Study On The Mechanism Of Meat Mud Pollution In

During the drilling process, drilling fluid plays a vital role, however, the solid and fluid phase in mud will inevitably invade the formation, and it will cause formation damage. A comprehensive analysis of the mechanism of mud contamination, and the establishment of assessment methods for mud contamination are not only help to diagnose the type of contamination and provide a theoretical basis for optimizing the type of drilling fluid, but also good for reservoir development safely, fast and efficiently. This paper uses the knowledge of reservoir physics, fluid mechanics and drilling engineering, and chooses laboratory experiments, mathematical methods, computer programming as a means, taking the study of formation damage mechanism, CT scans damage assessment and mathematical models damage evaluation as a key point, for a multi-aspects evaluation drilling mud contamination. The research includes four aspects.First, study the damage mechanisms, dynamic procedure and influencing factor about drilling mud invasion, including particles and filtrate of drilling mud.Second, in the analysis of mud pollution mechanism, combined SEM and EDS analysis to explain the micro pollution form, and get the images and data of this reactions.Third, use CT scanning the five whole diameter cores from Tarim Oilfield DB101-1wells after mud contamination experiment, and get a different perspective3D images of each core, as well as the gray curve for different section of along the crack direction for research solid invasion depth and distribution, and discusses the factors.Fourth, on the basis of physical model of laboratory core sample, established mud invasion mathematical model in porous media and fracture medium to obtain the relationship slurry concentration versus time and distance, and deduced the permeability distribution model and epidermal model, and simplified and solved the model.Fifth, physical parameters and the experimental parameters of contaminated cores from DB101-1well were used to validate the model, and obtained the relationship slurry concentration versus time and distance, as well as invasion depth, permeability and other parameters, and then discussed factors.Through the above work, we evaluated drilling mud contamination in multi-aspects from theory to experiment, and initially established laboratory evaluation methods for porosity fractured reservoir damaged by drilling mud.