Mud Flow Rate Research Articles

Rheological behavior of a bentonite mud

Abstract Predicting drilling fluids rheology is crucial to control/optimize the drilling process and the gas extraction from drilling fluids in logging systems. A Couette viscometer measured the apparent viscosity of a bentonite mud at various shear rates and temperatures. The bentonite mud behaved as a yield-pseudoplastic fluid, and a modified Herschel-Bulkley model predicted the shear rate and temperature effects upon the shear stress. A pipe viscometer was built to seek a correlation between the mud flow rate and the pressure drop and thereby determine refined Herschel-Bulkley parameters. Coupling a rheological model to a pipe viscometer enables the continuous acquisition of apparent viscosities of Newtonian or non-Newtonian fluids at a rig-site surface.

Optimization of the Gas-Extraction Process in a New Mud-Logging System

SummaryAn advanced gas analysis heated system (AGAHS) analyzes the gas extracted from a water-based mud (WBM) to estimate the hydrocarbons contents in drilled rock formations. Operating conditions within the gas-extraction device (gas trap) such as the gas concentration in the mud, stirring velocity, mud-flow rate and temperature, and ditch-line flow rate and pressure are studied to maximize the gas-extraction efficiency in the gas trap. The operating conditions that most affect the gas-extraction efficiency are the stirring velocity and the mud-flow rate. The highest and most stable gas-extraction efficiencies are obtained at 1,680 rev/min and 1.0 L/min.

Development and testing of a mathematical model of the permafrost thawing processes during drilling of wells

A mathematical model conjugate heat exchange of the well consideration phase transitions and drilling fluid circulation during to drilling was developed. The method was tested on the experimental data. Good agreement with the experiment was shown. The calculation of the permafrost thaw around the well during drilling was carried out. Dependences of the thaw radius on the flow rate and properties of the drilling mud were obtained.

Bayesian prediction of rotational torque to operate horizontal drilling

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.

High pressure measurement of mud density and flow rate for oil and gas well construction: Making the case for X-Ray metering

Abstract With a myriad of flow and density sensors available, it can be difficult to decide on the right metering technology to make density and mass flow rate measurements, that suits both application and cost requirements. Operational specifications listed in product brochures typically apply to tests done under highly controlled conditions and generally fail to account for the extreme variability in flow conditions of drilling and completions fluids in the real world. Thus, time and other resources can be wasted by the end users in trying to validate the various meters. Even when right metering technology is selected the measured values often have low accuracy and low measurement frequency. The intent of this paper is to provide a high level overview of the working principles of some of the mainstream metering technologies, identify applications they are well suited for, clarify their limitations, and provide an overview into current research to address these limitations. The paper will allow the reader to narrow down options for appropriate density and flow metering solutions for particular applications, and at the same time highlight the gaps and needs that need to be addressed by further research and development. The paper also discusses an X-ray based metering technology that overcomes some of the disadvantages and deficiencies of established meters. Recent work on characterizing the drilling fluid density and flow rate at the high pressure well inlet using X-rays has shown that these measurements can now be made with greater than 99% accuracy and at 1 Hz measurement frequency. Such level of accuracy and measurement frequency is not offered by any of the mainstream metering technologies. It is expected that the X-ray based technology when implemented will lead to a step-change improvement in current density and delta flow (flow in – flow out) assessment, and will thereby positively contribute to improved hydraulics management, better and earlier kick detection, and further enhanced managed pressure drilling control. In this paper we build upon the existing work on X-ray based density and flow rate measurements of drilling fluids. Specifically, we discuss preliminary work towards development of a new flow measurement technique which can measure flow rate using an X-ray flat panel detector. Using a flat panel detector offers a cheaper alternative to the existing high speed imaging based flow measurement methods. We also share results from a method developed for real-time calibration of the X-ray detectors. Using the calibration method X-ray measurements are shown to have a repeatability of greater than 99%. A section is also dedicated to characterizing the intensity output from the X-ray source. Finally, we show that X-ray density measurements conducted with static fluids in existing literature remain unaffected when the same density fluid flows through a pipe.

Three-dimensional hydro-mechanical model of borehole in fractured rock mass using discrete element method

Borehole stability, in heavily fractured rock mass has been a significant issue in deep earth resources exploration and extraction. In this study, a three-dimensional model using 3DEC is developed to simulate a borehole drilled in fractured rock mass. A model with overbalanced drilling conditions is simulated in this study. In doing so, different depths of a borehole, MB-1 borehole, in Northern Perth basin was simulated. The developed model was validated against log measurements of Caliper log and strength of rock is found as a governing factor in controlling the stability. Then, hydro mechanical modelling was carried out and it was observed that high mud flow rates and high pore pressure increased the instability around borehole. Furthermore, a parametric study was performed to investigate the influence of viscosity and fluid flow on the stability. Shear displacement linearly increase with an increase in flow rate while fluid pressure decreases due to increase in fractures aperture with an increase in flow rate. Similarly, increase in viscosity caused increase in fracture shearing and therefore instability around borehole.

The formation and broken of cuttings bed during reaming process in horizontal directional drilling

Horizontal Directional Drilling (HDD) is an environment-friendly and high efficient method for underground utilities and pipelines crossing. The formation of cuttings bed, due to low Cuttings Transport Performance (CTP) in large-size HDD, has resulted in the overwear of reamer and been required additional borehole cleanups which will result in high construction risk and extending the work period. In order to investigate the formation and broken mechanism of cuttings bed, two tests were designed to determine the potential effect of mud rheological properties, flow rate, borehole inclination and rotation of drill rod on the cuttings bed state. The drill rod laid down at the invert of the borehole, broke the stability state of cuttings bed and take some cuttings away from the cuttings bed, which causes an incremental trend of CTP, even for the cuttings bed consisting of 8–12 mm diameter cuttings. The observations and results of the tests indicated that drill rod rotation had a positive impact on the instability of cuttings bed, whereas, YP of mud, average velocity of mud and borehole inclined shown a limited effect on it for the large-scale HDD reaming. Further study is needed to determine the details about drill rod behavior and extend the tests results by the finite element method.

Challenges and Lessons of Implementing a Real-Time Drilling Advisory System

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 187447, “Challenges and Lessons From Implementing a Real-Time Drilling Advisory System,” by Benjamin J. Spivey, SPE, Gregory S. Payette, SPE, and Lei Wang, SPE, ExxonMobil Upstream Research Company; Jeffrey R. Bailey, SPE, ExxonMobil Development Company; Derek Sanderson, XTO Energy; and Stephen W. Lai, SPE, Behtash Charkhand, SPE, and Aaron Eddy, SPE, Pason Systems, prepared for the 2017 SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, 9–11 October. The paper has not been peer reviewed. This paper discusses the technical challenges related to implementing a rigsite, real-time drilling advisory system and current solutions to these challenges. The system uses a data-driven response-surface model based on physics-based calculations to optimize rate of penetration (ROP) while minimizing drilling-vibration dysfunction with regard to lateral (whirl) and torsional (stick/slip) vibrational modes. Minimizing these vibrations is important to mitigate bit damage that can lead to reduced ROP and increased bit trips. Technical Overview The system is a rigsite software application that should be deployed in view of the driller. Fig. 1 shows a driller-cabin deployment. The software contains capabilities for real-time surface drilling-data acquisition, drilling-performance estimation, vibration analysis, surface trends for drilling performance, and drill- off-test guidance for drilling optimization. The system primarily serves as an open-loop advisory tool but retains capabilities for closed-loop autodriller and topdrive control. The user interface provides the rigsite personnel with drilling-performance surface trends (e.g., ROP, drilling efficiency, and stick/slip vibration), bit aggressiveness and depth-of-cut (DOC) calculations, and drilling-parameter set-point recommendations on the basis of the surface trends. Data Input and Output. The system operates on 1-second data provided from the electronic data-recording equipment. Input data consist of data channels included among standard or spare Well Information Transfer Specification (WITS) Record 1 items—block height, weight on bit (WOB), rotary speed, mud-flow rate, hole depth, bit depth, torque, and differential pressure. Drilling-Performance Estimation. The system filters and preprocesses the raw WITS Record 1 data to calculate the drilling performance variables: ROP, surface mechanical specific energy (MSE), motor MSE, DOC divided by WOB, torsional-severity estimate (TSE), bit aggressiveness, and DOC. Performance Averaging and Modeling. The measures of drilling performance, primarily the ROP, drilling efficiency, and stick/slip indicator, are averaged over depth drilled to produce a mean or median value referred to as a “response point.” A clustering algorithm groups these response points in the 2D drilling-parameter space. The response-point groups, or “calibration points,” serve as estimates of the drilling set points to measure whether the drilling-parameter space is explored sufficiently to produce an accurate response-surface model. Optimization. An objective function merges the response surfaces of multiple performance objectives into a single objective surface. This objective function makes a tradeoff between the ROP, drilling efficiency, and stick/slip terms.

Enhancing the Lifting Capacity of Drilling Fluids in Vertical Oil Wells

Of the many functions that are performed by the drilling fluid, the most important is to transport cuttings from the bit up the annulus to the surface. Various drilling fluid have been widely used in the oil industry to improve lifting capacity. In this study, three mud type have been used which they are, oil base mud, X-anthan polymer and a mixture of CMC and bentonite ,by using Carrying Capacity Index calculation (CCI) , the Xanthan gave good values of CCI than other studied drilling fluid. By using Sifferman chart and field data from well in south of Iraq and API equation to find cutting concentration in the annulus, The results showed that the used of thick mud increase the lifting capacity and decrease volumetric drill cuttings in the annulus but the using thin mud lead to decrease lifting capacity and increase volumetric drill cuttings in the annulus .The results show that the mud viscosity and flow rate have important role in hole cleaning. Also, the effect of annulus velocity and flow pattern on cutting transport ratio is studied by using field data. The effect of cutting size and OD of drill pipe is also studied. Cutting size is one of the parameters that influence the hole cleaning; large size cutting makes the hole cleaning more difficult. The reducing of annular size of hole by increasing the OD of drill pipe lead to increasing the annular velocity.

Effect of Drilling Mud Density and Flow Rate on Tri-Cone Bit Pressure Drop

In this study, non Newtonian turbulent flow simulation was obtained through a drill bit to show the effect of flow rate, drilling mud density, and nozzle size on the tri-cone bit pressure drop calculations. Nozzle sizes of 7/32, 9/32, 10/32, and 11/32 inch were selected, and three nozzles of equal size were used in each solution. Eight drilling mud was selected and Herschel-Bulkley rheological model employed. Rheological data were obtained using a Fann viscometer. The calculated pressure drops from simulations were compared to experimental data. The results show that flow simulation model has the good prediction of pressure drop with a percent error of 7.67. The results indicate pressure drop increase as the nozzle size decreases, while the flow rate and drilling mud density increases.

Robust gain switching control of constant bottomhole pressure drilling

Automation of managed pressure drilling is crucial in order to enhance safety. This process is highly nonlinear and the system varies considerably with changes in drilling conditions. In this work we have analyzed the effect of various operating conditions on plant parameters and designed a controller which will deliver consistent performance for different working conditions and will also be robustly stable. The control objectives of robustness and good performance are achieved by using multiple robust loop shaping controllers. Based on choke opening and mud flow rate, an appropriate controller is selected by utilizing a gain schedule. An observer for estimation of the reservoir pressure is also implemented so that an appropriate bottom hole pressure setpoint can be selected to maintain overbalanced conditions.

Simulation of Heave-Induced Pressure Oscillations in Herschel-Bulkley Muds

Summary Heave induces pressure oscillations when drilling offshore from floating rigs. A time-domain model is proposed to analyze and predict such pressure oscillations. The model considers the coupled dynamics of the mud and the drillstring, Herschel-Bulkley-type rheology, and realistic geometries. A computationally efficient method to evaluate friction as a nonlinear function of the mud-flow rate and drillstring velocity is discussed. In a simulation study, we illustrate several nonlinear phenomena that have important practical implications but were not included in previous, simpler models. In particular, muds with a yield point can increase the pressure amplitudes significantly, and severe downhole-pressure oscillations are not detectable from topside measurements in many cases.

Use of machine learning and data analytics to increase drilling efficiency for nearby wells

Data-driven models can be used as an efficient proxy to model complex concepts in engineering. It is common engineering practice to optimize some controllable input parameters in a model to increase efficiency of operations. Machine Learning can be used to predict the rate of penetration (ROP) during drilling to a great accuracy as shown by Hegde, Wallace, and Gray (2015). This paper illustrates the use of machine learning to predict and increase ROP effectively. The machine learning model is first used to predict ROP – with input parameters such as weight on bit (WOB), rotations per minute of the drill bit (RPM), and flow rate of the drilling mud. The input parameters are then modified to increase ROP. This process has been applied to field drilling data from a vertical well consisting of different rocks and formations. The procedure can be used to determine the maximum achievable ROP in each formation, and map out operational guidelines for drilling of pad wells. A post drilling analysis can be conducted for pad wells to cut costs and save time while drilling. This model is very innovative because only surface measured parameters are used, without a priori requirements for geological, laboratory, or drilling data.

Research on Mud Flow Rate Measurement Method Based on Continuous Doppler Ultrasonic Wave

In deep-water drilling processes, the flow rate of drilling mud inside an annular pipe is significant judgment data for early kick detection. On the basis of the continuous-wave Doppler ultrasound, this paper proposes a new detection method of nonoriented continuous-wave Doppler ultrasound. The method solves the problem of the ultrasound having great attenuation in mud and not receiving effective signals by using a continuous ultrasound. Moreover, this method analyzes the nonoriented characteristics of ultrasound reflection on principle and proposes the detection of ultrasound Doppler frequency shift by detecting Lamb wave, which releases the detection of oil-based mud flow rate in a nonintrusive annular pipe. The feasibility of the method is verified through theoretical analysis and numerous experiments on a gas kick simulation platform. The measurement result has reached a flow accuracy approximating to the intrusive flow meter.

Analysis of Wellbore Drilling Hydraulics Applying a Transient Godunov Scheme Considering Variations of Injected Flow Rates

A new application of the Godunov scheme to describe dynamic oil-well behavior is presented. The numerical model is able to capture discontinuities associated with surface flow-rate variations. The finite volume method and Riemann problems are utilized for building the unsteady discrete solution. Initial and boundary conditions are related to cases of static, steady and transient well condition. Well data used in simulation are taken from true operational conditions and well mechanical configuration. The results of Godunov’s modeling describe the behavior of transient pressure and transient flow rate inside drill pipe and annulus. These profiles are commonly caused by turning on, adjusting mud flow rate and turning off the rig pumps. The evaluated rig indicators are: back pressure, pumping pressure, bottomhole pressure and injected flow rate. Calculated transient profiles are physically consistent and in good agreement with published well data. Therefore, engineering contribution is the application of first-order Godunov method to evaluate the transient hydraulics whereas variations of mud flow rate; also, the analysis and interpretation of the dynamic pressure behavior travelling inside the well. The Godunov scheme has robust engineering applications for modeling the transient drilling hydraulics, e.g., managed pressure drilling, hydraulics of pipe connections, and foam cementing, as well.

PDC Bit Hydraulic & Mud Rheological simulation to model pressure drop across Bit

During fluid flow from larger to smaller diameter pipes, a drop in pressure is experienced. High pressure drop across bit indicated high energy loss in the hydraulic system and also a setback to ROP performance. This is inefficient and pressure pumps would have to be of bigger sizing to make up for the losses. Present form of pressure drop models is in terms of mud density, flow rate, and total flow area. The objective of this paper is focused on the analysis of CFD simulation and to propose optimized parameters for improved ROP. Single phase flow study of Yield Power Law mud rheology was simulated at bottom hole of horizontal section. Parametric study on mud rheology was carried using DOE. Design points of DOE were sampled mostly using Latin Hypercube Sampling and a few by Central Composite Design. It is found that Kriging Response Surface method generated the best regression model where the predicted values are closest to the observed values and has the lowest Maximum Relative Residual (0.000336%). Inlet velocity and Power Index have significant effect on pressure drop. Consistency Index showed moderate effect while Yield Stress showed small effect to pressure drop. This research has proven that pressure loss model should take into account of mud rheology. Further research can be done with PDC bit rotation and its effect on mud behaviour.

Influence of the Technological Gap Value of the Tool-Joint Tapered Thread on the Drilling Mud Flow Rate in Its Screw Coupling

Influence of the Technological Gap Value of the Tool-Joint Tapered Thread on the Drilling Mud Flow Rate in Its Screw Coupling

Estimation of lost circulation amount occurs during under balanced drilling using drilling data and neural network

Lost circulation can cause an increase in time and cost of operation. Pipe sticking, formation damage and uncontrolled flow of oil and gas may be consequences of lost circulation. Dealing with this problem is a key factor to conduct a successful drilling operation. Estimation of lost circulation amount is necessary to find a solution. Lost circulation is influenced by different parameters such as mud weight, pump pressure, depth etc. Mud weight, pump pressure and flow rate of mud should be designed to prevent induced fractures and have the least amount of lost circulation. Artificial neural network is useful to find the relations of parameters with lost circulation. Genetic algorithm is applied on the achieved relations to determine the optimum mud weight, pump pressure, and flow rate. In an Iranian oil field, daily drilling reports of wells which are drilled using UBD technique are studied. Asmari formation is the most important oil reservoir of the studied field and UBD is used only in this interval. Three wells with the most, moderate and without lost circulation are chosen. In this article, the effect of mud weight, depth, pump pressure and flow rate of pump on lost circulation in UBD of Asmari formation in one of the Southwest Iranian fields is studied using drilling data and artificial neural network. In addition, the amount of lost circulation is predicted precisely with respect to two of the studied parameters using the presented correlations and the optimum mud weight, pump pressure and flow rate are calculated to minimize the lost circulation amount.

Engineered Shale Completions Based on Common Drilling Data

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 174839, “Engineered Shale Completions Based on Common Drilling Data,” by W.D. Logan, C&J Energy Services, prepared for the 2015 SPE Annual Technical Conference and Exhibition, Houston, 28–30 September. The paper has not been peer reviewed. Current best practices in North America’s shale basins deliver inconsistent production results because of a lack of reservoir understanding along the lateral. Reservoir data is difficult and expensive to obtain in horizontal sections; therefore, most completions are designed geometrically, with little or no concern for reservoir heterogeneity. In this study, the authors demonstrate a reliable, cost-effective methodology that empowers shale operators with reservoir data on every well. Introduction The industry needs a reliable, low-cost reservoir-evaluation methodology that can be leveraged to deliver an engineered completion on every lateral. Such a technique would make engineered completions part of the factory approach on every lateral completed. The solution described in the complete paper starts with data that already exist on every lateral. Current drilling practices include use of an electronic drilling recorder that collects data such as weight on bit (WOB), torque (TOR), rotational speed (RPM), rate of penetration (ROP), mud-flow rate (Q), standpipe pressure (SPP), and differential pressure (DIFP) on every well. The completions department can leverage these data to drive superior well productivity through a drilling parameter known as mechanical specific energy (MSE). Adapting MSE for Reservoir Evaluation The completions department can take advantage of MSE by recognizing the close relationship between it and unconfined compressive strength (UCS). MSE can be used as a qualitative predictor of UCS within each fracturing stage. By calculating MSE from drilling data (a process discussed in the complete paper), one can then predict zones of comparable UCS within each stage. This will enable placement of perforation clusters in zones of similar UCS within each stage, which is exactly what many completions departments are attempting to do with wireline measurements.

Study on open-hole extended-reach limit model analysis for horizontal drilling in shales

The published extended-reach well (ERW) limit theory can be used to predict how far the horizontal ERW can extend. However, the use of this theory in shale formation remains poorly understood. Therefore, an open-hole extended-reach limit model of horizontal drilling in shales must be established based on the published ERW limit theory and models. First, the published models are modified for convenient practical calculation, and the core of this modified model is to predict the horizontal-section limit of horizontal ERW. The horizontal-section limit and the final open-hole extended-reach limit primarily depend on the annular pressure drop and fracture pressure in shales. Secondly, the characteristic of shale hydration swelling is considered. The stress state of the wellbore wall changes when the hydration stress is treated as a part of the effective stress. Moreover, the hydration stress can also significantly affect the horizontal-section limit and final open-hole extended-reach limit. In addition, a case study is performed, and the results indicate that the horizontal-section limit is 7292 m when there is no hydration stress, whereas it decreases by several thousand meters if the hydration swelling effect is considered. Finally, through the sensitivity analysis of the main factors in the modified model, the following results are obtained: the longer horizontal-section limit can be achieved in conditions with smaller flow behavior index, lower mud density, smaller mud flow rate, and lower temperature; meanwhile, a reasonable eccentricity range is also necessary, which is approximately 30–35 mm in this paper. The model in this paper provides a theoretical guidance for the optimization design method and operating parameters of horizontal ERW in shales to achieve a longer horizontal-section limit, which is significant for the use of shale gas.