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ቤተ መጻሕፍቲ ባይዱ
-1-
The 16th Formation Evaluation Symposium of Japan, October 7-8, 2010
connectivity of effective fractures from borehole surface into deep formation which are key factors to control producibility of volcanic formations. The approach has integrated current-available measurements with multiple depth-of-investigations in a systematic manner. Typical measurements considered are: drilling events such as mud loss, high resolution borehole images, advanced borehole sonic, and Borehole Acoustic Reflection Survey (BARS). A workflow is development to carefully evaluate fracture effectiveness. In particular, shear anisotropy enhanced by dispersion analysis enables us to evaluate producible fractures into formation up to several wellbore radius away from the borehole surface by distinguishing different dominant anisotropy mechanisms in rock, including homogeneous isotropic, inhomogeneous isotropic, stress induced anisotropy, and intrinsic anisotropy. More interestingly, BARS technique, instead of detecting formation reflection boundaries, has been applied in vertical wells in order to assess probable fracture networks deep into formation up to maximally over 10 meters (depending on tool configuration and signal-noise ratio) by a new generation sonic tool.
1. PetroChina 2. Schlumberger
This paper was selected for presentation by a JFES program committee following review of an abstract submitted by the author(s).
ABSTRACT
Volcanic reservoirs have become important exploration & development targets in China recently. This paper presents an integrated fracture delineation approach which uses available measurements with multi-scale depth of investigation (DOI) covers “borehole surface near wellbore - deep formation”. This paper will mainly focus on delineation of fracture effectiveness and assessment of extension and connectivity of effective fractures from borehole surface into deep formation which are key factors to control producibility of volcanic formations.
The 16th Formation Evaluation Symposium of Japan, October 7-8, 2010
Fracture Delineation in Volcanics – Case Studies in Junggar Basin, China
Sun Zhong Chun1, Wang Guo Bing1, Luo Xin Ping1, Wu Jin Long2, Xian Cheng Gang2, Yang Lei2, and He Yu Lou2
Conventionally, borehole image has been used a lot for fracture evaluation, because it can show very small fractures with direction and quantitatively calculate the fracture properties. However, borehole image used to classify fractures into conductive or resistive fractures is based on image morphology, but conductive fractures don’t equal to producible fractures which are Operators’ real main interest. Moreover, fracture reservoirs usually contain complex fracture networks, fractures detected from borehole image are only small fractures intersecting the borehole, the depth of investigation is too shallow to avoid borehole condition affection, and fractures without intersecting the borehole can’t be described by image. Mixing results from several wells drilled in volcanics reservoirs in Junggar basin confirmed the limitation of this method. Therefore, a more reliable approach is required.
This multi-scale approach has been implemented into multiple wells drilled in volcanic formations in Junggar Basin, West China. BARS technique was very firstly demonstrated here to evaluate probable fracture system in deep formation in vertical wells. Field cases demonstrated that this approach has helped more realistic or reliable evaluation of producible fracture zones and well producibility for better decision making.
The approach has integrated current-available measurements with multiple depth-of-investigations in a systematic manner. Typical measurements considered are: drilling events such as mud loss, high resolution borehole images, advanced borehole sonic, and Borehole Acoustic Reflection Survey (BARS). A workflow is development to carefully evaluate fracture effectiveness. In particular, shear anisotropy enhanced by dispersion analysis enables us to evaluate producible fractures into formation up to several wellbore radius away from the borehole surface by distinguishing different dominant anisotropy mechanisms in rock, including homogeneous isotropic, inhomogeneous isotropic, stress induced anisotropy, and intrinsic anisotropy. More interestingly, BARS technique, instead of detecting formation reflection boundaries, has been applied in vertical wells in order to assess probable fracture networks deep into formation up to maximally over 10 meters (depending on tool configuration and signal-noise ratio) by a new generation sonic tool.
INTRODUCTION
Volcanic reservoirs have become important exploration & development targets in China recently. In this kind of reservoir, porosity is usually very low; fractures play an important role not only as the migration pathway, but also as reservoir space. In Junggar basin, volcanics reservoirs are generally very deep. To test a drilled deep well in volcanics often is very costly. One key task is to identify producible fractures which are full of hydrocarbon as well as permeable. These producible fractures can directly contribute to the production of oil and gas, and high permeability provides increased productivity. Producible fracture delineation can help to select perforating intervals and optimize completion design. Secondly, preferential fluid path may cause drilling problems such as fluid losses or unwanted production; besides, producible fracture delineation can also offer great help in reservoir management and production optimization.
This paper presents an integrated fracture delineation approach which uses available measurements with multi-scale depth of investigation (DOI) covers “borehole surface - near wellbore - deep formation”. This paper will mainly focus on delineation of fracture effectiveness and assessment of extension and
-1-
The 16th Formation Evaluation Symposium of Japan, October 7-8, 2010
connectivity of effective fractures from borehole surface into deep formation which are key factors to control producibility of volcanic formations. The approach has integrated current-available measurements with multiple depth-of-investigations in a systematic manner. Typical measurements considered are: drilling events such as mud loss, high resolution borehole images, advanced borehole sonic, and Borehole Acoustic Reflection Survey (BARS). A workflow is development to carefully evaluate fracture effectiveness. In particular, shear anisotropy enhanced by dispersion analysis enables us to evaluate producible fractures into formation up to several wellbore radius away from the borehole surface by distinguishing different dominant anisotropy mechanisms in rock, including homogeneous isotropic, inhomogeneous isotropic, stress induced anisotropy, and intrinsic anisotropy. More interestingly, BARS technique, instead of detecting formation reflection boundaries, has been applied in vertical wells in order to assess probable fracture networks deep into formation up to maximally over 10 meters (depending on tool configuration and signal-noise ratio) by a new generation sonic tool.
1. PetroChina 2. Schlumberger
This paper was selected for presentation by a JFES program committee following review of an abstract submitted by the author(s).
ABSTRACT
Volcanic reservoirs have become important exploration & development targets in China recently. This paper presents an integrated fracture delineation approach which uses available measurements with multi-scale depth of investigation (DOI) covers “borehole surface near wellbore - deep formation”. This paper will mainly focus on delineation of fracture effectiveness and assessment of extension and connectivity of effective fractures from borehole surface into deep formation which are key factors to control producibility of volcanic formations.
The 16th Formation Evaluation Symposium of Japan, October 7-8, 2010
Fracture Delineation in Volcanics – Case Studies in Junggar Basin, China
Sun Zhong Chun1, Wang Guo Bing1, Luo Xin Ping1, Wu Jin Long2, Xian Cheng Gang2, Yang Lei2, and He Yu Lou2
Conventionally, borehole image has been used a lot for fracture evaluation, because it can show very small fractures with direction and quantitatively calculate the fracture properties. However, borehole image used to classify fractures into conductive or resistive fractures is based on image morphology, but conductive fractures don’t equal to producible fractures which are Operators’ real main interest. Moreover, fracture reservoirs usually contain complex fracture networks, fractures detected from borehole image are only small fractures intersecting the borehole, the depth of investigation is too shallow to avoid borehole condition affection, and fractures without intersecting the borehole can’t be described by image. Mixing results from several wells drilled in volcanics reservoirs in Junggar basin confirmed the limitation of this method. Therefore, a more reliable approach is required.
This multi-scale approach has been implemented into multiple wells drilled in volcanic formations in Junggar Basin, West China. BARS technique was very firstly demonstrated here to evaluate probable fracture system in deep formation in vertical wells. Field cases demonstrated that this approach has helped more realistic or reliable evaluation of producible fracture zones and well producibility for better decision making.
The approach has integrated current-available measurements with multiple depth-of-investigations in a systematic manner. Typical measurements considered are: drilling events such as mud loss, high resolution borehole images, advanced borehole sonic, and Borehole Acoustic Reflection Survey (BARS). A workflow is development to carefully evaluate fracture effectiveness. In particular, shear anisotropy enhanced by dispersion analysis enables us to evaluate producible fractures into formation up to several wellbore radius away from the borehole surface by distinguishing different dominant anisotropy mechanisms in rock, including homogeneous isotropic, inhomogeneous isotropic, stress induced anisotropy, and intrinsic anisotropy. More interestingly, BARS technique, instead of detecting formation reflection boundaries, has been applied in vertical wells in order to assess probable fracture networks deep into formation up to maximally over 10 meters (depending on tool configuration and signal-noise ratio) by a new generation sonic tool.
INTRODUCTION
Volcanic reservoirs have become important exploration & development targets in China recently. In this kind of reservoir, porosity is usually very low; fractures play an important role not only as the migration pathway, but also as reservoir space. In Junggar basin, volcanics reservoirs are generally very deep. To test a drilled deep well in volcanics often is very costly. One key task is to identify producible fractures which are full of hydrocarbon as well as permeable. These producible fractures can directly contribute to the production of oil and gas, and high permeability provides increased productivity. Producible fracture delineation can help to select perforating intervals and optimize completion design. Secondly, preferential fluid path may cause drilling problems such as fluid losses or unwanted production; besides, producible fracture delineation can also offer great help in reservoir management and production optimization.
This paper presents an integrated fracture delineation approach which uses available measurements with multi-scale depth of investigation (DOI) covers “borehole surface - near wellbore - deep formation”. This paper will mainly focus on delineation of fracture effectiveness and assessment of extension and