MAXIMIZING WELL INTEGRITY CHARACTERIZATION IN SCALED/CORRODED COMPLETIONS:EXPERIENCE WITH LOWER COMPLETION ABANDONMENT OF NORWEGIAN SHELF WATER ALTERNATING GAS(WAG)INJECTOR

摘要

Mature fields deliver nearly three-quarters of today’s global hydrocarbons production,but feature multiple well integrity problems that require extensive maintenance.As the industry focuses its efforts on monitoring these conditions while increasing intervention efficiency,a logging solution has been developed to successfully characterize cement and pipe conditions with reduced well downtime,particularly in aging wellbores. Combining technologies to overcome individual tool limitations is not a new concept;sonic and ultrasonic tools are often run in tandem to determine various levels of cement bonding. Despite the combined use of these tools,however, the presence of corrosion,scale,or parted casing can adversely affect acoustic response,and ultimately result in ambiguous or unsuccessful logs. The addition of an electro-mechanical caliper tool to a sonic/ultrasonic toolstring has been the key factor for maximizing interventions in compromised wells.All three tools operate on a single telemetry,and acquire ultrasonic,cement bond log(CBL),and caliper measurements simultaneously.This package can provide a wealth of information,including conventional logs,3D interactive maps,and statistical pipe wear reports. In addition,pipe and cement integrity breaches can be determined by cross-referencing acoustic log quality control(LQC)data to individual caliper measurements to create an additional degree of LQC between tool responses. The sonic/ultrasonic/caliper tandem toolstring was recently used in the Statfjord C-30A water alternating gas(WAG)injector,in which liner and cement integrity determination was required before abandoning the well.Statoil’s well engineering team was aware that both corrosion and scale were present in the well completion,but did not know their extent or whether the legally mandated,75-m annular cement column maintained hydraulic isolation of the injection horizon.The log results indicated that some corrosion and several choke points existed inside the 7-in.liner,but did not indicate a loss of cement bond or lack of pipe integrity. The multi-tool well integrity solution was important to reduce intervention time and abandonment costs in the Statfjord C-30 well by ensuring lower completion barrier integrity without multiple runs-in-hole.The added benefits of monoconductor wireline operations, deployment flexibility(coiled tubing,tractor),and rigless logging make this intervention service highly applicable to most well conditions or construction challenges.