基于启发式算法的套管柱组合优化设计方法

针对深井、超深油气井中套管柱组合设计存在非线性、多目标和离散变量组合的问题，提出了一种基于启发式算法的套管柱组合优化设计方法。采用树状结构表示套管柱组合并将其参数化，给出了体现套管柱成本、质量和安全因素的设计需求向量，建立了以该向量为基础的可调多目标数学模型，并给出了利用启发式算法求解该模型的方法。通过与经典的套管柱设计案例进行比较分析，在最经济方案的情形下，利用所建立数学模型得出的解在适应值方面比原方法更好，如解3在成本和质量方面均有所降低，解2的成本降低4.057%，但质量增加0.274%。研究结果表明，基于启发式算法的套管柱组合优化设计方法得出的解具有合理性，且在一定程度上比原有解更优，可解决深井、超深井套管柱组合设计存在的问题。 

Optimization Design Method for Casing String Combination Based on Heuristic Algorithm

Casing string combination design in deep wells and ultra-deep oil and gas wells, has inherent problems, which are nonlinear, multi-objective and combinatorial with discrete variables. This paper presents a method for design optimization of casing string based on a heuristic algorithm. The casing string combination was represented by a tree structure and parameterized, the design requirement vector reflecting the cost, weight and safety factors of casing string was given, and the adjustable multi-objective mathematical model based on this vector was established. A heuristic algorithm was proposed to solve the model. The analysis involved the comparison and analysis with the typical cases of casing string design. Considering that, the mathematical model established in this paper was used to obtain a solution that had better value than the original method in terms of fitness in the case of the most economic program. For example, solution 3 led to a reduction of cost and weight, and solution 2 led to a reduction in cost by 4.057%, but in increase in weight by 0.274%. The results show that the solution obtained by this method is reasonable and better than the original solution to some extent. This approach can effectively solve the complex casing string combination design problem in deep and ultra-deep wells.