Horizontal wells on a global basis continue to serve as a primary well type for improving recovery efficiency, increasing reservoir drainage area, delaying water and gas coning, and increasing production rate. However, in longer, highly deviated and horizontal wells, non-uniform flow profiles can result in premature water or gas breakthrough, screen plugging, and erosion which can shorten well life and decrease well profitability.
This paper describes historical and new applications of a proven production technology system that optimizes production, delays water and gas coning, minimizes annular flow to prevent erosion, and ensures uniform inflow along the lateral at the cost of a minimized pressure drop in high-rate horizontal wells. Global applications to date of this system include sandstone and carbonate formations as well as light weight and heavy oil. The case histories presented include the Norwegian Sector of the North Sea and carbonate formations of Saudi Arabia, where this production technology, combined with sand control technology, has resulted in significant savings for the operator and improved production in horizontal oil wells.
In the effort to improve upon the economics in the production of oil and gas, highly deviated and horizontal wellbores are being utilized in new field development as well as brown field development to maximize reservoir contact, increase reserve recovery per wellbore and improve total well productivity. With the increase in reservoir contact via longer lateral sections, frictional effects in the wellbore can limit the useful length of a horizontal well unless a method to balance the inflow along the lateral length is implemented.
If inflow is not balanced along the lateral length, wells in reservoirs with an aquifer and/or gas cap face the risk of early breakthrough of water or gas. The frictional effects associated with producing from the entire lateral in long horizontal wells can be significant relative to the typically low drawdown pressures required to achieve target production rates. Neglecting friction effects without balancing inflow into the wellbore commonly leads to non-uniform encroachment of water or gas contacts resulting in premature breakthrough of water and/or gas as well as lower productivity and reduced reserve recovery. As illustrated in Figure 1, depending on reservoir characteristics, the point of breakthrough can vary based on variations in permeability or as in homogeneous reservoirs, breakthrough at the heel of the lateral section.
Globally, field applications balancing inflow into the wellbore have proven to prevent water and/or gas coning in sandstone formations as well as prevent excessive water breakthrough in naturally fractured carbonate formations. Field installations utilizing EQUALIZERTM technology to balance inflow into the wellbore have lateral lengths ranging from a 1000 ft of open hole reservoir contact to single lateral lengths approaching 12,000 ft as in the North Sea Troll Field. These longer single laterals in addition to wells with two or more laterals integrating EQUALIZERTM technology are allowing increased reserve recovery with fewer wells.
UNIFORM Inflow Control System