Simulation of underbalanced drilling operation and comparison of economic feasibility with overbalanced drilling

Underbalanced drilling operation has been discussed which is classify as unconventional drilling method by making the bottom hole pressure lower than the formation pressure. To accomplish underbalanced, with lightweight drilling fluids, gas injection down the drill pipe, and gas injection through a string. It categorized in relation to the density of the fluids into five main fluid types based mainly on equivalent circulating density (gas, mist, foam, gasified liquid and liquid). Fluid type is detect by the boundary conditions of the drilling system. The economic feasibility and the comparison to the conventional drilling was covered with case studies for x well used to show beneficial effectiveness circumstances to do underbalanced drilling. The operation has been simulated in Geological formations of Egypt which help to predict whether it is possible to achieve a stable underbalanced condition by showing changes of bottom hole pressure with specific data such as design for drill string, reservoir data, mud program and well trajectory. The study is helpful to rise recovery of hydrocarbon, to reduce problems related with aggressive formation destruction and decreased cost when related with the cost of conventional drilling for the same formation. Further aids of this method help in the decrease in drilling time, larger penetration rates, increased bit life, a fast-productive reservoir areas indication, avoid loss of circulation and differential pressure sticking. One of the most significant phases of the underbalanced drilling operation is the planning phase. The applicant reservoir must assess for its appropriateness for underbalanced drilling before undertaking an Underbalanced Drilling project. It used when the formation has a flow that could be ranges under control while drilling. So, it can be used in Southern Iraq if there is much more understanding of the formations with instructions.