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47th Annual AAPG-SPE Eastern Section Joint Meeting

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Issues of Horizontal Well Previous HitLogNext Hit Interpretation: an example Longmaxi-Wufeng Shale in Fuling Gas Field of Eastern Sichuan Basin

Guochang Wang1, Shengxiang Long2, Yiwen Ju3,4, Cheng Huang3,4, and Yongmin Peng2


1School of Science, Saint Francis University, Loretto, PA 15940, USA
2State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China
3College of Earth Science, University of Chinese Academy of Sciences, Beijing 100049, China
4Key Laboratory of Computational Geodynamics, Chinese Academy of Sciences


October 7-11, 2018 – 47th Annual AAPG-SPE Eastern Section Joint Meeting, Pittsburgh, Pennsylvania

Posted: May 3, 2019

Abstract

The wireline logs in horizontal wells provide a great opportunity to estimate the lateral variation of reservoir properties. This is a big benefits compared to the Previous HitlogNext Hit data from vertical wells. But the interpretation of horizontal well Previous HitlogNext Hit data also brings many new issues. One major issue arises from the data acquiring of Previous HitlogNext Hit data in horizontal wells. Due to the difference of detection depth and detection direction of various logging tools, the measured zones are not the same. This is not a significant problem for vertical wells, but it has caused some abnormal phenomenon that were observed in horizontal well Previous HitlogNext Hit data. In this research, we summarized these abnormal phenomenon, then explained the reasons, and finally proposed the methods to deal with it. Another issue is the instability of horizontal wells in mudrocks reduced the quality of logging data in multiple parts of the horizontal section. To generate a reliable assessment of shale reservoir, this researched proposed a methods to detect the low-quality data by caliper logs. The third issues is related to identify the formation tops in the horizontal section of horizontal wells. Repeat of formation tops become common in horizontal wells, especially in the areas where the structure is complex. This makes it a challenge to pick the formation tops in horizontal wells for shale reservoirs. Longmaxi-Wufeng Shale in Fuling Gas Field is a high-quality, organic-rich mudrock. Shale gas production from this formation has been significantly increased in the last three years. In Fuling Gas Field, horizontal wells have been predominantly drilled with a few vertical wells, which is typical for shale reservoirs. In this research, we use it as an example to discuss the issues of petrophysical analysis of horizontal wells. First, we carried out the Previous HitlogNext Hit correlation primarily based on gamma ray and the set of Previous HitporosityNext Hit logs, to estimate the spatial distribution of Longmaxi-Wufeng Shale. Then, Previous HitlogNext Hit normalization and quality control were completed to improve the reliability of the interpretation results. Uranium Previous HitlogNext Hit with the differences among Previous HitdensityNext Hit, Previous HitneutronNext Hit and acoustic logs were combined together to interpret TOC content, which was verified by core-measured TOC content. Finally, the volume percentage of clay minerals were estimated by CGR (gamma ray from thorium and potassium only) Previous HitlogNext Hit and neutron Previous HitlogTop in aid of XRD data and ECS logs, as an intermediate step to proximately estimate the brittleness of organic shale.

AAPG Datapages/Search and Discovery Article #90335 © 2018 AAPG 47th Annual AAPG-SPE Eastern Section Joint Meeting, Pittsburgh, Pennsylvania, October 7-11, 2018