Quantification of the Loss Conduit Aperture During Lost Circulation in Fractured Carbonates

Ruzhnikov, Alexey; Johnson, A.

doi:10.2118/206446-ms

Cited by 2 publications

References 10 publications

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Qualitative Analysis of Drilling Fluid Loss Through Naturally-Fractured Reservoirs

Keshavarz

Moreno

2023

SPE Drilling &Amp; Completion

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Summary Drilling becomes extremely challenging when dealing with naturally fractured reservoirs (NFR). A comprehensive solution is developed in this study to perform qualitative analysis on drilling fluid loss rate and volume to examine how they can be affected by NFR characteristics, drilling fluid rheology, leakoff phenomenon, and wellbore condition. In this regard, the solution is applied to generate type curves to facilitate the sensitivity analysis (refer to the provided Supplementary Materials). The presented solution accounts for not only drilling fluid pseudoplasticity in the total system but also matrix medium under wellbore constant pressure assumption (by including dimensionless matrix contribution parameter). It is also able to measure mud loss advancement not only through NFR but also through homogeneous reservoirs. The developed solution is validated by reducing it to the preexisting solution (designed for Newtonian fluid case) by incorporating assumptions into it. The result demonstrates the significance of NFR properties and drilling fluid pseudoplasticity on the leakoff phenomenon and total loss volume, especially when constant pressure is established inside the wellbore. The finding reveals that three periods can be identified through generated type curves depending on NFR characteristics, drilling fluid rheology, and leakoff coefficient. Therefore, different drilling fluids with specific pseudoplasticity should be used in each period to mitigate drilling fluid loss effectively. In this regard, the study is supposed to design drilling fluid in a way to maintain its pseudoplasticity at a higher level at early and late times, while being maintained at a lower level during the transient period, a critical aspect for managed pressure drilling techniques, particularly in the context of dual-gradient drilling applications. Additionally, a procedure should be implemented to lessen the transient period while attempting to keep drilling fluid advancement occurrence at a lower rate, which shows that drilling fluid pseudoplasticity can be used as an effective tool to manage this period. The obtained result also indicates that the importance of drilling fluid rheology to control total loss volume is greater for NFR with higher leakoff than with lower leakoff. Furthermore, the greater the differential pressure inside the wellbore, the greater the importance of mud rheology to reduce drilling fluid loss. The outcome of the study not only facilitated qualitative and quantitative analyses through NFR but also enabled decision-makers to instantaneously select optimal wellbore conditions and drilling fluid pseudoplasticity.

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Qualitative Analysis of Drilling Fluid Loss Through Naturally-Fractured Reservoirs

Keshavarz

Moreno

2023

SPE Drilling &Amp; Completion

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Real-Time Evaluation of the Lost Circulation Zone Based on a Changepoint Analysis of the Mechanical Specific Energy and Standpipe Pressure

Ruzhnikov,

Guillot,

Corona

2024

Day 2 Tue, February 13, 2024

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There are multiple mechanisms that may drive a lost circulation event while drilling a well. Efficiently dealing with those events requires that the operations team quickly get an understanding of subsurface conditions that caused the event. Globally, some lost circulation events are cured by basic lost circulation materials (LCM) / bridging, while others fail to be cured even after days of attempts with lost circulation cement plugs (LCP) and novel materials. The aperture of the lost circulation zone (LCZ) remains unknow in most of the cases unless open hole logs ran to identify it. The standard approach to cure the losses is to start with less aggressive materials followed by more aggressive, and the curing based on the field practices, rather being linked to the potential opening of LCZs. The manuscript will investigate the hypothesis that the lost circulation events related to penetration of large, connected, open cavities (karsts) can be characterized, and those large open cavities can be identified in near-real time by analyzing the dynamic drilling parameters with help of Machine Learning. There are different mechanisms that are driving the lost circulation events. Within the same formation some of lost circulation zones can be easily cured with LCM/LCP, others require more effort and time and may be uncurable. The invention proposes a workflow and an algorithm to detect from dynamic drilling parameters what is the likely mechanism at play, and whether the lost zone is curable. Large fracture and dissolution cavities will have different mechanical properties, and drilling through those features will require significantly less energy than through a competent rock formation. They are also discrete events within a geological formation, and therefore will have outlier mechanical properties within a formation. The test was performed in over 300 wells, across different lost circulation zones (some wells had several zones). The developed algorithm was incorporated into the software in Real-time Monitoring center, allowing near real-time estimation of the aperture to decide regarding the LCM or LCP to be used. The results showed that in upper sections the multiple lost circulations zones presented with different thickness. The majority of the identified karsts are within range of 2-to-8 ft, with some going over 10 ft. In the deeper formations LCZ with the aperture of 4-to-9 ft were identified. The interesting part was related to the significant difference between MSE while drilling competent formation and the lost circulation zone, when MSE values were dropping almost to zero. The manuscript provides the novel approach allowing to use machine learning to identify the aperture of the lost circulation based on the real time parameters. The proposed approach can be used at any drilling project worldwide.

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Quantification of the Loss Conduit Aperture During Lost Circulation in Fractured Carbonates

Cited by 2 publications

References 10 publications

Qualitative Analysis of Drilling Fluid Loss Through Naturally-Fractured Reservoirs

Qualitative Analysis of Drilling Fluid Loss Through Naturally-Fractured Reservoirs

Real-Time Evaluation of the Lost Circulation Zone Based on a Changepoint Analysis of the Mechanical Specific Energy and Standpipe Pressure

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