Formation Fracture Gradient Correlation for Niger Delta Basin Natural Gas Wells

Offshore drilling of gas wells in the Niger Delta is becoming very expensive and requires high skilled manpower. Therefore, it is essential to accurately update the fracture pressure data, maintain adequate measurement while drilling and ensure acceptable prediction with the conventional empirical correlations as drilling operations is going on to avoid any Non-Productive Time (NPT) event. To effectively drill an offshore well and deliver it safely without endangering the safety of personnel, safeguard the environment and equipment, the drillers must ensure that the wellbore pressure is enough to balance the pore pressure without exceeding the fracture pressure anywhere along the open section of the well. In order to drastically reduce offshore drilling nonproductive time and take control the safety of men and materials on site, the need to calculate and predict fracture pressure is important. There are many correlations for predicting fracture pressure. However, they are mostly limited to onshore and shallow water fields, but as wells are being drilled deeper in Offshore Niger Delta field, there is the need to develop a correlation (equation) using offshore Leak-Off Test (LOT) report data that can reliably predict fracture pressure. Thus, this research adopts the concept of mathematical modelling technique to develop an improved offshore fracture gradient equation from Leak-Off test data to suit offshore Niger Delta needs was obtain to literature. The developed correlation (equation) was statistically analysed and it gave a reliable coefficient of determination. It was further tested with field cases and the results were comparable to Leak-Off Test results. Keyword: Natural Gas Well, Formation Fracture Gradient Correlation, Niger Delta