I. Le Nir

Schlumberger (British Virgin Islands)

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Sheng Yang

University of Calgary

R.F. Bloemenkamp

Schlumberger (British Virgin Islands)

M. Ponziani

Deltares

Evert Slob

Delft University of Technology

Josselin Kherroubi

Schlumberger (British Virgin Islands)

Shiduo Yang

Schlumberger (British Virgin Islands)

Stefan M. Lüthi

Lucerne University of Applied Sciences and Arts

Tianhua Zhang

Fuzhou University

N. Springer

Geological Survey of Denmark and Greenland

Randy Brown

Cooperative Institutions

Schlumberger (British Virgin Islands)

Schlumberger (United States)

Schlumberger (France)

Schlumberger (Norway)

Delft University of Technology

Geological Survey of Denmark and Greenland

Chinese Academy of Sciences

China University of Mining and Technology

North China Electric Power University

Shell (Netherlands)

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Stratigraphie sismique tertiaire de la Mer du Nord.

I. Le Nir

On etudie la region du Graben Viking et ses environs, en Mer du Nord. Environ 3000 km de leves de sismique reflexion permettent de reconnaitre 6 sequences sismiques, de realiser un ensemble de cartes isopaques et isochrones et enfin de reconstruire les avenements sedimentaires cenozoiques. On caracterise la sedimentation dans ce bassin et on compare les taux relatifs de subsidence et de sedimentation.

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Sedimentology from Wellbore to 3-D Reservoir with High-Definition Borehole Images in both Water-Based and Oil-Based Muds

Proceedings (2014)

S. Yang Robert Laronga I. Le Nir R.F. Bloemenkamp T. Zhang

Recently two near-offset wells were drilled at the Catoosa, Oklahoma USA. The first well was drilled vertically with WBM and logged with an industry-standard high-definition microresistivity imager. The second well was drilled at 25 degrees deviation with OBM and logged with a prototype of a new-generation high-definition OBM-adapted imager. Significant specifications of the new OBM-adapted imager include 192 sensors providing 0.23 in vertical resolution and 98% coverage in 8-in borehole. A quick comparison of the various images acquired validates the quality of the new-generation high-definition OBM-adapted images. The OBM-adapted imager is able to deliver images that are equal to or better than an industry-standard imager run in a WBM environment. The high-definition borehole microresistivity images are increasingly well-established as key input to 3D modelling workflows in clastic reservoirs drilled with water-based fluids (WBM), providing structural and sedimentological control in the near-wellbore space with a much higher degree of confidence than seismic. We focus on demonstrating the use of such images in a workflow for 3D structural and facies modelling. The workflow consists of the several steps to enhance field models based on 3D seismic data, or to produce standalone models that do not depend on the availability of seismic data.

Environmental geology

Wellbore

Geophysical Imaging

10.3997/2214-4609.20142316

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Deep-Learning-Based Automated Sedimentary Geometry Characterization From Borehole Images

Petrophysics – The SPWLA Journal of Formation Evaluation and Reservoir Description (2021)

Marie‐Paule Lefranc Zikri Bayraktar Morten Kristensen Hedi Driss I. Le Nir

Sedimentary geometry on borehole images usually summarizes the arrangement of bed boundaries, erosive surfaces, crossbedding, sedimentary dip, and/or deformed beds. The interpretation, very often manual, requires a good level of expertise, is time consuming, can suffer from user bias, and becomes very challenging when dealing with highly deviated wells. Bedform geometry interpretation from crossbed data is rarely completed from a borehole image. The purpose of this study is to develop an automated method to interpret sedimentary structures, including the bedform geometry resulting from the change in flow direction from borehole images. Automation is achieved in this unique interpretation methodology using deep learning (DL). The first task comprised the creation of a training data set of 2D borehole images. This library of images was then used to train deep neural network models. Testing different architectures of convolutional neural networks (CNN) showed the ResNet architecture to give the best performance for the classification of the different sedimentary structures. The validation accuracy was very high, in the range of 93 to 96%. To test the developed method, additional logs of synthetic data were created as sequences of different sedimentary structures (i.e., classes) associated with different well deviations, with the addition of gaps. The model was able to predict the proper class in these composite logs and highlight the transitions accurately.

Data set

10.30632/pjv62n6-2020a4

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Lithological and Petrophysical Core-Log Interpretation in CO2SINK, the European CO2 Onshore Research Storage and Verification Project

SPE Reservoir Evaluation & Engineering (2010)

Ben Norden Andrea Förster D. Vu-Hoang Fons Marcelis N. Springer

Summary The storage of carbon dioxide (CO2) in saline aquifers is one of the most promising options for Europe to reduce emissions of greenhouse gases from power plants to the atmosphere and to mitigate global climate change. The CO2SINK (CO2 Storage by Injection into a saline aquifer at Ketzin) project is a research and development (R&D) project, mainly supported by the European Commission, the German Federal Ministry of Education and Research, and the German Federal Ministry of Economics and Technology, targeted at developing an in-situ laboratory for CO2 storage. The preparatory phase of the project involved a baseline geological-site exploration and the drilling of one injection and two observation wells, as well as the acquisition of a geophysical baseline and geochemical monitoring, in Ketzin, located near Berlin. The target saline aquifer is the lithologically heterogeneous Triassic Stuttgart formation, situated at approximately 630- to 710-m (2,070- to 2,330-ft) depth. A comprehensive borehole-logging program was performed consisting of routine well logging complemented with an enhanced logging program for one well that recorded nuclear-magnetic-resonance (NMR) and borehole-resistivity images, to characterize the storage formation better. A core analysis program carried out on reservoir rock and caprock included measurements of helium porosity, nitrogen permeability, and brine permeability at different pressure conditions. The saline aquifer at Ketzin shows a variable porosity/permeability distribution, which is related to grain size, facies variation, and rock cementation with values in the range from 5 to > 35% and 0.02 to > 5,000 md for porosity and permeability, respectively. On the basis of core analysis and logging data, an elemental loganalysis model for the target formation was established for all three wells. In addition, permeability was estimated using the Coates equation and compared with core data and NMR log-derived permeability, which seems to provide meaningful permeability estimates for the Ketzin reservoir. On the basis of the good core control that guided the petrophysical well-log interpretation in the first two CO2SINK wells, a porosity and permeability prediction by analogy for the third well is appropriate and applicable. The availability of cores was crucial for a sophisticated formation evaluation at borehole scale that characterizes the real subsurface conditions.

Caprock

Petrophysics

10.2118/115247-pa

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Citations (89)

Particle Shape Analysis for Conglomerate Reservoir Using Borehole Resistivity Images

A. Aviantara Sheng Yang Wei‐Feng Huang C. Chen I. Le Nir

Summary We develop this advanced analysis tool to get more precise results include the long axis length, area, sphericity and roundness. Moreover, the large/flatten patch can be used as paleocurrent analysis from the azimuth of long axis.

Sphericity

Paleocurrent

Roundness (object)

Conglomerate

Skeletonization

Traverse

10.3997/2214-4609.201903306

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Experimental validation of fracture aperture determination from borehole electric microresistivity measurements

Geophysics (2015)

M. Ponziani Evert Slob Stefan M. Lüthi R.F. Bloemenkamp I. Le Nir

We studied the electric response of fractures with laboratory experiments and numerical simulations for a full-bore formation microimaging tool. The laboratory setup was designed and built to perform controlled experiments with accurate measurements of all principal properties involved for electric borehole imaging. These properties are formation resistivity, mud resistivity, fracture aperture, pad position, and button current. The experiments were conducted on two types of limestone for fracture apertures ranging from 0.1 to 0.9 mm and mud/formation resistivity contrasts varying from 1/100 to 1/10,000. A numerical model was used to reproduce the laboratory configuration and to validate the results. The model proved to be an effective tool to optimize the experimental setup, and it was also used to study the effect of standoff (up to 5 mm) on the measured integrated additional current. Linear relationships between the fracture aperture and measured integrated current were found to be valid for the laboratory experiment and the corresponding numerical simulation. The measured integrated current could therefore be used to determine the fracture aperture if the other parameters are known. Two coefficients in the relationship were found to differ from those previously found using numerical simulations for the actual borehole situation. These differences are attributed to tool- and scale-dependent factors.

Aperture (computer memory)

Electric current

10.1190/geo2014-0334.1

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Citations (14)

Fracture Characterization from Formation MicroImager Data

Proceedings (2013)

M. Ponziani Evert Slob S.M. Luthi R.F. Bloemenkamp I. Le Nir

The Formation MicroImager (mark of Schlumberger) is an electric imaging tool that produces electrical scans of the borehole walls. These measurements provide useful information on the fracture aperture of naturally fractured reservoirs. In this paper, we present a laboratory set-up that was realized to perform controlled experiments on fractured samples using a Formation MicroImager pad. A three-dimensional numerical model was used to develop the laboratory set-up. Numerical simulations were run to investigate the relationship between the fracture aperture and its electrical response for different properties (mud resistivity, formation resistivity and tool standoff). Preliminary results showed the capability of the set-up to be used to perform controlled experiments for a wide range of fracture properties and investigate their influence on the determination of the fracture aperture.

Characterization

10.3997/2214-4609.20130805

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Citations (5)

High Resolution Sequence Stratigraphy Analysis in a Carbonate Reservoir from Borehole Resistivity Image: a Case Study from Tarim Basin, West China

All Days (2014)

Sheng Yang C. Xiao Wei Guo I. Le Nir

Abstract Formation heterogeneity due to fractures, vugs, and mixed lithologies complicates the characterization of carbonate reservoirs. The lithology distribution is controlled by multiple factors, such as sediment source, depositional environment, and diagenesis. In addition, fracture development is influenced by lithology, burial depth, local structure, and far-field stress. High-resolution sequence stratigraphy is one of the advanced methods that can be used to solve the lithology challenge. The method combines core analysis, conventional logs, outcrop studies, and seismic data. However, the analysis results are frequently constrained by the low resolution of the seismic and conventional log data and by limited core data. A new workflow for high-resolution sequence stratigraphy analysis integrates borehole resistivity images with seismic, log, and core data. First, the borehole resistivity images are compared with core data, and the depositional facies are identified from calibrated resistivity image data combined with multiple-domain data. Second, sequence stratigraphic surfaces are identified from seismic and image data and the thicknesses of crossbedding and sequence cycles are used to classify the strata stacking patterns. Finally, the distribution of depositional environments within a sequence stratigraphy framework is analyzed by integrating the sequence stratigraphy patterns with seismic attribute maps and petrophysical log interpretation to predict the sweet spot. This new approach was implemented in Block A8 of the Tazhong uplift in the Tarim basin. Six different depositional facies were identified from the core data from three wells and applied to an additional four wells and to noncored intervals. Isopach maps of the first long term sequence cycle were used to estimate the size of buildups (reef, mound) and predict the vug distribution. A recently drilled well confirmed the analysis results. This workflow can be applied to similar thick carbonate reservoirs in the shoal-reef margin of a carbonate platform. Introduction The Tarim basin has three main belts: the Mesozoic and Cenozoic foreland, the Tabei uplift, and the Tazhong uplift (Xianming Xiao et al. 2004). The Tazhong uplift, which has an area of 30 000 km2 is the most complex and difficult area for exploration. The Tazhong-1 slope-break zone extends 200 km from east to west adjacent to a major thrust fault zone in Lower to Upper Ordovician carbonate rocks. Much of the oil and gas discovered in the area occurs in the Upper Ordovician Lianglitage formation. A complex shelf depositional system developed during deposition of the Lianglitage formation. At the same time, the continental shelf margin subfacies along the Tazhong I faulted slope-break zone was developed, and high-energy reef, shoal, and mound facies developed. Within the Tazhong shelf, tidal flat, gently sloping shelf shoal, shelf wash, and mound subfacies developed. The study area, block A8, is located in the western part of the Tazhong I slope break. The first well was drilled in 2005. Eight wells have been drilled, and three of these show good production (Fig. 1). One more appraisal well was recently drilled.

Sequence Stratigraphy

Lithology

Isopach map

Outcrop

Petrophysics

10.2523/iptc-17411-ms

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Fracture Aperture Calculations From Wireline and Logging While Drilling Imaging Tools

SPE Annual Technical Conference and Exhibition (2014)

Carlos Maeso M. Ponziani I. Le Nir Josselin Kherroubi Daniel Quesada

Abstract The presence of fractures in reservoirs can have a large impact on short and long term production. Electrical imaging tools have a long history in the identification and quantification of fractures in boreholes drilled with water base muds. These tools are particularly sensitive to conductive fractures. The width (also known as aperture) of open fractures is calculated by a well-established equation, relating the fracture width to the excess current measured by the imaging tool (Luthi and Souhaité, 1990). Both mud resistivity and background resistivity of the formation need to be known or measured. The equation was derived from 3-D finite element modeling of the borehole imaging tools of the time. Recent work has revisited the fracture aperture calculations. The work has verified the approach for electrical imaging from modern wireline tools and extended the principle to Logging While Drilling (LWD) tools. A twofold approach has been taken for the work. Firstly 3-D finite element modeling had been carried out. This includes detailed modeling of the tool sensors' geometry and the analysis of the electromagnetic responses when the sensors are passed in front of a range of fracture widths. The modeling is complemented by a series of physical experiments carried out at Delft University. Setups utilized either a wireline pad or an LWD sensor from the relevant imaging tools. The sensors were traversed across two blocks separated by a precisely measured gap. Measured excess current relates to the fracture apertures and verifies the theoretical modeling work. This combined work confirms the equation for the fracture aperture calculation. In addition the coefficients for both the modern wireline and LWD electrical imaging tools are determined. Workflows for the quantification of conductive fractures identified on borehole images have been refined and implemented. Fractures are commonly not continuous across the borehole. The workflow includes a fast automatic extraction of both discontinuous and continuous fracture segments. Fractures are grouped into sets based on relevant criteria (such as orientation). Apertures are calculated using the relevant tool coefficients. The fracture density and porosity are then accurately computed along the well. This enables quantification and characterization of the fracture network, including a fast and easy recognition of intervals with specific aperture or porosity ranges. The workflow is demonstrated by examples.

Wireline

Logging while drilling

Aperture (computer memory)

10.2118/170848-ms

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Citations (10)

A New Approach for Automatic Quantitative Resistivity Image Calibration in Water-based Mud

Song Yang T. Zhang I. Le Nir Redha Hasan Al Lawatia

Summary We provide a new automatic system and apparatus that generates quantitative resistivity image from the apparent electrical downhole acquired images. The analysis results from two case studies show that the new system is not only automatic, but also reducing the uncertainty to get more accurate fracture and vug evaluation parameters because of the processing steps take the hardware bedding response into consideration.

Semi automatic

Bedding

10.3997/2214-4609.202178011

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