Screen sand retaining precision optimization experiment and a new empirical design model

Abstract

In the design of sand retaining precision, the existing design methods consider unilateral factors or have limited applicability. A series of experimental tests for screen sand retaining precision optimization were performed. An empirical model was worked out by experiment results fitting. The experimental tests were performed using screen evaluation experimental apparatus with 35 types of formation sand samples and 9 types of screen samples. For all sand samples with different sizes, the optimum sand retaining precisions were determined by calculating the sand-passed ratios and flow capacity index under different sand retaining precisions. The experiment results were fitted, and a new model was put forward to design reasonable screen precision for a given formation sand, considering the median size, the characteristic size of fine composition and uniformity coefficient of the sand and real production condition. The model has been applied in more than 20 wells and the effect is very good. The model considers most important factors affecting sand control effect and has excellent adaptability. And the model provides an effective method to optimize the screen precision without the need of performing lots of experiment tests and is easy to be used. Key words: mechanical screen pipe, sand retaining precision, design optimization, sand retention experiment, sand control