain permeability, and the permeability can be adjusted, so this agent is proper for use to control lost circulation in reservoir.

First Managed Pressure Cementing with 7" Liner Overcoming a Challenging ERD Well Offshore Madura

2021 ◽  
Author(s):  
Galih Samudera ◽  
Hafidz Ali ◽  
Mohammad Zarir Bin Musa ◽  
Helmi Fauzi ◽  
Irwan Rubianto
Keyword(s):  
Pressure Profile ◽  
Wellbore Stability ◽  
Bottom Part ◽  
Wellbore Instability ◽  
Lost Circulation ◽  
Carbonate Formation ◽  
Execution Phase ◽  
Fractured Carbonate ◽  
Extended Reach Drilling ◽  
And Control

Abstract ZX is a development well located in offshore Madura, Indonesia. ZX is classified as an Extended Reach Drilling (ERD) well with 2.40 ERD ratio. ZX well is in KX field which known to have several drilling hazards. The formation has multiple lost circulation zones below the 9 5/8" casing shoe that is prone to total and partial losses due to combination depleted formation in the upper side and the nature of karst or fractured carbonate formation in middle and lower part of the interval. In addition, the bottom part of the hole section has problematic wellbore instability. These hazards lead to the necessity to closely monitor and control the pressure profile throughout the operation to find balance between loss circulation and wellbore stability to ensure an efficient and safe operation. An automated MPD system is used to precisely control bottom hole pressure. MPD system was used to drill 8-1/2" section of ZX well smoothly to target depth and geological objective was achieved without NPT. MPC was performed successfully for 7" liner cementing. This was the first MPC operation in offshore Madura and the application mitigated the loss circulation and avoided the unnecessary remedial cementing job. The paper will share the success story of MPD application in drilling narrow window ERD well in offshore Madura, Indonesia. It aims to describe the application of MPD for this specific ERD case from planning phase to execution phase as well as the lesson learned.

Inter-country inequality as a dynamic process and the problem of post-industrial development

2018 ◽  
pp. 5-29 ◽  
Author(s):  
L. M. Grigoryev ◽  
V. A. Pavlyushina
Keyword(s):  
Economic Growth ◽  
Political Institutions ◽  
Industrial Development ◽  
Modern World ◽  
New Approach ◽  
Development Level ◽  
The World ◽  
Long Time ◽  
The Difference ◽  
Post Industrial

The phenomenon of economic growth is studied by economists and statisticians in various aspects for a long time. Economic theory is devoted to assessing factors of growth in the tradition of R. Solow, R. Barrow, W. Easterly and others. During the last quarter of the century, however, the institutionalists, namely D. North, D. Wallis, B. Weingast as well as D. Acemoglu and J. Robinson, have shown the complexity of the problem of development on the part of socioeconomic and political institutions. As a result, solving the problem of how economic growth affects inequality between countries has proved extremely difficult. The modern world is very diverse in terms of development level, and the article offers a new approach to the formation of the idea of stylized facts using cluster analysis. The existing statistics allows to estimate on a unified basis the level of GDP production by 174 countries of the world for 1992—2016. The article presents a structured picture of the world: the distribution of countries in seven clusters, different in levels of development. During the period under review, there was a strong per capita GDP growth in PPP in the middle of the distribution, poverty in various countries declined markedly. At the same time, in 1992—2016, the difference increased not only between rich and poor groups of countries, but also between clusters.

Psychology: Volume 5

2019 ◽  
Keyword(s):  
World View ◽  
Science Volume ◽  
Western World ◽  
Mental Life ◽  
Long Time ◽  
The Difference ◽  
New Perspective ◽  
Indian Setting ◽  
The Mind ◽  
The Relationship

This survey of research on psychology in five volumes is a part of a series undertaken by the ICSSR since 1969, which covers various disciplines under social science. Volume Five of this survey, Explorations into Psyche and Psychology: Some Emerging Perspectives, examines the future of psychology in India. For a very long time, intellectual investments in understanding mental life have led to varied formulations about mind and its functions across the word. However, a critical reflection of the state of the disciplinary affairs indicates the dominance of Euro-American theories and methods, which offer an understanding coloured by a Western world view, which fails to do justice with many non-Western cultural settings. The chapters in this volume expand the scope of psychology to encompass indigenous knowledge available in the Indian tradition and invite engaging with emancipatory concerns as well as broadening the disciplinary base. The contributors situate the difference between the Eastern and Western conceptions of the mind in the practice of psychology. They look at this discipline as shaped by and shaping between systems like yoga. They also analyse animal behaviour through the lens of psychology and bring out insights about evolution of individual and social behaviour. This volume offers critique the contemporary psychological practices in India and offers a new perspective called ‘public psychology’ to construe and analyse the relationship between psychologists and their objects of study. Finally, some paradigmatic, pedagogical, and substantive issues are highlighted to restructure the practice of psychology in the Indian setting.

scholarly journals Macular buckling versus vitrectomy on macular hole associated macular detachment in eyes with high myopia: a randomised trial

2021 ◽  
pp. bjophthalmol-2020-317800
Author(s):  
Xiujuan Zhao ◽  
Yonghao Li ◽  
Wei Ma ◽  
Ping Lian ◽  
Xiling Yu ◽  
...  
Keyword(s):  
Success Rate ◽  
Macular Hole ◽  
High Myopia ◽  
Randomised Trial ◽  
Case Series ◽  
Primary Treatment ◽  
Closure Rate ◽  
Macular Detachment ◽  
The Difference ◽  
Myopic Maculopathy

AimTo compare the efficacy of macular buckling (MB) and pars plana vitrectomy (PPV) for full-thickness macular holes (FTMH) and associated macular detachment (MD) in highly myopic eyes.MethodsProspective interventional case series of eyes undergoing PPV or MB for FTMH and MD.Main outcome measuresBest-corrected visual acuity (BCVA) at postoperative month 24. Other measured outcomes include the initial surgical success rate, macular hole closure rate and the progression of myopic maculopathy.ResultsA total of 53 eyes from 53 participants were included in this study (26 participants receiving MB and 27 participants receiving PPV), and finally 49 eyes from 49 participants (25 participants in the MB group and 24 participants in the PPV group) were analysed. At postoperative month 24, the BCVA had improved significantly in those that underwent either MB (p<0.001) or PPV (p=0.04). The difference between the groups was not significant (p=0.653). The surgical failure rate after the primary treatment was significantly higher in the PPV group than the MB group (25.00% vs 4.00%, respectively; p=0.04). The macular closure rate was higher in the MB group compared with the PPV group, but the difference was not statistically significant (64.00% vs 58.33%, respectively; p=0.45). Myopic maculopathy development may be more severe following PPV than following MB surgery.ConclusionPatients with high myopia obtained anatomical and functional improvements from either MB or PPV. However, MB achieved a significantly higher success rate in retinal reattachment compared with PPV.Trial registration numberNCT03433547.

scholarly journals Condensation of SIP Particles and Sticky Brownian Motion

2021 ◽  
Vol 183 (3) ◽  
Author(s):  
Mario Ayala ◽  
Gioia Carinci ◽  
Frank Redig
Keyword(s):  
Brownian Motion ◽  
Interacting Particle Systems ◽  
Particle Systems ◽  
Self Duality ◽  
Inclusion Process ◽  
Interacting Particle ◽  
New Information ◽  
Homogeneous Product ◽  
Coarsening Dynamics ◽  
The Difference

AbstractWe study the symmetric inclusion process (SIP) in the condensation regime. We obtain an explicit scaling for the variance of the density field in this regime, when initially started from a homogeneous product measure. This provides relevant new information on the coarsening dynamics of condensing interacting particle systems on the infinite lattice. We obtain our result by proving convergence to sticky Brownian motion for the difference of positions of two SIP particles in the sense of Mosco convergence of Dirichlet forms. Our approach implies the convergence of the probabilities of two SIP particles to be together at time t. This, combined with self-duality, allows us to obtain the explicit scaling for the variance of the fluctuation field.

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