Improving the Productivity of Highly Damaged Intervals in Low Draw-Down Oil Wells Using Dynamic Under-Balance Gun Type: Case Study in Gulf of Suez Offshore Field, Egypt

Abstract

Through tubing perforating guns that are deployed by means of electric line has been the most economic perforation technique to provide connectivity between the pay zone and the wellbore in cased hole wells. Conventional E-line guns was the most common type of guns used, however during the last two decades various types of guns has been raised to improve the perforation efficiency. In offshore operating companies including Gulf of Suez Petroleum Company "GUPCO" rig-less perforation has been proved to be the cheapest stimulation method, in case of re-perforating an existing interval, when compared to coiled tubing jobs that requires rig-assist or even acid bull-heading which will need at least a fully prepared vessel for chemical tank storage in addition to the highly cost acid itself. Moreover, it is much cheaper than tubing conveyed type that is always accompanied with rig work-over. So using dynamic under-balance gun has become a smart solution that will recover all debris in perforation tunnels in order to achieve the maximum oil recovery. When using conventional guns for re-perforating existing intervals there is a large contrast in the degree of success, and it was obvious that in law draw-down wells re-perforating the low productivity intervals has minor improvement and in most cases it was useless this was latterly explained to be resulted from the insufficient underbalance. In this work, implementation of a specific type of guns (Dynamic under-balance perforating guns) will be presented. The mentioned type generates in-situ underbalance creating an instantaneous and controlled surge of formation fluids into the well, which cleans the perforation tunnels up to 97% and enhances the well's productivity. The dynamic under-balance perforation technique has been tried in four wells that seemed from production logs are contributing with little share or sometimes not sharing at all which has been attributed to skin effect. After re-perforation, the results were outstanding with an increase of 20–40% in the total liquid rate and incremental increase in the oil rate with more than 2000 BOPD in the mentioned wells. The stated results revealed that the oil-bearing intervals are now competing with the high productivity high water cut intervals which considered a valuable gain with considerable very low job cost. The new guns type has proved its success especially when compared its results with the previous re-perforation jobs using conventional guns in the same wells where the incremental oil gain was much less. It can be used as a cheap alternative for near well-bore stimulation jobs especially for offshore platform wells.