The Parameters Optimization Of Nitrogen-injection In Coiled Tubing

With the continuous exploration and development in deep zone gas fields, especially in low-voltage and low-yield wells, flowing back after fracture as an important part of deliverability rating had become a prominent issue in evaluating layer gas production rate. The means of the present flowing was concerned, coiled tubing nitrogen-injection was the most effective and safest methods, and it had many advantages, such as deep delivery, easy to operate, fast, efficient, short cycle and a high degree of safety. In this paper, an experimental would be designed to explore two-phase fluid in annulus space between coiled tubing and oil tube, define the calculation and formula of critical flow velocity, select the computational method of annulus pressure drop, and research the method of judging natural flow and the effect of different parameters. Then a mathematical model and a calculator program of coiled tubing service would be designed, which can calculate critical flow velocity, judge natural flow, analysis the affection when operation time and optimize them, all of these can provides a theoretical basis and technical guidance for field operation.