Abstract
PDVSA, began its first pilot test of a steam assisted gravity drainage (SAGD) production system in Latin America during June 1997. The "dual well" SAGD process requires the horizontal drilling of two wells one above the other. The upper well is dedicated to injecting steam in a continuous form and the lower to produce the reservoir fluids.
The pilot test was carried out in the Tia Juana Field, Western Venezuelan, where reservoir fluids are highly viscous (typically 20,000 cp. under reservoir conditions). Reservoir depth is approximately 1000 ft with a porosity of 38% and a permeability of 1-2 darcies. The pilot wells consisted of two pairs of infill wells within an original seven spot pattern with a well spacing of 231 meters.
The planning and implementation of the test was done between June and December 1997. Production started on December 15, 1997. The drilling stage of the pilot required the use of a "Magnetic Guidance Tool" (MGT) to drill the horizontal wells with a 5 meter distance between producer and injector along the horizontal section.
The paper shows pressure and temperature data acquired during the SAGD process from both conventional single point gauges and the latest generation of fibre optic distributed temperature measurements providing real time thermal profiles along the complete well bore.
The production results during the first year of operation show an average production of 700 bopd, which is above the initial production expected. This performance is promising, and it is expected that the initial objective of 60% recovery in the pilot area will be reached approximately 3 ½ years from the onset of production.
During the first year of production, a history match was performed using the Stars simulator. The comparison of real and simulated production shows close agreement and a final recovery in the order of 60 % of STOIIP has been estimated.
