Abstract
As gas wells mature, the problem of liquid loading and the resultant intermittent flow can reduce production to rates below the anticipated decline curve. It has been demonstrated that the introduction of surfactants such as foamers can mitigate the problems caused by liquid loading, and experience has shown that the introduction of these production enhancing chemicals in a continuous stream at the perforations can significantly reduce critical velocity and extend the productive life of gas wells. At the same time, especially in offshore wells, Operators must maintain a fully functional safety system including the downhole safety valve and the surface master valves and actuators which are controlled by an operating panel and are an integral part of the emergency shutdown system. This is especially true for operators in the North Sea who must adhere to some of the most rigid safety requirements in the industry. Clearly a new system was needed to allow the continuous injection of production enhancing chemicals through the safety systems in the well while maintaining their full integrity.
This paper will detail the conception and development of a new downhole safety valve and wellhead penetration system, incorporating a capillary string, to allow an operator to inject production enhancing chemicals through the safety valve while maintaining full control of the surface and subsurface safety equipment. The new system, the deployment of which is also detailed in this paper, is installed by means of slick line and capillary string using a combination of proven intervention methods thus eliminating the need for a major rig operation and saving the operator substantial workover cost.
