scholarly journals The near-wellbore pressure calculation model incorporating thermochemical effect

2018 ◽  
Vol 22 (1 Part B) ◽  
pp. 623-630
Author(s):  
Zhiqiang Tang ◽  
Qian Li ◽  
Hu Yin
Keyword(s):  
Pore Pressure ◽  
Drilling Fluid ◽  
Solute Concentration ◽  
Calculation Model ◽  
Hydraulic Pressure ◽  
Fluid Temperature ◽  
Wellbore Instability ◽  
Wellbore Pressure ◽  
Pressure Calculation ◽  
Tight Formation

The potential difference of hydraulic pressure, solute concentration and temperature between the drilling fluid and the formation fluid can induce the flow of solvent and cause changes in the pore pressure during drilling a tight formation, which may result in wellbore instability. According to the continuity equation of fluid, the pore pressure calculation model considering the effect of thermochemical coupling is established and the solution of the pore pressure in the Laplace domain is given. Using this model, the effects of the temperature, solute concentration and viscosity of drilling fluid on the pore pressure around the wellbore are simulated. The results show that, when the wellbore pressure is higher than the formation pressure and the solute concentration of the drilling fluid is larger than that of the formation fluid, the near-wellbore pore pressure will decrease first and then increase during drilling a tight formation, and increasing the drilling fluid temperature will decrease the pore pressure. Increasing the solute concentration of the drilling fluid can inhibit the increase of the pore pressure.

Effect of Pore Pressure Variation on Borehole Stability of Drilling in Sandstone Reservoir

2012 ◽  
Vol 577 ◽  
pp. 163-166
Author(s):  
Yu Wei Li ◽  
Jia Liu ◽  
Chao Yang Hu ◽  
Shuang Li ◽  
Yu Liu
Keyword(s):  
Pore Pressure ◽  
Effective Stress ◽  
Drilling Fluid ◽  
Calculation Model ◽  
Pressure Variation ◽  
Stress Factor ◽  
Borehole Stability ◽  
Porosity Variation ◽  
Sandstone Reservoir ◽  
Variation Model

Considering pore pressure variation of sidewall rock, which is caused by drilling fluid filtering, the porosity variation model of sidewall rock in sandstone reservoir and effective stress factor variation model are established, and according to relationship between pore pressure and total volume strain of sandstone, the calculation model of safe window of drilling fluid density on sandstone reservoir, with which considered variation of porosity and effective stress factor are finally established. Applying the calculation of this model shows that: with increased function of drilling fluid filtering, which is as increased as pore pressure of sidewall rock, caving pressure that ensures well hole stability is increased, fracturing pressure is decreased, safe window of drilling fluid is narrowing, and that is against of safety drilling.

Engineering Fluids and Hydraulics to Drill the First Sub-Horizontal Well with Narrow ECD Window in Eastern Urengoy License Area

2021 ◽  
Author(s):  
Pavel Nikolayevich Sergeev ◽  
Alexander Fyodorovich Mordyukov ◽  
Alexander Sergeyevich Kozyrev ◽  
Evgeny Vasilyevich Bembak ◽  
Aleksander Mikhailovich Matsera ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Pore Pressure ◽  
Horizontal Well ◽  
Drilling Fluid ◽  
Fluid Management ◽  
Support Service ◽  
Lessons Learned ◽  
Hydraulic Pressure ◽  
Time Step ◽  
Fluid Parameters

Abstract The Operator's challenge was the construction of a sub-horizontal well with 1500 m liner section in area with limited offset experience. The main development difficulty of the East Urengoy license area is the abnormally high pore pressure Achimov deposit. The widely used practice of drilling for these reservoirs with S-shaped profile wells has been utilized for a long while. However, the construction of sub-horizontal wells is still a challenge, and often accompanied by high incident rates. Before drilling the well, all necessary fluid engineering modelling was performed. According to the hydraulic calculations, drilling of the horizontal well with traditional fluid properties was not possible due to exceeding the maximum ECD range. Multiple laboratory tests were performed to optimize the drilling fluid parameters and rheological properties with respect to ECD reduction and reducing potential for weight fluctuations due to barite sag. Based on the data obtained, recommendations were issued to predict ECD levels while drilling and tripping. At the same time, step-by-step action plans were developed for trouble-free drilling. While utilizing this optimized fluid, with close interaction and cooperation between the project Operator (ROSPAN International), the Customer's research and development center, technical support service and the drilling contractor, the first sub-horizontal well on this licensed site has been successfully drilled. The following main actions were developed and executed during the well construction process: Maintained the hydraulic pressure (marginally) above the pore pressure through careful fluid management. The rheological properties of the drilling fluid were maintained to the developed (lab verified) specifications. Careful hydraulic pressure management during tripping. Extensive planning of the tripping operations included increasing the mud weight before tripping to create the necessary margin and optimization of the tripping rate. Ensuring effective drilling parameters and preparing the wellbore for the casing run according to hydraulic calculations. Recommended optimized drilling fluid parameters aimed at preventing barite sag under abnormally high pore pressure and high bottom hole temperatures (up to 110 deg C). Use of specialized pills to assist prevent the loss of circulation and wellbore instability. This article is devoted to the development of drilling fluid solutions and practical techniques for effectively drilling wells in the area with challenging formations. This case study, as well as the lessons learned will be used for ongoing drilling projects in the area.

Undrained compressibility characteristics and pore pressure calculation model of foam-conditioned sand

2021 ◽  
Vol 118 ◽  
pp. 104161
Author(s):  
Haibo Wang ◽  
Shuying Wang ◽  
Jiazheng Zhong ◽  
Tongming Qu ◽  
Zhengri Liu ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Calculation Model ◽  
Pressure Calculation ◽  
Compressibility Characteristics

Analysis of Chemo-Poro-Thermo-Mechanical Effects on Wellbore Strengthening

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Jia Li ◽  
Zhengsong Qiu ◽  
Hanyi Zhong ◽  
Xin Zhao ◽  
Weian Huang
Keyword(s):  
Heat Conduction ◽  
Pore Pressure ◽  
Thermal Convection ◽  
Drilling Fluid ◽  
Solute Concentration ◽  
Fracture Aperture ◽  
Strengthening Effect ◽  
Coupled Models ◽  
Fracture Width ◽  
Wellbore Strengthening

Abstract The application of wellbore strengthening treatment has less effect on shale formations. Several numerical studies were developed to describe the mechanism, which promoted the development of wellbore strengthening theory. Previous studies explored the mechanism mainly by considering the seepage flow. Therefore, multi-field coupled models were established to analyze the solute transmission, thermal convection, and heat conduction on wellbore strengthening by introducing the theory of multi-field coupling into physical model. First, the fracture width distribution and wellbore tangential stress were investigated to research the interaction of thermal and chemical effects with different gradients. Then, the concrete mechanism of temperature and solute concentration gradient was analyzed based on the distribution of pore pressure and stress field. Results show that the prediction of hoop stress and fracture aperture may not be accurate without considering the influence of solute transfer, thermal convection, and heat conduction, because stress state is mainly affected by temperature field and the pore pressure varies greatly under different chemical gradients. Additionally, the lower temperature and larger solute concentration improve the wellbore strengthening effect of drilling fluid.

The Effect of Water Activity in Shale on Wellbore Instability

2012 ◽  
Vol 616-618 ◽  
pp. 970-974
Author(s):  
Tian Tai Li ◽  
Ming Zhang
Keyword(s):  
Water Activity ◽  
Chemical Potential ◽  
Drilling Fluid ◽  
Water Flux ◽  
Wellbore Stability ◽  
Hydraulic Pressure ◽  
Pressure Balance ◽  
Wellbore Instability ◽  
Key Factor ◽  
The Difference

It is accepted that the water flux in/out of the shale during drilling is the key factor, which controls wellbore instability. This flow can be divided into two components:1) the hydraulic flow due to the difference between the wellbore and pore hydraulic pressure; 2) the osmotic flow due to the imbalance between activities of the shale and the drilling fluid. The former can be prevented by adjusting the wellbore hydraulic pressure balance in the well hole, while the latter is much more difficult to control . The water activity of shale is a controlling factor in many areas of drilling. It impacts all situations wherein the temperature or the stress state of a shale is altered such as in wellbore stability, drilling rate and hydraulic fracturing. This chemical “potential activity interaction” produces a mechanical failure due to the movement of water in/out of shales. In order to have no shale alteration, it requires that the chemical potential of each component must be the same in all phases. This is seldom the case. After a lot of studies the shale activity is shown to be a function of pressure and temperature. Results showed inverse relationship between the platelet distance and the shale water activity. This experimental method proves to be a reliable and efficient way for studying the relationships for the shale water activity, comfining pressure, temperature, and platelet distance.

Research on Wellbore Stability in Formation with Anisotropic Strength

2013 ◽  
Vol 765-767 ◽  
pp. 3151-3157
Author(s):  
Hui Zhang ◽  
Fang Jun Ou ◽  
Guo Qing Yin ◽  
Jing Bing Yi ◽  
Fang Yuan ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Rock Body ◽  
Collapse Pressure ◽  
Wellbore Instability ◽  
Transversely Isotropic Rock ◽  
Fracture Development ◽  
Anisotropic Formation ◽  
The Impact

As most of sedimentary rocks are anisotropic, it is significant to research the impact of the anisotropy of strength on wellbore stability in drilling engineering. Particularly, in the Kuqa piedmont exploration area, the anisotropy of strength caused by various jointed surfaces, fracture surfaces and fault planes in formation cause the formation of several groups of weak low-intensity planes traversing borehole . These weak planes will become failure earlier than the rock body in the context of strong stress and high pore pressure, causing chipping, breakouts and sticking. If fractures have good permeability and drilling fluid column pressure is greater than pore pressure, loss may occur. The loss pressure would not be controlled by fracturing pressure and horizontal minimum principal stress, but it depends on the relationship between fracture occurrence and triaxial stress state. In the event of loss, the drilling fluid will flow into these weak structural planes, causing the decrease of friction between rocks and increase of wellbore instability. As a result, for strongly anisotropic formation, the collapse pressure and leakage pressure of weak planes are key factors for evaluating well drilling stability. In this study, according to the stability evaluation on the transversely isotropic rock mechanics in Keshen zone of Kuqa piedmont, the impacts of fracture development on wellbore instability is analyzed; relevant suggestions on engineering geology for the special pressure window in strong anisotropic formation are also put forward.

Study of dynamic pressure on the packer for deep-water perforation

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 215-223
Author(s):  
Hao Huang ◽  
Qiao Deng ◽  
Hui Zhang
Keyword(s):  
Deep Water ◽  
Peak Pressure ◽  
Orthogonal Design ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Calculation Model ◽  
Well Testing ◽  
Technical Problems ◽  
Wellbore Pressure ◽  
Three Dimensional Finite Element

Abstract The packer is one of the most important tools in deep-water perforation combined well testing, and its safety directly determines the success of perforation test operations. The study of dynamic perforating pressure on the packer is one of the key technical problems in the production of deep-water wells. However, there are few studies on the safety of packers with shock loads. In this article, the three-dimensional finite element models of downhole perforation have been established, and a series of numerical simulations are carried out by using orthogonal design. The relationship between the perforating peak pressure on the packer with the factors such as perforating charge quantity, wellbore pressure, perforating explosion volume, formation pressure, and elastic modulus is established. Meanwhile, the database is established based on the results of numerical simulation, and the calculation model of peak pressure on the packer during perforating is obtained by considering the reflection and transmission of shock waves on the packer. The results of this study have been applied in the field case of deep-water well, and the safety optimization program for deep-water downhole perforation safety has been put forward. This study provides important theoretical guidance for the safety of the packer during deep-water perforating.

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.

Application of R/S Rheometer in Low Temperature Drilling Fluid Rheology Determination

2012 ◽  
Vol 490-495 ◽  
pp. 3114-3118
Author(s):  
Xiao Ling Jiang ◽  
Zong Ming Lei ◽  
Kai Wei
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Low Temperature ◽  
High Speed ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Rheological Parameter ◽  
Fluid Temperature ◽  
Fluid Rheology ◽  
Rotary Viscometer

With six-speed rotary viscometer measuring the rheology of drilling fluid at low temperature, during the high-speed process, the drilling fluid temperature is not constant at low temperature, which leads to the inaccuracy in rheological measurement. When R/S rheometer is used cooperating with constant low-temperature box , the temperature remains stable during the process of determining the drilling fluid rheology under low temperature. The R/S rheometer and the six-speed rotational viscometer are both coaxial rotational viscometers, but they work in different ways and the two cylindrical clearance between them are different.How to make two viscometer determination result can maintain consistent?The experimental results show that, The use of R/S rheometer, with the shear rate for 900s-1 shear stress values instead of six speed rotary viscometer shear rate for 1022s-1 shear stress values.Then use two-point formula to calculate rheological parameters.The R/S rheometer rheological parameter variation with temperature has a good linear relationship,Can better reflect the rheological properties of drilling fluids with low temperature changerule

Effect of Drilling Fluid Temperature on Formation Fracture Pressure Gradient

2021 ◽  
Author(s):  
Ahmed Mostafa Samak ◽  
Abdelalim Hashem Elsayed
Keyword(s):  
High Temperature ◽  
Pressure Gradient ◽  
Thermal Effect ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Cooling Effect ◽  
Fluid Temperature ◽  
Lost Circulation ◽  
Fracture Pressure ◽  
Downhole Temperature

Abstract During drilling oil, gas, or geothermal wells, the temperature difference between the formation and the drilling fluid will cause a temperature change around the borehole, which will influence the wellbore stresses. This effect on the stresses tends to cause wellbore instability in high temperature formations, which may lead to some problems such as formation break down, loss of circulation, and untrue kick. In this research, a numerical model is presented to simulate downhole temperature changes during circulation then simulate its effect on fracture pressure gradient based on thermo-poro-elasticity theory. This paper also describes an incident occurred during drilling a well in Gulf of Suez and the observations made during this incident. It also gives an analysis of these observations which led to a reasonable explanation of the cause of this incident. This paper shows that the fracture pressure decreases as the temperature of wellbore decreases, and vice versa. The research results could help in determining the suitable drilling fluid density in high-temperature wells. It also could help in understanding loss and gain phenomena in HT wells which may happen due to thermal effect. The thermal effect should be taken into consideration while preparing wellbore stability studies and choosing mud weight of deep wells, HPHT wells, deep water wells, or wells with depleted zones at high depths because cooling effect reduces the wellbore stresses and effective FG. Understanding and controlling cooling effect could help in controlling the reduction in effective FG and so avoid lost circulation and additional unnecessary casing points.

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