深水表层钻井循环压降计算研究

RESEARCH ON CALCULATING CYCLE PRESSURE DROP IN DEEP WATER DRILLING

考虑深水低温对钻井液流变性的影响,采用分段计算不同深度井段钻柱内循环压降,然后迭加的方法计算钻柱内总的循环压降。海水越深海底钻柱内温度越低,采用分段计算然后迭加的方法计算钻柱内循环压降更准确。环空层流循环压降计算,运用相关系数法对深水表层钻井液流变模式进行优选,最适合的流变模式是幂律模式。若用宾汉模式计算环空层流循环压降,其计算结果比幂律模式计算结果高好几倍。因而要准确预测环空循环压降必须采用优选出的钻井液流变模式计算环空循环压降。

Considering the impact of deepwater hypothermia on drilling fluid rheological property,through subparagraph calculating the loop pressure drop in the drill string of different depth,and the total loop pressure drop within drill string was obtained by superposition method.The deeper of the sea water,the lower temperature within drill string,so it was more accurately to calculate the loop pressure drop inside the drill string by using the method of superposition.The annular laminar flow loop pressure drop was calculated,the drilling fluid rheology model of deepwater surface layer was optimized,and the most suited rheological model was the power-law model.If using Bingham model calculated the annular laminar flow circulating pressure drop,the calculated results were several times higher than power-law model.Thus to predict annular-space cycled pressure drop must be the optimized rheological model to calculate the annular-space cycled pressure drop.