Abstract
There are several large carbonate reservoirs that have drawn great attention of researchers in recent years. After optimization of drilling technologies, how to deploy artificial lift technologies to develop them more efficiently is another concern. Conventional zonal water injection technologies require repetitive operation with wirelines and cables, causing extensive tests and low efficiency. However, an intelligent zonal water injection string consisting of several preset cable packers, water injection pressure gauges, formation pressure gauges and downhole flow meters has simply optimized water injection parameters and efficiently developed all reservoirs in some China's mature oilfields, especially when the string is integrated with remote monitoring and control methodologies.
With the rapid development of horizontal drilling and extended reach well drilling technologies, borehole conditions are becoming more and more complicated, which has brought more challenges to water adsorption testing of horizontal intervals and deployment of zonal water injection instruments. Compared with vertical wells, the water adsorption test and string running are more challenging for horizontal wells, in which we are faced by many a problem during zonal water injection, such as competitive slack off and tight pull, excessive or inadequate water injection, complicated operation process. Besides, well deviation, dog leg and horizontal section length shall be all taken into consideration during zonal water injection for horizontal wells. Therefore, novel strings and tools should be deployed.
Now tight pull, slack off and long operation periods are common problems during zonal water injection of horizontal intervals. After dedicated research, a set of wireless intelligent water injection strings for horizontal wells has been invented. Based on pressure pulse water distribution technique, the water injection string is eligible for 32-stage adjustment, so one strip may accomplish testing, adjusting, injection, measurement and downhole data collection, in addition to automatic error correction during water injection. The field trial shows that this novel string may be tripped in and out smoothly, packers are set securely and released easily, in order to adjust opening of each water injection nozzle in the ground, with an error of no more than ±10%. Therefore, the novel completion and water zonal water injection string is capable of injecting water precisely via remote control methods.
The wireless intelligent water injection string for horizontal wells that combines testing, adjusting, injection, measuring and data collection in one trip provides us with many downhole data, such as pressure, flow rate, temperature and so on. Therefore, water injection volume for each zone is monitored and controlled down hole. This technology is applicable for both horizontal and vertical wells that require zonal water injection.