An Experimental Evaluation of the Effects of Filtercake in Wellbore Strengthening: Filtercake Rupture Resistance and Fracture Sealing Time

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Mingzheng Yang ◽  
Yuanhang Chen
Keyword(s):  
Drilling Fluid ◽  
Experimental Tests ◽  
Fracture Initiation ◽  
Vital Role ◽  
Fracture Sealing ◽  
Initiation Stage ◽  
Induced Fractures ◽  
Wellbore Strengthening ◽  
New Criterion

Abstract Recent research studies have indicated that filtercakes play a role in preventing fracture initiation, blocking pre-existing narrow fractures, and isolating drilling-induced fractures at the initiation stage. The ability of the filtercakes to effectively strengthen the wellbore expectedly depends on its capability in maintaining its integrity and providing the barrier to isolate pressure and fluid transmission between the wellbore and fractures. In this research, a modified permeability apparatus was used to evaluate the quality of drilling fluid filtercakes. A new criterion defined as filtercake rupture resistance is proposed to characterize the filtercake quality regarding its ability to sustain pressure over an open fracture. Experimental tests were conducted to investigate how filtercake thickness and filtercake yield strength affect the rupture resistance. The mechanism of filtercake in sealing the narrow fractures is explored, and it was observed that solid's plugging/bridging plays the vital role in this mechanism. A thicker and stronger filtercake also contributes to a faster establishment of complete fracture seal. The results of this research can be utilized as a reference that guides the optimization of drilling fluid for continuously strengthening the wellbore.

An Experimental Investigation of Filtercake Reinforced Wellbore Strengthening and Fracture Sealing

2019 ◽  
Author(s):  
Mingzheng Yang ◽  
Yuanhang Chen ◽  
Frederick B. Growcock ◽  
Feifei Zhang
Keyword(s):  
Experimental Investigation ◽  
Critical Role ◽  
Fracture Initiation ◽  
Fluid Loss ◽  
Lost Circulation ◽  
Fracture Sealing ◽  
Sealing Pressure ◽  
Wellbore Strengthening ◽  
Mud Loss ◽  
Lost Circulation Materials

Abstract Drilling-induced lost circulation should be managed before and during fracture initiation rather than after they propagate to form large fractures and losses become uncontrollable. Recent studies indicated the potentially critical role of filtercake in strengthening the wellbore through formation of a pressure-isolating barrier, as well as plugging microfractures during fracture initiation. In this study, an experimental investigation was conducted to understand the role played by filtercake in the presence of lost circulation materials (LCMs). A modified permeability plugging apparatus (PPA) with slotted discs was used to simulate whole mud loss through fractures of known width behind filtercake. Cumulative fluid loss upon achieving a complete seal and the maximum sealing pressure were measured to evaluate the combined effects of filtercake and LCMs in preventing and reducing fluid losses. The effects of some filtercake properties (along with LCM type, concentration and particle size distribution) on filtercake rupture and fracture sealing were investigated. The results indicate that filtercake can accelerate fracture sealing and reduce total mud loss. Efficiently depositing filtercake while drilling can reduce the concentration of LCM that is required to plug and isolate incipient fractures.

Investigation on the Effect of Mud Additives on the Gelation Performance of PAM/PEI System for Lost Circulation Control

2021 ◽  
Author(s):  
Mohamed Shamlooh ◽  
Ahmed Hamza ◽  
Ibnelwaleed A. Hussein ◽  
Mustafa S. Nasser ◽  
Saeed Salehi
Keyword(s):  
Storage Modulus ◽  
Oil And Gas ◽  
Loss Modulus ◽  
Drilling Fluid ◽  
Gelation Time ◽  
Drilling Fluids ◽  
Lost Circulation ◽  
Reservoir Conditions ◽  
Induced Fractures ◽  
Wellbore Strengthening

Abstract Lost circulation is one of the most common problems in the drilling of oil and gas wells where mud escapes through natural or induced fractures. Lost circulation can have severe consequences from increasing the operational cost to compromising the stability of wells. Recently, polymeric formulations have been introduced for wellbore strengthening purposes where it can serve as Loss Circulation Materials (LCMs) simultaneously. Polymeric LCMs have the potential to be mixed with drilling fluids during the operation without stopping to avoid non-productive time. In this study, the significance of most common conventional mud additives and their impact on the gelation performance of Polyacrylamide (PAM) / Polyethyleneimine (PEI) has been investigated. Drilling fluid with typical additives has been designed with a weight of 9.6 ppg. Additives including bentonite, barite, CarboxyMethylCellulose (CMC), lignite, caustic soda, desco, and calcium carbonate has been studied individually and combined. Each additive is mixed with the polymeric formulation (PAM 9% PEI 1%) with different ratios, then kept at 130°C for 24 hrs. Rheological performance of the mature gel has been tested using parallel plate geometry, Oscillatory tests have been used to assess the storage Modulus and loss modulus. Moreover, the gelation profile has been tested at 500 psi with a ramped temperature to mimic the reservoir conditions to obtain the gelation time. The gelation time of the polymer-based mud was controllable by the addition of a salt retarder (Ammonium Chloride), where a gelation time of more than 2 hours could be achieved at 130°C. Laboratory observations revealed that bentonite and CMC have the most effect as they both assist in producing stronger gel. While bentonite acts as a strengthening material, CMC increases the crosslinking network. Bentonite has successfully increased the gel strength by 15% providing a storage modulus of up to 1150 Pa without affecting the gelation time. This work helps in better understanding the process of using polymeric formulations in drilling activities. It provides insights to integrate gelling systems that are conventionally used for water shut-off during the drilling operation to replace the conventional loss circulation materials to provide a higher success rate.

Full Fluid–Solid Cohesive Finite-Element Model to Simulate Near Wellbore Fractures

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Saeed Salehi ◽  
Runar Nygaard
Keyword(s):  
Finite Element ◽  
Hoop Stress ◽  
Fracture Propagation ◽  
Fracture Initiation ◽  
Element Model ◽  
Cohesive Elements ◽  
Element Simulation ◽  
Initiation And Propagation ◽  
Fracture Sealing ◽  
Wellbore Strengthening

This paper presents finite-element simulation for hydraulic fracture's initiation, propagation, and sealing in the near wellbore region. A full fluid solid coupling module is developed by using pore pressure cohesive elements. The main objective of this study is to investigate the hypothesis of wellbore hoop stress increase by fracture sealing. Anisotropic stress state has been used with assignment of individual criteria for fracture initiation and propagation. Our results demonstrate that fracture sealing in “wellbore strengthening” cannot increase the wellbore hoop stress beyond its upper limit when no fractures exist. However, this will help to restore part or all of the wellbore hoop stress lost during fracture propagation.

Quantification of the Effects of Filtercake on Wellbore Strengthening: Filtercake Rupture Resistance and Fracture Sealing Time

2019 ◽  
Author(s):  
Mingzheng Yang ◽  
Yuanhang Chen ◽  
Frederick B. Growcock
Keyword(s):  
Yield Strength ◽  
Time Pressure ◽  
Critical Role ◽  
Fracture Initiation ◽  
Fluid Loss ◽  
Drilling Fluids ◽  
Shear Yield ◽  
Fracture Sealing ◽  
Lower Permeability ◽  
Wellbore Strengthening

Abstract Wellbore strengthening (WBS) has proven to be an effective method for expanding the pressure windows of drilling operations. Recent research on WBS disclosed the critical role of filtercake in sealing microfractures during the initial stages of fracture initiation and propagation. In this study, a new parameter — “filtercake rupture resistance” — is proposed to simplify the quantitation of the filtercake’s potential to withstand pressure over a small fracture. A modified permeability plugging apparatus (PPA) was used to experimentally simulate the processes of filtercake rupture over a fracture on the wellbore wall and fracture sealing. The effects of filtercake thickness (permeability), filtercake yield strength in shear, and concentration of bentonite and a fine fibrous LCM on filtercake rupture resistance were investigated, along with the effects of these parameters on the effectiveness of filtercake in reducing fracture sealing time. Pressure spikes and fluctuations were observed when applying differential pressure across the filtercakes after formation of the cake. Filtercake of lower permeability and higher shear yield strength produce greater filtercake rupture resistance and shorter fracture sealing time. These results can be used to guide drilling fluids design for improved control of fluid loss.

Cytoprotective Agents to Avoid Chemotherapy Induced Sideeffects on Normal Cells: A Review

2019 ◽  
Vol 19 (10) ◽  
pp. 765-781
Author(s):  
Seema Rohilla ◽  
Harish Dureja ◽  
Vinay Chawla
Keyword(s):  
Adverse Effects ◽  
Anticancer Agents ◽  
Therapeutic Index ◽  
Chemotherapeutic Agents ◽  
Vital Role ◽  
Normal Cells ◽  
Normal Tissues ◽  
Organ Specific ◽  
Delay In Treatment

Anticancer agents play a vital role in the cure of patients suffering from malignancy. Though, the chemotherapeutic agents are associated with various adverse effects which produce significant toxic symptoms in the patients. But this therapy affects both the malignant and normal cells and leads to constricted therapeutic index of antimalignant drugs which adversely impacts the quality of patients’ life. Due to these adversities, sufficient dose of drug is not delivered to patients leading to delay in treatment or improper treatment. Chemoprotective agents have been developed either to minimize or to mitigate the toxicity allied with chemotherapeutic agents. Without any concession in the therapeutic efficacy of anticancer drugs, they provide organ specific guard to normal tissues.

Solidifying Mud Cake to Improve Cementing Quality of Shale Gas Well: A Case Study

2015 ◽  
Vol 8 (1) ◽  
pp. 149-154 ◽  
Author(s):  
Jun Gu ◽  
Ju Huang ◽  
Su Zhang ◽  
Xinzhong Hu ◽  
Hangxiang Gao ◽  
...  
Keyword(s):  
Shale Gas ◽  
Calcium Silicate Hydrate ◽  
Drilling Fluid ◽  
Cement Slurry ◽  
Gas Well ◽  
Safety Requirements ◽  
Mud Cake ◽  
Gas Bearing

The purpose of this study is to improve the cementing quality of shale gas well by mud cake solidification, as well as to provide the better annular isolation for its hydraulic fracturing development. Based on the self-established experimental method and API RP 10, the effects of mud cake solidifiers on the shear strength at cement-interlayer interface (SSCFI) were evaluated. After curing for 3, 7, 15 and 30 days, SSCFI was remarkably improved by 629.03%, 222.37%, 241.43% and 273.33%, respectively, compared with the original technology. Moreover, the compatibility among the mud cake solidifier, cement slurry, drilling fluid and prepad fluid meets the safety requirements for cementing operation. An application example in a shale gas well (Yuanye HF-1) was also presented. The high quality ratio of cementing quality is 93.49% of the whole well section, while the unqualified ratio of adjacent well (Yuanba 9) is 84.46%. Moreover, the cementing quality of six gas-bearing reservoirs is high. This paper also discussed the mechanism of mud cake solidification. The reactions among H3AlO42- and H3SiO4- from alkali-dissolved reaction, Na+ and H3SiO4- in the mud cake solidifiers, and Ca2+ and OH- from cement slurry form the natrolite and calcium silicate hydrate (C-S-H) with different silicate-calcium ratio. Based on these, SSCFI and cementing quality were improved.

Phamacognostical and Pharmaceutical Evaluation of Chandrashakaladi Vataka - A herbal formulation

2016 ◽  
Vol 1 (3) ◽  
Author(s):  
Dr. Akash S Changole ◽  
Mandip Goyal ◽  
Harish CR
Keyword(s):  
Classical Method ◽  
Raw Materials ◽  
Herbal Medicines ◽  
Vital Role ◽  
Published Data ◽  
Herbal Formulation ◽  
Physico Chemical ◽  
Good Manufacturing Practices ◽  
Solvent Systems

Background: Quality control and the standardization of herbal medicines involve steps like standard source and quality of raw materials, good manufacturing practices and adequate analytical screening. These practices play a vital role in guaranting the quality and stability of herbal preparations. Chandrashakaladi Vataka is an Ayurvedic herbal formulation mentioned to be beneficial in Kushtha. Till date no published data is available on its analytical profile. Aim: To develop the Pharmacognostical and Phyto-chemical profile of Chandrashakaladi Vataka. Material and Methods: Chandrashakaladi Vataka was prepared as per classical method and analytical findings were recorded. Samples were subjected to organoleptic analysis, physico-chemical analysis and HPTLC examination by optimizing the solvent systems. Results and Conclusions: Pharmacognostical profile of Chandrashakaladi Vataka was established. Loss on drying, Ash value, Acid insoluble extract, Methanol soluble extract, Chandrashakaladi Vataka was found within prescribed limits. HPTLC profile of Chandrashakaladi Vataka revealed 12 spots at 254 nm and 13 spots at 366 nm.

scholarly journals A Systematic Review of Healthcare Professionals’ Knowledge, Self-Efficacy and Attitudes Towards Working with Autistic People

2021 ◽  
Author(s):  
Kirsten Corden ◽  
Rebecca Brewer ◽  
Eilidh Cage
Keyword(s):  
Health Professionals ◽  
Self Efficacy ◽  
Healthcare Professionals ◽  
Assessment Tool ◽  
Vital Role ◽  
Narrative Synthesis ◽  
Quality Assessment Tool ◽  
Professional Background ◽  
Autistic People

AbstractHealthcare professionals play a vital role in identifying and supporting autistic people. This study systematically reviewed empirical research examining healthcare professionals’ knowledge, self-efficacy and attitudes towards working with autistic people. Thirty-five studies were included. The included studies sampled a range of countries and professional backgrounds. A modified quality assessment tool found the quality of the included studies was moderately good. Narrative synthesis indicated that healthcare professionals report only moderate levels of autism knowledge and self-efficacy, and often lack training. Variation within and between countries and professional background was not explained by demographic factors. The reviewed evidence suggests health professionals’ limited knowledge and self-efficacy in working with autistic people is a challenge to the provision of healthcare for autistic individuals.

Revisiting competences of adult learning facilitators: Perspectives from the Mongolian context

2021 ◽  
pp. 147797142110031
Author(s):  
Togtokhmaa Zagir ◽  
Helga Dorner
Keyword(s):  
Professional Development ◽  
Adult Learners ◽  
Adult Learning ◽  
Needs Assessment ◽  
Vital Role ◽  
International Studies ◽  
Teaching Role ◽  
Core Competences ◽  
Key Stakeholders

Competent adult learning facilitators play a vital role in improving the quality of adult learning programmes. This article thus explores common and core competences of adult learning facilitators from the perspective of key stakeholders, such as facilitators, adult learners and administrators. By synthesising previous international studies, we developed a survey and collected data in Mongolia ( n = 227). We identified adult learning facilitators’ common and core competences focusing on their teaching role. As found, areas of adult learners’ needs assessment, communication and motivation should be integrated in professional development programmes in order to aim for a better completion rate and higher participation of target audiences in adult learning programmes.

scholarly journals The Effect of Process Parameters in Helical Rolling of Balls on the Quality of Products and the Forming Process

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2125 ◽  
Author(s):  
Janusz Tomczak ◽  
Zbigniew Pater ◽  
Tomasz Bulzak
Keyword(s):  
Metal Flow ◽  
Experimental Tests ◽  
Rolling Process ◽  
Helical Rolling ◽  
Forming Process ◽  
University Of Technology ◽  
Quality Of Products ◽  
Skew Rolling

This paper presents selected numerical and experimental results of a skew rolling process for producing balls using helical tools. The study investigates the effect of the billet’s initial temperature on the quality of produced balls and the rolling process itself. In addition, the effect of billet diameter on the quality of produced balls is investigated. Experimental tests were performed using a helical rolling mill available at the Lublin University of Technology. The experiments consisted of rolling 40 mm diameter balls with the use of two helical tools. To determine optimal rolling parameters ensuring the highest quality of produced balls, numerical modelling was performed using the finite element method in the Forge software. The numerical analysis involved the determination of metal flow kinematics, temperature and damage criterion distributions, as well as the measurement of variations in the force parameters. The results demonstrate that the highest quality balls are produced from billet preheated to approximately 1000 °C.

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