The Root Cause Analysis and Successful Control of an Oilwell Blowout in the Middle East

Ashena, Rahman; Ghorbani, Farzad; Mubashir, Muhammad; Sarem, Mahdi Nazari; Iravani, Amin

doi:10.2118/207834-ms

Cited by 3 publications

(1 citation statement)

References 3 publications

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“…After the initial kick response and the formation flow are stopped, a kick must be circulated out of the well to allow ordinary operations to resume (Ashena et al, 2021). To prevent more kicks, the kick must be cycled to the surface while the wellbore pressure is kept constant.…”

Section: Driller's Methodsmentioning

confidence: 99%

Understanding the Well Control Procedures for optimizing the Well Control System during Drilling

Sultan¹,

Ahmed²,

Ali³

et al. 2022

AJCE

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Well control is an essential part of any drilling operation. Improper well control procedure may result in blowout, and blowouts must be controlled to ensure a smooth drilling operation. The majority of well control incidents occur as a result of a failure to understand the fundamental principles involved. As a result, proper training and understanding are required for a drilling engineer. Every company in the world provides drilling engineers with training and an overview of various well control operations. The goal of taking well control as an engineering project is to think about and visualize the significance of well control in any drilling job. The purpose of this paper was to understand of well control procedures as well as the selection of the most effective well control system. The concurrent technique should only be utilized in exceptional circumstances; in the majority of occasions, the driller method is employed. However, if a suitable casing shoe is available, Wait & Weight method should also be used.

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Section: Driller's Methodsmentioning

confidence: 99%

Understanding the Well Control Procedures for optimizing the Well Control System during Drilling

Sultan¹,

Ahmed²,

Ali³

et al. 2022

AJCE

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Statistical analysis of past kicks and blowouts occurred in a Middle Eastern oilfield

Ashena

Bahreini²,

Lotfi³

2023

J Petrol Explor Prod Technol

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In 2017, blowouts and then explosions occurred in a Middle Eastern oilfield. A root cause of the incident is lack of study and investigation of the past kicks and blowouts data. Therefore, as a pioneer work in the region, data gathering and analysis of past kicks and blowouts were made in the studied oilfield to learn lessons and find gaps. Out of the 149 drilled wells, a total of 117 kicks and three (3) blowouts occurred. In this work, a list of drilling parameters to be considered in data gathering and analysis were suggested as a guideline for future works elsewhere. The statistical analysis not only showed all the three exploration wells kicked which is not a surprise, but it also showed that 39 out of 146 (26.71%) also experienced kicks during reservoir drilling. The large number of kicks in development wells proved that possibility of kick occurrence in development wells is not low. In exploration wells, the predominant kick causes were gas-cut mud and insufficient mud weight which indicates the necessity of using pressure while drilling in addition to drilling rate control systems in exploration wells. However, in development wells, lost circulation was the predominant kick cause indicating the necessity of using low-weight drilling fluids and managed pressure drilling systems. The direct role of human error exists at least in 60% of kicks occurred in this field, which shows the great importance of improved drilling personnel training. Although only 3.45% kicks in development wells occurred due to improper hole fill-up during tripping, this cause should not only be deemed trivial, but it should also be taken seriously as being the cause of the blowout. The 2.56% possibility of kick conversion to blowouts and 67% risk of blowout conversion to explosion emphasize the necessity of maintaining primary well control and using efficient and early kick detection systems. Bullhead was the more commonly used method than standard well control methods; as this kill method may not always be safe, its application should be revised.

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Factors Influencing the Precision of Swab and Surge Predictions During Tripping Operations

Cayeux,

Ambrus,

Dvergsnes

et al. 2024

Day 1 Tue, March 05, 2024

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Tripping operations are the source of possible serious drilling incidents caused by swab and surge pressures exceeding the geo-pressure margins. Yet, it is difficult to monitor the actual downhole pressure during tripping because of telemetry limitations but also because there are no available methods to measure downhole pressure below the bit. Hydraulic models are therefore necessary to estimate the downhole pressure along the whole open hole section, also below the bit. It is therefore important to understand the factors influencing downhole pressure estimations when the drill-string is only subject to axial displacement. In most cases tripping procedures consist in a series of drill-string movements intertwined with connection procedures. While tripping, the drill-string needs to accelerate from a stand-still position and to stop at another position. As a result of these accelerations and decelerations, hydraulic calculations must be transient. Furthermore, the movement of the bottom of the string is not synchronous with the top of string displacement because of the elasticity of the string, meaning that transient torque and drag estimations are also necessary. Actually, when using a floater, the top of string movement is influenced by heave also during connection. When the drill-string is displaced, drilling fluid needs to be added or is returned to the trip tank, depending on the direction. Consequently, the drilling fluid columns in the string and in the annulus change position affecting the downhole temperature conditions. As the fluid density and viscous behavior depends much on the local condition of pressure and temperature, heat transfer estimations also play a role on downhole pressure estimations. The evaluation of downhole pressure requires the combined estimations of transient hydraulic, mechanical and heat transfer models. The drilling fluid is also subject to gelling in a non-uniform manner along the borehole. Drilling fluid with high viscosity at low shear rate may take several minutes to return to hydrostatic conditions like for example during connection. Depending on the static and kinetic friction factors, part of the drill-string may remain stretched also after the top of string movement has stopped. Consequently, connection time influences the swab and surge variations for the next stand. Therefore, a tripping operation is typically a non-holonomic process which requires a continuous follow-up of the time evolution of the hydraulic, mechanical and heat transfer variables to be able to predict accurately the downhole pressure. Through several examples from actual tripping operations, the importance of the mutual interaction between transient hydraulic, mechanic and heat transfer, as well as the non-holonomy of tripping operations is shown. Understanding the factors that influence swab and surge estimations is of paramount importance to progress with the automation of tripping operations.

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The Root Cause Analysis and Successful Control of an Oilwell Blowout in the Middle East

Cited by 3 publications

References 3 publications

Understanding the Well Control Procedures for optimizing the Well Control System during Drilling

Understanding the Well Control Procedures for optimizing the Well Control System during Drilling

Statistical analysis of past kicks and blowouts occurred in a Middle Eastern oilfield

Factors Influencing the Precision of Swab and Surge Predictions During Tripping Operations

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