Perpustakaan Digital ITB

Wellbore stability is a vital aspect for the success practice of drilling planning and operation. An accurate estimation of sub-surface pressure is a necessity to maintain the wellbore stability which leads to safe and cost-effective drilling. One of the essential part of this sub-surface pressure is the fracture pressure profiles. Fracture gradient is the gradient required to induce fractures in the rock at a given depth and the estimation method can be classified into direct and indirect. Direct method relies on the measuring the required pressure to fracture while the indirect method is based on analytical or numerical models. The purpose for this study is to present an improved estimation for fracture gradient using well log data in which the well log data will be used for determining the in-situ variable. This study is a continuation from previous study by Corina et al. (2015) with addition of other in-situ variable determination method to be compared such as Zhang et al. (2017) and sonic log method. The continuation from previous study is including redo and improvement in lithology segmentation, overburden modelling, and pore pressure prediction. Although this study is specifically done for X field, it should be reliable as guidance for estimating fracture gradient on other fields and also for the verification of which existing fracture gradient in-situ variable determination method is the most suitable. Furthermore, The fracture gradient of each model is validated with the Gercek et al. (2007) value of typical poisson’s ratio. As a result, the method based on the sonic log from well log data is the most suitable in-situ variable determination method to be applied on this well.