New Milling Solution for Flapper Valve Removal on E-Line in Dry Well Environment

摘要

In 2017,offshore North Africa,a well in a dry environment utilized a new application of e-line milling technology in combination with a specialized bit to mill out a failed flapper.This was the first time this special bit with the e-line milling toolstring was used to mill out a flapper valve in a dry environment.With this paper the author will describe the history behind the milling bit design,the actual operation and production improvements.A gas well experienced a malfunctioning 7"x 4.56" 13 Cr.steel downhole flapper valve.Due to several operational challenges including limited well site access and temperatures over 150°C,there was a need for an alternative solution to mill the valve and allow access below it to re-perforate the well.The operator's method of choice was an e-line tractor and milling assembly that had previous success in the same area in similar conditions.Furthermore,a new milling bit was developed that drastically reduces milling debris and eliminates potential fishing runs.Finally,heavier intervention methods like coiled tubing were not possible to mobilize because of the weather conditions plus the risk of reservoir damage if introducing fluids required to mill on CT After the completion of the milling phase of the operation,another run was performed to set an access sleeve in the milled-out flapper valve utilizing an electromechanical setting tool.This access sleeve ensured that entry/re-entry through the milled flapper valve would be easily accomplished each time.The installation of the access sleeve was confirmed by first running a drift to TD,followed by the perforating guns toolstring and re-perforating the well.Milling of flapper valves and other well bore obstructions on electric line offers a cost efficient alternative technology to existing methods.Furthermore,it provides HSE benefits and logistical advantages by reducing the amount of required equipment and personnel.