Successful Chemical Water Shut-Off Treatment in Heavy Oil Fields of India

Abstract The instant paper relates to the successful water shut-off treatment in heavy-oil fields of India through squeezing polymer into the gravel pack completion well. Santhal and Balol are heavy oil fields with viscosities ranging from 50 cp-1500 cp, API gravity 16-17°, permeability 3-5 darcy, and both fields are supported by active edge water aquifer support. Due to mobility contrast, viscous fingering is a prominent issue in the reservoir, further aided by high permeability, leading to the formation of high permeable streaks, resulting in a drastic increase in WC in wells. To counter this problem, water shutoff jobs were carried out in the wells flowing with high water cut. Since the reservoir is highly unconsolidated and sand production is a challenge, all the wells are completed with Gravel pack. GP completion further complicates the water shutoff jobs in these wells as the standard practice requires GP retrieval and re-completion with GP, which is a costly affair and limits the number of jobs that can be taken up for WSO. To address this problem, bullhead WSO operations were carried out in Heavy oil fields, both with rig and rig-less methods. WSO in these fields has given very encouraging results with WC decreasing from ~95% to 70%. In some cases, no free water is observed after the job, indicating the sealing of permeable sand streaks which were contributing to the high water cut in these wells. Rig-less WSO was carried out in 13 horizontal wells in these fields producing with more than 95% WC and reduction of WC observed in 10 wells with incremental oil gain of ~44 tpd. The average production time after the job was around 3 to 4 months before the wells again started producing liquid with high WC %.