本研究利用以往在台灣新竹及苗栗地區油氣井的井下資料，計算現地應力包括：孔隙液壓、地殼上覆荷重壓力、以及最大及最小水平應力。這些井下資料包括：1、水力破壞試驗 (在完整不含裂隙的岩層段實施滲漏實驗、長時間滲漏實驗或是迷你液裂)；2、井壁因大地應力集中造成裸孔伸張(borehole breakouts)的破壞；3、因鑽井導致人為的伸張裂縫。進一步配合實驗室的三軸岩石破壞試驗的強度資料和高解析度井壁的影像電測，可計算井壁附近水平應力值。搭配雙偶極剪力波異向性井測，不僅可以驗證最大水平應力的方向，同時亦可顯示此一方向在深度及空間上的變化。近來利用枯渴的油氣田作為地下儲氣窖的例子日益增加，儲存的氣體包括可重新採收的液化天然氣(LNG)以及永久埋藏造成地球暖化的CO2氣體。經由定量的應力量測值，配合斷層的方位以及地層的孔隙液壓, 可評估因注/產氣造成孔隙液壓變化，個別斷層的穩定以及在斷層不同部位可能重新滑動造成氣體洩漏的潛在風險值。進一步，由蓋岩強度形成水力破壞上限值，規劃最適當的注/產氣的壓力與速率。 This research is targeted to study the subsurface in-situ stress state in the Hsinchu-Miali area of western Taiwan using the drilled and log data of oil and gas wells. Collected data include: 1) Hydraulic fracturing test; include: leak-off test, extended leak-off test and mini-frac within intact formation intervals which preclude the existing of fractures or faults; 2) borehole breakouts derived from borehole-wall images logs (formation micro-resistivity images), and 3) drilling induced tensile fractures. These data, coupled with the overburden stress calculated from density logs and measured pore pressures, a more quantitative and precise stress state can be obtained, and on which a better drilling plan and evaluation of borehole stability can be based. There have been increasing cases of using depleted oil and gas reservoir as underground sequestration for liquid natural gas (LNG) or green-house gas such as CO2 in recent years. Geomechanics of both seal and cap rocks are important factors affecting the stability of underground storage site. Combined precise measurements of in-situ stress and changes of pore pressure during injection and extraction of fluid, one can evaluate the stability of individual faults and potential leakage in different parts of a fault. In addition, the failure strength of the cap rocks provide a upper bound limit of the maximum fluid column and optimum rate of injection and extraction that should be applied. 研究期間：9901 ~ 9912
