Numerical Investigation of the Influence of the Drill String Vibration Cyclic Loads on the Time Dependent Wellbore Stability Analysis

2021 ◽  
Author(s):  
Arnaud Regis Kamgue Lenwoue ◽  
Jingen Deng ◽  
Yongcun Feng ◽  
Naomie Beolle Songwe Selabi
Keyword(s):  
Cyclic Load ◽  
Drill String ◽  
Wellbore Stability ◽  
Time Dependent ◽  
Cyclic Loads ◽  
Drilling Mud ◽  
Collapse Pressure ◽  
Wellbore Instability ◽  
String Vibration ◽  
Fracture Pressure

Abstract Wellbore instability is one of the most important causes of Non-Productive Time causing billions of dollars of losses every year in the petroleum industry. During the drilling operations, the drilling mud is generally utilized to maintain the wellbore stability. However, the drilling mud is subjected to fluctuations caused by several processes such as the drill string vibration cyclic loads which can result into wellbore instability. In this paper, a nonlinear finite element software ABAQUS is utilized as the numerical simulator to evaluate the time dependent pore pressure and stress distribution around the wellbore after integration of drill string vibration cyclic loads. A MATLAB program is then developed to investigate the wellbore stability by computation of the time dependent wellbore collapse pressure and fracture pressure. The numerical results showed that the safe mud window which was initially constant became narrower with the time after integration of vibration cyclic load. The collapse pressure without vibration cyclic load increased by 14.33 % at the final simulation time while the fracture pressure decreased by 13.80 %. Interestingly, the safe mud windows widened with the increase of the normalized wellbore radius as the wellbore fracture pressure increased and the collapse pressure decreased. This study provides an insight into the coupling of the wellbore stability and the continuous cyclic loads generated by drill string vibrations which is an aspect that has been rarely discussed in the literature.

scholarly journals Numerical Investigation of the Influence of the Drill String Vibration Cyclic Loads on the Development of the Wellbore Natural Fracture

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 2015
Author(s):  
Arnaud Regis Kamgue Lenwoue ◽  
Jingen Deng ◽  
Yongcun Feng ◽  
Haitao Li ◽  
Adefarati Oloruntoba ◽  
...  
Keyword(s):  
Cyclic Load ◽  
Drill String ◽  
Natural Fracture ◽  
Circulation Rate ◽  
Cyclic Loads ◽  
Percentage Increase ◽  
Fracture Width ◽  
Wellbore Instability ◽  
Fracture Length ◽  
String Vibration

Wellbore instability is one of the most serious issues faced in the drilling process. During drilling operations, the cyclic loads applied on the fractured formation progressively modify the initial parameters (i.e., length and width) of the fractured formation, thus resulting into undesirable wellbore instability. In this paper, using a nonlinear finite element software (ABAQUS) as the numerical simulator, a poro-elasto-plastic model has been established which aimed at analyzing the influence of drill string vibration cyclic loads on the development of the wellbore natural fracture. The numerical results showed that the fracture width as a function of time profiles followed a sinusoidal behavior similar to the drill string vibration cyclic load profiles. For different cyclic load magnitudes with constant number of cyclic loads, the highest percentage increase of the fracture width after integration of cyclic loads was 64.77%. Interestingly, the fracture width increased with the fracture length in the near wellbore region while it globally decreased in the region far away from the wellbore. But for constant cyclic load magnitude with different number of cyclic loads, the biggest percentage increase of the fracture width after integration of cyclic loads was slightly lower representing 63.12% while the oscillating period of the fracture width increased with the number of cyclic loads. The parametric study revealed that the drill string vibration cyclic loads were relatively independent of the fracture length and the bottom hole pressure. However, the fracture width and the loss circulation rates were considerably impacted by the drill string vibration and the highest percentage increase of the loss circulation rate after integration of cyclic loads was 14.3%. This study provides an insight into the coupling of the fracture rock development and the continuous cyclic loads generated by drill string vibrations which is an aspect that has been rarely discussed in the literature.

Wellbore Stability of Salt and Anhydrite Formation of Fauqi Oilfield in Iraq

2014 ◽  
Vol 641-642 ◽  
pp. 462-468
Author(s):  
Yun Long Mu ◽  
Lei Wang ◽  
Ke Ming Liu ◽  
Jin Gen Deng ◽  
Bao Hua Yu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wellbore Stability ◽  
Drilling Process ◽  
Power Law Model ◽  
Lower Strength ◽  
Creep Properties ◽  
Collapse Pressure ◽  
Wellbore Instability ◽  
Fracture Pressure ◽  
Salt Creep

Salt and anhydrite formation of Fauqi oilfield in Iraq contains salt, anhydrite and shale. Complex situations have occurred in drilling process, such as overflow and sticking. The cores of the three lithology rock are fetched and their strength and creep mechanical properties are tested. Anhydrite is with higher strength and lower creep properties, and shale and salt is with lower strength and higher creep properties. The collapse pressure and fracture pressure of the three lithology rock are calculated. The safe density window of anhydrite is the most widest and there is no risk of wellbore instability, and the safe density window of shale is the narrowest and wellbore instability easily occur. The low limit of mud density to prevent shale and salt creep are calculated by power law model. The safe drilling density window is determined and successfully applied in drilling field.

On the Influence of the Equivalent Circulent Density Fluctuations on the Development of the Wellbore Natural Fracture

2021 ◽  
Author(s):  
Arnaud Regis Kamgue Lenwoue ◽  
Jingen Deng ◽  
Yongcun Feng ◽  
Naomie Beolle Songwe Selabi
Keyword(s):  
Finite Element ◽  
Drill String ◽  
Natural Fracture ◽  
Cyclic Loads ◽  
Fracture Width ◽  
Wellbore Instability ◽  
Fracture Length ◽  
String Vibration ◽  
String Vibrations ◽  
Drilling Operations

Abstract Wellbore instability is one of the most important causes of Non-Productive Time during drilling operations causing billions of dollars of losses every year. During the drilling stage, the Equivalent Circulent Density (ECD) is subjected to fluctuations caused by some factors such as the drill string vibrations cyclic loads. The fluctuating ECD applied on the fractured formation progressively modifies the initial parameters of the fractured formation such as its length and its width and this process finally results into wellbore instability. In this research, a poroelastic model based on a finite element method has been established to analyze the influence of the drill string vibration cyclic loads on the development of the wellbore natural fracture. The analysis was conducted with a two-dimensional plane strain model. A traction-separation law based on energy has been proposed for the Cohesive Zone Model. A nonlinear finite element software ABAQUS was utilized as the numerical simulator. The numerical results showed that the profiles of the fracture width as a function of time follow a sinusoidal behavior similar to the behavior of the drill string vibration cyclic loads profile. For different values of the Weight On Bit (WOB) and constant drill string Revolution Per Minute (RPM), an increase of the fracture width with the fracture length is observed in the near wellbore region. In the region far away the wellbore, the fracture width globally decreases with an increase of the fracture length for each fracture profile. the investigation of the effect of some drilling operational parameters on the development of the wellbore natural fracture also demonstrated that the drillstring vibration cyclic loads lead to an increase of the fracture length, fracture width, the loss circulation and the Bottom Hole Pressure. This study couples the integration of the fracture rock development with the continuous cyclic load generated by drill string vibrations. This aspect has been rarely discussed in the literature. The study indicates that the cyclic loads significantly affect the development of the wellbore natural fracture during drilling operations, and therefore has an important impact on the wellbore stability analysis.

Analysis of creep-induced strains and stresses in notches subjected to a cyclic load

2007 ◽  
Vol 42 (5) ◽  
pp. 361-375 ◽  
Author(s):  
J E Nuñez ◽  
G Glinka
Keyword(s):  
Finite Element ◽  
Plane Stress ◽  
External Load ◽  
Cyclic Load ◽  
Time Dependent ◽  
Cyclic Loads ◽  
Creep Response ◽  
Stress Components ◽  
Estimation Of Time ◽  
Good Agreement

A method for the estimation of time-dependent strains and stresses in notches subjected to a cyclic load is discussed in the paper. The proposed solution is an extension of the methodology proposed previously for notches under a steady external load. A new algorithm is proposed to predict the creep response near notches in plane stress components subjected to cyclic loads. Predictions were compared with finite element data, and good agreement was obtained for various geometrical and material configurations.

The Effects of Filter-Cake Buildup and Time-Dependent Properties on the Stability of Inclined Wellbores

SPE Journal ◽  
2011 ◽  
Vol 16 (04) ◽  
pp. 1010-1028 ◽  
Author(s):  
Minh H. Tran ◽  
Younane N. Abousleiman ◽  
Vinh X. Nguyen
Keyword(s):  
Pore Pressure ◽  
Filter Cake ◽  
Wellbore Stability ◽  
Time Dependent ◽  
Transient Effects ◽  
Drilling Mud ◽  
Property Variation ◽  
Lost Circulation ◽  
Wellbore Strengthening ◽  
Formation Pore Pressure

Summary The effects of filter-cake buildup and/or filter-cake-property variation with time on wellbore stability have been plaguing the industry. The increasing use of lost-circulation materials (LCMs) in recent years for wellbore strengthening in weak and/or depleted formations necessitates models that can predict these effects. However, the complexities of effective-stress and pore-pressure evolution around the borehole while drilling, coupled with the transient variation of mud-filtration properties, have delayed such modeling efforts. In this paper, the analytical solutions for the time-dependent effects of mudcake buildup and mudcake properties on the wellbore stresses and formation pore pressure, and thus the safe-drilling-mud-weight window, are derived. The transient effects of mudcake buildup and mudcake buildup coupled with its permeability reduction during filtration on the safe-drilling-mudweight window are illustrated through numerical examples. The results showed that the safe-mudweight windows were greatly affected by the buildup of filter cake and its permeability variation. For example, the analysis for filter-cake buildup with cake permeability of 10–2 md showed that the safe-mudweight window was widened by 0.5 g/cc after 2.5 hours post-excavation when compared to the case of a wellbore without mudcake. On the other hand, a lower mudcake permeability of 10–3 md widened the mudweight window by as much as 1 g/cc. Last but not least, the analyses revealed that even for mudcake permeability as low as 10–3 md, neglecting the permeable nature of the mudcake can result in overestimation of the safe-drilling-mudweight window.

scholarly journals Optimization of Deviated and Horizontal Wells Trajectories and Profiles in Rumaila Oilfield

2020 ◽  
Vol 10 (2) ◽  
pp. 36-53
Author(s):  
Hussein Saeed Almalikee ◽  
Fahad M. Al-Najm
Keyword(s):  
Horizontal Wells ◽  
Wellbore Stability ◽  
Type I ◽  
Type Ii ◽  
Drilling Mud ◽  
Wellbore Instability ◽  
Type Iv ◽  
Planning And Design ◽  
Horizontal Wellbore ◽  
Wellbore Failure

Directional and horizontal wellbore profiles and optimization of trajectory to minimizeborehole problems are considered the most important part in well planning and design. Thisstudy introduces four types of directional and horizontal wells trajectory plans for Rumailaoilfield by selecting the suitable kick off point (KOP), build section, drop section andhorizontal profile. In addition to the optimized inclination and orientation which wasselected based on Rumaila oilfield geomechanics and wellbore stability analysis so that theoptimum trajectory could be drilled with minimum wellbore instability problems. The fourrecommended types of deviated wellbore trajectories include: Type I (also called Build andHold Trajectory or L shape) which target shallow to medium reservoirs with lowinclination (20o) and less than 500m step out, Type II (S shape) that can be used topenetrate far off reservoir vertically, Type III (also called Deep Kick off wells or J shape)these wells are similar to the L shape profile except the kickoff point is at a deeper depth,and design to reach far-off targets (>500m step out) with more than 30o inclination, andfinally Type IV (horizontal) that penetrates the reservoir horizontally at 90o. The study alsorecommended the suitable drilling mud density that can control wellbore failure for the fourtypes of wellbore trajectory.

A Comprehensive Wellbore Stability Model Considering Poroelastic and Thermal Effects for Inclined Wellbores in Deepwater Drilling

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Xuyue Chen ◽  
Deli Gao ◽  
Jin Yang ◽  
Ming Luo ◽  
Yongcun Feng ◽  
...  
Keyword(s):  
Thermal Effects ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Wellbore Stability ◽  
Pressure Gradients ◽  
Stress Regime ◽  
Collapse Pressure ◽  
Wellbore Instability ◽  
Deepwater Drilling ◽  
Stability Model

Exploring and developing oil and gas in deepwater field is an important trend of the oil and gas industry. Development of deepwater oil and gas fields from a platform always requires a number of directional wells or extended reach wells targeting to different depth of water in various azimuth. Drilling of these wells is mostly associated with a series of wellbore instability problems that are not encountered in onshore or shallow water drilling. In the past decades, a number of studies on wellbore stability have been conducted. However, few of the models are specific for wellbore stability of the inclined deepwater wellbores. In this work, a comprehensive wellbore stability model considering poroelastic and thermal effects for inclined wellbores in deepwater drilling is developed. The numerical method of the model is also presented. The study shows that for a strike-slip stress regime, the wellbore with a low inclination poses more risk of wellbore instability than the wellbore with a high inclination. It also shows that cooling the wellbore will stabilize the wellbore while excessive cooling could cause wellbore fracturing, and the poroelastic effect could narrow the safe mud weight window. The highest wellbore collapse pressure gradients at all of the analyzed directions are obtained when poroelastic effect is taken into account meanwhile the lowest wellbore fracture pressure gradients at all of the analyzed directions are obtained when both of poroelastic effect and thermal effect are taken into account. For safe drilling in deepwater, both of thermal and poroelastic effects are preferably considered to estimate wellbore stability. The model provides a practical tool to predict the stability of inclined wellbores in deepwater drilling.

Predrill Geomechanical Evaluation Helps in Successful Drilling in High Depletion Wells in a Mature Field, Offshore Sarawak, Malaysia

2021 ◽  
Author(s):  
Mohamad Hafiz Abdul Latip ◽  
Avirup Chatterjee ◽  
Amitava Ghosh ◽  
Priveen Raj Santha Moorthy
Keyword(s):  
Stress Path ◽  
Wellbore Stability ◽  
Drilling Fluids ◽  
Drilling Mud ◽  
Wellbore Instability ◽  
Pressure Depletion ◽  
Loss Event ◽  
Mature Field ◽  
The Stability ◽  
Fracture Gradient

Abstract Hydrocarbon-bearing reservoirs in a mature field, offshore Sarawak, Malaysia, contains multiple reservoir cycles interbedded with weak shale and coal formations. Years of production from these reservoirs caused significant pressure depletion, as well as reduced fracture gradient and a narrower drilling mud weight window. An improperly weighted mud may induce wellbore instability in weaker, but normally pressured, formations or mud losses in the heavily depleted reservoirs. Globally, mud losses are considered the most expensive well control operation incidents. Earlier drilling campaigns in ths field encountered numerous wellbore instability incidents; hence, a study was conducted to develop an understanding of the drilling issues and assess the stability of the heavily depleted reservoirs. Collaboration between the drilling and geomechanics teams facilitated better understanding of the stability challenges and helped in mitigating risk related to wellbore instability. A field scale geomechanical model was developed and validated using data from exploration and development wells from different phases of drilling in the study area. The stress path factor (SPF), which determines the reduction in fracture gradient with pore pressure depletion is crucial for defining drilling mud windows, is difficult to constrain in the absence of measured formation fracturing data in virgin and depleted reservoirs. A mud loss event in the depleted zone from a recent drilled well and regional information were used to estimate the range of SPF in the study area. Recorded bottom hole pressures from pressure while drilling (PWD) data suggested that the maximum equivalent circulating density (ECD) recorded was close or within the depleted section. The loss event was associated with reduced fracture gradient due to depletion from its pre-depleted range. This paper describes how geomechanical evaluation with effective well drilling practices and fit for purpose-drilling fluids have helped drilling through depleted reservoirs with ECD management. At the end, it shows a comparison of the predrill wellbore stability mud weight estimates with the actual mud weights used to successfully drill and complete the planned wells.

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