The Bulkhead Principle – Delaying Water Cut and Improving Horizontal Well Productivity through Compartmentalization Using Short Swellable Packers

Abstract

Inflow control devices (ICDs) are used extensively to address the challenges of water management, particularly with the coning effects of water and gas inflow as well as permeability heterogeneity in horizontal wells. Historically, in Saudi Aramco wells, the horizontal open hole has been segmented in up to 6 compartments using mechanical openhole packers However, economic restraints and the risks have limited the running of a larger number of these packers. This paper discusses the development and results of a concept proposed to maximize the production potential from horizontal passive inflow control completions.In any well, there are uncertainties, both in the reservoir itself and in the operational events that work sequences can cause. A planned completion may not reach total depth (TD), or there may be undetected fractures or high permeability streaks in the reservoir section. A study has been undertaken to further enhance production and to maximize the benefit of inflow-control-device completions with the usage of slip-on swelling packers to increase the number of compartments in the open hole. It is assumed that shorter compartments will lead to an increase in net oil production, because water breakthrough can be managed more efficiently; i.e., the principle similar to that in a ship, where if there are no compartments and the ship leaks, it will fill with water and sink. If the ship uses bulkheads to form small discrete compartments and leaks, only the compartment with the hole is water filled. Likewise, if a well starts to produce water but is compartmentalized, only the section or sections with water will flood; the rest will continue to produce oil.In addition, we know through wireline logs, logging while drilling (LWD), or through the actual drilling results where we expect water or gas breakthrough to occur, but we are not able to predict with repeatable accuracy the nature of the fracture network in the matrix behind what we can see in the near wellbore environment. Then, it becomes beneficial to attempt to eliminate this uncertainty by increasing the number of compartments where the breakthroughs can occur.The short slip-on swellable packer, which was developed to provide a cost-effective annular isolation method, will be described in the paper along with the testing processes and field-trial validation that included nearbore simulation and modelling. The system has been proven as successful for sandstone and carbonate reservoirs. IntroductionThe development of horizontal wells has contributed greatly to increased productivity and is well documented. The industry drive to improve individual well output and overall field management has led to the adoption of many wellbore technologies such as multilaterals, maximum reservoir contact (MRC) wells, active inflow control completions, and openhole completions in both carbonate and sandstone reservoirs. Many of the earlier horizontal wells demonstrated challenges associated with the tendency for premature water breakthrough to shorten the productive life o...