Experimental Research on Brittle Shale Failure Caused by Drilling Fluid Activity

2013 ◽  
Vol 807-809 ◽  
pp. 2550-2553 ◽  
Author(s):  
Ming Wang Peng ◽  
Hang Wen ◽  
Wei Zhou ◽  
Zhao Jun Wen ◽  
Xiao Ming Liu ◽  
...  
Keyword(s):  
Internal Structure ◽  
Experimental Research ◽  
Rock Strength ◽  
Drilling Fluid ◽  
Expansion Ratio ◽  
Wellbore Stability ◽  
Test Results ◽  
Fracture Formation ◽  
Set Up ◽  
Activity Window

The crack formed under the action of circular medium fluid around the wellbore of brittle shale has been a hot issue in recent years. This paper considers the brittle shale micro fracture formation mechanism from the perspective of inhibitive ability of drilling fluid activity. The model of activity-swelling-hydration is set up firstly through revising generalized Usher model, it states the drilling fluid activity range to keep wellbore in osmotic hydration stage with the critical expansion ratio, thus puts forward the concept of activity window and is verified by indoor test. Results show that the different activity of drilling fluid brings difference in rock strength in macro and time sensitive effect for internal structure of rock in micro. This mechanism can provide a more accurate range design for drilling fluid activity and strong guarantee for wellbore stability.

Experimental Research on the Engineering Properties of Foam-Improved Red Clay Soil

2011 ◽  
Vol 261-263 ◽  
pp. 1831-1835
Author(s):  
Guo Gang Qiao ◽  
Da Jun Yuan ◽  
Bo Liu
Keyword(s):  
Experimental Research ◽  
Clay Soil ◽  
Soil Improvement ◽  
Engineering Properties ◽  
Screw Conveyor ◽  
Test Results ◽  
X Ray Diffraction ◽  
Shield Tunneling ◽  
Red Clay ◽  
Improvement Measures

Red clay soil is widely distributed in south China, the microstructure of red clay soil was studied applying scanning electron microscopy (SEM), and the X-ray diffraction analysis (XRD) test found that a large number of swelling inducing minerals, for example, montmorillonite, illite-montmorillonite or chlorite-smectite were contained in the red clay soil. Shield tunneling in this kind of stratum is prone to arising “cake” and “arch” phenomena and it prone to lead screw conveyor device unsmooth dumping, so soil improvement measures must be taken. Foam as the most advanced soil conditioner has been widely used in shield construction. Using self-developed foam agent, experimental research on foam conditioning red clay soil was carried out, test results show that foam can not only significantly reduce the soil shear strength, but also can greatly enhance the soil's compressibility and fluidity, which is significant for the smooth dumping and excavation face stability maintenance.

The Analytical and Experimental Research of In-Vessel Corium Retention in CPR1000

2010 ◽  
Author(s):  
Xing Chen ◽  
Shishun Zhang ◽  
Jiming Lin ◽  
Huiyong Zhang
Keyword(s):  
Experimental Research ◽  
Success Probability ◽  
Outer Wall ◽  
Test Results ◽  
Pressurized Water Reactor ◽  
Structural Failure ◽  
Pressurized Water ◽  
Thermal Failure ◽  
Near Future ◽  
Preliminary Phase

The analytical and experiment research of In-Vessel Corium Retention (IVR) in the Chinese Pressurized-water Reactor 1000 MWe (CPR1000) are introduced. The IVR research consists of preliminary phase and detailed phase. The analysis of thermal failure, structural failure and penetration failure of Reactor Pressure Vessel (RPV) and the experimental research of External Reactor Vessel Cooling (ERVC) are performed at preliminary phase. Analysis results show that the RPV failure is the dominated by thermal failure mode and the probability of the thermal failure is very low. Test results show that the IVR success probability for CPR1000 is about 99% if the Critical Heat Flux (CHF) of CPR1000 is the same as that of AP600. Further works, including the ERVC enhancement design, the CHF test of the RPV outer wall and the recalculation of the IVR success probability for CPR1000, will be performed at detailed phase in the near future.

A Novel Method to Determine the Drilling Fluid Density for Gypsum-Salt Layer

2021 ◽  
Author(s):  
Jitong Liu ◽  
Wanjun Li ◽  
Haiqiu Zhou ◽  
Yixin Gu ◽  
Fuhua Jiang ◽  
...  
Keyword(s):  
Drilling Fluid ◽  
In Situ Stress ◽  
Wellbore Stability ◽  
Shrinkage Rate ◽  
Fluid Density ◽  
Salt Layer ◽  
Rock Creep ◽  
Key Factor ◽  
Well Abandonment

Abstract The reservoir underneath the salt bed usually has high formation pressure and large production rate. However, downhole complexities such as wellbore shrinkage, stuck pipe, casing deformation and brine crystallization prone to occur in the drilling and completion of the salt bed. The drilling safety is affected and may lead to the failure of drilling to the target reservoir. The drilling fluid density is the key factor to maintain the salt bed’s wellbore stability. The in-situ stress of the composite salt bed (gypsum-salt -gypsum-salt-gypsum) is usually uneven distributed. Creep deformation and wellbore shrinkage affect each other within layers. The wellbore stability is difficult to maintain. Limited theorical reference existed for drilling fluid density selection to mitigate the borehole shrinkage in the composite gypsum-salt layers. This paper established a composite gypsum-salt model based on the rock mechanism and experiments, and a safe-drilling density selection layout is formed to solve the borehole shrinkage problem. This study provides fundamental basis for drilling fluid density selection for gypsum-salt layers. The experiment results show that, with the same drilling fluid density, the borehole shrinkage rate of the minimum horizontal in-situ stress azimuth is higher than that of the maximum horizontal in-situ stress azimuth. However, the borehole shrinkage rate of the gypsum layer is higher than salt layer. The hydration expansion of the gypsum is the dominant reason for the shrinkage of the composite salt-gypsum layer. In order to mitigate the borehole diameter reduction, the drilling fluid density is determined that can lower the creep rate less than 0.001, as a result, the borehole shrinkage of salt-gypsum layer is slowed. At the same time, it is necessary to improve the salinity, filter loss and plugging ability of the drilling fluid to inhibit the creep of the soft shale formation. The research results provide technical support for the safe drilling of composite salt-gypsum layers. This achievement has been applied to 135 wells in the Amu Darya, which completely solved the of wellbore shrinkage problem caused by salt rock creep. Complexities such as stuck string and well abandonment due to high-pressure brine crystallization are eliminated. The drilling cycle is shortened by 21% and the drilling costs is reduced by 15%.

Development and Verification of Modeling Practice for CFD Decay Calculations to Obtain Roll Damping of FPSO

2021 ◽  
Author(s):  
Arjen Koop ◽  
Pierre Crepier ◽  
Sebastien Loubeyre ◽  
Corentin Dobral ◽  
Kai Yu ◽  
...  
Keyword(s):  
Model Test ◽  
Test Results ◽  
Cfd Modelling ◽  
Roll Damping ◽  
Natural Period ◽  
Computational Mesh ◽  
Safety Studies ◽  
Offshore Industry ◽  
Decay Tests ◽  
Set Up

Abstract Estimates for roll damping are important input parameters for simulation studies on vessels operating at sea, e.g. FPSO mooring in waves, wind and current, workability and operability investigations, Dynamic Position studies, ship-to-ship operations and safety studies of vessels. To accurately predict the motions of vessels this quantity should be determined with confidence in the values. Traditionally, model experiments in water basins using so-called decay tests are carried out to determine the roll damping. With recent advancements in CFD modelling, the offshore industry has started using CFD as an alternative tool to compute the roll damping of FPSO’s. In order to help adopt CFD as a widely accepted tool, there is a need to develop confidence in CFD predictions. Therefore, a practical CFD modelling practice is developed within the Reproducible CFD JIP for roll decay CFD simulations. The Modelling Practice describes the geometry modelling, computational mesh, model set-up and post-processing for these type of CFD calculations. This modelling practice is verified and validated by three independent verifiers against available model test data. This paper provides an overview of the developed modelling practice and the calculated CFD results from the verifiers. The CFD modelling practice is benchmarked against available model test results for a tanker-shaped FPSO. By following this modelling practice, the CFD predictions for the equivalent linear damping coefficient and natural period of the roll motions are within 10% for all verifiers and within 10% from the model test results. Therefore, we conclude that when following the developed modelling practice for roll decay simulations, reliable, accurate and reproducible results can be obtained for the roll damping of tanker-shaped FPSOs.

Interdisciplinary Approach for Wellbore Stability During Slimhole Drilling at Volga-Urals Basin Oilfield

2021 ◽  
Author(s):  
Anna Vladimirovna Norkina ◽  
Sergey Mihailovich Karpukhin ◽  
Konstantin Urjevich Ruban ◽  
Yuriy Anatoljevich Petrakov ◽  
Alexey Evgenjevich Sobolev
Keyword(s):  
Drilling Fluid ◽  
Interdisciplinary Approach ◽  
Wellbore Stability ◽  
Vertical Wells ◽  
Wellbore Instability ◽  
Water Based ◽  
Chemical Studies ◽  
Fluid Rheology ◽  
Selection Of

Abstract The design features and the need to use a water-based solution make the task of ensuring trouble-free drilling of vertical wells non-trivial. This work is an example of an interdisciplinary approach to the analysis of the mechanisms of instability of the wellbore. Instability can be caused by a complex of reasons, in this case, standard geomechanical calculations are not enough to solve the problem. Engineering calculations and laboratory chemical studies are integrated into the process of geomechanical modeling. The recommendations developed in all three areas are interdependent and inseparable from each other. To achieve good results, it is necessary to comply with a set of measures at the same time. The key tasks of the project were: determination of drilling density, tripping the pipe conditions, parameters of the drilling fluid rheology, selection of a system for the best inhibition of clay swelling.

Addition of Tubifex accelerates dewatering of oil sands tailings

2016 ◽  
Vol 43 (12) ◽  
pp. 1025-1033 ◽  
Author(s):  
Xiaojuan Yang ◽  
Miguel de Lucas Pardo ◽  
Maria Ibanez ◽  
Lijun Deng ◽  
Luca Sittoni ◽  
...  
Keyword(s):  
Oil Sands ◽  
Land Reclamation ◽  
Test Results ◽  
Anionic Polymer ◽  
Fine Tailings ◽  
Fluid Fine Tailings ◽  
Oil Sands Tailings ◽  
Set Up ◽  
Solids Content

Accelerating dewatering of fluid fine tailings (FFT) to facilitate land reclamation is a major challenge to the oil sands industry in Canada. A new method was tested, addition of Tubifex to FFT. Tubifex is an indigenous earthworm in Canada. The survival rate tests showed that Tubifex can survive in oil sands tailings and penetrate to 42 cm depth (maximum depth tested). Columns (5 L of FFT) were set-up with tailings alone, Tubifex treated tailings and polymer-Tubifex treated tailings. Test results showed that (a) the final mud–water interface of tailings alone was 26% higher than that of Tubifex treated tailings; (b) solids content of Tubifex treated tailings was 21% more than that of tailings alone; (c) Tubifex was capable to accelerate the dewatering process of both cationic and anionic polymer treated tailings; (d) anionic polymer was superior in facilitating long-term dewatering and its coupled effects with Tubifex were better than the cationic polymer.

Theoretical Calculation and Experimental Research on Sequential Turbocharging of a Marine Diesel Engine

2011 ◽  
Vol 305 ◽  
pp. 416-422
Author(s):  
Peng Qi Zhang ◽  
Qing Lin He ◽  
Yin Yan Wang
Keyword(s):  
Diesel Engine ◽  
Theoretical Calculation ◽  
Experimental Research ◽  
Marine Diesel Engine ◽  
Test Results ◽  
Low Load ◽  
Marine Diesel ◽  
Working Principle ◽  
Test Result

The paper introduces the working principle of the sequential turbo-charging (STC) system of multi-turbocharger. To improve low-load performance and operating economy of the 234V12 diesel engine, a STC system of multi-turbocharger for the diesel engine was designed. Theoretical calculation and experimental research was done on this improved marine diesel engine. Then, a 3-phase STC system is presented by analyzing and comparing the test result and the switching boundary of this system is confirmed. The test results show that the low-load performance is improved obviously by use of multi-turbocharger STC system.

scholarly journals Effect of Gadung Tuber Extract (Dioscorea hispida) on Mortality of Caterpillars (Spodoptera exigua) in Shallots (Allium cepa) in East Lombok

2021 ◽  
Vol 20 (3) ◽  
pp. 556
Author(s):  
Muhammad Mustarsidin ◽  
Syachruddin AR ◽  
Ahmad Raksun
Keyword(s):  
Allium Cepa ◽  
Analysis Of Variance ◽  
Experimental Research ◽  
Spodoptera Exigua ◽  
Test Results ◽  
Significance Level ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
Tuber Extract ◽  
Range Test

Plants that can be used as pesticides are Gadung tubers. Gadung tubers contain cyanide acid to kill armyworm pests because they contain dioscorin toxins which can cause nervous disorders. The purpose of this study was to determine the effect of Gadung tuber extract (Dioscorea hispida) on Caterpillar mortality (Spodoptera exigua) in Shallot plants. This type of research is experimental research. This study used a completely randomized design (CRD). The sample used was 5 caterpillars (Spodoptera exigua) in each polybag with 5 repetitions for each concentration of Gadung tuber extract, namely 0%, 0.5%, 1.0%, 1.5%, 2.0% and 2.5%, so the total Caterpillar used was 150 Caterpillars. Gadung tuber extraction was carried out by maceration method with methanol solvent. Data were analyzed using a one-way analysis of variance at the 95% significance level, followed by DMRT (Duncans Multiple Range Test). The results showed that the Gadung tuber extract had a significant effect on the mortality of caterpillars (Spodoptera exigua) because the F count was greater than the F table (45.40>2.62), and the DMRT test results showed that the optimal concentration of Gadung tuber extract was 2.5%. Therefore, it can be concluded that the extract of Gadung tuber (Dioscorea hispida) affects the mortality of Caterpillars (Spodoptera exigua) in Shallots (Allium cepa).

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