Review of Drilling, Completion and Remediation Methods for ASR Wells in Unconsolidated Aquifers

Segalen, AS ; Pavelic, P ; Dillon, P

CSIRO Land and Water

RP-ID  :  procite:f90ea51a-1727-4df4-b6ee-b9c22c700c9a

学科分类：地球科学(综合)

澳大利亚|英语

来源: CSIRO Research Publications Repository

【 摘 要 】

Executive Summary:The report is a literature review on the efect that alternative drilling techniques, well completion designs, and redevelopment and maintenance methods have in reducing the risk of perational problems for ASR wells in unconsolidated formations, and in particular, their influence on the rate of clogging of these wells.The goal is to find a combination of drilling, completion and maintenance techniques that optimize the productive life of conventional and ASR wells in unconsolidated aquifers.Although surprisingly few comparative cases studies were found, these revealed that: *production wells drilled with cable tool significantly outperformed reverse circulation rotary drilled wells in the same formation, * wells drilled using biodegradable mud gave rise to less clogging than when bentonite based mud was used in the same formation , * residual mud on or in the vicinity of the borehole wall severly limited recharge capacity, and reaming of mud-drilled wells prior to completion was highly effective in increasing specific capacity, * wire-wrapped screens and natural gravel pack completion significantly enhanced well performance compared with slotted casing and emplaced gravel pack in the same formation.These conclusions demonstrate the importance of the choice of drilling technique, and the quality of the drilling, well completion and design, in very significantly enhancing ASR well performance.Site-specific investigations are required to determine the nature and location of clogging material in order to define protocols to rehabilitate severely clogged injection wells.Furthermore, research is needed to determine; geological conditions under which reverse circulation rotary drilling is more effective than standard rotary drilling; the effect of reaming following rotary drilling with biodegradable mud; the effectiveness of dual-wall reverse circulation drilling; and to assess the potential for clogging and rehabilitation of horizontally drilled ASR wells.there appears to be inadequate data to reliably predict life-cycle costs of ASR wells accounting for rehabilitation.