The Impact of Diagenesis and Compaction on Drilling Failure Detection

2017 ◽  
Author(s):  
Nur Suriani Mamat
Keyword(s):  
Failure Detection ◽  
Complex Problem ◽  
Wellbore Stability ◽  
Related Factors ◽  
Wellbore Instability ◽  
Lost Circulation ◽  
Drilling Parameters ◽  
Sensitive Clay ◽  
A Chain ◽  
The Impact

An important problem during drilling operation is wellbore instability; a complex problem caused by mechanical and chemical related factors. Even the best drilling practice could evade small instability problems that later may become irreparable. The risk of wellbore stability is mostly related to drilling, tripping and reaming activity with, including lost circulation, sloughing repair and loss of penetration. In this paper, the impact of historical and state of diagenesis and compaction on borehole instability has been studied, systematized, and used for general modelling. All the concepts are presented as symbolic concepts in a hierarchical order and linked in a chain of cause-effect relationships to wellbore failures. Through surveillance of drilling parameters, diagenesis and compaction were identified through formation hardness, well depth, shale type, and cuttings/cavings characteristic. From the analysis, kaolinite, which normally exists in intermediate diagenesis, is most likely to cause bit balling when hydrated. Smectite, which is water-sensitive clay, would cause chemical wellbore instability in water-based mud. Carbonates formation such as dolomite and limestone is more likely to result in lost circulation as compared to shale. Our work demonstrates how state of diagenesis and compaction could influence wellbore instability condition. This knowledge could be applied to understand the behavior of rock formation being drilled and would influence the prediction of probable failures as an end result. The method presented here integrates theoretical knowledge and real-time drilling data to envisage the most likely failure.

Wellbore Shielding Technique Increases Operative Window, Avoiding Formation Instability and Losses, Minimizing NPT, and Optimizing Drilling Operations in the Unconventional Plays

2021 ◽  
Author(s):  
Gaston Lopez ◽  
Gonzalo Vidal ◽  
Claus Hedegaard ◽  
Reinaldo Maldonado
Keyword(s):  
Drilling Fluid ◽  
Drilling Fluids ◽  
Wellbore Instability ◽  
Lost Circulation ◽  
Drilling Performance ◽  
Drilling Parameters ◽  
Vaca Muerta ◽  
Drilling Operations ◽  
Fracture Gradient ◽  
Vaca Muerta Formation

Abstract Losses, wellbore instability, and influxes during drillings operations in unconventional fields result from continuous reactivity to the drilling fluid causing instability in the microfractured limestone of the Quintuco Formation in Argentina. This volatile situation becomes more critical when drilling operations are navigating horizontally through the Vaca Muerta Formation, a bituminous marlstone with a higher density than the Quintuco Formation. Controlling drilling fluids invasion between the communicating microfractures and connecting pores helps to minimize seepage losses, total losses, wellbore fluid influxes, and instabilities, reducing the non-productive time (NPT) caused by these problems during drilling operations. The use of conventional sealants – like calcium carbonate, graphite, asphalt, and other bridging materials – does not guarantee problem-free drilling operations. Also, lost circulation material (LCM) is restricted because the MWD-LWD tools clearances are very narrow in these slim holes. The challenge is to generate a strong and resistant seal separating the drilling fluid and the formation. Using an ultra-low-invasion technology will increase the operative fracture gradient window, avoid fluid invasion to the formation, minimize losses, and stop the cycle of fluid invasion and instability, allowing operations to maintain the designed drilling parameters and objectives safely. The ultra-low-invasion wellbore shielding technology has been applied in various fields, resulting in significantly improved drilling efficiencies compared to offset wells. The operator has benefited from the minimization of drilling fluids costs and optimization in drilling operations, including reducing the volume of oil-based drilling fluids used per well, fewer casing sections, and fewer requirements for cementing intervals to solve lost circulation problems. This paper will discuss the design of the ultra-low-invasion technology in an oil-based drilling fluid, the strategy for determining the technical limits for application, the evaluation of the operative window with an increase in the fracture gradient, the optimized drilling performance, and reduction in costs, including the elimination of NPT caused by wellbore instability.

scholarly journals Integrated 3D Mechanical Earth Modelling to Intensively Investigate the Wellbore Instability of Zubair Oil Field, Southern Iraq

2021 ◽  
Vol 54 (2E) ◽  
pp. 38-58
Author(s):  
Abbas Dakhiel
Keyword(s):  
Three Dimensional ◽  
Horizontal Wells ◽  
Horizontal Stress ◽  
Oil Field ◽  
Wellbore Stability ◽  
Normal Faults ◽  
Wellbore Instability ◽  
Lost Circulation ◽  
Clastic Rocks ◽  
The North

Wellbore instability in the Zubair oil field is the main problem in drilling operations. This instability of the wellbore causes several problems including poor hole cleaning, tight hole, stuck pipe, lost circulation, bad cementing, and well kick or blowout that lead to an increase in the nonproductive time. This article aims to set up an appropriate drilling plan that mitigates these instability issues for further well drilling. Field data from six wells (logs, drilling and geological reports as well as offset well tests) were used to build a one-dimensional mechanical earth modeling for each well. The constructed model of selected wells was combined to construct the three-dimensional mechanical earth modeling, which can enable the distribution of all estimated geomechanical parameters along the field of interest. The results revealed that the strip slip and normal faults are the common fault regimes in Zubair oil field located in carbonate rocks and clastic rocks, respectively. The Mogi-Coulomb failure criterion is conservative in determining the minimum and maximum mud weight, and it agrees with the determination of real failure from the image/and caliper logs. The best direction to drill the deviated and horizontal wells was towards the minimum horizontal stress with 140o azimuth from the north. The recommended ranges of mud weight along the sections of 12.25" and 8.5" of the highly deviated and horizontal wells were (between 1.46 and 1.58 gm/cm3) without any expected wellbore instability problems. Based on the outcomes of 3D model, it is expected that the wellbore instability issues are most likely to occur in the domes of; Shauiba and Hamma and in formations; Tanuma, Khasib and Nahr-Umr. In contrast the less wellbore instability problems are expected to expose in Rafidya dome. The study presents an appropriate mud window that can be used to design to minimize the wellbore stability problems when new wells will be drilled in Zubair oil field.

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.

Optimize Internal Phase Salinity to Improve Wellbore Stability and Mitigate Lost Circulation

2021 ◽  
Author(s):  
Jianguo Zhang ◽  
Alan Rodgerson ◽  
Stephen Edwards
Keyword(s):  
Water Activity ◽  
Wellbore Stability ◽  
Chemical Effect ◽  
Wellbore Instability ◽  
Lost Circulation ◽  
Main Challenge ◽  
Internal Phase ◽  
Naturally Fractured ◽  
Drilling Operations ◽  
Shale Formation

Abstract Wellbore instability and lost circulation are two major sources of non-productive time (NPT) in drilling operations worldwide. Non-aqueous fluid (NAF) is often chosen to mitigate this and minimize the chemical effect on wellbore instability in reactive shales. However, it may inadvertently increase the risk of losses. A simple method to optimize internal phase salinity (IPS) of NAF is presented to improve wellbore stability and mitigate the increased possibility of losses. Field cases are used to demonstrate the effects of salinity on wellbore instability and losses, and the application of the proposed method. IPS is optimized by managing bidirectional water movement between the NAF and shale formation via semi-permeable membrane. Typically, higher shale dehydration is designed for shallow reactive shale formation with high water content. Whereas, low or no dehydration is desired for deep naturally fractured or faulted formation by balancing osmotic pressure with hydrostatic pressure difference between mud pressure and pore pressure. The simple approach to managing this is as follows: The water activity profile for the shale formation (aw,shale) is developed based on geomechanical and geothermal information The water activity of drilling fluid (aw,mud) is defined through considering IPS and thermal effects The IPS of NAF is manipulated to manage whether shale dehydration is a requirement or should be avoided If the main challenge is wellbore instability in a chemically reactive shale, then the IPS should be higher than the equivalent salinity of shale formation (or aw,shale > aw, mud) If the main challenge is losses into non-reactive, competent but naturally fractured or faulted shale, then IPS should be at near balance with the formation equivalent salinity (or aw, shale ≈ aw, mud) It is important that salt (e.g. calcium chloride – CaCl2) addition during drilling operations is done judiciously. The real time monitoring of salinity variations, CaCl2 addition, water evaporation, electric stability (ES), cuttings/cavings etc. will help determine if extra salt is required. The myth of the negative effects of IPS on wellbore instability and lost circulation is dispelled by analyzing the field data. The traditional Chinese philosophy: "following Nature is the only criteria to judge if something is right" can be applied in this instance of IPS optimization. A simple and intuitive method to manage IPS is proposed to improve drilling performance.

Research on Wellbore Stability in Formation with Anisotropic Strength

2013 ◽  
Vol 765-767 ◽  
pp. 3151-3157
Author(s):  
Hui Zhang ◽  
Fang Jun Ou ◽  
Guo Qing Yin ◽  
Jing Bing Yi ◽  
Fang Yuan ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Rock Body ◽  
Collapse Pressure ◽  
Wellbore Instability ◽  
Transversely Isotropic Rock ◽  
Fracture Development ◽  
Anisotropic Formation ◽  
The Impact

As most of sedimentary rocks are anisotropic, it is significant to research the impact of the anisotropy of strength on wellbore stability in drilling engineering. Particularly, in the Kuqa piedmont exploration area, the anisotropy of strength caused by various jointed surfaces, fracture surfaces and fault planes in formation cause the formation of several groups of weak low-intensity planes traversing borehole . These weak planes will become failure earlier than the rock body in the context of strong stress and high pore pressure, causing chipping, breakouts and sticking. If fractures have good permeability and drilling fluid column pressure is greater than pore pressure, loss may occur. The loss pressure would not be controlled by fracturing pressure and horizontal minimum principal stress, but it depends on the relationship between fracture occurrence and triaxial stress state. In the event of loss, the drilling fluid will flow into these weak structural planes, causing the decrease of friction between rocks and increase of wellbore instability. As a result, for strongly anisotropic formation, the collapse pressure and leakage pressure of weak planes are key factors for evaluating well drilling stability. In this study, according to the stability evaluation on the transversely isotropic rock mechanics in Keshen zone of Kuqa piedmont, the impacts of fracture development on wellbore instability is analyzed; relevant suggestions on engineering geology for the special pressure window in strong anisotropic formation are also put forward.

A Study On Impact Of Work Life Related Factors On Employee Engagement In Health Care Sector Workers In Dindigul District.

2019 ◽  
Vol 118 (7) ◽  
pp. 20-26
Author(s):  
S. JAYARAMAN ◽  
R. Sindhya ◽  
P. Vijiyalakshmi
Keyword(s):  
Health Care ◽  
Path Analysis ◽  
Employee Engagement ◽  
Health Care Workers ◽  
Health Care Sector ◽  
Work Life ◽  
Primary Data ◽  
Related Factors ◽  
Care Workers ◽  
The Impact

this research aims to find out the intensity of Employee Engagement of the health care sector workers and the relationship between the Work life factors and Employee Engagement of Health care sector workers in Dindigul District. Primary data were used in this research, were collected from 298 Health care workers from Dindigul District. Questionnaire was the major tool used to gather the primary data from the selected sample respondents. For this purpose, a well structured questionnaire was constructed with the help of professionals and the practiced employees of various health care units in Dindigul District. The health care employees were chosen by simple random sampling method. The investigative measures of regression Path analysis, and simple percentage analysis were utilized to find the impact of work life related factors with the Employee Engagement. The maximum Health care workers were generally satisfied with their jobs. The analytical procedure of path analysis multiple regressions was utilized to determine the predicting strength among Work life factors and the employee engagement. This study provides an another view about the importance of Work life factors and Employee engagement for organizational effectiveness and performance .

scholarly journals Effective Demand Forecasting in Health Supply Chains: Emerging Trend, Enablers, and Blockers

Logistics ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 12
Author(s):  
Lakshmy Subramanian
Keyword(s):  
Supply Chains ◽  
Demand Forecasting ◽  
Weak Links ◽  
Key Factors ◽  
Scarce Resources ◽  
Weakest Link ◽  
Emerging Trends ◽  
A Chain ◽  
Health Commodities ◽  
The Impact

Health supply chains aim to improve access to healthcare, and this can be attained only when health commodities appropriate to the health needs of the global population are developed, manufactured, and made available when and where needed. The weak links in the health supply chains are hindering the access of essential healthcare resulting in inefficient use of scarce resources and loss of lives. A chain is only as strong as its weakest link, and demand forecasting is one of the weakest links of health supply chains. Also, many of the existing bottlenecks in supply chains and health systems impede the accurate forecasting of demand, and without the ability to forecast demand with certainty, the stakeholders cannot plan and make commitments for the future. Forecasts are an important feeder for budgeting and logistics planning. Under this backdrop, the study examines how improved forecasting can lead to better short-term and long-term access to health commodities and outlines market-related risks. It explores further how incentives are misaligned creating an uneven distribution of risks, leading to the inability to match demand and supply. For this purpose, a systematic literature review was performed, analyzing 71 articles from a descriptive and content approach. Findings indicate the emerging trends in global health and the consequences of inaccurate demand forecasting for health supply chains. The content analysis identifies key factors that can pose a varying degree of risks for the health supply chain stakeholders. The study highlights how the key factors emerge as enablers and blockers, depending on the impact on the overall health supply chains. The study also provides recommendations for actions for reducing these risks. Consequently, limitations of this work are presented, and opportunities are identified for future lines of research. Finally, the conclusion confirms that by adopting a combination of approaches, stakeholders can ensure better information sharing, identify avenues of diversifying risks, and understand the implications.

scholarly journals The Impact of Intervention-Related Risk Factors on the Risk of Ventilator-Associated Pneumonia Is High in a Neurosurgical Intensive Care Unit

2020 ◽  
Vol 41 (S1) ◽  
pp. s407-s409
Author(s):  
Ksenia Ershova ◽  
Oleg Khomenko ◽  
Olga Ershova ◽  
Ivan Savin ◽  
Natalia Kurdumova ◽  
...  
Keyword(s):  
Risk Factors ◽  
Mechanical Ventilation ◽  
Negative Slope ◽  
Infection Prevention And Control ◽  
Ventilator Associated Pneumonia ◽  
Related Factors ◽  
Icu Patients ◽  
The Impact ◽  
Adf Test ◽  
Over Time

Background: Ventilator-associated pneumonia (VAP) represents the highest burden among all healthcare-associated infections (HAIs), with a particularly high rate in patients in neurosurgical ICUs. Numerous VAP risk factors have been identified to provide a basis for preventive measures. However, the impact of individual factors on the risk of VAP is unclear. The goal of this study was to evaluate the dynamics of various VAP risk factors given the continuously declining prevalence of VAP in our neurosurgical ICU. Methods: This prospective cohort unit-based study included neurosurgical patients who stayed in the ICU >48 consecutive hours in 2011 through 2018. The infection prevention and control (IPC) program was implemented in 2010 and underwent changes to adopt best practices over time. We used a 2008 CDC definition for VAP. The dynamics of VAP risk factors was considered a time series and was checked for stationarity using theAugmented Dickey-Fuller test (ADF) test. The data were censored when a risk factor was present during and after VAP episodes. Results: In total, 2,957 ICU patients were included in the study, 476 of whom had VAP. Average annual prevalence of VAP decreased from 15.8 per 100 ICU patients in 2011 to 9.5 per 100 ICU patients in 2018 (Welch t test P value = 7.7e-16). The fitted linear model showed negative slope (Fig. 1). During a study period we observed substantial changes in some risk factors and no changes in others. Namely, we detected a decrease in the use of anxiolytics and antibiotics, decreased days on mechanical ventilation, and a lower rate of intestinal dysfunction, all of which were nonstationary processes with a declining trend (ADF testP > .05) (Fig. 2). However, there were no changes over time in such factors as average age, comorbidity index, level of consciousness, gender, and proportion of patients with brain trauma (Fig. 2). Conclusions: Our evidence-based IPC program was effective in lowering the prevalence of VAP and demonstrated which individual measures contributed to this improvement. By following the dynamics of known VAP risk factors over time, we found that their association with declining VAP prevalence varies significantly. Intervention-related factors (ie, use of antibiotics, anxiolytics and mechanical ventilation, and a rate of intestinal dysfunction) demonstrated significant reduction, and patient-related factors (ie, age, sex, comorbidity, etc) remained unchanged. Thus, according to the discriminative model, the intervention-related factors contributed more to the overall risk of VAP than did patient-related factors, and their reduction was associated with a decrease in VAP prevalence in our neurosurgical ICU.Funding: NoneDisclosures: None

Rehospitalization as a predictor of mortality in Polish population of heart failure patients-national registry

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
M Zaleska-Kociecka ◽  
K Witczak ◽  
K Bartolik ◽  
D Was ◽  
A Kleinork ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cox Regression ◽  
National Registry ◽  
Funding Source ◽  
Polish Population ◽  
The European Union ◽  
Related Factors ◽  
Comorbidity Burden ◽  
All Cause Mortality ◽  
The Impact

Abstract Background High mortality risk in heart failure (HF) is related to repeat HF hospitalizations but also individual patient characteristics. Purpose To evaluate the impact of HF re-/hospitalizations and patient-related factors (sex, HF etiology, age, comorbidity) on all-cause mortality. Methods Our study represents one of the most extensive retrospective cohort analyses consisting of 1,686,861 adult Polish HF patients who presented into public health system in years 2013–2018. It is a part of a nationwide National Health Fund registry covering out- and in-patient data for the entire Polish population (38,495,659 in 2013) since 2009. HF hospitalizations were extracted using ICD-10 coding, whereas the comorbidity was evaluated by means of Charlson Comorbidity Index (CCI). Results In years 2013–2018 the absolute number of HF hospitalizations in Poland grew by 33% to 264,808 in 2018, whereas the number of rehospitalizations increased 1.5-fold to reach 137,708 in 2018. In fact, nearly half of HF patients (n=817,432; 48.5%) experienced at least one hospitalization, while 15.4% (n=259,868) were rehospitalized during the study period. After initial hospitalization the readmission rate due to HF/all circulatory diseases at 30, 60, 180, 360, and 720 days was 10.4%/15.1%, 21.2%/28.3%, 43.9%/52.8%, 62%/70.4%, and 81%/87%, respectively. As compared to patients who were hospitalized just once, those who underwent at least one rehospitalization were more often female (p<0.001), slightly older (p<0.001), and with higher burden of comorbidities based on CCI (p<0.001). Patient survival was highly dependent on hospitalization frequency (Fig. 1). Mean survival rate at day 720 was 66.4%, 59.8%, 54.9%, 51%, and 43.9% for 1st, 2nd, 3rd, 4th, and ≥5th hospitalization, respectively. After adjusting for age, sex, etiology (ischemic/non-ischemic) and CCI using a multivariate stratified Cox regression model, the estimated hazard ratios (HR) for all-cause mortality amounted to 1.22 (95% CI: 1.21–1.23, p<0.001) for 2nd, 1.4 (95% CI: 1.39–1.42, p<0.001) for 3rd, 1.58 (95% CI: 1.56–1.6, p<0.001) for 4th, and 1.97 (95% CI: 1.95–1.98 p<0.001) for 5th and subsequent hospitalizations, as compared to the first hospitalization. Conclusions Hospitalization rate in Poland is alarmingly high. Repeat HF hospitalizations strongly predict mortality rate for HF patients even after adjustment for age, sex, etiology, and comorbidity burden. Figure 1. Kaplan-Meier for survival post hosp. Funding Acknowledgement Type of funding source: Public grant(s) – EU funding. Main funding source(s): The project is co-financed by the European Union from the European Social Fund under the Operational Programme Knowledge Education Development and it is being carried out by the Analyses and Strategies Department of the Polish Ministry of Health.

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