Heidrun - Results from Pre-Completed Techniques ells Using Innovative Gravelpacking

Abstract

Abstract During the initial phase of the Heidrun Field development, 5 wells were pre-completed using state of the art cased hole gravel packing techniques. The wells were tested and temporarily abdomen, awaiting tie-back to the Heidrun Tension Leg Platform (TLP). This paper describes the completion techniques applied and preaenta results of an evaluation of gravel pack efficiency for the wells. Flow and build-up tests were carried out on the semi-submersible drilling rig before and after gravel packing to evaluate initial productivity. Stabilized well test data acquired on the Heidrun TLP at full production is presented to document ultimate completion performance for each well. Many innovative completion techniques were applied to ensure high well productivity and secure the operational efficiency required for the Heidrun TLP. Innovations. The production casing was perforated via Tubing Conveyed Perforating (TCP) guns, 12 shots per foot, on a Drill Stem Test (DST) string with down hole gauges, thus allowing perforating, perforation clean-up and flow back, pre-gravel pack testing, and gravel pre-packing to be performed in a single run. A unique loss control formulation (LCM) was developed and applied to control fluid losses to the formation. This was the first application of an LCM which had an internal, temperature actuated, acid breaker integral to the LCM filter cake. Pre-pack modeling and alternating stage a of clear brine and slurry were used to optimize gravel placement. Zones ranged from 164 to 300 ft MD, and 1 to 10 Darcy permeability, in wells with inclinations from 45 to 53 degrees. A temporary abandonment system was developed and installed which utilized a weight actuated ball valve, run in the same trip as the post-gravel pack test string, in order to temporarily abandon the well without placing any damaging fluids across the production zone. This allowed the potions to be temporarily suspended with hydrocarbons across the zone and two mechanical barriers in place. The gravel pack screen assemblies included alternative path gravel placement utilizing 4 shunt tubes per gravel pack screen assembly. The innovative gravel packing techniques used at Heidrun resulted in high completion productivity and correspondingly high flow rata. A study performed to evaluate the economic impact of acceleration showed that going from a 20,000 BOPD well rate to a 30,000 BOPD well rate added $108 million in pre-tax NPV to Heidrun project economics. Actual results will be grater since well rates have exceeded 43,000 BOPD.