Abstract
The Corvina field is located to the north-west of Peru, in Tumbes Basin, Block Z1 (Offshore Perú), Figure 1. The reservoir, Zorritos Oil is defined as an anticlinal structure of fine- to medium-grained sandstone. The Field begins its exploitation in 2007 by 21XD well completion and it was not until late 2010 when the commerciality of the field was declared. The wells produced by natural flow of non-selective completions. The dominant reservoir mechanism drive is solution gas, with an initial pressure of 3300 psi, bubble pressure of 2850 psi and an estimated current static pressure of 2450 psi. To date 13 wells have been drilled between delineation and development wells, two wells have dual completion to meet functions as a producer and injector, an injector and the remaining wells are producers.
Production behavior of the field, production logging (PLT / MPLT) in existing wells and electrical logging in new wells confirm the formation of a secondary gas cap of higher pressure at the top of the reservoir, due to the effect of being the reservoir below the bubble pressure and gas injection through injection wells in these sands, this began from late 2011. The production behavior of wells shows a low lift efficiency of oil along tubing, due producing in conjunction with high volumes of gas and back-pressure on wellhead.
The workover campaign in 2012 was performed in order to select gas and oil producing sands, and install an “Auto Gas Lift” (AGL) installation, in the gas cap by including in the mechanical completion conventional gas Lift equipment, this permitted optimizing the production of gas and increased oil production.
For design of an installation, a commercial software was used to calculate the size of the injection port, so that allow the passage of required gas volume according to the well flow dynamics derived from nodal analysis.
The application of the technique of AGL in Corvina has been successful, achieving an increase in production wells, noting that one of them was up to 300 BOPD. These results have allowed expanding this technique to other fields of block Z-1, with positive results.
