Study On Optimization Of Drilling Down - Tube Drilling Technology

Conventional the conduit casing operations commonly is drilling, casing and then cementing. However, unstable mud line, other issues and traditional practices are no longer suit for under the conduit for offshore deep-water operations due to the presence of the shallow strata relatively soft. The current emerged jetting casing drilling technology can solve the problems much better which tradition conduit casing practice do not work. In this text, based on jetting casing drilling technology in the offshore drilling practice, the depth of casing into the mud line and the key parameters of drilling pressure and displacement during the conduit jetting have been studied, the main contents and results are as follows:(1)According to the relevant known seabed soil parameters, the seabed minimum pressure gradient has been calculated and a shallow undersea formation breakdown pressure calculation model is established; The models of the minimum depth of the casing into the mud line and the suspension casing depth model have been established, at the same time the established models were calculated, analyzed and compared with a successful jetting case, the results showed:the model of minimum depth of the clay to calculate the waiting time can guide field operations and the minimum time of relieving CADA can be determined; Utilizing the suspension casing depth model, the depth while the waiting time can be obtained; taking into account the actual operating time and the depth of the casing into the mud line can be verified, and ultimately the depth of casing below the mud line can be determined.(2)Analyzing the impact of drill pressure on bit and displacement on jetting casing operation, the weighed selection calculation model and simplified calculation model are created and are calculated compared with the casing jetting operation, the result shows that two models can fit the calculating process. By study the jetting drilling theory, the minimum displacement is ascertained and the experiment has been taken. The experiment result and the jetting displacement control method are exactly the same, thus, the experiment are verified to be right.(3)According to the established model of formation burst weight on drill bit, the mud depth model and drilling weight on drill bit displacement model, a jetting drilling optimization software is programmed. The software can be sued to offer the conduit for jetting under drilling technology services, provide computing shallow seabed formation pressure gradient calculation and optimization of drilling depth into the mud displacement parameters such as weight on drill bit and offer curve corresponding to the result.