Innovative borehole treatment utilising inflatable packer straddle system technology

Abstract

Open hole fracturing and acid stimulation utilising the traditional cemented liner and hydro jet perforations or mechanical packers with ball-activated frac sleeves have been deployed successfully in the US and Canada for years. One of the primary concerns about the conventional liner methods is assurance of knowing where the fracture or acid is placed. There is no way to determine if there is adequate annular isolation to ensure the planned treatments are placed in the zone of interest.

In cased holes, conventional methods to stimulate perforated zones through matrix and fracture acidising would require isolating and stimulating each zone separately in multiple trips. Otherwise, bull-heading treatments with large volumes of fluid would make it difficult to control the penetration rate into the fractures, and zones could not be selectively acidised. To eliminate these issues, an inflatable packer straddle system was run in eight tight CSG reservoirs in the Bowen Basin (Queensland). The system was run to stimulate these reservoirs in two vertical wells with cased hole perforations.

It is understood that this was the first use of this process in Australian CSG wells.

This paper addresses the main considerations of tool operation, case histories highlighting job procedures, and lessons learned from previous operations. It also addresses the use of other tools with the straddle system and possible modifications to the system to make it suitable for operational conditions where higher rates and abrasive sand-laden fluids are required.