Winner of the standing ovation award for best powerpoint templates from presentations magazine. These stability problems are often encountered in the shalelike rock layers above the foreword. The fluid system always has been a vital part of drilling engineering, dating back to spindletop, when a herd of cattle was turned loose in a partiallyfilled water pit to grind the saturated soil into mush with their hooves. Borehole stability technology includes chemical as well as mechanical methods to maintain a stable borehole, both during and after drilling. Theyll give your presentations a professional, memorable appearance the kind of sophisticated look that todays audiences expect. Our new crystalgraphics chart and diagram slides for powerpoint is a collection of over impressively designed datadriven chart and editable diagram s guaranteed to impress any audience. The analysis of wellbore stability in deepwater gas wells is vital for effective drilling operations, especially in deepwater remote areas and for modern drilling technologies. Keywords casing design, dynamic displacement, geomechanical model, ground motion, well bore stability 1. To describe causes of wellbore instability problems. Worlds best powerpoint templates crystalgraphics offers more powerpoint templates than anyone else in the world, with over 4 million to choose from.
However, it is necessary while drilling to maintain stability over the entire openhole section between casing points. It also displays a summary of the wells history as well as the current data. The lower figures show the mud weight in ppg required to maintain stability as a function of wellbore orientation for a highly anisotropic shale if the weak bedding planes are ignored on the left and considered on the right. Blowout of fluids under high pressure lost circulation often leading to blowouts massive shale instability chemical reasons ductile unfractured shales, incompatibility with oilbase mud mechanical reasons highly fractured shale or coal, fissile shale and. A wellbore is a borehole or a hole drilled in the earths surface so as to carry out exploration and extraction of natural resources like water, oil or gas. Introduction to wellbore stability analysis youtube. A borehole may be constructed for many different purposes, including the extraction of water, other liquids such as petroleum or gases such as natural gas, as part of a geotechnical investigation, environmental site assessment, mineral exploration, temperature measurement, as a pilot hole for installing. Wellbore stability analysis for trouble free drilling. Wellbore stability problems are known to cost the oil and gas industry billions of dollars each year. The analyses predict critical mud pressure values necessary to maintain wellbore stability at different deviation angles and stress histories. It also causes mechanical problems such as stuck pipes, high torque and backreaming, instigating further dangers when setting the casing and removing cuttings, jon explains.
Wellbore stability requires a proper balance between theuncontrollable factors of earth stresses, rock strength, and pore pressure, andthe controllable factors of wellbore fluid pore pressure, and the controllablefactors of wellbore fluid pressure and mud chemical. Wellbore stability in oil and gas drilling with chemical. Wellbore mechanics and stability in shale mehrabian 2019. Introduction casings are of fundamental importance in the building of any well. Lwd azimuthal acoustic technology, free from chemical sources, was used for the first time both in drilling and wipes modes to facilitate timelapse field stress and well bore stability analysis principal stress orientations were. The main aspect of the well bore stability analysis is to mitigate these drilling problems. Pdf wellbore instability is one of the major problems hampering the drilling speed in the fergana basin. A wellbore is a hole that is drilled to aid in the exploration and recovery of natural resources including oil, gas or water. Apr 09, 2015 ensuring wellbore stability with geomechanics and pore pressure prediction duration. Well bore stability free ebook download as powerpoint presentation. To narrow down the possible causes of wellbore instabilities in this field, a problemdiagnostic scheme was done by analyzing well log data, drilling reports.
A number of theoretical borehole stability models use a different criterion for shear failure called the druckerprager dp criterion. Wellbore stability in geomechanics nottingham eprints. It is the actual hole that forms the well and it can be uncased or encased by cement and steel. By turning the well to the southwest in the problematic area, wellbore stability could be achieved with a mud weight less than the fracture gradient. Predrill wellbore stability analysis using rock physical. Wellbore storage and its impact on well test interpretation. It has been compiled by stephen willson and jianguo zhang in bps exploration and production technology drilling group. In the reservoir hole section, the mud weight was increased to 18. Shale, with its inherent heterogeneity and anisotropy, has always been problematic in many operations ranging from seismic exploration, welllog data interpretation, well drilling and wellbore stability problems, to production. Borehole may refer to the inside diameter of the wellbore wall, the rock face that bounds the drilled hole. Best practices from previous hpht wells were carefully studied and replicated to ensure success of the well. Borehole instabilities can be encountered at any stage in the life of a well and they are the main cause of drilling difficulties, resulting in substantial expenditures, expensive loss of time, sometimes even in the loss of part of or even whole boreholes. When the coals are at an overpressured condition, or the formations encountered are unstable, it may be necessary to drill in an overbalanced condition to provide borehole stability and pressure control. Dec 29, 2016 pore pressure prediction from well logs has spatial and depth limitation.
Wellbore stability modeling in vertical and horizontal. In the analysis of the effect of borehole radius on wellbore stability, r 0. Pdf wellbore instability is one of the main problems that engineers meet during drilling. Wellbore stability problems in deepwater gas wells article pdf available in world journal of engineering and technology 0504. A wellbore diagram is used to get complete information related to the components used in the operations. In this research, we investigate the wellbore instability issues in. A calibrated regional area, using analogue wells, can provide sufficient data to study subsurface pore pressures and to analyze characteristics contributing to wellbore instability. These do not account for the fact that stress changes induce pore pressure changes, and vice versa. Frac rock gradient properties pore pressure the causes of wellbore instability are often classified into either mechanical for cause rapid pore pressures increases in the near wellbore area sometimes. Basic introduction to wellbore stability analysis designed and presented by sam saeed hashemi.
Borehole stability an overview sciencedirect topics. A wellbore stability analysis was carried out by fuf et al. The chayvo z44 extendedreach well took the title of the worlds longest borehole on 27 august 2012. This is typically investigated by a constitutive model to estimate stress around the well bore, coupled with failure criterion. Borehole stability overview of methods of hole improvement. Wellbore stability problems usually occur when drilling through hydrocarbon formations such as shale, unconsolidated sandstone, fractured carbonate formations and hpht formations with narrow safety mud window. Borehole stability and field stress analysis with azimuthal. Efforts are given to ensure that all information given by the diagram is readily accessible so as to take effective decisions. Pdf wellbore stability problems in deepwater gas wells. Guidelines for efficient wellbore stability analysis sciencedirect. The influence of well structure on wellbore stability rests with the size of borehole radius.
You can also evaluate the drilling risk for proposed well plans by. He has been an spe distinguished lecturer on 2 occasions,20072008, 20112012 to several countries to make presentations on wellbore stability and well design and construction. The mite3 model predicted higher deformations at reference mud pressure and estimated higher values of mud pressures than the underbalanced limit to prevent failure in highly deviated wellbores in nc clays. Frac rock gradient properties pore pressure the causes of wellbore instability are often classified into either mechanical for cause rapid pore pressures increases in. The causes of wellbore instability are often classified into.
Babs oyeneyin, in developments in petroleum science, 2015. The key factors which contribute to wellbore instability problems in oil and gas fields can be grouped as nonchangeable and changeable. It also causes mechanical problems such as stuck pipes, high torque and backreaming, instigating further dangers when setting. The techlog wellbore stability module comprises mechanical earth model 1dmem building, wellbore stability, sand management, and fracture stability computation. The drilling for oil and gas exploration and production under increasingly difficult geological conditions has revealed a need for better understanding of borehole stability issues. Wellbore stability has been considered as a major issue in troubled shale, salt, poorly consolidated sandstone and fractured formations. The 1dmem is the backbone of every geomechanical workflow for which it provides the stress field, pore pressure, and mechanical properties. Chart and diagram slides for powerpoint beautifully designed chart and diagram s for powerpoint with visually stunning graphics and animation effects. Specifically, you can plan wells by calculating a critical mud weight window and a casing design that prevents wellbore failure. Wellbore stresses after drilling drilled wellbore results in a new set of stresses known as wellbore stresses axial, tangential, and radial mud hydraulic pressure if the redistributed stressstate exceeds rock strength, instability may result.
However, these costs can be significantly reduced through the application of comprehensive geomechanical models. Zehner, method and apparatus for generation of 3d graphical borehole analysis. Hydration is produced in shale formation owing to the influence of the chemical property of drilling fluid. Horizontal and fractured wells will have larger wellbore storage effects with c. Summary wellbore instability is the major cause of nonproductive time and increased well cost in oil and gas drilling. Ensuring wellbore stability with geomechanics and pore pressure prediction duration. The impact of drilling unloading on wellbore stability of shale formations. Jul 24, 20 wellbore stability problems are known to cost the oil and gas industry billions of dollars each year. Ppt wellbore instability types powerpoint presentation. One consequence is that the fourth casing section has an extremely narrow mud window. Optimizing drilling performance by wellbore stability evaluation and directional drilling practices. Thermally induced stresses may be detrimental to a well integrity or enhance the stability depending on if the temperature rises or declines near a wellbore. Well bore stability how is well bore stability abbreviated.
The main aim of this research is to use new method and theory in geomechanics to conduct the stability analysis of wellbore. The drilling for oil and gas exploration and production under increasingly difficult geological. Field x, a mature oil and gas sandstone reservoir located in north sumatra, indonesia. Numerical wellbore stability casing well integrity in this work we present a workflow to evaluate the geomechanical behavior displacement field, strain state and stress state of the rock salt and the integrity of well casing without cement in the annulus submitted to the uniform loading by the rock salt during the creep phenomenon. Shale, with its inherent heterogeneity and anisotropy, has always been problematic in many operations ranging from seismic exploration, well log data interpretation, well drilling and well bore stability problems, to production. In spite of more than 20 years of advances in the application of geomechanical principles to improve understanding of its causes and improvements in drilling practices to reduce its effects, wellbore instability continues to be perhaps the largest single source of nonproductive drilling time. Practical approach to solving wellbore instability problems. The principal goals in this dissertation are to constrain the full insitu stress tensor. Overview wellcheck wellbore stability analysis software. Predrill wellbore stability analysis using rock physical parameters for a deepwater high angle well. World journal of engineering and technology, 5, 626647. This dissertation investigates the stability of wellbores drilled in koconsolidated clays using nonlinear finite element method fem and effective stress soil models to characterize the behavior of clay and unconsolidated shale formations.
Using the right data and tools will help well designer to do better job for more wellbore stability, using the right computer algorithms that analyzed and qced by drillers not it guys only will do. From 2011 until august 2012 the record was held by the 12,345metre 40,502 ft long sakhalini odoptu op11 well, offshore the russian island sakhalin. Weighting additives will then be needed in the cement slurry to maintain well control and provide good zonal isolation. To narrow down the possible causes of wellbore instabilities in this field, a problemdiagnostic scheme was done by analyzing well log data, drilling reports, mud logging reports, and pore pressure measurements. Pore pressure prediction from well logs has spatial and depth limitation. Wellbore instability in oil and gas drilling is resulted from both mechanical and chemical factors. After collecting data, a pore pressure 1d model and a wellbore stability wbs model can be generated based on client goals and data availability. In many cases, wellbore stability analysis can be carried out with very simple models that are timeindependent and relate stress and pore pressure, only through the effective stress law. A typical wellbore storage coefficient for a vertical well is c 0. The drilled hole or borehole, including the openhole or uncased portion of the well. State key laboratory of oil and gas reservoir geology and exploitation southwest petroleum university, chengdu, sichuan, 610500, china. Using the results, the positions of casings can be adjusted to maximize wellbore stability while staying within engineering constraints. The colour indicates the mud weight in ppg required to stabilize the well at a given depth. Therefore, analyses of stability must be carried out over that entire depth range.
Two kinds of well structure applied in daniudi gas field are given in fig. Lwd azimuthal acoustic technology, free from chemical sources, was used for the first time both in drilling and wipes modes to facilitate timelapse field stress and well bore stability analysis principal stress orientations were identified from three different. Wellbore stability analysis for trouble free drilling onepetro. Wellbore stability requires a proper balance between theuncontrollable factors of earth stresses, rock strength, and pore pressure, andthe controllable factors of wellbore fluid pore pressure, and the controllablefactors of wellbore fluid pressure and mud chemical composition. Pdf wellbore stability analysis and its application in the fergana. The most common approach for stability analysis is a linear elastic and isotropic. Enhancing well bore stability, focus of fluid system advances. May 24, 2015 basic introduction to wellbore stability analysis designed and presented by sam saeed hashemi. Horizontal well drilling includes mwd, borehole trajectory control, borehole stability, drillingcompletion fluids, and other key techniques. The smaller the radius of curvature from a vertical well section to a horizontal well section, the higher the construction difficulty. The cavity contraction theory is used to get the new elasticperfectly plastic solutions for vertical borehole with anisotropic stress field.
A new experimental method to measure diffusion coefficient of shale hydration is given, and the calculation method of experimental results is introduced. The main reason for using stress variants is that the dp criterion is expressed in socalled stress. To describe wellbore stability before, during, and after drilling wells. Factors influencing wellbore stability during underbalanced. For many years, the worlds longest borehole was the kola superdeep borehole in russia. Drilling fluids range from water to oil to complex chemical systems with properties designed for specific site conditions to aid the drilling process. Results of wellbore stability assessment are required to mitigate consequences of instability. A borehole is a narrow shaft bored in the ground, either vertically or horizontally. The principal goals in this dissertation are to constrain the full insitu stress tensor using drillinginduced tensile fractures and wellbore breakouts.