Abstract
Most of horizontal wells was completed with uncemented screens to prevent from sand production in some oilfields near Bohai Bay east China. In recent years oil production of the wells have begun to decline due to water out of the wells, especially water rates in part of the wells were more than 98%. Finally higher water out resulted in the wells to be closed. A technique of water shut-off was developed. First of all, a tools string for chemical agent injection (TSCAI) was run into the wellbore. The chemical agent was injected into the annular space between the screens and the formation to form annular chemical packers (ACP). So the ACP could separate the formation into several sections to avoid annular communication. Secondly, a liner hanger with sliding switches and swelling packers (LHSSP) was run after TSCAI was pulled out of the well. The liner hanger was released after the packers were set. Finally a mechanical on-off element for the sleeves with coiled tubing string (ESCTS) was run to open\close the switches separately. By analyzing the well production date the operators determine that which layer water ed out. The ESCTS was run to closed water out layer. Well-A was a horizontal well drilled in 2006 in the Gaoqianbei zone of Jidong Oilfield. In 2010 production logging date showed that water content was 98.7%. A water shut-off action was done. The whole horizontal interval was separated three sections (No.1, No.2, No.3 layer). Finally after No. 1 layer was confirmed to be water cut layer to be closed, daily oil production was improved from 2 tons to 4 tons. Water content reduced to 70.9%. Generally, the successful water shut-off for well-A showed that the technique could efficiently enhance oil recovery with simple operation and low cost. It provides a new water shut-off method for other wells with different completions.
