Study On Prediction And Treatment Of Gas Outflow In Gas Drilling

Gas drilling technology has developed rapidly with increasingly wide application in oilfields. Compared to conventional drilling, gas drilling has more technical ad-vantages such as high penetration rate, well leakage prevention and reservoir protec-tion.However, in the actual drilling, if formation water production has been encoun-tered, it is much more likely to cause formation collapse, sticking and other compli-cated downhole accidents., which imposes restriction on the application range of gas drilling. Therefore, accurate prediction of water production interval, confirmation of water flow and how to deal with formation water production have become the bottle-neck of promoting the application of gas drilling technologyBased on hydrogeology, hydrodynamics, oilfield chemicals and welll logging in-terpretation and basic theory of multiphase flow, through model building, visual sim-ulation experiment, laboratory evaluation and other ways, combined with the actual conditions of gas drilling, with the research on the prediction methods of formation water production in gas drilling and evaluation methods of super-absorbent polymer (SAP) treatment, the paper has acchived the following results:1) Summarized the influence factors of formation water production during gas drilling, divided the produced water into two kinds, shallow water and deep water, got the corresponding prediction method.2) With the unsteady seepage flow model as the foundation, coupled with the formation stress, we established the dynamic mathematical model for predicting water production,got the dynamic water production law and an example is given to prove the accuracy of the model.3) According to the gas drilling condition, the experimental scheme is designed to adapt to the annular space after the mist flow and liquid flow, by comparing the six kinds of super absorbent which were commonly used in engineering projects,we got the performance differences of temperature resistance, salt resistance, acid resistance and alkaline resistance, provided a theoretical basis for the further optimization.This study can provide theoretical basis for well selection, optimization selection of production layer in gas drilling and approach to dealing with information produc-tion.It is also of important guiding significance to the parameter optimization in gas drilling and well construction safety.