Assessment of Cold Production Strategies to Revitalize Mature Heavy Oilfields in the Peruvian Jungle

摘要

Mature heavy oilfields in the Peruvian jungle have been produced for more than 40 years with natural strong water drive assisted with ESPs. Primary recovery factor with cold production methods reached 15% in average, and ultimate recovery will arrive to 17% at economic limit of 98% water cut. Traditional completion systems in mature Peruvian oilfields include both some deviated wells with ESPs inmmediatly above 7" liner hanger, and horizontal wells completed open hole; thus, selective production is not possible and water flow eventually breakthrough to the well while reducing relative permeability to oil and oil rates. This paper proposes a methodology to evaluate cold production strategies to look for "new oil" in mature fields either by redefining completion technology alternatives or by applying new development schemes, which focus on delaying gas or water breakthrough, and avoiding by-pass oil. Based on experience and application in many oilfields in the region, some cold production strategies were identified as critical to bring new life to brown fields such as active inflow control devices (AICD), horizontal and multilateral wells from one slot and production optimization with real-time monitoring. Many successful applications of AICDs with horizontal wells were reported worldwide, and some recent projects in sub-Andean basins have recorded successful results in Colombia and Ecuador (10% to 30% increase in cummulative oil production and 10% to 50% decrease in water production, during the first two years). In addition, preliminary numerical simulation studies for mature heavy oilfields in Peru shows 10% increase in cummulative oil production and 15% decrease in water production during the first two years. On the other hand, automation and real-time monitoring of brown fields came up with a considerable reduction of downtime and production deferment (in between 65% and 85%) due to a proper planning of well interventions, as well as, an improved operational efficiency of equipment. Active inflow control devices (AICD) allows equalizing the influx of oil and unwanted fluids (water or gas) by creating additional backpressure in zones that produces at higher rates. Heavy oil (higher viscosity fluid) takes a relatively non-restrictive path while water or gas (lower viscosity fluid) flows through a tortuous path causing a decrease in its flow rate. On the other hand, both horizontal and multilateral wells increase drainage area, sweep efficiency, well productivity and recovery factors while delaying water breakthrough. Finally, the transformation of a mature field into a digital oilfield means not only downtime and reduction of oil production deferment, but also, a better well production performance, protection of equipment and maximization of operational efficiency.