Study On Lost Circulation Diagnosis And Decision-making System Based On Case-based Reasoning

The lost circulation happened in drilling operation is sudden and difficult to control.The prevention and plugging of the lost circulation has always been a difficulty in drilling process.At present,the research and application of artificial intelligence technology in the field of lost circulation has become a major trend.Machine learning algorithms such as BP neural network and support vector machine(SVM)have been applied to the diagnosis of lost circulation.Case-based reasoning technology should also be applied to the construction of lost circulation decision-making database.However,there are some shortcomings in these studies,such as the single parameters of algorithm analysis and the high time complexity of case similarity calculation.This paper studies the system of the lost circulation diagnosis and decision-making based on case-based reasoning using machine learning algorithm on this basis.The research is divided into two modules: pre-drilling diagnosis and intelligent analysis of lost circulation treatment measures.The pre-drilling diagnosis module is divided into two parts: using GBDT to design drilling fluid parameters;analyzing the data affecting the lost circulation to carried out the pre-drilling diagnosis.Intelligent analysis module of lost circulation treatment measures uses case-based reasoning technology to establish lost circulation case decision-making database and retrieve lost circulation cases and puts forward corresponding measures for lost circulation treatment.Gradient Boosting Decision Tree(GBDT),as a machine learning algorithm,has the characteristics of high prediction accuracy and ability to deal with non-linear data,meeting the requirements of lost circulation parameter processing and lost circulation diagnosis.LB?Keogh algorithm can reduce the time complexity of case similarity calculation and improve the calculation efficiency.Analyzing the factors affecting lost circulation,this paper selects 17 parameters,such as formation parameters and drilling parameters,as calculation parameters of GBDT and LB?Keogh algorithm,realizing the purpose of drilling fluid design,pre-drilling diagnosis and intelligent decision analysis of lost circulation.