Maintenance of desirable water, injection rates has been a problem at Bentonand is a problem to many waterflooding projects. Inability to maintain desirable injection rates is generally the result of plugging by precipitates in the injected water, skin effects incurred during completion, and limited reservoir capacity; Several methods have been used to alleviate this problem in the Benton field and one of the most successful has been hydraulic fracture treating.
Data from 29 fracture treatments of 26 injection wells at Benton show that water injection rates have been substantially increased. Although the behavior of other injection wells mask the effects of increased injection rates in treated wells, total liquid production has been increased in surrounding producing wells without adversely affecting produced water-oil ratios.
Fracture treatments have been varied, but an optimum treatment has not been conclusively indicated. However, results of water-base treating liquids compare favorably with the results obtained from the use of more expensive acid-base and/or oil-base liquids.
The physical nature of the fractures has been investigated by several different injection profiling methods. Pronounced profile changes have not been observed. It appears that existing zones of weakness in the formation have been extended and that a single vertical or horizontal fracture plane has not occurred.
Maintenance of desirable water injection rates has been a problem at Benton since the initiation of waterflood operations in November, 1949. The Benton water flood is not unique in this respect, since the problem of maintaining water injection rates is common to many waterflood operations. Considerable effort has been expended in an effort to solve this problem because of its importance to the success of any waterflood project. Inadequate water injection rates create unbalanced flood conditions which reduce flood efficiency, and cause flood life to be extended.