| After more than 40 years'water flooding development, the distribution of the formation pressure in Xing 1-3 Area has changed enormously compared with original one. The pressure has the characteristics which abnormal high pressure formation and low pressure formation is vertically co-existing and local well area becomes abnormal high pressure zone. If the formation pressure can't be predicted accurately, equivalent drilling fluid density can't be designed reasonablly and so that all sorts of complex accident are likely to happen during the production of drilling.Before drilling in Xing 1-3 Area, drilling complex conditions are analyzed by drawing drilling fluid density contour maps and the distribution maps of complex conditions and the causes of high pressure formation are analyzed by casing damage, static and dynamic data. The types and range of high pressure zone and the size of formation pressure are determined to provide evidence for drilling fluid density design. The pressure prediction and application of Xing Er Middle high pressure zone is used as an example to provide before drilling.During drilling, the way that high pressure formation, low pressure formation and normal formation are judged qualitatively is worked out by studying formation pressure data and the characteristics of logging curve. Based on principle of natural electric potential logging and field testing under the conditions of different resistivity and drilling fluid density, the perience formula that forecasts formation pressure by using natural electric potential logging data are fitted out.In the respect of drilling fluid density design, according to stratum properties, fluid property and formation pressure, the dangerous degree of the layers in the formation pressure section is evaluated and pick out the most harmful one to trace. By interpolating to the adjacent wells and the recursive method, equivalent drilling fluid density is designed one by one.
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