No two shale plays are the same. Experimental and field data shows that shale formations act differently when exposed to similar conditions. The instability of shale formation is considered one of the major problems facing drilling operations. Bit balling, cutting dispersion, washouts, and stuck pipes are some of the problems faced when drilling shale formation. Only recently, shale formation became a target for hydrocarbon production. Shale plays are the new frontier for drilling and development. When the oil price was high, it was economical to drill and produce from shale formation. Now that the price of oil is relatively low, drilling and producing from shale formation might not be that lucrative. To reduce the cost of developing shale plays, we need to understand the producing shale geomechanical properties. There have been many studies on conventional shale formation and it has helped reduce potential drilling problems in those formations. However, not all shale formations are the same, and solutions that worked with one will not necessarily work with others. That is why we need to conduct studies focused on producing shale. Two producing shale formations were used in this study they are Marcellus shale and Arabian Peninsula (AP) shale. This study is exploring the difference in swelling behavior between the one side of shale core sample that is in direct contact with fluid with the other side of shale that is not in contact with drilling fluid. This is meant to represent the swelling at the wall of the wellbore and the swelling near the wall of the wellbore. Six samples from Marcellus shale and six samples from AP shale were used in this study. Two samples from each formation were used to collect the mineralogy data using XRD/XRF tests and the remaining four samples were used in the swelling tests. For the swelling tests, the samples were half submerged in various drilling fluids where half of the core sample is inside the fluid and the other half hangs above the fluid level. Strain gauges attached to both side collect the swelling behavior continuously for seven days. Results shows that at low swelling levels the back side of the wellbore (near well bore) shrinks while the wall of the wellbore swells. However, at high swelling rate both the wall of the wellbore and near the well bore increase in size following a similar swelling profile.

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