The pre-drill and real time while drilling overpressure prediction based on effective basin model concept

The problem of the pre-drill predictability of an overpressure phenomenon has been considered within the range of the Effective Basin Model concept. The inherent and numerical origins of the relevant prediction scenarios have been analysed. The solutions of numerical problems are attached in the form of the appendixes. The approach to the stabilisation of an inherent prediction error has been proposed. The real time correction of a pre-drill prediction in during drilling ("Look Ahead") mode has been considered in the context of the re-calibration or/and adjustment of a prediction model and a framework earth model respectively. The re-calibration problem has been introduced as an extension of the single-well data inversion problem. The corresponding ill-posed task has been formulated and the approach to getting its locally unique solution has been discussed. The relevant computer algorithm has been described in details. The applicability of the new approach and solution to the real time drilling conditions have been tested based on the speculative (North Sea area) and real data (Gulf of Mexico) examples. These tests confirm high converging speed of the updating routine and flexibility of the algorithm. The achieved results correspond to higher accuracy in comparison with available standard methods.