Experimental Study of the Impact of Drilling Fluid Contamination on the Integrity of Cement-Formation Interface

2012 ◽  
Author(s):  
Nnamdi Agbasimalo ◽  
Mileva Radonjic
Keyword(s):  
Drilling Fluid ◽  
Drilling Mud ◽  
Overburden Pressure ◽  
Interface Zone ◽  
Fluid Displacement ◽  
Before And After ◽  
Zonal Isolation ◽  
Primary Cementing ◽  
Flow Through ◽  
The Impact

Primary cementing is performed during drilling and completion of wells mainly to provide zonal isolation. Ideally, 100% drilling fluid displacement should be achieved during cementing. This is difficult to achieve and some mud is left on the wellbore walls. This study investigates the effect of the undisplaced mud on the integrity of the cement-formation interface. Flow-through experiments were conducted at 14.48 MPa (2100 psi) overburden pressure and temperature of 22° C (72° F) with cement-sandstone composite cores and brine at a flow rate of 1 ml/min. The cement-sandstone composite cores had 0% and 10% drilling mud contamination respectively. Variations in the permeability of the composite cores were recorded throughout the flow-through experiments by measuring the pressure drop across the composite cores. The composite cores were characterized before and after the flow-through experiments to delineate the alterations in the composite cores due to the flow-through experiments. Higher pH values were observed in the effluent brine from the 10% mud contaminated core than the 0% mud contaminated core due to increased dissolution of cement. Microtomography revealed higher porosity at the interface zone of the 10% mud contaminated core. These show that mud contamination has a deleterious effect on the cement-sandstone interface and may create pathways for inter-zonal communication.

scholarly journals Comparative Analysis of the Effect of Barite and Hematite on the Rheology of Water-Based Drilling Mud

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Osei H
Keyword(s):  
Rheological Properties ◽  
Drilling Fluid ◽  
Attrition Rate ◽  
Drilling Mud ◽  
Cleaning Efficiency ◽  
Drilling Operation ◽  
Water Based ◽  
Petroleum Resources ◽  
Drilling Muds ◽  
The Impact

High demand for oil and gas has led to exploration of more petroleum resources even at remote areas. The petroleum resources are found in deeper subsurface formations and drilling into such formations requires a well-designed drilling mud with suitable rheological properties in order to avoid or reduce associated drilling problems. This is because rheological properties of drilling muds have considerable effect on the drilling operation and cleaning of the wellbore. Mud engineers therefore use mud additives to influence the properties and functions of the drilling fluid to obtain the desired drilling mud properties especially rheological properties. This study investigated and compared the impact of barite and hematite as weighting agents for water-based drilling muds and their influence on the rheology. Water-based muds of different concentrations of weighting agents (5%, 10%, 15% and 20% of the total weight of the drilling mud) were prepared and their rheological properties determined at an ambient temperature of 24ᵒC to check their impact on drilling operation. The results found hematite to produce higher mud density, plastic viscosity, gel strength and yield point when compared to barite at the same weighting concentrations. The higher performance of the hematite-based muds might be attributed to it having higher specific gravity, better particle distribution and lower particle attrition rate and more importantly being free from contaminants. The water-based muds with hematite will therefore be more promising drilling muds with higher drilling and hole cleaning efficiency than those having barite.

scholarly journals Exploring overcrowding trends in an inner city emergence department in the UK before and during COVID-19 epidemic

2021 ◽  
Author(s):  
J Panovska-Griffiths ◽  
J Ross ◽  
S Elkhodair ◽  
C Baxter-Derrington ◽  
C Laing ◽  
...  
Keyword(s):  
Waiting Time ◽  
Hospital Emergency ◽  
Number Of Patients ◽  
Before And After ◽  
Ed Overcrowding ◽  
University College London ◽  
Flow Through ◽  
Multifaceted Interventions ◽  
The Uk ◽  
The Impact

AbstractBackgroundWe compared impact of three pre-COVID-19 interventions and of the COVID-19 UK-epidemic and the first UK national lockdown on overcrowding within University College London Hospital Emergency Department (UCLH ED). The three interventions: target the influx of patients at ED (A), reduce the pressure on in-patients’ beds (B) and improve ED processes to improve the flow of patents out from ED (C).MethodsWe analysed the change in overcrowding metrics (daily attendances, the proportion of people leaving within four hours of arrival (four-hours target) and the reduction in overall waiting time) across three analysis. The first analysis used data 01/04/2017-31/12-2019 to calculate changes over a period of six months before and after the start of interventions A-C. The second and third analyses focused on evaluating the impact of the COVID-19 epidemic, comparing the first 10 months in 2020 and 2019, and of the first national lockdown (23/03/2020-31/05/2020).ResultsPre-COVID-19 all interventions led to small reductions in waiting time (17%, p<0.001 for A and C;9%, p=0.322 for B) but also to a small decrease in the number of patients leaving within four hours of arrival (6.6%,7.4%,6.2% respectively A-C,p<0.001).In presence of the COVID-19 pandemic, attendance and waiting time were reduced (40% and 8%;p<0.001), and the number of people leaving within four hours of arrival was increased (6%,p<0.001). During the first lockdown, there was 65% reduction in attendance, 22% reduction in waiting time and 8% increase in number of people leaving within 4 hours of arrival (p<0.001). Crucially, when the lockdown was lifted, there was an increase (6.5%,p<0.001) in the percentage of people leaving within four hours, together with a larger (12.5%,p<0.001) decrease in waiting time. This occurred despite the increase of 49.6%(p<0.001) in attendance after lockdown ended.ConclusionsThe mixed results pre-COVID-19 (significant improvements in waiting time with some interventions but not improvement in the four-hours target), may be due to a ‘spill-over effect’ where clogging up one part of the ED system affects other parts. Hence multifaceted interventions and a system-wide approach to improve the pathway of flow through the ED system is necessary.During 2020 and in presence of the COVID-19 epidemic, a shift in public behaviour with anxiety over attending hospitals and higher use of virtual consultations, led to notable drop in UCLH ED attendance and consequential curbing of overcrowding.Importantly, once the lockdown was lifted, although there was an increase in arrivals at UCLH ED, overcrowding metrics were reduced. Thus, the combination of shifted public behaviour and the restructuring changes during COVID-19 epidemic, maybe be able to curb future ED overcrowding, but longer timeframe analysis is required to confirm this.

Using Lightweight or Low Viscosity Preflushes for Primary Cementing of Surface Casing

2018 ◽  
Author(s):  
Amir Maleki ◽  
Ian Frigaard
Keyword(s):  
Contact Time ◽  
Drilling Fluid ◽  
Two Dimensional ◽  
Drilling Mud ◽  
Dimensional Model ◽  
Chemical Cleaning ◽  
Low Viscosity ◽  
North Eastern ◽  
Primary Cementing ◽  
Intermediate Density

Preflushes are often used as part of the sequence of fluids pumped in primary cementing. Usually two functions are served by preflushes: I) to wash the drilling fluid ahead, by a combination of turbulence and chemical reaction; II) to provide a chemically compatible spacer between the lead slurry and the drilling mud. In some cases a wash precedes a spacer, but often only a single preflush is used. We consider well parameters typical of surface casing cementing in North Eastern British Columbia. Using a two-dimensional model of annular displacement flows, we show that the wash concept is flawed. In particular, in a sequence of simulations varying from intermediate density to low density we show that the wash progressively advances ahead of the lead slurry, channeling rapidly up the wide side of the annulus. Even when fully turbulent, it is ineffective at displacing mud from around the annulus, invalidating the motivation of chemical cleaning through contact time. Furthermore, the advance along the wide side of the annulus drains the volume of fluid separating the cement from drilling mud. Thus, the idea that the wash provides a barrier between slurry and and mud is invalid.

Comparative experimental evaluation of drilling fluid contamination on shear bond strength at wellbore cement interfaces

2014 ◽  
Vol 11 (6) ◽  
pp. 597-604 ◽  
Author(s):  
Mileva Radonjic ◽  
Arome Oyibo
Keyword(s):  
Bond Strength ◽  
Shear Bond Strength ◽  
Oil And Gas ◽  
Drilling Fluid ◽  
Cement Slurry ◽  
Geothermal Wells ◽  
Sustained Casing Pressure ◽  
Zonal Isolation ◽  
Casing Pressure ◽  
The Impact

Wellbore cement has been used to provide well integrity through zonal isolation in oil and gas wells as well as geothermal wells. Failures of wellbore cement result from either or both: inadequate cleaning of the wellbore and inappropriate cement slurry design for a given field/operational application. Inadequate cementing can result in creation of fractures and microannuli, through which produced fluids can migrate to the surface, leading to environmental and economic issues such as sustained casing pressure, contamination of fresh water aquifers and, in some cases, well blowout. To achieve proper cementing, the drilling fluid should be completely displaced by the cement slurry, providing clean interfaces for effective bond. This is, however, hard to achieve in practice, which results in contaminated cement mixture and poor bonds at interfaces. This paper reports findings from the experimental investigation of the impact of drilling fluid contamination on the shear bond strength at the cement-formation and the cement-casing interfaces by testing different levels of contamination as well as contaminations of different nature (physical vs. chemical). Shear bond test and material characterization techniques were used to quantify the effect of drilling fluid contamination on the shear bond strength. The results show that drilling fluid contamination is detrimental to both cement-formation and cement-casing shear bond strength.

DEVELOPMENT AND EVALUATION OF SOLID CONTROL SYSTEM TO OPTIMIZE DRILLING PERFORMANCE

2016 ◽  
Vol 78 (6-7) ◽  
Author(s):  
Imros Kinif ◽  
Sonny Irawan ◽  
Abhilash M. Bharadwaj
Keyword(s):  
Control System ◽  
Yield Point ◽  
Drilling Fluid ◽  
Plastic Viscosity ◽  
Dilution Method ◽  
Drilling Fluids ◽  
Drilling Mud ◽  
Low Gravity ◽  
Drilling Performance ◽  
The Impact

The nature of solid content mechanism in drilling fluids directly affects its properties and causes adverse impact on drilling performance. It has rapidly evolved and become a paramount issue over the years because of challenging drilling operations. To control the impact of the drilled solids on drilling fluid properties, solid control system unit must be capable of removing the drilled solids before the re-circulation. Failure to establish good solid control management may end the operation strategy with dilution method. A rigorous analysis of drilled solid effects and its correlation with poor performance of solid control system significantly reflects on the overall rig performance in optimizing drilling operation. This paper presents a study of two different solid control system configuration used in two drilling wells. The study shows that installation of distributor tank reduces mud overflow and brings in flow control stability. Mud rheologies – Plastic viscosity, Yield Point and Low Gravity Solid are considered for the two solid control systems. The results of the new solid control system design are better than the old one. Plastic viscosity, yield point and low gravity solid values improve by 14 %, 17 % and 25 % respectively. These results can be used to check the drilling performance and also in characterization of the solid control system to enhance the drilling mud capabilities. This research shows the need of engineering evaluation in the solid control system to reduce the chances of frequent drilling problems, rig components wear issue and other drilling fluid related hazards.

ENVIRONMENTAL ASSESSMENT OF SYNTHETIC-BASED DRILLING MUD DISCHARGES TO BASS STRAIT, AUSTRALIA

1998 ◽  
Vol 38 (1) ◽  
pp. 610
Author(s):  
G.W. Terrens ◽  
D. Gwyther ◽  
M.J. Keough
Keyword(s):  
Joint Venture ◽  
Drilling Fluid ◽  
Sampling Site ◽  
Recovery Period ◽  
Monitoring Program ◽  
Oil Field ◽  
Ocean Current ◽  
Drilling Mud ◽  
Water Based ◽  
The Impact

Esso Australia Ltd. (Esso) on behalf of the Esso/BHP joint venture undertakes exploration and development drilling activities to produce oil and gas from the Gippsland Basin in eastern Bass Strait. As part of the environmental management of the operation, a field monitoring program was undertaken to verify the predicted limited effect on the seabed of the discharge of residual synthetic based mud (SBM) adhered to drill cuttings.Reservoir studies of the mature Fortescue oil field identified scope to more efficiently deplete existing reserves as well as develop undrained oil pools within the known reservoir system. As such, 18 additional wells were drilled from the Fortescue platform in 1994-1996 following the original development drilling program when 21 wells were drilled in 1983-1985.Esso's standard drilling fluid in Bass Strait is an environmentally acceptable water based mud (WBM). However, due to the high frictional forces involved the greater lubricating properties of a non-water based drilling mud were required to drill the long reach, high angle sections of seven of the additional wells. The ester SBM was chosen on the basis of its lubricity and biodegradability, to reduce any potential environmental effects from the persistence of non-water based mud in seabed sediments.A seabed monitoring program was undertaken around the Fortescue platform by taking seabed samples from August 1995 to August 1997 at sites along a transect following the predominant ocean current and at control sites, before, during and after the period in which SBM cuttings were discharged. The seabed sediments were measured for esters, barium, biological changes and grain size. Results show clearly the increase in esters concentration in sediments during drilling, then the rapid decrease after completion of cuttings discharge. After a recovery period of 11 months from completion of SBM drilling, SBM esters were not detected in sediments. Sediment barium concentration was also found to be elevated, but only after SBM had been used, indicating greater dispersion of WBM than the more cohesive SBM. The barium concentrations found generally do not have measurable effects on biota. The impact on the sediment biology was found to be limited to the sampling site 100 m from the platform discharge point with recovery evident within four months of completion of drilling.Mechanisms for recovery of the minimal zone of effect are thought to be a combination of the biodegradation of the ester SBM used and the physical seabed dispersion process evident in eastern Bass Strait generated by the continuous series of storms which pass through especially in winter.

scholarly journals Exploring overcrowding trends in an inner city emergence department in the UK before and during COVID-19 epidemic

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
J. Panovska-Griffiths ◽  
J. Ross ◽  
S. Elkhodair ◽  
C. Baxter-Derrington ◽  
C. Laing ◽  
...  
Keyword(s):  
Emergency Department ◽  
Waiting Time ◽  
Number Of Patients ◽  
Before And After ◽  
Ed Overcrowding ◽  
University College London ◽  
Flow Through ◽  
Indirect Impacts ◽  
The Uk ◽  
The Impact

Abstract Background The COVID-19 pandemic and the associated lockdowns have caused significant disruptions across society, including changes in the number of emergency department (ED) visits. This study aims to investigate the impact of three pre-COVID-19 interventions and of the COVID-19 UK-epidemic and the first UK national lockdown on overcrowding within University College London Hospital Emergency Department (UCLH ED). The three interventions: target the influx of patients at ED (A), reduce the pressure on in-patients’ beds (B) and improve ED processes to improve the flow of patents out from ED (C). Methods We collected overcrowding metrics (daily attendances, the proportion of people leaving within 4 h of arrival (four-hours target) and the reduction in overall waiting time) during 01/04/2017–31/05/2020. We then performed three different analyses, considering three different timeframes. The first analysis used data 01/04/2017–31/12–2019 to calculate changes over a period of 6 months before and after the start of interventions A-C. The second and third analyses focused on evaluating the impact of the COVID-19 epidemic, comparing the first 10 months in 2020 and 2019, and of the first national lockdown (23/03/2020–31/05/2020). Results Pre-COVID-19 all interventions led to small reductions in waiting time (17%, p < 0.001 for A and C; an 9%, p = 0.322 for B) but also to a small decrease in the number of patients leaving within 4 h of arrival (6.6,7.4,6.2% respectively A-C,p < 0.001). In presence of the COVID-19 pandemic, attendance and waiting time were reduced (40% and 8%; p < 0.001), and the number of people leaving within 4 h of arrival was increased (6%,p < 0.001). During the first lockdown, there was 65% reduction in attendance, 22% reduction in waiting time and 8% increase in number of people leaving within 4 h of arrival (p < 0.001). Crucially, when the lockdown was lifted, there was an increase (6.5%,p < 0.001) in the percentage of people leaving within 4 h, together with a larger (12.5%,p < 0.001) decrease in waiting time. This occurred despite the increase of 49.6%(p < 0.001) in attendance after lockdown ended. Conclusions The mixed results pre-COVID-19 (significant improvements in waiting time with some interventions but not improvement in the four-hours target), may be due to indirect impacts of these interventions, where increasing pressure on one part of the ED system affected other parts. This underlines the need for multifaceted interventions and a system-wide approach to improve the pathway of flow through the ED system is necessary. During 2020 and in presence of the COVID-19 epidemic, a shift in public behaviour with anxiety over attending hospitals and higher use of virtual consultations, led to notable drop in UCLH ED attendance and consequential curbing of overcrowding. Importantly, once the lockdown was lifted, although there was an increase in arrivals at UCLH ED, overcrowding metrics were reduced. Thus, the combination of shifted public behaviour and the restructuring changes during COVID-19 epidemic, maybe be able to curb future ED overcrowding, but longer timeframe analysis is required to confirm this.

scholarly journals Impact of Drilling Fluid Contamination on Performance of Rock-Based Geopolymers

SPE Journal ◽  
2021 ◽  
pp. 1-8
Author(s):  
E. Eid ◽  
H. Tranggono ◽  
M. Khalifeh ◽  
S. Salehi ◽  
A. Saasen
Keyword(s):  
Mechanical Properties ◽  
Drilling Fluid ◽  
Petroleum Industry ◽  
Early Time ◽  
American Petroleum Institute ◽  
Drilling Fluids ◽  
Before And After ◽  
Pressure Water ◽  
Time Strength ◽  
The Impact

Summary Our objective is to present selected rheological and mechanical properties of rock-based geopolymers contaminated with different concentrations of drilling fluids. The possible flash setting and the maximum intake of drilling fluids before seeing a dramatic deterioration of the geopolymers are presented. Rock-based geopolymers designed for cementing conductor and surface casing were prepared and cured for up to 28 days at 22°C and atmospheric pressure. Water-based drilling fluids (WBDFs) and oil-based drilling fluids (OBDFs) were designed in accordance with the recommendations from the petroleum industry. The fluid samples were prepared, and their viscous behavior was characterized before and after hot-rolling. The geopolymeric slurries were mixed and then blended with the prepared drilling fluid volumes. The contaminated geopolymeric slurries were cured and tested at different time intervals. American Petroleum Institute (API) Class G neat cement was used as a reference. These samples were cured and contaminated with the same drilling fluids. The properties of contaminated geopolymer slurries were benchmarked with those of the contaminated Class G cement. The obtained mechanical properties showed that the rock-based geopolymers are more sensitive to WBDFs than to OBDFs. However, for contaminated Portland cement samples, the obtained results were opposite, and the contamination effect of OBDF on cement was more noticeable than WBDF. The impact of geopolymer contamination is a function of curing time. Although geopolymeric samples showed dramatic strength retrogression at the early time, strength buildup of the samples compensated for the impact of contamination.

Nanoparticles As Promising Additives to Improve the Drilling of Egyptian Oil and Gas Fields

2020 ◽  
Author(s):  
Ahmed Mady ◽  
Omar Mahmoud ◽  
Abdel Sattar Dahab
Keyword(s):  
Oil And Gas ◽  
Nile Delta ◽  
Drilling Fluid ◽  
High Surface ◽  
Wellbore Stability ◽  
Western Desert ◽  
Drilling Process ◽  
Drilling Mud ◽  
Gas Field ◽  
The Impact

Abstract Egypt is both one of the major oil-producing non-OPEC countries and one of the oldest energy producers in the Middle East. Recently, the Egyptian government have signed several agreements for the exploration of oil and gas in several provinces/regions including; the Mediterranean, the Western Desert, the Nile Delta, and the Gulf of Suez. Petroleum companies have given great attention to Egypt’s new discoveries such as Zohr Gas Field and Nour exploration prospect. Successful drilling operations to reach the oil and gas targets depends strongly on the effectiveness of the drilling fluid (mud). It can be considered as the heart of the drilling process, where they are used to fulfil several valuable functions. Drilling fluid technology is one of the most targeted and developed technologies worldwide. Several studies have examined the use of various types of nanoparticles (NPs) to enhance the properties and improve the performance of muds. NP can be defined as a simple particle structure with a size in the range of nanometers. The effectiveness of NPs can be accredited to their small size and high surface-area-to-volume ratio. Using NPs showed promising enhancements on the rheological and filtration characteristics as well as thermal stability and carrying capacity of the drilling fluid. Moreover, adding NPs to the drilling mud was found to minimize the shale permeability and thus, promote wellbore stability. The swelling and collapse of shale formations is expected under drilling with water-based mud, which might complicate the drilling operation. In the present work four types of NPs (nanosilica, nanoaluminium, nanotitanium, and nano copper oxide) were tested as promising additives to improve the characteristics of KCL-Polymer mud, which is mainly used to drill shaly formations. The impact of NPs-type, -size, and -concentration were thoroughly investigated using standard viscometer and API filter press. The results showed higher potential of nanotitanium and nanoaluminium to enhance the mud properties when used at small concentrations (0.3–0.5 wt.%). This research paper discusses a latest application and presents the most valuable findings concerning the efficient use of NPs in the drilling fluid industry. On this basis, different recommendations are stated, which might help researchers to better understand NPs’ functionality in this area of application and promote using NPs-based drilling muds as cost-effective and environmental-friendly fluids to drill the Egyptian oil and gas wells.

scholarly journals Exploring overcrowding trends in an inner city emergence department in the UK before and during COVID-19 epidemic

2021 ◽  
Author(s):  
Jasmina Panovska-Griffiths ◽  
Jack Ross ◽  
Samer Elkhodair ◽  
Christopher Baxter-Derrington ◽  
Chris Laing ◽  
...  
Keyword(s):  
Waiting Time ◽  
Hospital Emergency ◽  
Number Of Patients ◽  
Before And After ◽  
Ed Overcrowding ◽  
University College London ◽  
Flow Through ◽  
Multifaceted Interventions ◽  
The Uk ◽  
The Impact

Abstract BackgroundWe compared impact of three pre-COVID-19 interventions and of the COVID-19 UK-epidemic and the first UK national lockdown on overcrowding within University College London Hospital Emergency Department (UCLH ED). The three interventions: target the influx of patients at ED (A), reduce the pressure on in-patients’ beds (B) and improve ED processes to improve the flow of patents out from ED (C).MethodsWe analysed the change in overcrowding metrics (daily attendances, the proportion of people leaving within four hours of arrival (four-hours target) and the reduction in overall waiting time) across three analysis. The first analysis used data 01/04/2017-31/12-2019 to calculate changes over a period of six months before and after the start of interventions A-C. The second and third analyses focused on evaluating the impact of the COVID-19 epidemic, comparing the first 10 months in 2020 and 2019, and of the first national lockdown (23/03/2020-31/05/2020).ResultsPre-COVID-19 all interventions led to small reductions in waiting time (17%, p<0.001 for A and C;9%, p=0.322 for B) but also to a small decrease in the number of patients leaving within four hours of arrival (6.6%,7.4%,6.2% respectively A-C,p<0.001).In presence of the COVID-19 pandemic, attendance and waiting time were reduced (40% and 8%;p<0.001), and the number of people leaving within four hours of arrival was increased (6%,p<0.001). During the first lockdown, there was 65% reduction in attendance, 22% reduction in waiting time and 8% increase in number of people leaving within 4 hours of arrival (p<0.001). Crucially, when the lockdown was lifted, there was an increase (6.5%,p<0.001) in the percentage of people leaving within four hours, together with a larger (12.5%,p<0.001) decrease in waiting time. This occurred despite the increase of 49.6%(p<0.001) in attendance after lockdown ended.ConclusionsThe mixed results pre-COVID-19 (significant improvements in waiting time with some interventions but not improvement in the four-hours target), may be due to a ‘spill-over effect’ where clogging up one part of the ED system affects other parts. Hence multifaceted interventions and a system-wide approach to improve the pathway of flow through the ED system is necessary.During 2020 and in presence of the COVID-19 epidemic, a shift in public behaviour with anxiety over attending hospitals and higher use of virtual consultations, led to notable drop in UCLH ED attendance and consequential curbing of overcrowding.Importantly, once the lockdown was lifted, although there was an increase in arrivals at UCLH ED, overcrowding metrics were reduced. Thus, the combination of shifted public behaviour and the restructuring changes during COVID-19 epidemic, maybe be able to curb future ED overcrowding, but longer timeframe analysis is required to confirm this.

Sign in / Sign up

Export Citation Format

Share Document