Abstract
A huge oil recovery opportunity waits in the reservoirs of mature oil fields. Reviving mature oil fields through advancements in oil recovery has opened the doors to renewed hydrocarbon production from wells that have been forgotten because of the natural depletion after years of providing.
One of these advancements is the effect of surging existing perforations using atmospheric chambers to create a dynamic underbalance at the instant perforations are created has been used in other oil and gas assets worldwide to improve production and, consequently, return on investment (ROI). This production increase was achieved with surge chambers to clean existing perforations.
This technology allows producers to obtain sustained higher productivity from their wells at a low cost. This system creates an instantaneous in-situ negative pressure in the wellbore that surges and cleans the perforated interval improving the wells inflow conditions. It is relatively inexpensive to treat a well because it can be deployed on wireline, slickline, jointed tubing, or coiled tubing (CT). These various deployment methods also make this technology available for rigless interventions.
This process uses fast-opening surge vents and atmospheric chamber assemblies that are activated milliseconds after the creation of perforations in the casing and perforation tunnels in the hydrocarbon reservoir. The dynamic underbalance in the wellbore surges these perforation tunnels, enabling the removal of debris and crushed material created by the high energy output of the explosive shaped charges.
This technique can be used to clean existing perforations that have become plugged-off or restricted as a result of scale buildup over time. To achieve this, the vent and chamber assembly are run without the perforating gun assembly.
This technology has been successfully used on rigless wireline operations, and in tubing-conveyed operations. The results have shown that it is possible to regain initial production rates at a relatively low cost as compared to other near-wellbore (NWB) stimulation techniques. This perforate and surge technique has also been used to reduce the operator's cost and time associated with a hydraulic fracturing operation in sandstone reservoirs. In scale-removal applications, this surge technique has been used to successfully remove barium sulfate (BaSO4). To validate these operations, using high-speed pressure/temperature recorders is recommended to capture the dynamic event (Schatz 1999).
In addition to the hardware associated with the vents, chambers, and perforating guns, a software component is used to accurately predict the amount of dynamic underbalance in a specific bottomhole assembly (BHA) to achieve the best perforation cleanup to maximize well productivity.
