Abstract

An operator in the Middle East is seeking to develop its natural gas resources to meet rising energy demand. This operator is drilling horizontal wells along the minimum horizontal stress direction in an attempt to generate multiple transverse fractures during stimulation to increase gas production in unconventional reservoirs. However, drilling operations in these wells is extremely difficult because of the in situ stress environment; these conditions result in a significantly increased number of stuck pipe incidents, wellbore collapse, incurring remarkably high nonproductive time. This paper describes the methodology used to define and calibrate the safe mud window for the curve and lateral section of the first horizontal well drilled in tight sandstone formation by conducting a wellbore stability study and real time drilling geomechanics and pore pressure monitoring. The wellbore stability study incorporates all logs and rock mechanical properties propagated on the direction survey and proposed formation tops of the planned horizontal well X-56. The well was drilled successfully with a mud weight of95 pcfto 98 pcf in the curve section and 100 pcfto 106 pcf in the horizontal section. Major technical contributions of this paper include: (1) Characterization of geopressures and stress field in different formations calibrated with real time data, (2) back analysis methodology to estimate fracture gradient from formation integrity test (FIT) & image logs, in addition to this (3) pore pressure zones designation along the stratigraphic column.

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