Study on the Lost Circulation Control Characteristics of a Reticulated Foam

A new reticulated foam was developed to deal with lost circulation. Laboratory study was conducted on the reticulated foam to examine its ability to control lost circulation in fractured formations with bridging method. A high performance lost circulation control slurry was developed through engineered concentrations of different lost circulation materials (LCMs), comparison between the reticulated foam and screen-type LCMs and compounding of the reticulated foam and screen-type LCMs. This LCM slurry was tried in a well drilled in the piedmont area in Kuche, Tarim, with a high density oil base drilling fluid. It was found that this LCM slurry had the ability of plugging long fractures, and was able to effectively increase the pressure bearing capacity of thief zones and to reduce the total amount of mud lost. The reticulated foam is deformable under pressure, suitable for plugging fractures of different shapes and sizes. Drilling fluid flowing within the foam was experiencing high flow resistance, and large amount of reticulated foam particles distributed inside the fractures formed multiple partitions of lower strengths to hinder the flow of mud, thereby buffering the pressure exerted on the end partition. The reticulated foam particles, along with rigid particles, can also effectively bridge the narrow parts of fractures to hinder mud flow in fractures. The reticulated foam becomes weak in oil base drilling fluids and at high temperatures; it therefore is suitable for use in water base drilling fluids and at low temperatures. The reticulated foam, with its raw materials readily available, is quite cost effective and is expected to find wide application in lost circulation control.