First Borehole Acoustic Reflection Survey mapping a deepwater turbidite sand

Maia, Wagner; Rúbio, Ricardo; Júnior, Fábio Sândoli de Brito; Haldorsen, J.; Guerra, R.; Dominguez, Cereza

doi:10.1190/1.2369864

Cited by 8 publications

(6 citation statements)

References 2 publications

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“…This in turn enables the use of acoustic tools for geosteering, which has several advantages compared to the resistivity-based geosteering methods discussed previously. In the case of a low-contrast resistivity environment, sonic-based geosteering has proved to be a good alternative method for well placement and is suitable for detecting boundaries at a distance of up to 10-20 m away from the borehole [61,62]. Unlike the resistivity methods, the depth of investigation of acoustic measurements is significantly less affected by properties of the surrounding medium such as rock electrical conductivity and others.…”

Section: Borehole Acoustic Reflection Survey (Bars)mentioning

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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Section: Borehole Acoustic Reflection Survey (Bars)mentioning

confidence: 99%

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

2021

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“…, ; Maia et al . ). The Sonic Scanner identifies the reflector azimuth by analysing variations in the distances to a reflector among different azimuthal receivers, and it can also locate the position of a nearby borehole (Jervis et al .…”

Section: Introductionmentioning

confidence: 97%

Experimental study on the performance of an azimuthal acoustic receiver sonde for a downhole tool

Che

Qiao

et al. 2016

Geophysical Prospecting

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A B S T R A C TA new azimuthal acoustic receiver sonde with a body and corresponding circuits was designed for a downhole tool. The 64-sensor receiver sonde holds eight receiver stations that can be combined into at least 64 three-sensor receiver subarrays. As a result, the receiver sonde can use different sensor combinations instead of different transducer types to produce multiple modes, including a phased azimuthal reception mode and conventional monopole, dipole, and quadruple modes. Laboratory measurements were conducted to study the performance of the azimuthal acoustic receiver sonde for a downhole tool, and the experimental results indicate that the receiver sonde provides a consistent reception performance. Individual sensors receive similar time-domain waveforms, and their corresponding frequency bands and sensitivities are consistent within the measurement errors of around 5%. The direction of the reception main lobe is approximately parallel to its exterior normal direction. In addition, a receiver subarray with three sensors receives waveforms that have higher energy and narrower beamwidths. For individual sensors, the angular width of the dominant reception lobe is 191.3°on average, whereas that of the individual receiver subarrays is approximately 52.1°on average. The amplitude of the first arrival received by the receiver subarray centred at the primary sensor directly pointing to the source is approximately 2.2 times the average amplitude of the first arrivals received by the other receiver subarrays in the same receiver station. Thus, the maximum amplitude of the waveforms received by the receiver subarrays can be used to determine the direction of the incident waves. This approach represents a promising method for determining the reflector azimuth for acoustic reflection logging and three-dimensional acoustic logging.

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“…A wide range of investigative logging while drilling measurements (LWD) can be used to detect karsts. For example, borehole acoustic reflected survey (BARS) [21], and ultradeep resistivity tools [22] are among the most promising. Although effective in certain cases [23,24], the main drawback of LWD tools is that the vast majority of them provide look-around measurements (also usually at a great distance from the bit) and do not look ahead of the bit.…”

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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First Borehole Acoustic Reflection Survey mapping a deepwater turbidite sand

Cited by 8 publications

References 2 publications

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

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

Experimental study on the performance of an azimuthal acoustic receiver sonde for a downhole tool

Real-Time Detection of Karstification Hazards While Drilling in Carbonates

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