Due to fact that the conventional clay oil based drilling fluid used in shale gas horizontal wells in the Changning Block ,Sichuan Basin ,is poor in rheology and easy to induce lost circulation ,the clay‐free oil based drilling fluid has been studied .To enhance the electric stability and suspension perform‐ance of the proposed oil based drilling fluid ,the composite emulsifier G326 and oil‐soluble polymer viscosi‐fier G336 were developed ,and determined the formula for the clay‐free oil based drilling fluid .Indoor test results showed that the clay‐free oil based drilling fluid had a higher electric stability and lower final gel strength than conventional clay oil based drilling fluids ,which is faverable for eliminating the thickening problem of oil based drilling fluids and lost circulation in complicated formations in the case of high densi‐ty .When the clay‐free oil based drilling fluid was deployed in four shale gas horizontal wells in the Changning Block ,drilling operations were performed smoothly with stable borehole wall ,no tight hole and sloughing , smooth tripping and clean wellbore , average ROP enhanced by 37 .8% . Research results showed that the clay‐free oil based drilling fluid could prevent the lost circulation that caused by conven‐tional oil based drilling fluid with high density due to its high structural strength ,which can meet the need of drilling shale gas horizontal wells fast and safely in Changning Block .

为适应非常规页岩气开发的需要,解决传统油基钻井液毒性大、悬浮稳定性差、成本高的问题,选用低毒环保且可再生的生物柴油作为基础油,研制出一种环保型全油基生物油钻完井液体系.给出了体系配方并对该体系的主要性能进行了室内评价.室内实验结果表明,环保型全油基生物油钻井液体系不含水,具有电稳定性好、塑性黏度低、滤失量小等特点,且具有抗温、抗钻屑、抗盐水污染性以及抑制性强的优点,对储层保护效果也较好,满足非常规页岩气开发安全钻井和环境保护的要求.

苏里格分支水平井难度最大的地方在于分支井眼,分支井眼首次将大斜度井段和水平段设计为全裸眼,针对苏里格气田分支井眼斜井段和水平段处于同一裸眼段的技术难题,室内研发了强抑制性有机-无机盐低伤害钻井（完井）液体系,并在桃7-14-18H分支井和桃7-15-20H分支井的分支井眼成功试验应用.室内和现场试验结果表明,该体系能有效解决气井水平井斜井段和水平段同处于裸眼段情况下的的泥页岩井壁失稳、气层保护、高摩阻大扭矩、井眼净化、携砂悬砂等一系列技术难题.该体系抑制性强,其页岩一次回收率达到了97.2％,二次回收率达90.3％;体系利于保护产层,对盒7和盒8产层岩心的平均伤害率为10.60％,属于低伤害.钻井液优良的综合性能保障了1742m装有裸眼封隔器的套管完井管串直接穿越裸眼斜井段安全下至水平段的预定位置.

Based on the material balance principle,by employing the Langmuir adsorption model and considering the changes of porosity volume in matrix and fracture with formation pressure,a material balance equation of closed shale-gas reservoir is derived.An example calculation shows that(1) the reserves of shale-gas reservoir can be calculated by the equation;(2) adsorption is the dominant storage mechanism of shale-gas reservoir;(3)matrix system's reserves are very little;and(4)fracture system's reserves are even less.

Based on the material balance principle,by employing the Langmuir adsorption model and considering the changes of porosity volume in matrix and fracture with formation pressure,a material balance equation of closed shale-gas reservoir is derived.An example calculation shows that(1) the reserves of shale-gas reservoir can be calculated by the equation;(2) adsorption is the dominant storage mechanism of shale-gas reservoir;(3)matrix system's reserves are very little;and(4)fracture system's reserves are even less.

High-density saturated brine drilling fluid is contaminated by formation materials during drilling into salt-gypsum layer, resulting in an increase of viscous shear thickening. In this study, the maintenance technology of viscosity shear suppression is adopted to solve this problem. A brine drilling fluid with density of more than 2.0g/cm3 is weighted with ordinary barite powder, and is applied to drilling high-pressure gas-bearing salt-gypsum layer in South Yoloten gasfield, Turkmenistan, which obtains good flow property. The problems such as formation creeping, drilling rig sticking, and oil, gas and water invasion are solved. A good application effect has been obtained, with a drilling success rate of 100% achieved.

针对在辽河油田区块水平井钻井过程中出现的问题，利用硅氟化合物的优点，开展了聚合物硅氟钻井液体系研究。通过室内试验对聚合物硅氟钻井液体系的润滑性、防塌性、降滤失性、抗温性、抗盐钙污染等性能的测试，得到了适合辽河油田的聚合物硅氟钻井液体系，结果表明，聚合物硅氟钻井液体系具有良好的润滑性、防塌性、降失水性能、抗温抗盐能力；降该钻井液体系在辽河油田沈257-沙H2井和前36井进行了应用，整个钻井过程顺利、钻井安全快速。