Cuttings Transport Research Articles

Cuttings Transport with Foam in Highly Inclined Wells at Simulated Downhole Conditions / Transport urobku wiertniczego przy użyciu piany w silnie nachylonych otworach w symulowanych warunkach w otworze

Along with the rapidly growing demand and development activities in unconventional resources, is the growth of environmental awareness and concerns among the public. Foam, as an alternative to traditional drilling fluid, is gaining more and more momentum in the drilling industry. Drilling with foam can minimize formation damage, water usage, and drag and torque. Foam also costs less and leaves a much smaller environmental footprint than other commonly used drilling fluids, such as synthetic oil-based fluids, when developing vulnerable formations such as shale gas. As drilling in horizontal and near horizontal sections has become very common, and the need for such sections is increasing, it is very important to understand cuttings transport and hole cleaning issues when drilling with foam in such sections. A team from University of Tulsa Drilling Research Projects (TUDRP) conducted a series of experiments focused on studying the effects of change in hole inclination angle from 90 degrees to 70 degrees on cuttings transport with foam under Elevated Pressure and Elevated Temperature (EPET) conditions. This experimental and theoretical study also includes other influential parameters such as foam quality, foam flow rate, polymer concentration and drill pipe rotary speed. We have observed that there is no significant difference in cuttings concentration and frictional pressure losses as inclination changes from 70 to 90 degrees. Also, an increase in superficial foam velocity reduces cuttings concentration within the annulus. Pipe rotation influences cuttings concentration and frictional pressure losses for low quality foams, but does not have a significant effect on high quality foams. A correlation for the cuttings bed area and a computer simulator are developed for practical design and field applications. The predicted results are compared with experimental results from this study and previous studies. The comparison shows good agreement. We believe that the findings of this paper will help designers with the choice of optimal drilling fluid for drilling horizontal wells in unconventional (shale) gas/oil reservoirs.

Simple Correlations and Analysis of Cuttings Transport With Newtonian and Non-Newtonian Fluids in Horizontal and Deviated Wells

In this study, simple empirical frictional pressure losses and cuttings bed thickness correlations including pipe rotation are developed for solid-liquid flow in horizontal and deviated wellbores. Pipe rotation effects on cuttings transport in horizontal and highly inclined wells are investigated experimentally. Correlations are validated experimental data with pure water as well as four different non-Newtonian fluids for hole inclinations from horizontal to 60 degrees, flow velocities from 0.64 m/s to 3.56 m/s, rate of penetrations from 0.00127 to 0.0038 m/s, and pipe rotations from 0 to 250 rpm. Pressure drop within the test section, and stationary and/or moving bed thickness are recorded besides the other test conditions. The new correlations generated in this study are believed to be very practical and handy when they are used in the field.

Cuttings Characteristics and Mechanics Behavior in Horizontal Wells of Liaohe Oil Field

Cuttings transport of drilling and washing process in horizontal well is a typical two-phase (liquid-solid) or three-phase (gas-liquid-solid) flow phenomena. In this paper, it analyzes the flow characteristics of Huan 127-Lian H2 horizontal wellbore , then uses experimental method to study the behavior of the particle size distribution and the mechanics. This study provides an important way to master cuttings settling in fluid medium, it can explain how the cuttings bed is generated and cleared, and why the procession of cuttings of migration is stopped. In addition, measurement and analysis of drill cuttings is the basis erosion and abrasion analysis of BHA.

Review of Hole Cleaning in Complex Structural Wells

Complex structural wells are widely used in the development of marine oilfield, old oilfield and low permeable oilfield. However, poor hole cleaning is often occurred in the highly-deviated sections and horizontal sections of the complex structural wells, which affects rate of penetration and downhole safety. The methods to study cuttings transport can be normally divided into four types: 1) experimental observations, 2) CFD simulations, 3) theoretical correlations and models and 4) field tests. Experimental observations and CFD simulations are mainly used to analyze the effects of different parameters on hole cleaning and obtain some valuable data. Theoretical models and correlations are mainly applied to calculate cuttings bed height, critical velocity and etc to provide the guidance for the design of hydraulic parameters. The accuracy of the first three types are checked by field tests. In this paper, the effects of flow rate, inclination, mud rheology, drillpipe rotation and other factors on hole cleaning, and some typical correlations and models were briefly reviewed before 2000 years, and some new research findings were detailedly addressed. In addition, CFD simulations also were introduced. Although major improvements have been achieved in the past several decades, building a comprehensive and proven model requires much more experimental researches, CFD simulations, in-depth theoretic studies and field tests due to the complexity of cuttings transport under multi-factor interactions.

Study on Cuttings Transport Efficiency Affected by Stabilizer's Blade Shape in Vertical Wells

Effective cuttings transport means a better hole cleaning in drilling operations, which can increase the rate of penetration (ROP), and avoids pipe sticking, higher drag and torque problems. This paper aimed to analyze cuttings transport efficiency affected by different blade shapes of stabilizers, which is often overlooked in drilling. For this purpose, Eulerian multiphase flow model was used to simulate the influence of different blade types of stabilizers on cuttings transport efficiency under rotating coordinates. Numerical simulations indicate that straight blade stabilizer is obviously superior to helical blade for cuttings transport efficiency in vertical wells using the same hydraulic parameter and rotating speed. Field tests were conducted in some medium-deep wells of Daqing Oil Field, and the results showed that repeated fragmentation of cuttings, bit balling and pipe sticking problems were improved, and ROP was obviously raised.

Effect of Drillpipe Rotation on Cuttings Transport during Horizontal Foam Drilling

In this study, we sought to experimentally investigate the effect of drillpipe rotation on pressure loss and cuttings transport in a horizontal annular pipe by considering both varied foam qualities of 80, 85 and 90 % and foam velocities. Additionally, the influence of foam velocity and foam quality on pressure loss and cuttings transport efficiency was investigated. The experiments were conducted in a flow loop with a 5-m long eccentric annular test section, representing the wellbore, with a 51.8-mm outer pipe and a 16-mm inner pipe that could be rotated up to 150 rpm. It has been observed that pipe rotation has a negligible effect when only foam flows in the annular pipe. Conversely, pipe rotation has a significant effect on the pressure loss and cuttings transport when the cuttings are injected into the annular pipe. Furthermore, with increasing rotational speed, the frictional pressure loss dramatically decreases and the delivered cuttings concentration increases. Moreover, experimental results show that higher foam quality and velocity increased the pressure loss and decreased the delivered cuttings concentration.

高傾斜地熱坑井掘削時の効果的掘屑運搬に関する実験的研究

高傾斜地熱坑井掘削時の効果的掘屑運搬に関する実験的研究

Cuttings Transport Models and Experimental Visualization of Underbalanced Horizontal Drilling

Aerated underbalanced horizontal drilling technology has become the focus of the drilling industry at home and abroad, and one of the engineering core issues is the horizontal borehole cleaning. Therefore, calculating the minimum injection volume of gas and liquid accurately is essential for the construction in aerated underbalanced horizontal drilling. This paper establishes a physical model of carrying cuttings and borehole cleaning in wellbore of horizontal well and a critical transport mathematical model according to gas-liquid-solid flow mechanism and large plane dunes particle transport theory.

Hydraulics Analysis System for Extended Reach Drilling in China and its Application

The extended reach drilling (ERD) is being adopted widely as an effective and economical way of developing oilfields in China. But it also brought a series of technical difficulties because of its own characteristics. Some progresses were made after several years of hard work in China about Hydraulics for extended reach drilling, which included cuttings transport models and rules, precise model of circulating system pressure loss calculation, hole cleaning calculating models and monitoring method, hydraulic extended limit calculation model and analysis, hydraulics design and optimization method for ERD. Based on the above studies, the author finally developed a system of hole cleaning monitoring and hydraulics design and its risk analysis which could provide theoretical support and useful tool for engineering design and risk assess before drilling. These researches are helpful to ERD and have enriched the hydraulic theory of ERD.

Impact of drilling fluid viscosity, velocity and hole inclination on cuttings transport in horizontal and highly deviated wells

Deviation from vertical path makes drill cuttings to accumulate on the lower side of the wellbore that induces the formation of cuttings bed. Subsequently, relative problems occur while drilling. Excessive torque and drag, difficulties in running casing in hole and accomplishing good cementing jobs and mechanical pipe sticking are few of the classical examples of such problems. Therefore, a comprehensive understanding of influential parameters on hole cleaning seems to be essential. This paper indicates the results of an experimental study that was carried out to evaluate cuttings removal efficiency using three types of drilling fluid. The experimental works were conducted using a 17-feet long opaque flow loop of 2-in. diameter as the test section. For each test, the amount of cuttings transport performance (CTP) was determined from weight measurements. Viscosity was investigated together with other two influential parameters, namely fluid velocity and hole inclination under various flow conditions. It is shown that the increase in drilling fluid viscosity has improved CTP by approximately 8 % at all angles provided the flow regime remained turbulent while velocity was kept constant. However, further increase of viscosity as flow regime was turning into transient or laminar flow, has lessened CTP by a total average of 12 %. It was also revealed that an incremental escalation in hole inclination from 60° to 90° has a positive effect on CTP, i.e., it will be improved up to 40 %. Drilling fluid velocity was found to have significant impact on CTP as it could attain maximum percentage of 98 %.

Pilot Test Shows Promising Technology for Gas Drilling

Young Technology Showcase Gas drilling has been widely promoted and applied in China in recent years. The cuttings-carrying media usually consist of air, nitrogen, and natural gas. Air is commonly used because of its free availability. However, the mixture of air and natural gas in a borehole can cause fire and explosion. Although the downhole fire problem is prevented with nitrogen or natural gas, other issues arise, such as costly nitrogen generation, restrictions to the use of natural gas, resource waste, and environmental concerns. The current gas drilling practice of handling gas returned from the borehole is to discharge it to the atmosphere directly. If the gas can be recycled in the same way as drilling mud, the energy consumption and drilling cost can be greatly reduced. The recycling system can also allow the produced gas from the reservoir to be compressed and transported to the gas gathering system in the field. The overall efficiency of gas drilling will be improved significantly. The gas recycling system (GRS) has been investigated at the China University of Petroleum, Beijing (CUPB), for several years. A systematic research and development group at the CUPB carried out a comprehensive study including an integration design, technological process investigation, cuttings transport analysis, separation and filter equipment selection, and control system design. To verify the feasibility of the new system and technology, CUPB recently conducted an open-loop field test at Sinopec Group’s Dayi 101 well in the Sichuan province in western China. The result of the test is very promising. It proved the feasibility of the innovative technology. System Description The general idea of the GRS is to separate gas effectively from the gas-liquid-solid mixtures returned from the well and reinject the gas back into the well. At the same time, cuttings and fluids are discharged after the separation. During the natural gas drilling process, the separated gas can be released to the gas gathering system in the field. The integrated design of the process is illustrated in Fig. 1.

Effect of Bentonite Mud Additives on Flow Structure and Cuttings Transport through The Eccentric Annulus of Wellbore

The effect of bentonite mud additives on flow structure and cuttings transport efficiency through drill hole (Wellbore) eccentric annular flow is studied numerically and presented in this work. velocity distribution profiles and contours of both drilling fluid and cuttings are examined in The presence of drill pipe rotating. cutting volume fraction distributions as well as flow contours is considered. The effect of additives on The cuttings slip velocity and transportation efficiency is studied. potassium cloride (KCI) and Potassium formate (KF), as wellbore stability, and viscosity control additives are investigated. PG gum as bentonite mud additive for filtration, viscosity, and gel strength control as well as barite additive to control mud density is studied. The study is carried out using fluent 6.3.26 package CFD software. The turbulent model considered is The realizable k-e model. flow passage considered is an eccentric annulus that has inner and outer diameters of 5 cm and 10 cm with 50% eccentricity, and length L =500 cm. base fluid considered is 4.3% bentonite mud. 3%bentonite mud is also investigated with PG gum additives. drilling fluid rheological model considered is The power law. results show that The axial, velocity distributions of both drilling fluids and cuttings, as well as drilled cuttings volumetric fraction distribution are strongly affected by drilling fluid additives. additives modify The flow structure and cuttings distribution, and The effect depends on drilling fluid's rheology as represented by their viscosities. bentonite mud additives reduce cuttings slip and increase cuttings transport efficiency.

A Novel Approach of Cuttings Transport with Bubbles in Horizontal Wells

Aiming at the cutting bed settling problems in horizontal section during drilling process, a novel additive FGC for cuttings transport is applied. The experimental results show that the wettability was converted to amphiphobic and the cuttings preferentially attached to gas bubbles after FGC adsorption on the cuttings’ surface. The surface area of the cuttings is increased and the density of it is reduced, making cuttings more easily to be driven by liquid and settlement decrease. Tested by the horizontal simulation device, the cuttings transport effect is good and most of cuttings can be circulated to the outlet position by drilling fluid.

Research Progresses of Hydraulics for Extended Reach Drilling in China, Part I: Cuttings Transport and Precise Calculation of Pressure Loss

The extended reach drilling (ERD) is being adopted widely as an effective and economical way of developing oilfields in China. But it also brought a series of technical difficulties because of its own characteristics. Some progresses were made after several years of hard work in China about Hydraulics for extended reach drilling, which included cuttings transport models and rules, precise model of circulating system pressure loss calculation, hole cleaning calculating models and monitoring method, hydraulic extended limit calculation model and analysis, hydraulics design and optimization method for ERD. Based on the above studies, the author finally developed a system of hole cleaning monitoring and hydraulics design and its risk analysis which could provide theoretical support and useful tool for engineering design and risk assess before drilling. These researches are helpful to ERD and have enriched the hydraulic theory of ERD. Due to space limitations, this article could only demonstrate part of these progresses, as the subtitle showed.

An Experimental Modeling of Cuttings Transport for an Iranian Directional and Horizontal Well Drilling

This article has experimentally investigated and modeled the influence of variables such as hole angle, fluid rheology, cuttings size, circulation rate, and annular size on cuttings transport velocity using the concept of minimum transport velocity (MTV). The proposed method was checked against field values and has produced excellent results. The results obtained from this model were compared with Larsen's (1997) model and insignificant differences were observed. The result shows that this work can be utilized as a superior tool in drilling of directional and horizontal wells in Iran.

Cuttings Transport In Horizontal And Highly Deviated Wellbores

Lencongan dari laluan tegak menyebabkan rincisan gerudi berkumpul pada bahagian bawah lubang telaga sehingga terbentuknya lapisan rincisan. Akibatnya, berlaku beberapa permasalahan operasi ketika berlangsungnya penggerudian. Daya seret dan kilas yang melampau, kesukaran yang dialami ketika penyorongan rentetan selongsong ke dalam lubang telaga, kesukaran untuk memperoleh operasi penyimenan yang baik, dan lekatan mekanikal paip gerudi adalah antara beberapa contoh lazim yang berkaitan dengan permasalahan terbabit. Sehubungan itu, pemahaman yang baik tentang parameter utama operasi yang mempengaruhi pembersihan lubang telaga adalah penting. Artikel ini mengetengahkan keputusan daripada kajian makmal yang telah dilaksanakan untuk menilai keberkesanan tiga jenis bendalir gerudi dalam menyingkir rincisan gerudi. Kajian makmal melibatkan penggunaan gelung legap aliran sepanjang 17 kaki dengan diameter 2 inci sebagai bahagian ujian. Bagi setiap uji kaji, prestasi pengangkutan rincisan (CTP - Cuttings Transport Performance) ditentukan menerusi pengukuran berat. Keputusan uji kaji dianalisis untuk memperoleh kesan menyeluruh ketiga-tiga parameter operasi, iaitu kelikatan bendalir gerudi, halaju bendalir, dan kecondongan lubang telaga. Kajian terkini membuktikan bahawa penggunaan bendalir gerudi berkelikatan tinggi berupaya meningkatkan CTP jika regim aliran adalah gelora. Walau bagaimanapun, peningkatan kelikatan dalam regim aliran peralihan atau laminar masing-masing mengurangkan CTP secara beransur atau mendadak. Kajian juga menunjukkan bahawa peningkatan sudut kecondongan dari 60° ke 90° memberikan kesan yang positif terhadap CTP. Parameter operasi yang memberikan kesan yang ketara dalam kajian ini ialah halaju aliran, dengan peningkatan kecil yang dialami oleh halaju aliran berjaya memberikan kesan positif yang nyata dalam pembersihan lubang telaga. Kata kunci: Kecekapan penyingkiran rincisan; prestasi pengangkutan rincisan; rincisan gerudi; bendalir gerudi; pembersihan lubang telaga Deviation from vertical path makes drill cuttings to accumulate on the lower side of the wellbore that induces the formation of cuttings bed. Subsequently, relative problems occur while drilling. Excessive torque and drag, difficulties in running casing in hole and accomplishing good cementing jobs and mechanical pipe sticking are few of the classical examples of such problems. Therefore, a comprehensive understanding of influential parameters on hole cleaning seems to be essential. This paper presents results of an experimental study that was carried out to evaluate cuttings removal efficiency of three types of drilling fluid. Experiments were conducted using a 17 feet long opaque flow loop of 2 inch diameter as test section. For each test, the amount of cuttings transport performance (CTP) was determined from weight measurements. Three operating parameters were considered, namely drilling fluid viscosity, fluid velocity, and hole inclination. It showed that the use of high-viscosity drilling fluid improved CTP if the flow regime was turbulent. However, increasing viscosity when flow regime was transient or laminar flow lessened CTP gradually or sharply respectively. It was also revealed that an incremental increase in hole inclination from 60° to 90° has a positive effect on CTP. The most influential parameter in this study was fluid velocity in which a small raise of fluid velocity resulted in a substantial positive effect on hole cleaning. Key words: Cuttings removal efficiency; cuttings transport performance; drill cuttings; drilling fluid; hole cleaning

Two-Region Average Model for Cuttings Transport in Horizontal Wellbores I: Transport Equations

The aim of this article is to derive a mathematical model without length-scale restrictions for cuttings transport in horizontal wellbores using the non-local forms of the volume averaging method, which is a technique used to derive transport equations for multiphase systems and one of the main approaches in two-phase flow modeling. The theoretical derivation of the cuttings transport problem is for a two-region system composed of a fluid bed (ω region) and a stationary bed (η region) of drill cuttings that it is considered as a porous medium. The volume-averaged mathematical model obtained in this work consists of the mass and momentum equations for the ω and η regions. The model was the starting point to obtain one-equation models for both regions. The one-equation models together with adequate jump conditions can be used to predict the hydrodynamics of the ω and η regions. The mathematical derivations of the momentum and mass flux transfer jump conditions are presented in Part II of this article.

A Review of Cuttings Transport in Directional-Well Drilling

A Review of Cuttings Transport in Directional-Well Drilling This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 132372, “Review of Cuttings Transport in Directional-Well Drilling: Systematic Approach,” by T. Nazari, SPE, and G. Hareland, SPE, University of Calgary, and J.J. Azar, SPE, University of Tulsa, originally prepared for the 2010 SPE Western Regional Meeting, Anaheim, California, 27–29 May. The paper has not been peer reviewed. Hole cleaning during directional-well drilling is a major concern in the oil field and must be monitored and properly controlled during the entire drilling operation. Inadequate drilled-cuttings removal can cause many costly problems. Low annular-fluid velocity, lack of drillpipe rotation, and the wrong mud properties are primary factors in ineffective hole cleaning. The full-length paper presents a review of previous hole-cleaning studies and discusses an approach that is better suited for monitoring and controlling hole-cleaning problems. Introduction The rotary-drilling process consists of a rock-cutting tool (drill bit) upon which a downward force is applied [weight on bit (WOB)] and rotation (rev/min) is imposed. The drilled cuttings generated by the drill bit are removed by circulating a drilling fluid from surface to bottomhole and back to surface (cuttings transport) (Fig. 1). During directional-well drilling, cuttings removal becomes more difficult and if not controlled properly can result in serious problems such as mechanical pipe sticking (fishing or hole loss), excessive frictional torque (increase in rotary-power requirement) and frictional drag (inability to reach target), difficulty in landing casing, channeling problems during cementing, and difficulty in logging. The factors that are known to affect hole cleaning include annular eccentricity, inclination angle, drillpipe rotation, fluid flow rate (annular velocity and flow regime), rate of penetration (ROP), mud rheology and density, and cuttings (i.e., size, shape, and density). It is well documented that flow rate and drillpipe rotation have the most positive effect on hole cleaning. However, an increase in flow rate causes an increase in frictional pressure losses, which in turn causes an increase in equivalent circulating density (ECD), pump-pressure requirement, and potential hole erosion. An increase in pipe rotation can result in premature pipe fatigue failures caused by the induced cyclic stresses. Cuttings-Transport Problem In contrast to other industrial processes, the cuttings-transport problem in the drilling industry is more complex because of the many parameters that are interconnected nonlinearly. In simpler processes, some of the steps could be neglected. Comparing this scheme to a drilling process results in the following correlations: Process—drilling procedure Reference—ECD limitation, pump hydraulic-horsepower limitation, hole erosion, ROP limitation, geological-target limitation, rotary-power limitation Process inputs—flow rate, rev/min, hookload Process outputs—pressures, ROP, torque Internal states—WOB, eccentricity, hole cleaning Monitoring/control—lost circulation, drag, torque, cuttings returns, ROP, circulating standpipe pressure For a complete and reliable automated design process, the following steps must be taken: Signal measurements Monitoring of critical parameters Modeling Control

Experimental Studies on the Effect of Mechanical Cleaning Devices on Annular-Cuttings Concentration

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 134269, ’Experimental Studies on the Effect of Mechanical Cleaning Devices on Annular Cuttings Concentration and Applications for Optimizing ERD Systems,’ by Ramadan Ahmed, SPE (currently with the University of Oklahoma), Munawar Sagheer, SPE, Nicholas Takach, SPE, Reza Majidi, SPE, Mengjiao Yu, SPE, and Stefan Miska, SPE, University of Tulsa, and, Christophe Rohart, SPE, and Jean Boulet, SPE, VAM Drilling, originally prepared for the 2010 SPE Annual Technical Conference and Exhibition, Florence, Italy, 19-22 September. The paper has not been peer reviewed. In horizontal and highly deviated portions of an extended-reach-drilling (ERD) well, cuttings beds form on the low side of the annulus. The cuttings bed partially blocks the annulus, resulting in excessive pressure loss and a higher equivalent circulating density (ECD). Recently, the use of downhole mechanical cleaning devices (MCDs) has been introduced to mitigate the problem without inducing excessive ECD. The full-length paper presents results of an experimental study that was conducted to evaluate cuttings-removal efficiency of MCDs. Results indicate that the tools significantly reduce the amount of cuttings in the annulus. Introduction Efficient cuttings transport is an important issue in drilling highly deviated and horizontal wells. In directional wells, drilled cuttings tend to accumulate on the low side of the annulus and form a thick cuttings bed when the flow velocity becomes insufficient to suspend the cuttings-bed particles. Particularly in high-angle and horizontal boreholes, the formation of a thick cuttings bed can give rise to numerous difficulties such as lost circulation, differential sticking, and high torque and drag. Recently, hydromechanical hole-cleaning devices (HHCDs) have been developed to enhance cuttings-transport efficiency in directional wells. These tools are introduced in the drillstring with different spacing arrangements. These tools have helical grooves or blades on their surface to assist cuttings-bed removal. A negative angle also is designed on each blade to improve the scooping effect on the cuttings bed. While rotating the drillpipe, the blades scoop the cuttings bed and help to bring the cuttings into suspension. At the same time, the circulation of the drilling fluid allows the suspended cuttings particles to be carried away, thus leading to better hole cleaning. Because of hydrodynamic and hydromechanical effects, the tools help to reduce the cuttings accumulation in highly deviated and horizontal sections of the wellbore where the buildup of a cuttings bed cannot be avoided. Thus, several of these tools are used in a typical drilling application to reduce the in-situ cuttings concentration and, hence, reduce the occurrence of hole-cleaning-related problems. HHCDs improve hole cleaning by creating more turbulence, bringing cuttings into suspension, and scooping the cuttings bed. The interaction between the tools and the slurry that contains cuttings particles and drilling fluid is a complex fluid-mechanics problem for which an analytical solution would be difficult to develop. Therefore, an experimental approach is the best option to provide practical solutions, perform sensitivity analysis, and obtain a better understanding of the use of these tools.

実坑井データを用いた傾斜坑井の掘屑運搬挙動と等価循環泥水比重のシミュレーション

実坑井データを用いた傾斜坑井の掘屑運搬挙動と等価循環泥水比重のシミュレーション