Mechanical and Geometrical Tortuosities: Vanishing and Appearing Tortuosities

2021 ◽  
Author(s):  
Robello Samuel ◽  
Jonathan Dale Lightfoot ◽  
William Turner
Keyword(s):  
Flexural Stiffness ◽  
Critical Factors ◽  
Hole Cleaning ◽  
Apparent Change ◽  
Drilling Performance ◽  
Open Hole ◽  
Conventional Methods ◽  
Minimum Curvature

ABSTRACT Tortuosity is one of the critical factors to be considered for complex directional well trajectories, complicated build rates, precise steering in thin reservoirs, and extended reach wells. This paper discusses the pitfalls of estimating tortuosity to quantify borehole quality and answers questions, such as whether the claimed benefits (i.e., enhanced drilling performance, improved hole cleaning, ease of running casing, and superior cement operations) can be fully attributed to reduced borehole tortuosity. Running casing may mask the tortuosity present in the as drilled open hole wellbore section. This vanishing tortuosity alters the apparent "wellbore quality" and the new tortuosity representative of the cased hole path may present new appearing tortuosity. Both vanishing and appearing tortuosity are generally neglected in engineering calculations. Conventional methods to calculate tortuosity are based on the predetermined shape of the trajectory using the minimum curvature method. Wellbore undulation (geometrical tortuosity) is determined using geometrical measurements such as inclination, azimuth, and calculated displacement; however, much of this wellbore undulation vanishes after the casing is run, and thus the cased off wellpath appears smoother. This apparent change in wellbore tortuosity results from the flexural stiffness and rigidity of the casing pipes, and the compression and tension loads along the length of the casing string. Acquiring a subsequent survey along the cased well path yields new inclinations, azimuths, and displacements. This new survey records wellpath undulations resulting from the casings path through the original open hole wellbore geometry and what we call tubular undulation (mechanical tortuosity) which is specific to the path and position of the casing within the wellbore. The smoothing of the wellpath resulting from the casing masking original wellbore tortuosity results in the original geometrical tortuosity vanishing while the new undulations resulting from the mechanical tortuosity of the casing causes additional tortuosity to appear. The comparison between the geometrical and mechanical tortuosity provides a method of quantifying the vanishing and appearing tortuosity.

Breaking ERD Records with Optimized Engineering and Practices: Making the Impossible Possible

2021 ◽  
Author(s):  
Hussien Alzaki ◽  
Nadhir Rahmani ◽  
Matthew Carr
Keyword(s):  
Progressive Increase ◽  
Main Step ◽  
Hole Cleaning ◽  
Optimum Placement ◽  
Open Hole ◽  
The Subject ◽  
Extended Reach Drilling ◽  
The Cost ◽  
First Time ◽  
Target Depth

Abstract Long-extended reach drilling (ERD) well has become necessary to reach untapped resources. This paper will describe pre-planning, execution and post results of drilling ERD wells with large bore design of 12¼" as the main step out section and deploying 9⅝" casing on shallow TVD of 4,200’. Progressive increase of the ERD ratio and complexity from one well to the next was planned and executed till we reached the longest well deploying 8 KM of 9⅝" casing with 5.4 ERD ratio at 26,179' TD horizontally all the way. A learning curve was established on drilled wells while progressively increasing reach and complexity. Subject well was the longest of any well planned in the field by far. Success involved implementation of technically modeled engineered solutions and verified during execution. Operational procedures including but not limited to: proper planning and execution of well profile to ensure optimum placement in a specific formation and minimum side forces. Drilling and tripping procedures to ensure the lowest friction factor (FF) and allow drilling to target depth (TD) with optimum rig capability. Engineered solution for casing running technologies, which involved rotation and conventional running and floatation. The longest ERD well was drilled to 26,179' TD with field ROP record in 12¼" hole section, maintaining very good hole quality proved by smooth bit trips out of hole and the final trip at TD on elevators. Hole cleaning and fluids strategy was developed and executed efficiently to measure FFs as low as possible for successful 9⅝" deployment. Engineered solution was proposed for 9⅝" deployment and was successfully trial tested on a shorter well to validate simulations. Casing rotation FFs came close to the modeled FFs. The 9⅝" Casing was deployed to bottom as planned and the cement job was performed successfully. Various records were achieved: the subject well achieved the deepest 9⅝" horizontal casing, the deepest 12¼" horizontal at TVD shallower than 5,000'. The longest 12¼" horizontal open hole at TVD shallower than 5,000' with section footage of 16,164'. The 9⅝" casing was deployed as a long string, eliminating the cost and challenges of a liner hanger and the need for a future tieback and also keeping hole sizes available for main and contingency sections to drill the reservoirs ahead. In addition to existing developed procedures and practices for ERD wells, subject well was dealing with the challenge of drilling a long 12 ¼" hole with a torque limitation of 30K lbsf.ft on TDS, and 4200 psi on surface equipment, and running the longest casing horizontally at such a shallow TVD, which is being done the first time globally. The success proved that challenging ERD wells can be drilled with optimum investments on rig capabilities.

Best Practice to Improve Slim Hole Maximum Reservoir Contact Well Drilling Performance

2021 ◽  
Author(s):  
Rodrigo Antillon Moreira ◽  
Ramanujan Jeughale ◽  
Toki Takahiro ◽  
Toma Motohiro ◽  
Kerron Andrews ◽  
...  
Keyword(s):  
Friction Factor ◽  
Best Practice ◽  
Drilling Fluid ◽  
Stock Selection ◽  
Well Drilling ◽  
Drilling Performance ◽  
Well Integrity ◽  
Drilling Parameters ◽  
Open Hole ◽  
Extended Reach Drilling

Abstract Reservoir sections in MRC (Maximum Reservoir Contact) & ERD (Extended Reach Drilling) wells are mainly designed to drill 8 ½" hole, because of drilling limitations with smaller hole size. However, slim hole sizes offer opportunities to revitalize existing wells using re-entry drilling techniques in association with MRC and ERD designs. This paper discusses the best practices to be implemented in order to mitigate risk, reduce complexity and ensure improved drilling performance. Re-Entry wells in the field have a risk of well integrity issues such as corroded 9 5/8" casing. In order to mitigate this risk, the corroded 9 5/8" casing should be covered by 7" liner & tied-back to surface before drilling reservoir section. In this situation up to 18,000 ft of 4" DP is used in the wells to drill 6" hole and run 4 ½" lower completion. Offset well analysis, whip stock selection criteria, BHA design, drilling fluid selection, drilling and tripping practices based on torque & drag and hydraulics calculations are most important to achieve the well objective. The Slim hole MRC well was completed without any issues and achieved good drilling performance. It was observed that the actual drilling parameters such as torque, drag and stand pipe pressure were less than simulated parameters. NAF was selected in the section to reduce the friction factor, while motorized RSS and a reamer stabilizer were used in the BHA to reduce torque, drag and ensure a smooth well profile. A back reaming practice was implemented in hole section to reduce dog leg severity and the open hole was eventually displaced to viscosified brine to minimize the friction factor for running the 4 ½' lower completion. 8500 ft of 6" hole section was drilled and TD was reached at +/- 19,000ft within 50 days including recovering the existing completion, drilling 8 ½" & 6" hole and running completion. This paper aims to contribute to the oilfield industry by sharing the successfully implemented engineering design and operation execution methodology to overcome the complexities present in Re Entry Wells MRC/ERD wells required to be drilled with slim hole conditions under an optimal cost, time effectiveness and low risk.

Continuous Circulation while Drilling: A New Approach to Maintain Hole Cleaning and Improve Drilling Performance in Swamp Drilling Operation

2021 ◽  
Author(s):  
B. K. Yuda
Keyword(s):  
Future Development ◽  
New Technology ◽  
Drill Pipe ◽  
Good Condition ◽  
Circulation System ◽  
Drilling Fluids ◽  
Hole Cleaning ◽  
Drilling Operation ◽  
Drilling Performance ◽  
Safety Incident

Swamp drilling operation in Mahakam has entered the industrialization period in which fast drilling is a common practice. However, fast drilling Rate of Penetration (ROP) causes hole cleaning issues to arise and induce a high Equivalent Circulating Density (ECD) trend. In some wells, this potentially leads to loss problems because of weak formation in shallow sections or depleted formation with relatively low fracture gradient. As a result, drilling parameter reduction was performed that causing lower ROP and additional circulation to reduce ECD. A new technology called Continuous Circulation Device (CCD) can help to tackle the problems mentioned above. It is a sub-based constant circulation system that enables the continuous circulation of drilling fluids downhole while making or breaking drill pipe connections. This system helps to maintain ECD and improve drilling performance as the cuttings are continuously carried out of the hole. This paper is introduced to analyze the benefits of CCD and opportunities for future development in the swamp drilling operation. The device was applied during drilling in the 12-1/4” and 8-1/2” sections. The challenge during drilling in these sections was to improve ROP without inducing bad hole cleaning that could lead to a high ECD trend. The result of CCD utilization shows that ECD during drilling could be reduced up to 2 points and become more stable compared to the previous trend. Since there was a reduction of ECD, the ROP could be improved up to 10%. Furthermore, only 1 cycle for circulation at well TD was performed as the minimum cuttings appeared. Pulling out the string and running the casing string was managed smoothly as the hole was already in a good condition. This utilization has been successfully implemented without any safety incident nor related Non-Productive Time (NPT). This positive result leads us to open the opportunity for future development in swamp fields asset.

The Virtual Well Engineer – A Real – Time Surveillance Tool for Managed Pressure Drilling Operations

2007 ◽  
Vol 18-19 ◽  
pp. 277-285
Author(s):  
Babs Mufutau Oyeneyin ◽  
Phil Burge ◽  
Lisa Hogg ◽  
Chris Anderson
Keyword(s):  
Multiphase Flow ◽  
Complex Environments ◽  
Hole Cleaning ◽  
Functional Capabilities ◽  
Drilling Performance ◽  
Underbalanced Drilling ◽  
Pressure Profiles ◽  
Managed Pressure Drilling ◽  
Engineering Team ◽  
Drilling Operations

Well engineers face ever increasing technical challenge of drilling in complex environments and the use of Managed Pressure Drilling(MPD) techniques to control annular pressure for improved drilling performance in the oil industry has growing interest[1-4]. Understanding hole cleaning and controlling annular pressure in this complex environment is becoming increasingly important for a range of applications. The Virtual Well Engineer[VWE] has been identified as the engineering tool to address these issues in order to deliver a successful MPD operation. The VWE is the product name for a suite of well planning , monitoring and simulation packages with focus on Managed Pressure Drilling includng underbalanced drilling that allows the well engineering team to interact with virtual reality. Recent works initiated by the Well Engineering Group at The Robert Gordon University have extended the knowledge of multiphase flow in a drilling annulus through the tracking of the transient multiphase flow pattern prevailing and effects on hole cleaning , the pressure profiles and identification of hot spots in concentric and eccentric annular sections . The mechanistic models developed at RGU form the core algorithms for the VWE. This paper presents the architecture and functional capabilities of the VWE – HydraulicsDTS™ , which is used in simulating well operations.

Hydraulic Behavior in Cased and Open Hole Sections in Highly Deviated Wellbores

2019 ◽  
Author(s):  
Jan David Ytrehus ◽  
Bjørnar Lund ◽  
Ali Taghipour ◽  
Birgitte Ruud Kosberg ◽  
Luca Carazza ◽  
...  
Keyword(s):  
Drilling Fluid ◽  
Transition To Turbulence ◽  
Low Flow ◽  
Wall Material ◽  
Outer Diameter ◽  
Flow Loop ◽  
Hole Cleaning ◽  
Hydraulic Behaviour ◽  
Lower Viscosity ◽  
Open Hole

Abstract In this paper we present results from flow loop experiments with an oil-based drilling fluid with micronized barite as weight materials. The use of micronized barite allows using lower viscosity drilling fluid, providing non-laminar flow, which is advantageous for particle transport in near-horizontal sections. While transition to turbulence and turbulent flow of non-Newtonian fluids has been well studied both theoretically and experimentally, there are very few published results on the effect of wellbore wall properties on flow regime transition and turbulence. This is relevant because horizontal sections are often open-hole with less well-defined surfaces than a steel casing surface. We have conducted a series of flow experiments with and without cuttings size particles in a 10 m long annular test section using steel and concrete material to represent the wellbore wall of a cased and open hole section. In both cases the annulus was formed by a freely rotating steel pipe of 2” outer diameter inside a 4” diameter wellbore. Experiments were conducted at 48°, 60° and 90° wellbore inclination from vertical. The two materials result in different hydraulic behaviour without particles with stronger turbulence when using concrete wellbore wall material than when using steel casing. While there is negligible difference at low flow rates, at 0.8 m/s and below, there is an increasing difference as the flow rate increases and becomes transitional to turbulence. Hole cleaning is found to differ dependent on the wall material. However, the effect on hole cleaning is less clear than for the pressure loss.

Hydraulic Behavior in Cased and Open-Hole Sections in Highly Deviated Wellbores

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Jan David Ytrehus ◽  
Bjørnar Lund ◽  
Ali Taghipour ◽  
Birgitte Ruud Kosberg ◽  
Luca Carazza ◽  
...  
Keyword(s):  
Drilling Fluid ◽  
Transition To Turbulence ◽  
Wall Material ◽  
Outer Diameter ◽  
Flow Loop ◽  
Hole Cleaning ◽  
Flow Regime Transition ◽  
Lower Viscosity ◽  
Open Hole ◽  
Flow Experiments

Abstract In this paper, we present results from flow loop experiments with an oil-based drilling fluid with micronized barite as weight materials. The use of micronized barite allows using lower viscosity drilling fluid, providing non-laminar flow, which is advantageous for particle transport in near-horizontal sections. While transition to turbulence and turbulent flow of non-Newtonian fluids has been well studied both theoretically and experimentally, there are very few published results on the effect of wellbore wall properties on flow regime transition and turbulence. This is relevant because horizontal sections are often open hole with less well-defined surfaces than a steel casing surface. We have conducted a series of flow experiments with and without cuttings size particles in a 10-m long annular test section using steel and concrete material to represent the wellbore wall of a cased and open-hole section. In both cases, the annulus was formed by a freely rotating steel pipe of 2” outer diameter inside a 4” diameter wellbore. Experiments were conducted at 48 deg, 60 deg, and 90 deg wellbore inclination from vertical. The two materials result in different hydraulic behaviors without particles with stronger turbulence when using concrete wellbore wall material than when using steel casing. While there is a negligible difference at low flowrates, at 0.8 m/s and below, there is an increasing difference as the flowrate increases and becomes transitional to turbulence. Hole cleaning is found to differ dependent on the wall material. However, the effect on hole cleaning is less clear than for the pressure loss.

Drilling System Optimization Leads to Expedited Wells Delivery

2021 ◽  
Author(s):  
Efe Mulumba Ovwigho ◽  
Saleh Al Marri ◽  
Abdulaziz Al Hajri
Keyword(s):  
Drill Pipe ◽  
System Optimization ◽  
Drill String ◽  
Stick Slip ◽  
Drilling Performance ◽  
Drilling Parameters ◽  
Single String ◽  
Innovative Solution ◽  
Open Hole ◽  
Weight On Bit

Abstract On a Deep Gas Project in the Middle East, it is required to drill 3500 ft of 8-3/8" deviated section and land the well across highly interbedded and abrasive sandstone formations with compressive strength of 15 - 35 kpsi. While drilling this section, the drill string was constantly stalling and as such could not optimize drilling parameters. Due to the resulting low ROP, it was necessary to optimize the Drill string in order to enhance performance. Performed dynamic BHA modelling which showed current drill string was not optimized for drilling long curved sections. Simulation showed high buckling levels across the 4" drill pipe and not all the weight applied on surface was transmitted to the bit. The drilling torque, flowrate and standpipe pressures were limited by the 4" drill pipe. This impacted the ROP and overall drilling performance. Proposed to replace the 4" drill pipe with 5-1/2" drill pipe. Ran the simulations and the model predicted improved drill string stability, better transmission of weights to the bit and increased ROP. One well was assigned for the implementation. Ran the optimized BHA solution, able to apply the maximum surface weight on bit recommended by the bit manufacturer, while drilling did not observe string stalling or erratic torque. There was also low levels of shocks and vibrations and stick-slip. Doubled the on-bottom ROP while drilling this section with the same bit. Unlike wells drilled with the previous BHA, on this run, observed high BHA stability while drilling, hole was in great shape while POOH to the shoe after drilling the section, there were no tight spots recorded while tripping and this resulted in the elimination of the planned wiper trip. Decision taken to perform open hole logging operation on cable and subsequently run 7-in liner without performing a reaming trip. This BHA has been adopted on the Project and subsequent wells drilled with this single string showed similar performance. This solution has led to average savings of approximately 120 hours per well drilled subsequently on this field. This consist of 80 hours due to improved ROP, 10 hrs due to the elimination of wiper trip and a further 30 hrs from optimized logging operation on cable. In addition, wells are now delivered earlier due to this innovative solution. This paper will show how simple changes in drill string design can lead to huge savings in this current climate where there is a constant push for reduction in well times, well costs and improved well delivery. It will explain the step-by-step process that was followed prior to implementing this innovative solution.

scholarly journals The Effect of Invisible Lost Time on Drilling Performance of Geothermal Wells

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Fernandez Sabar Hasudungan Pangaribuan ◽  
Sugiatmo Kasmungin ◽  
Suryo Prakoso
Keyword(s):  
Performance Indicator ◽  
Night Shift ◽  
Drilling Performance ◽  
Open Hole ◽  
Geothermal Wells ◽  
Lost Time ◽  
Geothermal Drilling ◽  
The Cost ◽  
Productive Time ◽  
Better Than

<em>Drilling activity has been focused in time on each activity to reach target depth (TD) immediately and efficient in cost. The priority also aimed to Geothermal drilling by doing specific measurement on Invisible Lost Time (ILT) as new focus to perform. Time becomes main aspect which it would affect the cost, therefore it is important to complete the well in time manner. The research was done to analyze the offset well of well A, B, C and D in order to identify Productive Time and Non Productive Time. Key Performance Indicator (KPI) has been identified from each activity also targeted from two wells of well B dan Well D due to time efficiency used during operation. The method used by comparing offset wells then continue to identify each KPI by measuring each activity based on ASCII time and Daily Drilling Report (DDR). The result from offset wells showed inefficiency in time with Flat time 49%, Drilling 42% and non-flat time (NPT) 9% from 28 days without completion. KPI based on the crew performance has confirmed that day shift crew performed better than night shift crew. KPI on rate of penetration (ROP) on day shift crew at 6 m/hr and night crew at 3 m/hr. KPI on Weight to Weight on day shift crew at 28.43 minute/stand faster than night shif crew at 34.65 minute/stand. KPI on Tripping in cased hole on day shift crew at 4.5 minute/stand faster than night crew shift at 4.6 minute/stand. KPI on Tripping in open hole on day shift crew at 2.7 minute/stand faster than night shift crew at 3.7 minute/stand. KPI on Tripping out open hole on day shift crew at 3.0 minute/stand slower than night shift crew at 2.8 minute/stand. KPI on Tripping out cased hole on day shift crew at 3.36 minute/stand faster than night crew shift at 3.74 minute/stand. ILT from both wells to 20 % or 5 days inefficiency on each well. It detects of potential savings to 10 billion rupiah from both wells.</em>

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