Adaptation of Capillary String for the Surfactants Delivery into a Gas Condensate Well and Optimization of its Operation Using Dynamic Multiphase Flow Simulator

Abstract

The studied productive formation of gas condensate field is at the stage of declining production. The inflow of bottom water due to the rise of the GWC and the design features of horizontal wells (large tubing and liner diameters) create the prerequisites for the development of a liquid loading of wells. This necessitate the optimization of the existing method of liquid unloading by dosing surfactants into the annulus. In order to increase the efficiency of well treatment with a foaming agent, the use of a surfactant injection system through a capillary string suspended inside a tubing is considered. The use of this system allows to increase the speed and depth of surfactant delivery, use the potential of the well by simultaneous work in tubing and annulus during significant watering period (water flow rate: 50 and more m3 / day), reduce reagent losses associated with retention on the casing walls, and reduce the required consumption of surfactant. The capillary string for the pumping surfactant is applicated to ensuring the stable operation of gas condensate wells during liquid loading. But today there are not ready-made applied solutions for correctly accounting surfactant action in unsteady flows conditions in the well. The paper presents the substantiation and analysis of the capillary string introduction into the well for the pumping surfactant using specialized software. In the course of work, the main analysis tool is the dynamic modeling of multiphase flows in the conditions of steady and unsteady processes in wells. This approach use is aimed at determining the optimal depth and diameter of capillary, the required consumption and concentration of surfactant, the rate of its delivery to the bottomhole, and the liquid removal efficiency from the horizontal wellbore.