| Popis: |
Cased-hole gravel packing is commonly utilized to control sand production from oil and gas wells. The success of a cased-hole gravel-pack job depends on the ability to effectively pack perforation tunnels, which act as conduits between the reservoir and the wellbore for hydrocarbon production. This project presents a system approach for removal of perforation damage, effective gravel placement, and packing of the perforation tunnels. It was found that surging the perforations greatly increased the ability to pack the perforation tunnels and improved the connectivity to the reservoir. Guidelines to surging the formation and executing the perforation packing job are presented. This study also discusses the current practices commonly employed in cased-hole gravel packing to pack perforation tunnels and the potential limitations of these practices. Incomplete packing of perforation tunnels is mostly encountered in gravel-pack jobs completed with brine as the carrier fluid (water packs). The proposed technique involves surging the perforations prior to the gravel-pack operation, followed by pumping the gravel slugs in a nondamaging carrier fluid in concentrations ranging from 1 to 3 ppa. These slugs range from 5 to 7 bbl and are pumped intermittently between stages of the completion fluid to minimize cost. The carrier fluid, by virtue of its viscosity and mechanical suspension capability, ensures that the gravel enters the perforations. This technique was successfully implemented at the Abu Cluster field in west Malaysia. This reservoir had extremely high permeability (1.5 to 3 Darcy), with sand production a major concern. Several jobs were completed with the above mentioned technique and perforation packing factors improved from 10 to 40 lb of gravel per foot of perforations. Discussion of the placement and production data is presented. Sand-free production has been achieved with reduced drawdown across the sandface and production rates as high as 5,000 BOPD. |
