Bit Selection for Offshore and Onshore Applications in Egypt

By

Gamal Gouda¹

(1) Halliburton, Egypt, Cairo, Egypt

 Achieving the highest rate of penetration with the least possible bit wear and minimal hole problems is the goal for every drilling engineer when selecting a drilling bit which is the main objective of this paper. Although there are many methods for bit selection, often more than one is used before reaching a decision. These methods are based on the following factors

-         Physical and mechanical Properties of formation units

-         Bit design

-         Roller cone bits & Fixed cutter bits

-         Applied drilling parameters

-         WOB - RPM Bit hydraulics

-         Bit dull Condition

-         Cost analysis

-         Offset bit record analysis

-         New bit features design

-         General geological considerations

-         Hole problems

-         Offset well logs analysis

-         Mud rehology

Field data survey for both onshore and offshore was collected from the Western Desert and Gulf of Suez in Egypt. All the data proved poor bit selection which resulted in slow penetration rate, extra tripping time, bit mechanical problems and higher estimated cost per foot. These problems are summarised based on IADC bit selection, applied mechanical parameters, bit working hours, and hydraulic parameters

Each individual area is investigated using the data set with regard to the conditions affecting bit performance in order to build a recommendation for a durable bit design and ideal bit working hours in motor applications. Additionally the process was used to determine the right application for the fixed cutter bits to improve the penetration rate and minimise bit mechanical problems in deep marine well