The crude oil produced by oil wells contains sediment, scale and other particles, which are deposited together with the wax in the process of crude oil pipeline transportation. It leads to a decrease in pipeline throughput, and may cause pipeline blockage and affect the safety of transportation in severe cases.The yield stress test and microscopic characteristic experiments show that there is a critical scale containing ratio in wax deposits of the influence of calcium carbonate scale on the strength of wax deposits. And it is found that the wax deposits containing scale will increase the breaking force on the wax layer and the pigging efficiency of the pig through the indoor pigging experiment of polyethylene pipeline. Based on the data of pigging experiment, a prediction model of pigging efficiency was established by using the π theorem. The model was validated by indoor experiments and third?party literature experimental data.

The evaluation of gas field development effect plays an important role in discovering the main contradictions existing in the current development, improving the level of gas field management and putting forward adjustment countermeasures. In this paper, a quantitative evaluation method for the development effect of condensate gas field is proposed from the three aspects of productivity, energy retention degree and well logistics property, and considering the recovery factor and pressure retention degree, et al. Firstly, the weight of each index is calculated based on the analytic hierarchy process, grey correlation method and RSR value comprehensive evaluation method, and then the membership matrix of each index is determined through the ridge distribution function and factor analysis method. Finally, the evaluation results are obtained through fuzzy change and optimal selection. The natural gas recovery rate of E+K gas reservoir in YH23 block is 82.95%, the condensate recovery rate is 58.57%, and the formation pressure maintenance degree is 87.8%. The development effect evaluation matrix Y =[0.623 7, 0.175 2, 0.201 1] can be obtained through calculation, which belongs to the class I development level. After verification, it is consistent with the actual evaluation results of the gas field, which proves that the proposed method is accurate and reliable, and points out the direction for the further development and adjustment of the gas field.