To address the unclear mechanical response mechanisms of the cement sheath in deep oil and gas well cementing under complex temperature-pressure conditions,this study systematically investigated the coupled effects of curing temperature,curing pressure,testing temperature,and confining pressure on the mechanical properties of Class G oil-well cement.Specimens were pre-pared at different curing temperatures ranging from 25℃ to 140℃ and curing pressures of the atmospheric pressure and 21.7 MPa.Triaxial compression tests were then conducted at different testing temperatures from 25℃ to 140℃ and confining pressures from 0 to 20 MPa to analyze the evolution of stress-strain curves,peak stresses,and elastic moduli.The results show that increasing curing tem-perature reduces the peak stress and elastic modulus of the set cement,while high-pressure curing significantly inhibits pore develop-ment and improves structural compactness.Increasing testing temperature helps enhance the mechanical performance of cement at the testing temperature close to its curing temperature.Increasing confining pressure improves the plasticity and residual strength of ce-ment,and the cement exhibits staged evolutionary characteristics under different coupled conditions.The findings of this study provide a theoretical basis and experimental support for the design of cement slurry systems and the integrity evaluation of cement sheaths in deep for-mations.
To address the challenges of high compressive strength,low drillability,and extended drilling time in the deep tight shale of the Mabei Fengcheng Formation,an experimental study on drilling parameter optimization for axial-torsional coupled percussive drill-ing was conducted.This study intended to identify the dominant factors affecting rock-breaking efficiency and to establish a parameter matching method suitable for this layer.Using a composite percussive rock-breaking efficiency testing device,drilling experiments were performed on core samples from the target layer under fixed conditions of weight-on-bit and rotational speeds with different com-binations of axial and torsional impact frequencies.The effects of impact frequency on rate of penetration(ROP),torque,and mechani-cal specific energy(MSE)were evaluated.The results show that axial-torsional coupled impact can significantly increase the ROP while reducing torque and MSE.High-frequency torsional impact plays a dominant role in torque reduction and energy saving,and a synergis-tic rock-breaking mechanism was identified in which axial impact promotes crack propagation,whereas torsional impact alleviates bit stick-ing.This study confirms that axial-torsional coupled impact technology provides significant benefits in improving drilling efficiency,reducing torque,and lowering energy consumption in this shale formation.The obtained parameter optimization method provides a theoretical basis for field drilling design and offers important engineering guidance for accelerating drilling in deep hard strata.
To address the common challenges of rheological deterioration,excessive fluid loss,and wellbore instability for drilling fluids under high temperature,high salinity,and high stress conditions in ultra-deep wells,a cationic nanogel viscosifier and plugging agent,P(AM-DMC),was designed and synthesized from acrylamide(AM)and methacryloxyethyltrimethylammonium chloride(DMC)via inverse suspen-sion polymerization.This material combines the viscosity-enhancing property of flexible polymer chains with the high interfacial activity and size effects of nano-particles.Scanning electron microscopy(SEM)showed the material has an irregular polyhedral morphology and a particle size distribution of 200-500 nm.The performance of the developed material was systematically evaluated in a low solid water based drilling fluid,including rheology,filtration control,and salinity tolerance,while the contact angle and Zeta potential measurements were used to reveal the micro-interfacial properties.The material exhibited high hydrophilicity(a contact angle of 13°)and excellent dispersion stability,facili-tated by its strong positive surface charge(Zeta potential of+59.1 mV),which forms the basis of the synergistic viscosity-enhancing and plug-ging mechanism.Results demonstrated that P(AM-DMC)significantly improves the structural viscosity and shear resistance capacity of the drilling fluid through strong electrostatic adsorption between its cationic chains and clay particles,along with the formation of a three-dimen-sional network of the materials.Increasing the dosage of P(AM-DMC)markedly enhanced the apparent viscosity and yield point while signifi-cantly reducing both API and HTHP fluid loss.The system maintained excellent rheological stability and low fluid loss after aging at 170℃,confirming its outstanding thermal stability.It is indicated that P(AM-DMC)nanogel is a novel additive for high-performance drilling fluids in deep complex formations,offering efficient viscosity enhancement,fine plugging,and superior temperature resistance and thus holding sig-nificant engineering value for the safe and efficient drilling of ultra-deep wells.
新疆油田公司近期在某井区开展高温光热制蒸汽与注汽锅炉耦合的先导试验,为稠油蒸汽辅助重力泄油(SAGD)开发提供低碳高品质蒸汽.先导试验的开展对油气勘探开发与新能源技术的融合具有先行示范意义."双碳"目标下新疆油田公司稠油生产面临减少天然气消耗,降低二氧化碳排放的挑战.结合太阳能聚光集热技术、绿电+电极熔盐加热技术、高温储热技术,提出不同场景下浅层稠油开采中注汽工艺的新能源供能配置方案.为太阳能高温光热技术在新疆油田稠油作业区规模化应用提供了具体思路与解决方法,在减少自用天然气的同时尽可能降低蒸汽成本,对稠油油田低碳可持续开发具有重要指导意义.
注气驱油过程中井筒内存在可燃气体爆炸风险,为了明确热采注氮井筒内发生可燃气体爆炸事故后果及爆炸演化规律,开展了高温高压条件下油管大长径比空间内,轻烃组分爆炸的数值模拟研究工作.研究结果表明,管内爆炸超压峰值随初始温度的升高而降低,此现象是由于升温引起管内可燃气体总量降低,升温对燃爆反应速率的增强作用被抵消,但管内爆炸超压峰值随初始压力的升高而快速增大,同时在相同的初始压力和温度下,与中部和顶部点火相比,超压的最高值出现在管内底部点火时的井口位置,且在井筒两端由于爆炸冲击波反弹使得超压迅速上升,爆炸产生的超压最高可达300 MPa以上,足以对油管和井筒等设施造成严重破坏.研究成果为注气采油井筒爆炸安全防控提供参考依据.
