Abstract
During drilling operations, it is essential to keep the wellbore pressure within the maximum value of the fracture pressure and minimum value of the pore pressure of the formation. To handle this challenge, the fracture pressure of the formation must be known as it is significant to determining the mud window design. This study developed a correlation that could predict the formation fracture pressure in the Niger Delta deep offshore field. Two different fields were considered for this model named Field 1 and 2. From these fields, fracture pressure data were gotten from 21 wells during leak off test (LOT) at different casing shoe depths. While carrying-out the analysis of data, assumptions were made that the formations throughout the Niger Delta basin obeys the principle of horizontality. Also, that the fracture pressure at same depth is uniform with the pressure at other location in the Delta. Scatter plot was used as the tool for the data analysis. A line of best fit was drawn to arrive at the correlation. This correlation has an R2 coefficient values of 0.9969. In conclusion, the correlation gotten from this study for predicting fracture pressure has shown to align with some data sets from the Niger Delta fields with very little variation. This can be used for planning of further drilling operations in the Niger Delta to make it easier, faster and more economical.
Highlights
Over the years, majority of exploration has been carried out in onshore and shallow offshore locations but changing economics and the depletion of the resource in shallow offshore has initiated the push for exploration to Deepwater and ultra-Deepwater locations
It is good to note at this point that fracture gradient is the relationship between formation fracture pressure with respect to depth
A model to predict the formation fracture pressure in the Niger Delta deep offshore which can help in saving cost and time of leak off test was generated
Summary
Majority of exploration has been carried out in onshore and shallow offshore locations but changing economics and the depletion of the resource in shallow offshore has initiated the push for exploration to Deepwater and ultra-Deepwater locations. As a result of this, drilling in Deepwater is on the increase than ever before but little is known about its geo-pressures; overburden, pore and fracturation pressures. The knowledge of these pressure parameters is needed in achieving optimum well design, drilling operations, casing design, stimulation treatments and economical well planning. There is the need to develop correlations that can yield improved prediction of fracture pressure for deep water wells so we can have more knowledge and control of the prediction process, as a more accurate geo-pressure prediction can lower cost, reduce problems and improve the safety of drilling operations generally
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