Theory And Practices Of Foam And Foamed Drilling Technology

This doctoral dissertation is actually a conclusion of the author's work and practices personally in foam and foamed drilling technology. It mainly has two parts as follows: theory research of foamed drilling fluids, and practice achievements in foam and foamed drilling technology.The first part--the foam fluid theory research is a collected contribution of theauthor's 10-year long research practice and the related documentations. As one of the research achievements, the cleading and lost circulation of aerated foamed drilling fluids is of great significance and innovation, which gained appreciation of experts home and abroad, and will also direct our further research in foam and foamed drilling technology.As the second part of this dissertation, the practice achievements of foam and foamed drilling technology, includes the following information: the development of the foaming agent PQ-1, the practice of PQ-1 in underhole foamed drilling and aerated foamed drilling. The maker development of PQ-1, a key equipment of aerated foamed drilling fluids, can satisfactorily meet the needs of aerating with the absence of air compressor. These studies for the research programmes from the Sichuan Province and the Ministry of State land and Resources have been conferred many honors including one 2nd Place, two 3rd Place, and two 1st Place and three 2nd Place in Chengdu University of Technology.In short, the complete theory and practice system of foam and foamed drilling technology is composes of foamed fluid theory, development of foam agent, underhole foamed drilling technology, and maker development of aerated foamed drilling fluids and foam maker. The achievements based on this system are as follows:1. Upon the theory of foam fluids, and through macro and micro observations, we found the existence of the holewall adsorption of foam, proved its foam absorption formation mechanism from the views of colloidal chemistry and physical chemistry, and also put forward the viewpoint of three phases, three absorptions, and three characteristics through the microstructure analysis of foam absorption formation.2. This research proved the dynamic plugging and hydrophobic shield of foam formation. Under the guidance of foam fluid theory, this dissertation first discussed the theories of foamed mud fluid cleading and collision, and also set up the theory references for its generalization and applications.3. Based on the surface active agent theory, we developed the DF-1 foam agent from anionic surfactant and modified non-ionic surface active agent for drilling porposes. DF-1 foam agent, easy to produce, is stable, of low in cost with calcium and salt resistances, environmental friendly, and can be easily biodegraded. Hence, DF-1 is a novel foaming agent for drilling proposes with advanced technology. By now, we have not found any similar product with DF-1.4. Underhole drilling technology solved the difficulties of drilling in wet layers, deepened the drilling under water, and found an effective method of drilling hi pouring crushing layer. So, it is a novel drilling technology, worthy of further research.5. The aerated foam mud fluids can used in negative drilling, and enlarge the life of drilling bits for its low density, and low sap pressure. It is an excellent drilling fluid especially in the high permeable strata, and can lower the loss of drilling fluids in middle permeable strata. What's more, because of its high structural rheological behaviours, this type of foamed drilling fluids can stabilize the holewall, and is a novel drilling fluid eith great social and economic essentials.6. Based on the jet theory, and aimed at high mixing of air and mud, PQ-1 foam maker, a blade worm foam separation and cutting apparatus, can make it true that is foam-dispersed evenly, micro-foamed, and air-fluid ratio adjusted easily. This foam maker is structurally simple, light in weight, and suitable for field operation, makes it reality of foaming without air compressor, and solve the problem of using aerated foaming mud fluids...