大庆油田微泡沫钻井液的研究与应用

微泡沫钻井液在保护油气层和防漏方面具有常规水基钻井液所无法替代的优势,特别适用于大庆油田低压、低产油藏。筛选了发泡剂、稳泡剂,将现用钻井液体系转化为微泡沫钻井液体系,研制了适合微泡沫发挥作用的微泡沫钻井液配方,并对其抑制性、抗温、抗污染(抗黏土、钙、油气)能力、油层保护效果(模拟岩心动态污染试验)以及微泡沫钻井液防塌机理和微泡沫钻井液流变特性进行了研究,建立了微泡沫钻井液的具体流变模型,通过API钻井液失水仪堵漏实验和API堵漏材料实验装置对微泡沫钻井液的堵漏机理进行了研究。研究表明:微泡沫钻井液密度较低,能适当降低井筒液柱压力,使井漏得到缓解;具有良好的润滑性,循环压耗小,泵压低,使钻井液循环当量密度降低;微泡沫钻井液的高黏度和高切力性能大大增加了钻井流体在裂缝和孔隙内的流动阻力,有利于阻止井漏的继续发生;微泡沫在裂缝和孔隙内聚结但不结合,具有"架桥"封堵作用,有效阻止了钻井液在漏失通道继续流动。现场应用表明,微泡沫钻井液可减少由于钻井造成的油层污染,提高油井产能。

Research and application of micro-foam drilling fluid in Daqing Oilfield

Micro-foam drilling fluid has advantage comparing with conventional water-based drilling fluid in such aspects as protecting oilgas layer and leakproof,especially suitable for low pressure and yield reservoir in Daqing Oilfield.Foaming agent and foam stabilizer are screened out which translates present well drilling fluid system into micro-foam drilling fluid system.Micro-foam drilling well fluid formula,suitable for micro-foam exerting function,whose properties such as inhibition,temperature resistance and antipollution(anti-clay,calcium and oil and gas) ability,oil layer protecting effect(simulation core dynamic pollution test) and anti-sloughing mechanism and rheology character of micro-foam well drilling fluid as well are researched,is established.And specific rheology model of micro-foam well drilling fluid is established.Plugging mechanism of micro-foam well drilling fluid is researched by API well drilling fluid water loss and leaking stoppage experiment and API leaking stoppage material experiment.It shows that micro-foam well drilling fluid has lower fluid density,which can reduce shaft liquid column pressure to mitigate well leakage,is of good lubricity,small circulating pressure loss and low pump pressure,which reduces circle equivalent density of well drilling fluid.High viscosity and shearing stress properties of micro-foam well drilling fluid increase flow resistance of well drilling fluids in fractures and pores,which is good for stopping continuous emergence of well loss.Micro-foam coalescing but binding in fractures and pores has bridging plugging effect,which stops continuous flow of well drilling fluid in leaking-out channel.Field application shows that micro-foam well drilling fluid can reduce oil layer pollution resulting from drilling and improve well productivity.