Injection Completion and Well Integrity Performance of First Cyclic Steam Stimulations to Horizontal Wells in the Huyaparí Field

Abstract

The first thermal pilot project in the Huyaparí field (formerly Hamaca) in the Orinoco Belt in eastern Venezuela was designed to use ‘non-thermal’ wells in an existing cold producing field to explore steam stimulation injection and production response while maintaining wellbore integrity and safe operations. The pilot project consisted of performing cyclic steam stimulations in active horizontal producers. The selected candidates were active wells producing extra heavy crude oil (8–9 °API) from prolific unconsolidated sands with 30% porosity and >5 Darcy permeability. A selection process was implemented to identify wells based on favorable sand quality and dynamic reservoir conditions to address potential issues of relatively high-pressure high-temperature saturated steam injection conditions. A risk analysis was implemented to design the injection completion and workover program to maintain well integrity during high-temperature steam injection (550 °F). Well injection completion consisted of concentric vacuum-insulated-tubing (VIT), thermal hydraulic-set packer, thermal wellhead conversion, and high temperature downhole sensors; all designed to protect Class B cement and 9.625-in. J-55 BTC production casing. In addition, open-ended injection tubing was installed inside standalone 7-in. slotted liner (0.020-in.) approximately 1500 feet past production casing shoe depth to mitigate potential steam backflow. The steam injection phase consisted of delivering 80% quality steam at wellhead using a portable steam generator (25MMBTU). Upon injection completion, the well was left shut-in for five days to undergo a soak period to dissipate heat to reservoir. Finally, the wells were converted back to production by safely removing the injection completion and installing a 5.5-in. production tubing, sucker rods, insert rod pump, and downhole intake temperature-and-pressure sensors for monitoring reservoir behavior. This paper will discuss well selection criteria to achieve reservoir injection and production results, injection completion design based on wellbore risk analysis, and well integrity performance based on strain-based design using the Modified Holliday Stress Ratio (HSR) approach for thermal service tubulars of the first cyclic steam stimulation project in ‘non-thermal’ wells.