Baltensperger PZ stated that erroneous estimation of hydrocarbon reserves can occur due to inaccurate forecast of formation pressures. Pore pressures prediction in shale is an intricate process as it canʼt be evaluated directly and requires inference from seismic velocities or acoustic travel time. As such, accurately predicting the pore pressure of the area will help to ensure an improved well design, mud weights program, risk assessment and field development plan. In an over-pressured region such as the Niger Delta, accurate prediction of formation pore pressure can greatly curtail non-productive time and destructive problems associated with drilling through over-pressured areas such as wellbore balance complications, influx of pore fluids into the well, blowouts, and lost circulations. Pore pressures determine where the casings are placed in the well and the magnitude of drilling mud to use in the course of drilling the well.
The forecast of pore pressure plays a crucial role in the planning and actual drilling phase of a hydrocarbon well. Keywords: Pore Pressure Niger delta Model
Given the above results, the modified Eatonʼs model showed more accurate predictions when compared with existing models and will be effective in predicting pore pressure in the study area. The statistical error analysis conducted revealed that the modified Eatonʼs model had the least absolute mean percentage error value of 2%. Results of the modelʼs sensitivity analysis revealed sonic velocity as the most sensitive parameter while findings from the Goal Seek analysis showed that increasing the exponent in the original Eatonʼs model from 3 to 3.9 yielded the most concordant result with the measured pressure data. In the development of an appropriate model for pore pressure prediction, Eaton model was modified for Niger Delta environment. Shale trend and overburden pressure were used as inputs in the models for predicting pore pressure using RokDoc. Density and sonic velocity logs were used in generating the overburden pressure and Normal Compaction Trend. A number of industries utilized pore pressure prediction models were appraised using offset well data from the Niger Delta. This paper provides a new approach for predicting pore pressures particularly for Niger Delta using offset well logs acquired in the Niger Delta. The existing models used for pore pressure predictions were developed using data outside Niger Delta environment as such a number of them yield inaccurate results. They predominantly occur as over-pressured zones, when these abnormal pressures are not predicted accurately prior to drilling, disastrous occurrences, such as kicks, and blowouts may occur. The pore pressure in most sedimentary formations such as it is in the Niger Delta, Nigeria are rarely normal.
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