A Massive Water Shut Off Job on the Ekofisk Field - An Inspiring Case History
by Daniela Arghir of ConocoPhillips
The presentation is a field case review of the process used to identify, characterize, design and execute a solution for a waterflood conformance problem in the Ekofisk field late 2014. The Ekofisk field is a highly fractures Maastrichtian Chalk reservoir located in the Norwegian sector of the North Sea. Large scale water injection in the field was initiated during 1987 and overall the field has responded well to waterflood operations. However, fault reactivation coupled with extensive natural fractures and rock dissolution has resulted in some significant conformance issues. Methodologies employed to identify and characterize these conformance issues will be outlined in the presentation. Details of diagnostic efforts and how they were used to identify, characterize and mitigate and injector/producer interaction through a void space conduit will be discussed. The selected approach involved pumping a large tapered nitrified cement job into the offending injector. This is believed to be the single largest nitrified cement job ever pumped in the oil industry. Due to extremely rapid communication with an offset producer, a protective gel was used to reduce the risk of cement entry into the producer. A brief review of alternative mitigation options and the reasons for selecting the nitrified cement treatment will be discussed. A complete review of the shutoff technique, product, damage mitigation strategy, and complications associated with timing and coordination in an offshore environment will also be discussed. Finally, a summary of lessons learned, job execution observations and post treatment performance results over the past three years, will be presented.
Daniela holds a staff reservoir engineer position with ConocoPhillips currently working on the Eldfisk field identifying water conformance and production enhancement opportunities. Previously she have worked with Petrom, Roxar and Halliburton before joining ConocoPhillips. Within ConocoPhillips she has held various positions working partner operated assets, the Ekofisk field and the Eldfisk field.