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Boyun Guo - One of the best experts on this subject based on the ideXlab platform.

  • Chapter Three – Mud Pumps
    Applied Drilling Circulation Systems, 2011
    Co-Authors: Boyun Guo
    Abstract:

    Publisher Summary This chapter presents theory and procedures for selecting Mud pumps. The selected Mud pump should be capable of providing Mud Flow Rates that are high enough to transport drill cuttings to the surface at all stages of drilling. Mud properties that influence the type of pump include Mud weight and rheological properties. For Newtonian fluids, viscosity is the only parameter describing fluid rheological characteristics. Plastic viscosity and yield point are the two parameters used to describe the rheological characteristics of Bingham plastic fluids. The minimum required Mud Flow Rate from the Mud pump is equal to the minimum required Mud velocity times the maximum possible cross-sectional area of annular space during drilling. The minimum required Mud Flow Rate demanded by the borehole geometry from the Mud pump is estimated based on the minimum required Mud velocity, which should be higher than the drill cuttings slip velocity. The selected Mud pump should also be capable of providing pressure that is strong enough to overcome the total pressure loss and pressure drop at the bit in the circulating system at the total hole depth.

  • An Innovation in Designing Underbalanced Drilling Flow Rates: A Gas-Liquid Rate Window (GLRW) Approach
    All Days, 2002
    Co-Authors: Boyun Guo, Ali Ghalambor
    Abstract:

    Abstract Underbalanced drilling (UBD) has gained strong momentum in recent years because of a number of advantages of the technology including reduced formation damage and minimized lost circulation. Due to the complex nature of water, oil, gas and solid multiphase Flow in the UBD systems, numerous runs of sophisticated computer programs are required to draw the boundary of the safe gas-liquid Rate envelope. It is highly desirable to have a simple and reliable procedure to perform optimum UBD designs. This paper describes an innovative procedure to delineate the boundary of the safe gas-liquid Rate envelope for UBD Flow Rates. In developing the safe gas-liquid Rate envelope, formation fluid pressure limits the upper bound of the Flowing bottom hole pressure and wellbore collapse pressure serves the lower bound of the circulation-break bottom hole pressure. The envelope is closed with boundaries determined by fluid's cutting carrying capacity and wellbore washout criteria. Detailed procedure for the development of the safe gas-liquid Rate envelope using a spreadsheet program is described in the paper. A successful field UBD case is reviewed and compared with the safe gas-liquid Rate envelope. This work provides drilling engineers and drilling supervisors an easy-to-use approach to designing and modifying gas and liquid injection Rates in UBD. The safe gas-liquid Rate envelope can also be used for evaluating feasibility of UBD under given geological conditions. Introduction The drilling operations where the drilling fluid pressures in the borehole are intentionally maintained to be less than the pore pressure in the formation rock in the open-hole section is called Underbalanced drilling (UBD). The low borehole pressures are achieved by using lightened drilling fluids. The light fluids used in UBD are usually air, gas, foam, and aeRated water. However, un-aeRated oil, water, even weighted Mud can be used for UBD in areas where formation pore pressure gradients are higher than hydrostatic pressure gradient of water. The advantages of UBD include increased penetration Rate, minimized lost circulation, prolonged bit life, minimized differential sticking, improved formation evaluation, reduced formation damage (reduced stimulation requirements), earlier oil production, larger wellbore available to production in offshore, and environmental benefits. The disadvantages of UBD include personnel and equipment safety issues, handling of produced formation fluids, and wellbore damages (washout, collapse, and cuttings accumulation in the borehole). Good designs are the key to the successful UBD operations. Sever wellbore damages and failures can result from poor UBD designs and/or deviation of the actual drilling programs from the original designs. The combination of Mud Flow Rate and gas injection Rate plays a very important role in preventing failure of the UBD. If the combination is chosen such that it gives too high bottom hole pressures, the degree of underbalance is reduced and the benefit of the UBD will be marginal. On the other hand, if the combination is chosen such that it gives too low bottom hole pressures, wellbore damage problem will fail the UBD operation. Currently computer simulators have been used in drilling industry to design liquid and gas injection Rate combinations for UBD. Both steady state and transient simulators are available.1–6 But the procedure is tedious and not transparent. It is difficult to make an optimum UBD design that balances all the aspects. A graphical method with methodology transparency is highly desirable for drilling engineers who are in charge of UBD designs and UBD field supervisions.

  • Balance between Formation Damage and Wellbore Damage: What Is the Controlling Factor in UBD Operations?
    All Days, 2002
    Co-Authors: Boyun Guo
    Abstract:

    Abstract Underbalanced drilling (UBD) has been considered as an effective means of formation damage control during drilling. However, there is a trade-off between formation damage and wellbore damage in UBD. The wellbore damage includes borehole collapse, cave-in and washout associated with the lowered bottom hole pressure. The damaged wellbore results in the increased drilling cost and also brings in completion problems such as poor cement bonding quality and/or cement collar being too thick to be penetRated during perforating job. While the highest bottom hole pressure during normal drilling condition affects the degree of formation damage, the lowest bottom hole pressure during pipe connection controls severity of the wellbore damage. Both the highest bottom hole pressure and the lowest bottom hole pressure are controlled by the combination of the liquid and gas Flow Rates. In order to minimize both the formation damage and wellbore damage problems, it is highly desirable to have an easy-to-use approach to geneRate balanced design of combinations of liquid and gas Flow Rates under given drilling conditions. The content of this paper fills the gap. This paper presents an innovative procedure to approach the optimum design of liquid and gas Flow Rates combinations for UBD under given geological constraints. The optimum Flow Rate combinations are selected from a liquid-gas Rate window. The liquid-gas Rate window is an envelope in the liquid Flow Rate vs. gas Flow Rate plot. In developing the liquid-gas Rate window, formation fluid pressure limits the upper bound of the Flowing bottom hole pressure and wellbore collapse pressure serves the lower bound of the circulation-breaking bottom hole pressure. The window is closed by fluid's cutting carrying capacity and wellbore washout criteria. This paper first time provides drilling engineers with an easy-to-understand procedure to optimize Mud and gas Flow Rates in UBD. Introduction Underbalanced drilling (UBD) is defined as the drilling operations where the drilling fluid pressure in the borehole is less than the pore pressure in the formation rock in the open-hole section. The borehole pressure is intentionally maintained not to balance formation pore fluid pressure by using light drilling fluids. The light fluids used in UBD are usually air, gas, foam, and aeRated water. However, un-aeRated oil, water, even weighted Mud can be used for UBD in areas where formation pore pressure gradients are higher than hydrostatic pressure gradient of water. The increasing coverage of wells being drilled with the UBD is due to many advantages of the technology. These advantages include increased penetration Rate, minimized lost circulation, prolonged bit life, minimized differential sticking, improved formation evaluation, reduced formation damage (reduced stimulation requirements), earlier oil production, larger wellbore available to production in offshore, and environmental benefits. The successfulness of UBD applications relies on good UBD designs. Sever wellbore damages, or failures, due to wellbore collapse and hole-wall caving-in problems can result from poor UBD designs. The combination of Mud Flow Rate and gas injection Rate plays a very import role in balancing the benefit and possible failure of the UBD. If the combination is chosen such that it gives too high bottom hole pressures, the degree of underbalance is reduced and the benefit of the UBD will be marginal. In the other hand, if the combination is chosen such that it gives too low bottom hole pressures, wellbore collapse problem will fail the UBD operation.

  • Computer Simulation Predicts Unfavorable Mud Rate and Optimum Air Injection Rate for AeRated Mud Drilling
    Spe Drilling & Completion, 1996
    Co-Authors: Boyun Guo, Geir Hareland, J.m. Rajtar
    Abstract:

    In certain areas, the use of aeRated Mud as a circulating medium for drilling oil and gas wells is becoming an attractive practice. This is because aeRated drilling has many advantages over conventional Mud drilling, such as a higher penetration Rate, less formation damage, minimized lost circulation, and lower drilling cost. The importance of maintaining adequate air and Mud Flow Rates is generally recognized in aeRated drilling operations. However, it remains unclear to drilling operators as to what constitutes an adequate Flow Rate. On the basis of computer simulation, this paper discusses carrying capacity of an aeRated Mud and the optimum air-injection Rate that ensures a maximum penetration Rate. it is found in this study that the carrying capacity of an aeRated Mud is very different from that of both the conventional Mud and pure air. There is an unfavorable range of Mud Flow Rate that provides lower carrying capacity of the aeRated fluid for a given air injection Rate. As a unique characteristic of multiphase Flow, there exists an air injection Rate that gives the lowest Flowing annulus pressure for a given well geometry and a Mud Rate. By considering both the carrying capacity and Flowing annulus pressure, anmore » optimum combination of Mud and air Rates can be determined. This optimum combination of Flow Rates should ensure a maximum penetration Rate for a given well geometry. This paper provides drilling operators with a means of optimizing aeRated Mud drilling.« less

  • Computer Simulation Predicts Unfavorable Mud Rate and Optimum Air Injection Rate for AeRated Mud Drilling
    SPE Drilling & Completion, 1996
    Co-Authors: Boyun Guo, Geir Hareland, J.m. Rajtar
    Abstract:

    Summary In certain areas, the use of aeRated Mud as a circulating medium for drilling oil and gas wells is becoming an attractive practice. This is because aeRated drilling has many advantages over conventional Mud drilling, such as higher penetration Rate, less formation damage, minimized lost circulation and lower drilling cost. The importance of maintaining adequate air and Mud Flow Rates is generally recognized in aeRated drilling operations. However, it remains unclear to drilling operators as to what constitutes "adequate Flow Rate". Based on computer simulation, this paper discusses carrying capacity of an aeRated Mud and the optimum air injection Rate that ensures a maximum penetration Rate. It is found in this study that the carrying capacity of an aeRated Mud is very different from that of both the conventional Mud and pure air. There is an unfavorable range of Mud Flow Rate which provides lower carrying capacity of the aeRated fluid for a given air injection Rate. As a unique characteristic of multi-phase Flow, there exists an air injection Rate which gives the lowest Flowing annulus pressure for a given well geometry and a Mud Rate. By considering both the carrying capacity and Flowing annulus pressure an optimum combination of Mud and air Rates can be determined. This optimum combination of Flow Rates will ensure a maximum penetration Rate for a given well geometry. This paper provides drilling operators with a means of optimizing aeRated Mud drilling. Introduction Oil and gas drilling activity is currently limited by the affordable operation cost. Improving penetration Rate of drilling has been considered as an effective means of reducing drilling cost. Among n-ny factors affecting the penetration Rate, the overbalance, which is often defined as the pressure differential between the borehole pressure and formation fluid pressure, is generally recognized as the most important one. Formation pressures less than the static pressure of column of fresh water require the use of a lighter fluid, such as air, to be injected with Mud in order to obtain less overbalance or underbalance both for enhancing penetration Rate and for minimizing lost circulation. Therefore, aeRated drilling is becoming an attractive practice in some areas. Many operators have also turned to aeRated drilling as a means of maximizing the productive potential of low-permeability reservoirs. This is because the use of the aeRated Mud minimizes formation damage due to less liquid filtration and particle invasion into the pay zone during drilling. AeRated drilling has been put into use only in recent years. Many problems involved in it need to be solved. Without question, the research devoted to aeRated drilling hydraulics is minuscule when compared to that associated with conventional fluids. This paper is intended to answer three questions related to aeRated Mud drilling:what is the carrying capacity of an aeRated Mud?what annulus pressure do we expect during drilling with an aeRated fluid? andwhat are the optimum Mud and air Rates that assure maximum penetration Rate?

Hadi Fattahi - One of the best experts on this subject based on the ideXlab platform.

  • Bayesian prediction of rotational torque to opeRate horizontal drilling
    Journal of Mining and Environment, 2019
    Co-Authors: Hadi Fattahi, N. Zandy Ilghani
    Abstract:

    Horizontal directional drilling is usually used in drilling engineering. In a variety of conditions, it is necessary to predict the torque required for performing the drilling operation. Nevertheless, there is presently not a convenient method available to accomplish this task. In order to overcome this difficulty, the current work aims at predicting the required rotational torque (RT) to opeRate horizontal directional drilling on the 7 effective parameters including the length of drill string in the borehole (L), axial force on the cutter/bit (P), total angular change of the borehole (KL), radius for the ith reaming operation (Di), rotational speed (rotation per minute) of the bit (N), Mud Flow Rate (W), and Mud viscosity (V). In this paper, we propose an approach based on the model selection criteria such as various statistical performance indices mean squared error (MSE), variance account for (VAF), root mean squared error (RMSE), squared correlation coefficient (R2), and mean absolute percentage error (MAPE) to select the most appropriate model among a set of 20 candidate ones to estimate RT, given a set of observed data. Once the most appropriate model is selected, a Bayesian framework is employed to develop the predictive distributions of RT, and to update them with new project-specific data that significantly reduce the associated predictive uncertainty. Overall, the results obtained indicate that the proposed RT model possesses a satisfactory predictive performance.

  • An Estimation of Required Rotational Torque to OpeRate Horizontal Directional Drilling Using Rock Engineering Systems
    Reaserch Institute of Petroleum Industry, 2018
    Co-Authors: Hadi Fattahi
    Abstract:

    Horizontal directional drilling (HDD) is widely used in soil and rock engineering. In a variety of conditions, it is necessary to estimate the torque required for performing the reaming operation. Nevertheless, there is not presently a convenient method to accomplish this task. In this paper, to overcome this difficulty based on the basic concepts of rock engineering systems (RES), a model for the estimation of rotational torque to opeRate horizontal directional drilling is presented. The newly proposed model involves seven parameters (axial force on the cutter/bit (P), rotational speed (revolutions per minute) of the bit (N), the length of drill string in the borehole (L), the total angular change of the borehole (KL), the radius for the ith reaming operation (Di), the Mud Flow Rate (W), and the Mud viscosity (V)) effective on required rotational torque to opeRate horizontal directional drilling while keeping simplicity as well. The performance of the RES model is compared with multiple regression models. The estimation abilities offered using RES and multiple regression models were presented by using field data given from nine projects. The results indicate that the RES-based model predictor with a higher coefficient of determination (R2), a smaller mean square error (MSE), a lower root mean square error (RMSE), and a lower mean absolute percentage error (MAPE) performs better than the other models.Horizontal directional drilling (HDD) is widely used in soil and rock engineering. In a variety of conditions it is necessary to estimate the torque required for performing the reaming operation. Nevertheless, there is presently not a convenient method to accomplish this task. To overcome this difficult, in this paper, based on the basic concepts of a rock engineering systems (RES), a model for the estimation of rotational torque to opeRate horizontal directional drilling is presented. The newly proposed model involves 7 effective parameters (axial force on the cutter/bit (P), rotational speed (revolutions per minute) of the bit (N), the length of drill string in the borehole (L), the total angular change of the borehole (KL), the radius for the ith reaming operation (Di), the Mud Flow Rate (W) and the Mud viscosity (V)) on required rotational torque to opeRate horizontal directional drilling with keeping simplicity as well. The performance of the RES model is compared with multiple regression models. The estimation abilities offered using RES and multiple regression models were presented by using field data given from nine projects. The results indicate that the RES based model predictor with higher coefficient of determination (R2) and less mean square error (MSE), root mean squared error (RMSE) and mean absolute percentage error (MAPE) performs better than the other models

  • A COMPARISON OF PERFORMANCE OF SEVERAL ARTIFICIAL INTELLIGENCE METHODS FOR ESTIMATION OF REQUIRED ROTATIONAL TORQUE TO OPERate HORIZONTAL DIRECTIONAL DRILLING
    Iran University of Science & Technology, 2017
    Co-Authors: Hadi Fattahi, Zohreh Bayatzadehfard
    Abstract:

    Horizontal Directional Drilling (HDD) is extensively used in geothechnical engineering. In a variety of conditions it is essential to predict the torque required for performing the reaming operation. Nevertheless, there is presently not a convenient method to accomplish this task. To overcome this problem, in this research, the application of computational intelligence methods for data analysis named Support Vector Regression (SVR) optimized by differential evolution algorithm (DE) and Adaptive Neuro-Fuzzy Inference System (ANFIS) to estimate of the required rotational torque to opeRate horizontal directional drilling is demonstRated. Three ANFIS models were implemented, ANFIS–subtractive clustering method (ANFISSCM), ANFIS–grid partitioning (ANFIS-GP) and ANFIS–fuzzy c–means clustering method (ANFIS-FCM). The estimation abilities offered using SVR-DE, ANFIS-FCM, ANFIS-SCM, ANFIS-GP were presented by using field data given in open source literatures. In these models, the rotational torque (M) is used as the output parameter, while the length of drill string in the borehole (L), axial force on the cutter/bit (P), rotational speed (revolutions per minute) of the bit (N), the radius for the i th reaming operation (Di), the Mud Flow Rate (W), the total angular change of the borehole (KL), and the Mud viscosity (V) are the input parameters. To compare the performance of models for rotational torque to opeRate horizontal directional drilling prediction, the coefficient of correlation (R 2 ) and mean square error (MSE) of the models were calculated, indicating the good performance of the ANFIS-SCM model.

J.m. Rajtar - One of the best experts on this subject based on the ideXlab platform.

  • Computer Simulation Predicts Unfavorable Mud Rate and Optimum Air Injection Rate for AeRated Mud Drilling
    Spe Drilling & Completion, 1996
    Co-Authors: Boyun Guo, Geir Hareland, J.m. Rajtar
    Abstract:

    In certain areas, the use of aeRated Mud as a circulating medium for drilling oil and gas wells is becoming an attractive practice. This is because aeRated drilling has many advantages over conventional Mud drilling, such as a higher penetration Rate, less formation damage, minimized lost circulation, and lower drilling cost. The importance of maintaining adequate air and Mud Flow Rates is generally recognized in aeRated drilling operations. However, it remains unclear to drilling operators as to what constitutes an adequate Flow Rate. On the basis of computer simulation, this paper discusses carrying capacity of an aeRated Mud and the optimum air-injection Rate that ensures a maximum penetration Rate. it is found in this study that the carrying capacity of an aeRated Mud is very different from that of both the conventional Mud and pure air. There is an unfavorable range of Mud Flow Rate that provides lower carrying capacity of the aeRated fluid for a given air injection Rate. As a unique characteristic of multiphase Flow, there exists an air injection Rate that gives the lowest Flowing annulus pressure for a given well geometry and a Mud Rate. By considering both the carrying capacity and Flowing annulus pressure, anmore » optimum combination of Mud and air Rates can be determined. This optimum combination of Flow Rates should ensure a maximum penetration Rate for a given well geometry. This paper provides drilling operators with a means of optimizing aeRated Mud drilling.« less

  • Computer Simulation Predicts Unfavorable Mud Rate and Optimum Air Injection Rate for AeRated Mud Drilling
    SPE Drilling & Completion, 1996
    Co-Authors: Boyun Guo, Geir Hareland, J.m. Rajtar
    Abstract:

    Summary In certain areas, the use of aeRated Mud as a circulating medium for drilling oil and gas wells is becoming an attractive practice. This is because aeRated drilling has many advantages over conventional Mud drilling, such as higher penetration Rate, less formation damage, minimized lost circulation and lower drilling cost. The importance of maintaining adequate air and Mud Flow Rates is generally recognized in aeRated drilling operations. However, it remains unclear to drilling operators as to what constitutes "adequate Flow Rate". Based on computer simulation, this paper discusses carrying capacity of an aeRated Mud and the optimum air injection Rate that ensures a maximum penetration Rate. It is found in this study that the carrying capacity of an aeRated Mud is very different from that of both the conventional Mud and pure air. There is an unfavorable range of Mud Flow Rate which provides lower carrying capacity of the aeRated fluid for a given air injection Rate. As a unique characteristic of multi-phase Flow, there exists an air injection Rate which gives the lowest Flowing annulus pressure for a given well geometry and a Mud Rate. By considering both the carrying capacity and Flowing annulus pressure an optimum combination of Mud and air Rates can be determined. This optimum combination of Flow Rates will ensure a maximum penetration Rate for a given well geometry. This paper provides drilling operators with a means of optimizing aeRated Mud drilling. Introduction Oil and gas drilling activity is currently limited by the affordable operation cost. Improving penetration Rate of drilling has been considered as an effective means of reducing drilling cost. Among n-ny factors affecting the penetration Rate, the overbalance, which is often defined as the pressure differential between the borehole pressure and formation fluid pressure, is generally recognized as the most important one. Formation pressures less than the static pressure of column of fresh water require the use of a lighter fluid, such as air, to be injected with Mud in order to obtain less overbalance or underbalance both for enhancing penetration Rate and for minimizing lost circulation. Therefore, aeRated drilling is becoming an attractive practice in some areas. Many operators have also turned to aeRated drilling as a means of maximizing the productive potential of low-permeability reservoirs. This is because the use of the aeRated Mud minimizes formation damage due to less liquid filtration and particle invasion into the pay zone during drilling. AeRated drilling has been put into use only in recent years. Many problems involved in it need to be solved. Without question, the research devoted to aeRated drilling hydraulics is minuscule when compared to that associated with conventional fluids. This paper is intended to answer three questions related to aeRated Mud drilling:what is the carrying capacity of an aeRated Mud?what annulus pressure do we expect during drilling with an aeRated fluid? andwhat are the optimum Mud and air Rates that assure maximum penetration Rate?

  • Volume Requirements for AeRated Mud Drilling
    SPE Drilling & Completion, 1995
    Co-Authors: Boyun Guo, J.m. Rajtar
    Abstract:

    Summary AeRated Mud drilling has been recognized as having many advantages over conventional Mud drilling, such as higher penetration Rate, less formation damage, minimized lost circulation, and lower drilling cost. In some areas, the use of aeRated Mud as a circulating medium for drilling oil and gas wells is becoming an attractive practice. Maintaining an optimum combination of liquid and air Flow Rates is important in aeRated drilling operations. However, most drilling operators are unclear on what constitutes the "optimum combination of the liquid and air Flow Rates." Guo et al. presented a mathematical approach to determining the Flowing bottomhole pressure (BHP) for aeRated Mud drilling. This paper addresses the use of Guo et al.'s mathematical model to determine liquid and air volume requirements considering wellbore stability, pipe sticking, and formation damage as well as the cuttings-carrying capacity of the aeRated Mud. From a formation-damage-prevention point of view, the liquid fraction in the fluid stream should be as low as possible. However, a sufficient Mud Flow Rate is always required to make the hole stable and to maintain the cuttings-carrying capacity of the aeRated Mud without injecting much air volume. This paper provides a simple approach to determining the liquid and air volume requirements for aeRated Mud drilling. Introduction Drilling cost is considered one of the major components of operating cost in the petroleum industry. Improving the penetration Rate of drilling and reducing drilling problems, such as pressure-differential pipe sticking and lost circulation, have long been considered effective ways of decreasing drilling costs. The overbalance pressure, generally recognized as the most important among the many factors affecting penetration Rate, is often defined as the pressure differential between the borehole pressure and formation fluid pressure. Formation pressures lower than the static pressure of a column of fresh water require the use of a lighter fluid, such as air, injected with liquid to obtain lower overbalance pressure to enhance penetration Rate and to minimize lost circulation and pipe sticking as well as formation damage. Therefore, aeRated Mud drilling is becoming an attractive practice in some areas. The commercial use of aeRated Mud drilling began only in recent years. Many of the problems associated with aeRated Mud drilling still have to be solved. One problem is the determination of air and liquid volume requirements. The objective of this paper is to provide a simple approach for determining the optimum combination of liquid and air injection Rates for aeRated Mud drilling operations. AeRated Mud is defined as a fluid consisting of liquid (usually water), air, and drill cuttings. It can be shown that the theories on gas/solid two-phase Flow developed for air and mist drilling and theories on liquid/gas two-phase Flow developed for oil production through tubing are inaccuRate when applied to aeRated Mud Flow in an annular wellbore. Therefore, a mathematical model for describing three-phase (air, water, and cuttings) Flow in a wellbore has been proposed by Guo et al. The modeling was validated by a comparison with field data obtained from aeRated Mud drilling. This paper uses the developed model to determine the liquid and air volume requirements considering cuttings-carrying capacity of the aeRated Mud, wellbore stability, pressure-differential pipe sticking, and formation damage.

  • Volume requirements for aeRated Mud drilling
    Spe Drilling & Completion, 1995
    Co-Authors: Boyun Guo, J.m. Rajtar
    Abstract:

    AeRated Mud drilling has been recognized as having many advantages over conventional Mud drilling, such ass higher penetration Rate, less formation damage, minimized lost circulation, and lower drilling cost. In some areas, the use of aeRated Mud as a circulating medium for drilling oil and gas wells is becoming an attractive practice. Maintaining an optimum combination of liquid and air Flow Rates is important in aeRated drilling operations. However, most drilling operators are unclear on what constitutes the ``optimum combination of the liquid and air Flow Rates.`` Guo et al. presented a mathematical approach to determining the Flowing bottomhole pressure (BHP) for aeRated Mud drilling. This paper addresses the use of Guo et al.`s mathematical model to determine liquid and air volume requirements considering wellbore stability, pipe sticking, and formation damage as well as the cuttings-carry capacity of the aeRated Mud. For a formation-damage-prevention point of view, the liquid fraction in the fluid stream should e as low as possible. However, a sufficient Mud Flow Rate is always required to make the hole stable and to maintain the cuttings-carrying capacity of the aeRated Mud without injecting much air volume. This paper provides a simple approach to determining the liquid andmore » air volume requirements for aeRated Mud drilling.« less

Rolv Rommetveit - One of the best experts on this subject based on the ideXlab platform.

  • A Drilling Well as Viscometer: Studying the Effects of Well Pressure and Temperature on the Rheology of the Drilling Fluids
    All Days, 1996
    Co-Authors: Roberto Maglione, Germana Gallino, Giovanni Robotti, Raffaele Romagnoli, Rolv Rommetveit
    Abstract:

    Abstract The current need of drilling ultradeep wells involves facing new technical problems, especially concerning the effects of high pressure and temperature values. When acting along all the vertical profile of the well, the pressure and temperature effects heavily influence the rheology of the drilling fluids. Some of the main drilling parameters which are involved are cutting lifting and hole cleaning efficiencies (resulting both from the variation of the velocity profile of the fluid Flow, and from the variation of the rheological parameters), and - of course - the pressure spatial distribution along the well profile. In order to characterise the real influence of pressure and temperature upon the rheology of the drilling fluids, circulation tests were performed and repeated at different depths inside cased hole (9 5/8" csg at 2973 m) with the 8 1/2" bit off bottom, while making trip (e. g. for the drilling out task of the casing shoe). Complete sets of data are available of circulation tests performed at 2400 m, 1400 m, 800 m and 198 m of the bit depth (while making the POOH trip), obtained by recording the Mud Flow Rate and the corresponding stand pipe pressure (SPP) values. By developing an original numerical procedure able to determine the equivalent rheological tern (n, k and o of any drilling fluid Flowing in the well) which fits the observed SPP data in the best way, it has been possible to characterise the rheological curves corresponding to the different testing depths. The processed rheological outputs are finally analysed and matched, pointing out the effects of pressure P and temperature T. The outcoming effects can be remarked with respect to the equivalent viscosity of the considered drilling fluids and to some of the main practical drilling parameters, such as the velocity profile and the pressure spatial distribution along the well profile. Qualitative trends of the field rheological data versus depth have been compared with the results of laboratory studies performed with an Huxley & Bertram HPHT rheometer with OBM systems. Some interesting analogies have been found with the two different approaches and the changes of the rheological parameters vs depth have been discussed also with reference to the Mud structure sensitivity to P and T. Introduction The rheological properties of drilling Muds under downhole conditions may be very different from those measured at ambient pressures and temperatures at the surface. High temperatures and pressures can influence the rheological properties of the drilling fluids in several way:–Physically: decreases in temperature and increases in pressure both affect the mobility of the systems and lead to an increase of apparent viscosities and viscoelastic relaxation times. The effect of pressure is expected to be greater with oil based systems owing to the oil phase compressibility.–Electrochemically: an increase in temperature augments the ionic activity of any electrolyte, and the solubility of any partially soluble salt that may be present in the Mud. This could alter the balance between the interparticle attractive and repulsive forces and so the degree of dispersion and flocculation of the Mud systems. Sometimes, this can also deeply affect the emulsion stability of oil based Muds. All these phenomena have a profound impact on rheological properties, especially as far as viscoelasticity and thixotropy are concerned.–Chemically: all hydroxides react with clay minerals at temperatures above 90 C. With many kinds of Muds, this can result in a change of the structure and therefore also in a change of the Mud rheological properties, Because of the large number of variables involved, the behaviour of drilling Muds at high temperatures and pressures may be very complicated so that it can be very difficult to get general guidelines for each group of Muds (water base Muds, oil base Muds, etc.) or even for the same type of Mud (little differences in the composition can result in considerable differences in the rheological behaviour). P. 115

  • Optimisation of the Return Gas Distribution During Kicks in Oil- and Water-Based Muds: Results From Full-Scale Kick Experiment
    All Days, 1993
    Co-Authors: Rolv Rommetveit, Frank Hovland, T.l. Olsen
    Abstract:

    SPE Members *Now with Petec A/S **Now with Baker Hughes INTEQ Abstract A number of gas kick experiments have been performed in a 2000 m long, 60 inclined research well. During the experiments a several of parameters were varied, such as Mud density, Mud type, gas concentration, and control Rate of the kick. The well was heavily instrumented during the experiments, both downhole and surface. The gas distribution at start of the kick has been computed, and compared to the gas distribution out of the well which was calculated based on, measurements of the mixture density through the choke line, choke pressure and pit gain. This was done for the majority of the 24 kicks which were performed. The effect of Mud density and solubility on the return distribution has been analysed. Effects of operational procedures during the kicks have been analysed as well (circulation Rates and duration of close-in). The work shows that the return gas Rate and gas distribution depends on the following variable; the initial gas distribution, Mud type (OBM or WBM), and operational history of the kick. Optimal operational control procedures which will create the most favourable return gas distribution are recommended. Introduction Gas kicks occur seldom during drilling operations. However, for exploration drilling the kick frequency is higher than the average, and for some special wells (like high pressure, high temperature wells in the Central Graben area of the North Sea) the frequency of kicks is extremely high (approx. 2 per well). The main reason for (his is the small difference between the pore pressure and the fracture pressure, in combination with the extreme conditions which makes the control of the well pressure more difficult than in "normal" wells. Kick incidents are generally poorly documented, and the data usually consist of pit volume, shut-in pressures and choke and pump pressure. The initial influx distribution is not logged, only the volume (pit gain). The return gas distribution is not logged either. So data on how the gas distribution change from kick start to end, and how operational factors influence this have been non-existent. In the DEA-E-9 project, 24 gas kick experiments were performed, and data from a number of surface and downhole sensors were logged [1]. The data from the experiments have been extensively analysed [2, 3]. This paper summarize the analysis of the gas distribution for the experiments. GAS KICK EXPERIMENTS In the gas kick experiments performed in the DEA-E-9 project, a number of data was logged. The gas was injected through a coiled tubing which was run into the drill string down to the bit. An overview of the kick experiments is given in Appendix B. The experiments were performed in a 2020 m long research well with a maximum inclination of 63. Nitrogen and Argon gas was injected, and parameters such as Mud type, Mud density, gas concentration, Mud Flow Rate, gas injection depth etc. was varied. Details of the experiments and the analysis of the data have been documented. GAS INFlow Rate Knowledge of the gas FlowRate into the well is essential to perform a detailed analysis of the kicks. The complete equation for the gas Flow into the well is: (1) P. 481^

  • Analysis of Gas-Rise Velocities From Full-Scale Kick Experiments
    All Days, 1992
    Co-Authors: Frank Hovland, Rolv Rommetveit
    Abstract:

    SPE Members Abstract Gas kick experiments in oil- and water-based Mud have been studied in a full scale inclined research well. One of the main objectives from these experiments has been the study of gas rise velocities. In order to analyse the gas velocities, the parameters varying during a real drilling operation have been systemized and gathered in a data base. The work represents a significant extension to existing correlations for gas/liquid Flows in a full scale inclined annulus with real drilling Muds. In high concentration gas kicks the gas rises faster than in low and medium concentration kicks, this is observed for both oil and water based Mud. The rise velocity correlations obtained from these experiments is not significantly dependent on gas void fraction, Mud density, inclination, Mud rheology, and surface tension. The results are quite different from other previously reported correlations, and this has a major implication on kick simulations. Introduction In October 1988, 24 full scale gas kick experiments were performed at Ullrigg in Stavanger by Rogaland Research. The experiments were carried out in a 2020 m long research well with a maximum inclination of 63 degrees. To simulate the gas entry during the gas kicks, Nitrogen and Argon gas was injected through a coiled tubing placed inside the drill string. Data from 19 downhole and surface sensors were collected in order to study the development and control phase of the kicks. In the experiments parameters such as Mud type, Mud density, gas concentration, Mud Flow Rate, gas injection depth, etc. was varied, and large quantities of data were collected. One of the main objectives from the gas kick experiments was to study the kick process, and how the gas is transported up the well. Data from the downhole and surface sensors, Mud and gas properties, Flow geometry, and Dow conditions have been systemized in a data base in order to study how these parameters affect the gas rise velocities. A key factor in the development of a gas kick is the Rate which free gas rises up the wellbore. Previously published data are mainly limited to experiments performed at laboratory scale, with Newtonian fluids (usually water and air), and pipe geometry's. The practical results of these experiments are limited. Full scale kick experiments with such extensive instrumentation have not been reported elsewhere, and the experiments performed at Ullrigg give the possibility of analysing data gathered under realistic conditions. Comparison between high concentration kicks in water- and oil-based Mud, and low and medium concentration kicks in oil-based Mud are presented. Two phase Flow in vertical and inclined annuli Much of the literature on two-phase Flow is experimental and mainly based on Flow in small pipes or annuli. P. 331^

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  • study of Mud weight window of horizontal wells drilled into offshore natural gas hydRate sediments
    Journal of Natural Gas Science and Engineering, 2020
    Co-Authors: Wenlong Li, Jin Yang
    Abstract:

    Abstract Drilling horizontal wells into natural gas hydRate (NGH) sediments may be one of the most promising methods to increase the cost effectiveness of the exploration of NGH. However, many challenges, such as wellbore collapse and wellbore fracturing, will be encountered. Therefore, an accuRate prediction of the Mud weight window (MWW) is very important. In this work, a model was built to calculate the MWW of horizontal wells drilled into offshore NGH sediments, considering the NGH saturation and the effects of inlet parameters of the drilling Mud, and was combined with the transient heat transfer model to calculate the temperature distribution of the borehole. A case study was carried out, and the effects of several parameters were discussed: 1) When drilling horizontal wells in NGH sediments, the dissociation of NGH in the formation will not occur. 2) With increasing circulation time, the borehole will be cooled, and the cooling effect will lead to a decrease in both the fracture pressure and collapse pressure of the target zone. 3) The Mud Flow Rate has a large influence on the Mud temperature profile, especially in the horizontal section, and a higher Mud Flow Rate leads to a lower fracture pressure and collapse pressure in the target zone. 4) The inlet temperature has limited influences on the Mud temperature profile in the horizontal section and the MWW of the target zone. 5) The saturation of NGH in a formation has a significant influence on the collapse pressure but little influence on the fracture pressure, and higher saturation will lead to a wider MWW. This study will support the safe control of well stability and application of horizontal wells drilled into offshore NGH sediments.