The problem of evaluating injection profile in Short Strings (SS) in a dual completion wells has been solved. The HPT/SNL combination to describe accurately and economically the injection profile within the borehole and behind pipe through long string will be demonstrated.
It is difficult and cost prohibitive to monitor injection in a dual completion. Because of this, injection with such completions often goes unchecked for years, wasting water, making wrong assumptions in reservoir performance and missing opportunities for effective water-flood management. Conventional production logging cannot be performed in Short String due to accessibility and are unable to determine the injection profile, therefore, advance tools are required. The objective of this study is to demonstrate how the HPT-SNL logs, run riglessly in the Long String(LS) only, track flow geometry and assess completion integrity.
The well WI-01 was re-completed as a dual water injector in Unit C and Unit D in SS and Unit F in LS in 2005. Due to several unresolved issues with well performance, it was decided to confirm injection distribution, determine any communication between the strings and check for cross-flows behind pipe. HPT/SNL in combination with standard production logging tool was run to meet the objectives reliably at minimal cost. Three logging runs were made in the Long String: First, with both strings shut-in, second with injection into SS and third, both string shut-in to measure transient responses.
The integrated response of High Precision Temperature (HPT) and Spectral Noise Logging (SNL) indicated Unit C and Unit D were active as expected. Additionally, HPT-SNL combination identified a thief Zone (Unit B) in a non-perforated interval contributing to injection. Injected water was observed flowing upward behind pipe between Unit C and Unit B even when the well was under shut-in condition, indicating cement failure.
The survey revealed no communication between the two strings, whereas minor injection was evident below the surveyed interval. The results from this survey will lead to injection optimization in both strings to increase ultimate recovery.