AAPG ACE 2018

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Utica-Point Pleasant Shale Structural Modeling in Carroll and Harrison County, Ohio

Abstract

The Utica-Point Pleasant Shale in the eastern Ohio became thicker and currently was the core area of Utica-Point Pleasant Shale oil and gas production. Along with the shale play development for near 10 years, several significant problems arise. What is the production rate in the next 10 or 20 years? What is the ultimate recovery factor? What is distribution of residual shale oil and gas? Where to drill the new wells to improve the recovery factor? Which are the candidate wells for refracturing? To answer these questions, reservoir simulation or hydraulic fracturing simulation is necessary and both of them need a high-precision structural model.

Structural modeling is not a new topic, but for shale reservoir the structural modeling becomes more difficult and complex due to horizontal wells. In the core area of shale plays (e.g., Carroll and Harrison County, Ohio for Utica-Point Pleasant Shale), horizontal wells are predominant with a few vertical wells. Different from vertical wells which are usually perpendicular or nearly perpendicular to formation surface, horizontal wells could have an angle ranging from 0o to 90o. In vertical wells the formation tops for all the formation surfaces should co-exist at the well location; however along the horizontal wells there is either only one formation top data for a certain formation surface or no any formation top data at all. Regardless of using 3-D seismic data or not, this makes the structural modeling a huge challenge to generate an accurate relationship between formation surfaces and horizontal wells in the area without any formation top data.

In this research, we collected both logs and trajectory data in Carroll and Harrison County, Ohio. Formation tops were interpreted from wireline logs (e.g., gamma ray log, density log and neutron log) and/or read from mud logs. With assumption that the trajectory data is accurate and the thickness of Utica-Point Pleasant Shale rarely varies in a small area along the wellbore, a method was developed to generate accurate surfaces having accurate spatial relationship with horizontal wells. The constructed structural model of Utica-Point Pleasant Shale provided the 3-D grids for reservoir simulation and hydraulic fracturing simulation, and should be useful for the trajectory design of horizontal wells in the future.