应用屏蔽暂堵技术提高致密砂岩气层测井识别能力

致密砂岩气层低孔低渗、低初始水饱和度和裂缝发育等特征使其极易受到钻井完井液损害。钻井完井液侵入诱发的水相圈闭损害将使测井数据不能反映地层真实情况,导致气层测井响应弱或无,错判漏失气层。屏蔽暂堵技术在井壁形成薄、韧和渗透率近于0的滤饼,能减少和防止固相侵入和水相圈闭损害。以鄂尔多斯盆地北部塔巴庙致密砂岩气藏为研究对象,通过屏蔽暂堵钻井完井液室内评价和现场应用前后常规测井资料分析指出,屏蔽暂堵技术改善滤饼质量、井径和井壁粗糙度,为测井数据提供良好的采集环境,提高气层测井响应和测井解释含气饱和度,促使了高产气层发现。通过毛细管自吸实验揭示出水相圈闭损害是暂堵技术前未发现盒2+3高产气层的原因。

Application of temporary and shielding plugging technology to improve well logging responses for tight sandstone gas reservoir

Tight gas bearing sands are vulnerable to the damage from drilling fluids due to its characteristics of low porosity and permeability, low initial water saturation and natural fractures. Owing to the water phase trap damage caused by drilling and completion fluids invasion, the logging data do not reflect the real characteristic of gas reservoirs, which results in weak or no well log response and response and gas formation miss. A thin and strong filter cake without permeability is formed by using the temporary and shielding plugging technology favorable for guarding against solids phase invasion and reducing formation damage. This paper regards the Tabamiao tight sandstone gas reservoir in the north of Ordos Basin as the research subject and analyzes the conventional logging data separately obtained from laboratory evaluation and field application of shielding and temporary plugging drilling-completion fluid, showing that the temporary and shielding plugging technology can improve the filter cake quality and the roughness of well diameter and borehole face, provide a good condition for well data acquisition, enhance well logging responses to gas zone and the logging test capacity to gas saturation, and is beneficial to the discovery of high gas production formation. The capillary imbibition experiment reveals that the water phase trap damage cause the high gas production formation-Box 2 3- not to be found before applying the temporary and shielding plugging technology