Enhancing well bore stability, focus of fluid system advances. Although important improvements have been achieved in the area of wellbore instability, the wellbore collapse mechanism has not been fully understood. As the development wells are generally directional wells or horizontal wells, and the wellbore instability risk is great, wellbore stability analysis is needed in the halfaya oilfield. Wellbore instability is one of the main problems that engineers meet during drilling. Improving wellbore stability of shale by adjusting its. Analysis of vertical, horizontal and deviated wellbores. Analysis of wellbore instability in vertical, directional, and horizontal wells using field data m. Wellbore instability is one of the major problems that hamper the drilling speed in halfaya oilfield. Wellbore stability in geomechanics nottingham eprints. The causes of wellbore instability are often classified into either mechanical for example, failure of the. The inhibition property and mechanism of a novel low.
Wellbore instability and formation sand production pose potential risks for wellbore drilling, completion and production operations. Wellbore instability in oil and gas drilling is resulted from both mechanical. The instability mechanism of a confined rod under axial vibrations we studied the stability of a con. Jan 01, 2014 read the mechanism and law of wellbore instability due to drill string impact in air drilling, international journal of oil, gas and coal technology on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
Cavings are often the primary cause of wellbore instability and account for approximately 40% of rig downtime gallant et al. So this quick look handbookmanual specially was compiled and prepared for students in order to help them to get into the swing of things in regards of reservoir geomechanics, geomechanical evaluation and wellbore stability. Part three studies the effects of consolidation on longterm wellbore stability. Wellbore stability problems tend to occur during the drilling phase in shale sections, hence the understanding of shaledrilling fluid interaction mechanisms is essential if wellbore instability is to be avoided when drilling through shale sections. The solution presented in this paper is a cloudbased, coherent trajectory planning solution with wellbore stability validation using a mechanical earth model mem. Wellbore stability analysis and its application in the. Analysis of vertical, horizontal and deviated wellbores stability. Chemicalmechanical wellbore instability model for shales.
As shales have very low permeability, the flux of ions and water is very slow. Mitigation of wellbore instability and mud losses in. Pdf formation susceptibility to wellbore instability and. Eight billion dollars are spent each year due to wellbore instability problems peng, 2007, causing an increase in the drilling budget by 10% aadnoy, 2003. A new experimental method to measure diffusion coefficient of shale hydration is given, and the calculation method of experimental results is introduced. To describe symptoms of the problems while drilling 4. Jan 10, 2014 maintaining wellbore stability is an important issue in the oil and gas industry.
Realtime geopressure and wellbore stability monitoring while. All the wellbore instability issues can lead to nonproductive time and increase the cost of well construction. There was a case study from a deepwater well with the history of wellbore stability and loss circulation problems. Wellbore instabilities are responsible for 1020% of the total drilling cost. Most wellbore stability problems occur in shale where the poroelastic effective stress, together with chemical and electrokinetic potential gradients in the rock pore space, enhances the rock failure mechanisms. It has been estimated that this causes worldwide losses of several billion dollars per year, so it is important to get it right. Wellbore stabilization strategies optimal design of the drilling mud to enhance hydrate stability use kinetic additives e.
The failure wellbore pressure, borehole closure, plastic zone distribution of different direction wells are given in this paper. Selection of casing cement with low hydration heat use predictive modeling analyze stability of the wellbore formation using. This mechanism can occur in tectonically active zones. Second, the influences of water activity, membrane efficiency, clay content and drilling fluid on shale wellbore instability are summarized. Wellbore stability problems are known to cost the oil and gas industry billions of dollars each year. Wellbore instability in hard brittle shale is a critical topic related to the. Typical occurrences of wellbore instability in shales soft, swelling shale brittleplastic shale brittle shale naturally fractured shale strong rock unit. Wellbore instability problems during drilling have also been reported in naturally fractured formations 3. This study was carried in selected fields field a and field b in niger delta, nigeria to evaluate the properties of the shales and its effects in wellbore instability during drilling operations. This easily causes the wellbore instability accordingly.
Jul 10, 20 wellbore instability in oil and gas drilling is resulted from both mechanical and chemical factors. Complex accidents such as wellbore collapse and sticking emerged frequently in this formation. Wellbore stability problems such as tight hole, packoff, stuck pipe, inflow, and lost circulation are most commonly associated with conventional reservoirs but also occur in unconventional reservoirs. Pdf wellbore instability mechanisms in very hard clay. Practical approach to solving wellbore instability problems. A proposal to develop an improved methodology for wellbore. Abstract maximum horizontal stress is a critical parameter used in drilling optimization and wellbore stability modeling. Wellbore mechanics and stability in shale mehrabian. Predrill wellbore stability analysis using rock physical.
Oct 08, 20 outputs, in order to show the accuracy of results and investigate the wellbore stability in different states of vertical, horizontal and deviated. In order to accurately predict the wellbore behaviour in soft and porous rocks, a suitable and advanced constitutive model of rocks is the key issue of the borehole instability research. Maintaining wellbore stability is an important issue in oil and gas industry 110. These parameters were used first on the drilling data of vertical wells to develop the procedure for the analysis of wellbore instability and identify the mechanisms of instability.
Among various types of formation rocks, naturally fractured shale formation has been recognized as one of the major sources of wellbore instability issues. Comprehensive analysis of geological and engineering data indicates that halfaya oilfield features fractured shale in the nahr umr formation. Ies global background 3 near wellbore deformation is an old and well established concept. Then, with the soaking time of drilling fluid increasing, the regions enlarge little.
Enhancing well bore stability, strengthening and cleanout focus of fluid system advances by ryen caenn laguna beach, ca. In this paper, we present a threedimensional hydromechanical finite element model for analyzing the evolution of damage zone around the wellbore and evaluating the stability of wells. Research article wellbore stability in oil and gas drilling with chemicalmechanical coupling chuanliangyan, 1,2 jingendeng, 1 andbaohuayu 1 state key laboratory of petroleum resource and prospecting, china university of petroleum, beijing, china department of petroleum engineering, china university of petroleum, beijing, china. As there are many factors affecting the fluid flow and mass transfer in the wellbore and formation, the mechanisms behind well integrity are still not completely understood and require further investigation. The wellbore instability control mechanism of fuzzy ball. Awal center for petroleum and minerals, research institute, king fahd university of petroleum and minerals. Pdf the wellbore instability control mechanism of fuzzy. Cutting mechanism of a drill bit modified after mostofi and franca, 2014. In many sandstone reservoirs worldwide, sand production has been observed to accompany oil and gas production. Pdf wellbore instability is one of the key problems that engineers encounter during drilling. Maximum horizontal stress and wellbore stability while. The analyses consider two different boundary conditions on seepage at the cavity. Using wellbore deformation to optimize drilling performance.
In the process of drilling, the economic losses caused by wellbore instability reaches more than one billion dollar every year 11, and the lost time is accounting for over 40% of all drilling related nonproductive time 12. Effect of shale properties on wellbore instability during. Request pdf study on wellbore stability and instability mechanism in piedmont structures piedmont tectonic belts are rich of oil and gas. The paper reported the major drilling problems related to wellbore instability and pore pressure in deepwater wells. Fluidsolid coupling model for studying wellbore instability. Without a well constrained stress tensor predictions about wellbore stability are not possible, and calculations of resolved stresses on faults are unreliable. Pdf on jun 20, 2011, sherif adel akl and others published wellbore instability mechanisms in clays find, read and cite all the research you need on researchgate.
Wellbore instability is the major cause of nonproductive time and increased well cost in oil and gas drilling. Pdf this paper summarizes the results of an integrated program of laboratory measurements and numerical analyses that have been performed to. Realtime geopressure and wellbore stability monitoring while drilling. Jpt mitigation of wellbore instability and mud losses in. Study on wellbore stability and instability mechanism in. Summary wellbore instability is the major cause of nonproductive time and. Characterization of shaledrilling fluid interaction. We concluded that using these two methods simultaneously can assist in the stability of wellbores effectively which result cost savings and minimizing time overruns on drilling projects. Many of the drilling parameters, as mud weight or the optimal orientation of the borehole, require some knowledge of the mechanical behaviour of the rock. Geomechanical modeling of insitu stresses around a borehole. Wellbore instability can results in ilost circulation where tensile failure occurred and in ii spalling andor hole closure in case of compressive failure of the rock. Wellbore instability during drilling is a major problem in the application of rock mechanics in petroleum engineering. The possibility of improving wellbore stability of shale by adjusting its wettability was investigated. Tests and theoretical analysis revealed that wellbore.
Borehole instability is the undesirable condition of an openhole interval that does not maintain its gauge size and shape andor its structural integrity. Study on wellbore stability and instability mechanism in piedmont structures the open petroleum engineering journal, 2015, 8. Information on fieldproven technologies, such as this wellbore stabilizing agent, are important to the continual improvement of drilling fluid to safely drill similar fields around the. Finally, the geomechanical model, wellbore stability parameters and the mechanism of drilling problems are applied to the drilling. Wellbore instability types is the property of its rightful owner. The objective of this paper is the comparison of four rock failure criteria, named the mohrcoulomb, mogi. Wellbore stability ws before drilling planning involves. Ppt wellbore instability types powerpoint presentation. The high tectonic stress, formation strength decreasing and fluid pressure rising after mud filtrate seepage are main reasons for borehole collapse. Research article wellbore stability in oil and gas drilling. Detailed well planning is required to mitigate all the wellbore. To describe causes of wellbore instability problems 2. A best practice will be developed and validated against available rock strength data from core samples, and used to provide consistent inputs to the wellbore stability models.
The inhibition property and mechanism of a novel low molecular weight zwitterionic copolymer for improving wellbore stability weichao du 1,2,y, michal slany 3,y, xiangyun wang 1, gang chen 1 and jie zhang 1 1 school of chemistry and chemical engineering, shaanxi province key laboratory of environmental. Prior to drilling, the mechanical stresses in the formation are less than the strength of the. Changes in pore pressure have a strong influence on wellbore stability when drilling a shale. 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. This articles discusses the causes, types, effects, and possible prevention of borehole instability. A new analytical model of wellbore collapse pressure based on. It proves by the experimental results above that fuzzy ball drilling fluid can enhance the strength of coal by changing its rock mechanical parameters and break the limitation of safety density windows, thereby realizing wellbore instability control. Performance by wellbore stability and pore pressure in deepwater exploration. Through analysis of in situ stress properties, bedding structure and mechanical characteristics, wellbore instability mechanism was expounded from rock mechanics, chemistry of drilling fluid and. The mechanical mechanism of wellbore instability in the fergana basin was analysed and a method to determine the proper drilling fluid density was proposed. The wellbore instability has serious impact for oilfield drilling, and it restricts the exploration and development in the oil field. Controlling wellbore instability, especially in shale and shalecomposite formations, is a key element of successful drilling in many fields across the globe. To discuss practical, preventive, and remedial actions for wellbore instability 10. Current maximum horizontal stress prediction from wellbore breakout was based on the maximum tangential stress on the wellbore.
Wellbore stability in oil and gas drilling with chemical. After setting the first string to isolate a shallow hazard, the remaining casing depth points were selected based on drilling experience in an offset block, supplemented by pore pressures predicted using seismic data. We use cookies to offer you a better experience, personalize content, tailor advertising, provide social media features, and better understand the use of our services. Conquering wellbore instability in kuwait onepetro.
Shielding technology prevents wellbore instability. However, these costs can be significantly reduced through the application of comprehensive geomechanical models. Severe wellbore instability in a complex lithology formation. Wellbore stability analysis for each of the selected wellbore stability modeling methods, an analytical wellbore. If so, share your ppt presentation slides online with. Chemical effect on wellbore instability of nahr umr shale. Hence, proper measure can be taken to prevent the potential hazards during drilling and production. Wellbore instability due to shear failure and tensile fracturing can increase drilling time and sometimes leads to wells being sidetracked or abandoned. We analyze the wellbore instability reasons combined with the drilling engineering measures of three horizontal wells in the nahr umr formation. Hydration is produced in shale formation owing to the influence of the chemical property of drilling fluid.
In the first two hours after the formation is drilled, the regions of hydrate dissociation and wellbore instability extend quickly. Pdf wellbore stability analysis and its application in the fergana. Instability mechanism abstract wellbore instability in hard brittle shale is a critical topic related to the effective exploitation of shale gas resources. Nonlinear coupled consolidation analyses are performed to simulate the postdrilling, timedependent deformations and pore pressures around the wellbore. Study on wellbore stability and instability mechanism in piedmont. A new analytical model of wellbore collapse pressure based. Hence, the maintenance of wellbore stability is of major concern to drilling engineers in the oil and gas industry. Pdf wellbore instability in hard brittle shale is a critical topic related to the effective exploitation of shale gas resources. They usually occur because of rock failure but may not necessarily lead to.
In the process of drilling, the economic losses caused by wellbore instability reach more than one billion dollars every year, and wellbore instability accounts for over 40% of the nonproductive drilling time. Secondly, based on rock mechanics experiments and wellbore information, the geomechanical mechanism research of wellbore instability was carried out under complex geologic conditions. In severe cases, hole instability can lead to stuck pipe, pack off and eventual loss of the open hole section n. Borehole instability gives rise to problems in drilling operations. Thus, a better understanding of the mechanisms of wellbore instability in naturally fractured shale formations is highly desirable. However, the risk of potential wellbore instability due to the rubble zones still remained and the vshape orientation of the fault could cause a natural fracture, thus the mud formulation had to be engineered to minimize wellbore instability issues. Research article chemical effect on wellbore instability of. This paper is relevant and is appropriate in the oil and gas industry. Geomechanical analysis of the wellbore instability.
To narrow down the possible causes of wellbore instabilities in this field, a problemdiagnostic scheme was done by analyzing well log data, drilling reports. The analyses compute the relationship between the drilling mud pressure and wellbore stability associated with either the onset of localized failure mechanisms or large plastic deformations around. An approach for wellbore failure analysis using rock. Determine the wellbore instability mechanism best honoring actual postwell data numerical modeling predrill modeling definitive analyses correlated to core data and wellbore instability events figure 1overview of project work scope. Wellbore stability in oil and gas drilling with chemicalmechanical. The methodologies employed to tackle the profitdraining ramifications of wellbore instability run the gamut, from pumping wellbore strengthening materials wsm with drilling fluid, to socalled stress caging, whereby fractures are actually created and subsequently sealed with exceptionally precise concentrations of bridging or sealing agents. To describe wellbore stability before, during, and after drilling wells 3. In 2004 geopressure and wellbore stability related problems were. Wellbore instability in oil and gas drilling is resulted from both mechanical and chemical factors. Geomechanical information is relevant to assure wellbore stability, i. Most of drilling hole problems are attributed to wellbore stability issues which. Oct 16, 20 the cohesion decreases by 25% when the hydrate totally dissociates in hbs.
Principle mechanisms driving flow of water and solute intoout of shales force flow fluid. In this paper, an analytical model was established based on the stability theory, to calculate the wellbore collapse pressure. Exploration and production as one of the most important parts of the petroleum industry encounters different problems, usually resulting in nonproductive time. Wellbore mechanics and stability in shale mehrabian 2019. Wellbore instability is a major concern during drilling operations. Actually, wellbore instability has long been a notorious problem in the drilling industry, resulting in remarkable nonproductive time and economical loss. Analysis of wellbore instability in vertical, directional. In order to solve the wellbore instability of the fractured and hardbrittle shale in nahr umr formation, the drilling fluid property and engineering countermeasures should be taken into account. Water content of shale changes by various mechanisms such as. Once a geomechanical model has been developed that quantifies the principal stress magnitudes and orientations, the pore pressure, and the rock properties, it is possible to predict the amount of wellbore instability as a function of mud weight and properties.
1314 1043 105 1444 1424 739 57 1091 1110 1456 1452 1181 1369 1146 127 550 1584 147 837 1128 742 599 667 184 1568 1250 668 1484 1092 1075 74 1336 273 1142 1225 1101 793 615 821 1112