ABSTRACT:

The concept of chemical enhanced "drilling" was first launched to the industry at the start of this century. This concept became reality end of 2005, and took place in Venezuela. Barefoot wells in a field in west Venezuela called Mara, equipped with bottomhole production pumps, have had significant oil production enhancement, when recompleted with additional drainage holes, using a chemically enhanced "drilling" method, herein referred as Acid Tunnelling. These lateral drainage holes are created on a rigless environment, with a specially made bottom-hole jetting assembly, with no rotating parts, such as turbine or drill motor. The assembly is mounted at the end of 1 1/2 "coiled tubing, and hydrochloric acid is pumped through, to create the lateral drainage holes. Hundreds of laterals (tunnels) were created on few wells, with a length up to 60 feet, at different and selected depths, with no directional control, based on available information (logs, reservoir geology, etc.). Considerable well production increment was observed as a result of these laterals, higher than previous production increments obtained by conventional stimulation techniques. This paper describes several wells where the "acid tunnelling" technique has been successfully deployed

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