控压钻井条件下井身结构优化设计

基于控制压力钻井技术进行了钻井液密度窗口分析,并且与常规方式下的钻井液密度窗口进行了对比。由对比分析结果可知,控制压力钻井能够扩宽钻井液密度窗口,且不同控压钻井方式对钻井液密度窗口的加宽方式和效果不同。这种扩宽方式能够使每开钻井深度增加,减少套管层次,进而优化井身结构设计。同时以自上而下的井身结构设计方法为基础,考虑了井口回压值和双密度梯度这两种方式对下部液柱压力的影响,建立了控压钻井井身结构优化设计模型。通过计算每层下深所用的钻井液密度窗口,在窗口内根据力平衡方程进行迭代判断,从而计算出最优下深。

Casing program optimization with the managed pressure drilling technique

Based on the managed pressure drilling technique (MPD), and compared it with the drilling fluid density window of the conventional drilling method the drilling fluid density window was analyzed. The results showed that the managed pressure drilling technique can broaden the drilling fluid window and different MPD methods widen and affect the window in different ways. This widening mode can increase the drilling depth of each drilling section and simplify casing program, consequently, the casing program design is optimized. Based on the casing program designed from top to bottom, an optimized design model for casing program with the managed pressure drilling technique was established by taking effects of wellhead backpressure and double-density gradient parameters on the downhole fluid column pressure into account. An optimal casing depth was consequently calculated by computing the drilling fluid density window used for the casing depth of each section and making iterative estimation by force balance equations within the drilling fluid density window.