Surface Karst Landforms of the Notranjska region (south-western Slovenia)

Gawor, Łukasz; Jonczy, I.

doi:10.7494/geotour.2014.37.55

Cited by 3 publications

(5 citation statements)

References 3 publications

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“…As shown in the Fig. 1, typical result of this process is development of some salient features such as division of limestone into blocks (clints) bordered by vertical fractures (gricks) [1]. This is a widespread sign of landscape karstification presented by variety of shapes and sizes, spanning up to tens of meters.…”

Section: Karst Phenomenamentioning

confidence: 95%

“…Karstified carbonates pose significant challenges in drilling, which can be associated with both the drilling process and unique geological properties. In subsequent sections, we will refer to common in karstology definition of the karst, introduced to describe the landscape, which contains caves, underground channels, and other associated with soluble rocks features [1]. Sudden encountering of some karst-forms during drilling in carbonates may lead to potentially dangerous scenarios.…”

Section: Introductionmentioning

confidence: 99%

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Drilling in Karstified Carbonates: Early Risk Detection Technique

Maksimov

Pavlov

Sangesland

2020

Volume 11: Petroleum Technology

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Heterogeneous nature and complex rock properties of carbonate reservoirs makes the drilling process challenging. One of these challenges is uncontrolled mud loss. Caves or a system of cavities could be a high-risk zone for drilling as the mud losses cannot always be controlled by conventional methods, such as mud weight (MW) / equivalent mud weight (ECD) optimization, or by increasing concentration of lost circulation material (LCM) in the drilling mud. Seismic-based detection of such karstification objects is inefficient due to relatively small size, various shapes and low contrast environment. In this paper we, based on drilling data from the Barents sea, analyzed possible patterns in real-time drilling data corresponding to drilling through karstification objects. These patterns can serve as real-time indicators of zones with higher risk of karsts and can be used as an online tool for decision support while drilling in karstified carbonates.

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Section: Karst Phenomenamentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Drilling in Karstified Carbonates: Early Risk Detection Technique

Maksimov

Pavlov

Sangesland

2020

Volume 11: Petroleum Technology

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show abstract

“…Green labels in the figure indicate the surface traces of karstification. For example, surface micro-forms can be presented by joints, which divide limestone into blocks with vertical cracks, called grikes [2]. These objects are the result of rock dissolution.…”

Section: Geological Signs Of Karstificationmentioning

confidence: 99%

“…Examples of such dangerous objects, which often occur when drilling in carbonates, are caves or systems of cavities formed due to complex karstification processes. We refer to the common definition of karst [2] that describes the landscape which contains caves, underground channels, and other associated soluble rock features.…”

Section: Introductionmentioning

confidence: 99%

Prediction and Early Detection of Karsts—An Overview of Methods and Technologies for Safer Drilling in Carbonates

2021

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The nature of carbonate deposition as well as diagenetic processes can cause the development of unique geological features such as cavities, vugs and fractures. These are called karsts. Encountering karsts while drilling can lead to serious consequences such as severe mud losses, drops of bottom hole assembly and gas kicks. To improve drilling safety in intervals of karstification, it is important to detect karsts as early as possible, preferably in advance. In this paper, we review methods and technologies that can be used for the prediction and early detection of karsts. In particular, we consider acoustic, resistivity, seismic and drilling-data methods. In addition to the inventions and technologies developed and published over the past 40 years, this paper identifies the advantages, limitations and gaps of these existing technologies and discusses the most promising methods for karst detection and prediction.

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“…Karstification processes often affect carbonate reservoirs and cause the development of a number of unique geological features called karsts. Here we refer to a common definition of the karst, introduced to describe the landscape, which contains caves, underground channels, and other features associated with soluble rocks [2]. Encountering karsts while drilling can cause critical safety incidents including uncontrollable losses of drilling fluid and gas kicks as reported in speciality reports [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Real-Time Detection of Karstification Hazards While Drilling in Carbonates

2022

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The nature of carbonate deposition can cause the development of unique geological features such as cavities and vugs called karsts. Encountering karsts while drilling can lead to serious consequences. To improve drilling safety in intervals of karstification, it is important to detect karsts as early as possible. The use of state-of-the-art geophysical methods cannot guarantee early or even real-time detection of karsts or karstification zones. In this paper we demonstrate, based on an analysis of 20 wells drilled in karstified carbonates in the Barents Sea, that a karst that is dangerous for drilling is often surrounded by one or more other karstification objects, thus forming a karstification zone. These zones can be detected in real time through certain patterns in drillstring mechanics and mud flow measurements. They can serve as indicators of intervals with a high likelihood of encountering karsts. The identified patterns corresponding to various karstification objects are summarized in a table and can be used by drilling engineers. Apart from that, these patterns can also be utilized for training machine learning algorithms for the automatic detection of karstification zones.

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Surface Karst Landforms of the Notranjska region (south-western Slovenia)

Cited by 3 publications

References 3 publications

Drilling in Karstified Carbonates: Early Risk Detection Technique

Drilling in Karstified Carbonates: Early Risk Detection Technique

Prediction and Early Detection of Karsts—An Overview of Methods and Technologies for Safer Drilling in Carbonates

Real-Time Detection of Karstification Hazards While Drilling in Carbonates

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