No abstract

A new workflow was implemented for the first time in three UAE onshore wells with the primary objective being to increase drilling efficiency while managing the associated risks. The workflow combines proven technologies, software and wellbore surveillance services to deliver risk-free wells ahead of authority for expenditure (AFE) targeting the reduction of nonproductive time (NPT) and invisible lost time (ILT), together with risk management. The workflow begins with a preliminary field analysis to identify the main challenges and areas that needed improvement. The observations are consolidated on a comprehensive drilling road map by well section that are used to outline prevention and mitigation measures, expected rate of penetration (ROP) and recommended drilling parameters. The study also allowed for identifying performance benchmarks such as average and on bottom ROP and connection time. Key performance indicators (KPI) were developed to monitor progress and track the well with respect to well improvements versus the benchmarks identified. The selection of the monitoring tools and modules required during the execution phase was developed based on the risks and KPIs identified during the field study and were further tailored to target specific challenges such as stuck pipe prevention, hole cleaning, shock and vibration, and connection time. The workflow enabled the flawless execution of three onshore wells ahead of AFE with zero NPT. The closed loop monitoring enabled real time interventions preventing risks such as stuck pipe, ensuring shoe-to-shoe drilling, and avoiding potentially lost-in-hole (LIH) costs. This monitoring process also enabled significant ILT reduction, saving approximately USD 500k for the three wells. This case study demonstrates the use of a novel approach to increase well construction efficiency by eliminating lost time while enhancing risk control. The main basis for success of this workflow is using existing and cost-effective technology while capitalizing on the renewed synergy between different departments such as drilling, mud logging, and well operations analysis. The workflow can be customized based on the different needs by combining specific modules for monitoring, analysis, and wellbore surveillance services to increase the efficiency of any well construction.

The paper explores the contributing factors impacting/constituting enhancement of the drilling in the 6' section in one of the giant offshore fields of ADNOC. While there is a tangible and obvious contribution from the surface manipulation of parameters, there is also an irrefutable connect between down hole factors and ROP. Factors such as formation density, porosity, Mechanical Specific Energy, Orientation, mud weight, DDI crestal or flank placement of the well and their impact on performance. The crestal wells have come with their own inherent downhole problems and challenges. While at times there is linearity between the formation Mechanical Specific Energy and formation Density, there isn't necessarily a linear relationship between the drilling parameters and the resultant ROP. The density and porosity of the formation not only impact the MSE but the ROP downhole as well. The required parameters to drill each formation also vary with these properties and their effectiveness can in turn be tracked with the MSE being seen as a direct result of the BHA and formation interaction. The analyses entailed cover the formation density, discrimination plots, Azimuth, mud weight, BHA stabilizations, MSE and the respective intra parameter interactions that form the overall resultant drilling performance.

On several occasions during drilling, the drill string or in cases of liner job the liner string comes across an overall regressive environment. By regressive environments, the condition of the well bore returning to its unconditioned and in some cases unstable phase, is implied. The objective of this paper is to see how the regression impacts the circulating pressures in particular and how best to anticipate such conditions to optimize/modify the practices. The circulating pressures in deteriorated/reverted cases start showing spikes in the actual values well beyond the predicted models subsequent to same flow rates at the same depths. Such deviations in the actual vs theoretical values can pose severe complications for the drilling and liner jobs. These resultant complications however can be countered with the help of hydraulic mapping and gel envelope estimation in conjunction with optimized tripping and circulation practices for the respective operations to ameliorate the conditions. This paper explores the impact of regressive hole conditions ranging from constraints, operability, mechanical loads and fluid regimes. It builds upon that impact and delves into how best to utilize the tool of hydraulic mapping for smooth tripping and drilling operations in conjunction with the real time monitoring to define the operational envelopes. Delving into the dynamics of the hole conditions in regards to tripping and drilling operations across open hole, the paper seeks to build upon experience and reach an optimized mantle for tripping, drilling, circulation and conditioning operations in compromised hole conditions without any time delay or complication. During the life span of the well operations, the open hole well bore conditions of the wells become adverse to continuing onwards with the operations without at first conditioning or changing the downhole states altogether. This is the modus operandi for the majority of operations but in instances where the ambient impact is time sensitive or where the operations altogether are too complex and constrained for that to be done, the well conditions worsen, and the complications related to the ongoing operations increase manifold, rendering the operation in extreme cases unfeasible altogether. This likelihood can however be circumvented with the help of preventive intervention tools such as hydraulic mapping. There is no broad stroke solution to operational complications though, techniques and tools vary with each instance and are very case specific in both spectrum of definition and application. The most significant take away though, is how the incorporation of hydraulic mapping ensures the impending operational problems and complications are efficiently and specifically managed without any downtime or operational delay, on the fly. There are cases when the hydraulic and dynamic parameters have been mapped with upper limits built within the model yielding successful execution of operations against odds. In presence of rapid gelation or excessive gel breaking pressures against high differential formations, the practice of rotating prior to circulation or reciprocation prior to circulation are also determined with this tool. Real time operations monitoring also play a pivotal role in benchmarking and tracking the operational parameters of interest that are critical for operations. In order to achieve that however, there needs to be a composite model for the real time broomstick to be in place that reflects the overall picture of the open hole well bore. The hydraulic mapping technique requires minor inputs from the routine operational practices but forms an integral tool that can help execute operations effectively in jeopardized environments, against staggering odds without forfeiting any of the operational parameters or objectives.

Ultrahigh-resolution electrical images (UHRIs) acquired with logging while drilling (LWD) tools have brought to light different side effects of using drilling tools such as rotary steerable systems (RSSs) and bits when drilling a horizontal borehole. This paper will go through the extensive analysis and simulations that followed, gathering data from almost thirty wells, to try and understand the root causes behind these side effects, along with the actions put in place to mitigate it. UHRIs were used while drilling a 6-in horizontal hole to achieve a 100% net-to-gross and perform advanced formation evaluation to optimize well production. Surprisingly, these images revealed more details: wellbore threading–a type of spiral–inside the formation. To understand the cause behind such marks, RSS and bit data was gathered from around thirty wells, compared, and analyzed. Simulations were run over months, considering rock types, drilling parameters, and bottom hole assembly (BHA) design to reproduce the issue and propose the best solution to prevent these events from reoccurring. After the data compilation, a trend emerged. Wellbore threading was observed in soft, high-porosity reservoir formations. It also appeared in tandem with controlled rate of penetration (ROP), low weight on bit (WOB), and a low steering ratio. At this point, advanced analysis and simulations were needed to determine the root cause of this phenomenon. A Finite Element Analysis (FEA) based 4D modeling software showed that the bit gauge pad length, combined with the RSS pad force, contributed to this threading. A pad pressure force higher than 7,000 N in conjunction with a short-gauge bit increased the likelihood of having this borehole deformation. Simulations comparing different size tapered and nominal bit gauge pad lengths were run to determine the effect on the borehole and on the steerability. Bit design is directly linked to the wellbore threading effect. It is more pronounced when associated with a powerful rotary steerable system and in a soft formation environment. However, altering a specific bit design can have a direct and undesirable effect on the steerability of the BHA. UHRI revealed details of borehole deformation that new drilling technologies are causing. It enabled an in-depth analysis of the different causes behind it, revealing ad-hoc solutions. Horizontal wells are being drilled in more challenging environments such as through thin formation layers, unpredictable geology, and unknown fluid movement. Detailed evaluation has a direct impact on the completion approach. But we also need to drill faster and more efficiently. The wellbore threading caused formation damage that masked information needed for formation evaluation. In a novel application of UHRI data, simulations gave birth to information which has been lacking and incentivized the development of new, formation-friendly technology.