The Mancos shale in the San Juan basin can present challenging conditions when hydraulic fracturing treatments are performed in horizontal wells. Some of the issues while completing a well in the Mancos can be caused by overall geomechanics and reservoir properties; for example, high horizontal stress anisotropy and the presence of discontinuities, such as microfractures and lamination. This paper presents three case studies in which hydraulic fracturing placement issues were explored.

Normally, the interactions of geomechanics and reservoir properties cause high treating pressures or premature screenouts, as presented in previous publications. Ramurthy et al. (2009a, 2009b) and Potocki (2012) explain how and why properties, such as process zone stress (PZS), pressure-dependent leakoff (PDL), and geomechanics, can affect the hydraulic fracturing conditions and production results. Depending on how the well is completed, these challenging conditions can be either enhanced or minimized. When the reservoir and geomechanics are not taken into consideration in the completion design of the well, issues can occur during the hydraulic fracturing of the formation.

Issues including screenouts, pressure outs, and high pressure while trying to initiate the fracture can lead to the formation not allowing the placement of the designed treatment, improper stimulation of the reservoir, excessive completion costs, and more commonly than not, poor production. This paper presents three case studies. In all three studies, similar reservoir characteristics and geomechanical conditions occur, which pose challenging obstacles for both completion and production. The challenges were each addressed in different ways, resulting in different outcomes. In one case, no action was taken to mitigate these obstacles. In the second case, the area was studied using analysis service data, treatment data, and public information. This knowledge was applied to assist in the completion of the treatment without issues. In a more recent case, in a well with similar conditions as the two previous studies, only a portion of the recommendations were applied, with mixed results.

This paper presents the knowledge gained from the three case studies conducted in the Mancos shale, San Juan basin. General suggestions are presented when similar conditions are encountered while completing a well.

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