Perpustakaan Digital ITB

Barium is one of the most important element on weighting agent additive commonly used in drilling fluid. As weighting agent, barium has important nature in increasing drilling fluid density without reacting with other additives. These nature of barium that usually in compound of barium sulfate (BaSO4) become often used in order to handle kick phenomena in drilling operation. Despite of its advantages, barium will surely increase drilling fluid’s solid content. A massive amount of solid content results in disadvantages, one of them is causing formation damage in a form of pore plugging. Exploration well X was drilled in order to prove hydrocarbon presence in a sandstone reservoir. Kick phenomena occurred when penetrating the reservoir, so it was decided to mitigate by adding Unibar (barium-based weighting agent) additive into drilling fluid. Then, the kick was handled nicely and operation continued until the well penetrated the whole reservoir thickness. Therefore, when drill stem test data interpreted, the engineer found a high value of skin which indicate formation damage. It was predicted that the formation damage caused by solid invasion of Unibar’s solid content. The common solution in repairing damaged reservoir is usually done by stimulation, either acidizing or hydraulic fracturing. Meanwhile, in a case of high skin value, sometimes stimulation won’t give efficient result. The other solution for this kind of case is sidetracking. Sidetracking will result in a new hole, which if can be designed properly won’t repeat the same mistake that result in high skin damage.