Publications

The Lengowangi field, located onshore East Java, Indonesia was discovered in 2006. The main challenges in this area have been the over-pressured Lower Ngrayong and Tuban formations. The first well, L-1, was successfully drilled in 2006 and currently produces up to 10 MMCFD. The second well, L-2, was drilled up-dip in 2008, but could not reach the target because of well control issues related to high pore pressure. Well was TDd about 2800 ft MD shorter than planned depth.The third well, L-3, was drilled as twin well near L- 2. To optimize drilling the L-3 well, a detail geomechanical evaluation study was conducted. The study utilized the drilling and log data gathered in L-1 and L-2 and aimed to establish the cause of overpressure and define the pore pressure profile of the field. The study concluded that significant overpressure exists in Lengowangi field. Subsequently, a Mechanical Earth Model was constructed for L-3 and safe and stable mud weight windows were established.L-3 was spud in early 2010 with study recommendations taken into account for well designing and drilling. Postdrill analysis of L-3 showed that pore pressure matched with the upper limit of the predrill estimate. The highest pore pressure estimated was 17.1 lbm/gal near the well bottom. For drilling further, mud weight could not be increased to recommended value of 17.4 lbm/gal due to drilling restrictions.Hence, some flows and connection gas were observed due to low overbalance. Drilling was considered a success as well TDd close to plan with improved borehole stability as compared to L- 1 and L-2. Mechanical Earth Model constructed for Lengowangi field can now be used for optimizing upcoming drilling activities in the field by improving borehole stability,defining the pore pressure profile and by establishing the safe and stable mud weight windows.