Pore and fracture pressure modeling using direct and indirect methods in Badri Field, Gulf of Suez, Egypt

Abstract

Abnormal formation pressure is one of globally dominant drilling hazards because of its direct impact on the drilling operations and exploration risk. An adequate pore pressure and fracture gradient modeling are considered the heart of the well planning and execution. Safe drilling to reach total depth of any well is the main concern for both engineers and geoscientists. Consequently, the main objectives of this paper are evaluation of pore pressure and fracture gradients as well as identification of the geo-pressured zones (over-pressured) in the subsurface sedimentary section.The pore pressure and fracture gradients were evaluated using well logging data namely density, resistivity, gamma-ray and sonic logs obtained from offshore wells in Badri Field. The overburden (overburden stress) was calculated using Amoco overburden equation, while sonic and resistivity logs were used for pore pressure and fracture gradient calculations using Eaton's method.The results of this study revealed that: 1) integration of direct and indirect method can lead to adequate and accurate pore pressure modeling; 2) pore pressure regime shows over-pressured, normal pressure and sub-normal horizons; 3) over-pressured zones was detected in the base of Zeit Formation, South Gharib Formation, Hammam Faraun Member and Kareem Formation, pore pressure were 10.3, 10.5, 9.3 and 9.6 ppg equivalent density in arrange; 4) Reservoirs of Hammam Faraun Member and Kareem Formation indicated Sub-normal pressure zones where pore pressure values are varying from 5.5 to 6.2 ppg for Hammam Faraun reservoir and from 5.2 to 8 ppg in Kareem Formation in equivalent density; 5) Normal pressure regime was detected in the upper part of Zeit Formation and Feiran, Sidri and Baba members, where pore pressure value was recorded as 8.7 ppg; 6) Best fitting parameter for Eaton resistivity and sonic logs are 0.9 and 1.65 respectively while for Amoco overburden empirical equations, the Amoco exponent best fit is 0.85 where the mud line density is 2.15 g/cm3. Finally, it is highly recommended to use low mud weight against the under compaction zones and high mud weights against the identified over-pressured intervals.