Effective perforating and gravel placement: Key to low-skin, sand-free production in gravel packs

Document Type

Article

Publication Date

1-1-2011

Abstract

Cased-hole gravel packing is commonly used 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 systematic approach for removal of perforation damage, effective gravel placement, and packing of the perforation tunnels. It was found that dynamic underbalanced perforating (DUP) greatly increased the ability to pack the perforation tunnels and iniproved the connectivity to the reservoir. Guidelines to DUP 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 DUP before the gravel-pack operation, followed by pumping the gravel slugs in a nondamaging carrier fluid in concentrations ranging from 1 to 3 Ibm of proppant added per gallon of fluid (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 implemented successfully at the Abu Cluster field in west Malaysia. This reservoir had extremely high permeability (1.5 to 3 darcies), with sand production a major concern. Several jobs were completed with the previously mentioned technique, and perforation-packing factors improved from 8 to 38 Ibm of gravel per foot of perforations. Discussion of the placenient and production data is presented. Sand-free production has been achieved with reduced drawdown across the sandface. The results show a linear relationship between pack factor and normalized productivity index (P1), indicating that gravel-packed perforations improve well productivity. Copyright © 2011 Society of Petroleum Engineers.

Publication Title

SPE Drilling and Completion

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