Resistivity Ahead of the Bit – from Vision to Reality

Constable, Monica Vik; Antonsen, Frank; Seydoux, Jean; Omeragić, Dževat; Salim, David; Jensen, K. R.

doi:10.3997/2214-4609.201803135

Cited by 6 publications

(6 citation statements)

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“…[1] [2] [3]). Deep EM measurements is a technological step change that gives more information about geological structures, fluid contacts and reservoir properties deeper into the formation than traditional Logging While Drilling (LWD) measurements, even ahead of the bit [4]. The technology contributes to closing the gap between seismic scale measurements and well scale measurements.…”

Section: Current Methods For Geosteeringmentioning

confidence: 99%

A Novel Method for Locally Updating an Earth Model While Geosteering

Suter¹,

Cayeux²,

Friis³

et al. 2017

IJG

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Earth models are important tools for support of decision making processes for optimal exploitation of subsurface resources. For geosteering and other realtime processes where time is a major constraint, effective model management is decisive for optimal decision support. During drilling, subsurface information is received which should optimally be used to modify the 3D earth model. Today this model is typically not altered during the operation. We discuss the principles of a novel method that enables a populated earth model grid to be locally modified when the topology (connectivity) of the geological structure is locally altered. The method also allows local updates of the grid resolution. The modelled volume is split into closed regions by the structural model. Each region is individually discretized and obtains its own subgrid. Properties are stored in separate functions, e.g. for each layer, and transferred into each subgrid via a mapping. A local update of the geological structure implies that only subgrids in regions that are directly affected by the updated structure must be discarded and rebuilt, and the rest of the populated earth model grid is retained. Our focus is on decision support for optimal well placement while geosteering. The proposed method aims to manage multiple model realizations that are never fixed and always locally updated with the most recent measurements and interpretations in real-time, and where each realization is always kept at an optimal resolution.

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Section: Current Methods For Geosteeringmentioning

confidence: 99%

A Novel Method for Locally Updating an Earth Model While Geosteering

Suter¹,

Cayeux²,

Friis³

et al. 2017

IJG

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“…Looking ahead of the bit has been an object of research since the 1990s and is currently ongoing [45]. The unpredictable environment in front of the bit can pose significant risks for drilling.…”

Section: Resistivity Measurementsmentioning

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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“…The well trajectory resulting from the bottom scenario has a value of 49.81 equivalent meters of sand drilled, which is approximately 58.6% of the theoretically possible value for that scenario. Note that new developments improving the pre-drill model or the look-around/look-ahead capability (such as in Constable et al (2016)) will improve the decision outcomes provided by DSS.…”

Section: Optimal Landing In Different Geological Scenariosmentioning

confidence: 99%

A decision support system for multi-target geosteering

Alyaev

Suter

Bratvold

et al. 2019

Journal of Petroleum Science and Engineering

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Geosteering is a sequential decision process under uncertainty. The goal of geosteering is to maximize the expected value of the well, which should be defined by an objective value-function for each operation.In this paper we present a real-time decision support system (DSS) for geosteering that aims to approximate the uncertainty in the geological interpretation with an ensemble of geomodel realizations. As the drilling operation progresses, the ensemble Kalman filter is used to sequentially update the realizations using the measurements from real-time logging while drilling. At every decision point a discrete dynamic programming algorithm computes all potential well trajectories for the entire drilling operation and the corresponding value of the well for each realization. Then, the DSS considers all immediate alternatives (continue/steer/stop) and chooses the one that gives the best predicted value across the realizations. This approach works for a variety of objectives and constraints and suggests reproducible decisions under uncertainty. Moreover, it has real-time performance.The system is tested on synthetic cases in a layer-cake geological environment where the target layer should be selected dynamically based on the prior (predrill) model and the electromagnetic observations received while drilling. The numerical closed-loop simulation experiments demonstrate the ability of the DSS to perform successful geosteering and landing of a well for different geological configurations of drilling targets. Furthermore, the DSS allows to adjust and reweight the objectives, making the DSS useful before fully-automated geosteering becomes reality.

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Resistivity Ahead of the Bit – from Vision to Reality

Cited by 6 publications

References 0 publications

A Novel Method for Locally Updating an Earth Model While Geosteering

A Novel Method for Locally Updating an Earth Model While Geosteering

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

A decision support system for multi-target geosteering

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