【作者】 黄有泉；

【导师】 王玉普； 刘永建；

【作者基本信息】 大庆石油学院 ， 油气田开发工程， 2007， 博士

【摘要】 海拉尔油田苏德尔特区主要储层是兴安岭群含凝灰质沉积岩储层和布达特群缝洞发育的变质岩储层,均属于低孔特低渗储层,自然产能低,压裂是最有潜力的增产措施,也是提交油田控制储量的关键技术,但是,由于储层的构造和岩性复杂,常规压裂施工难度大,裂缝起裂和延伸不易预测和控制,施工过程中压裂液滤失大,易低砂比砂堵,改造强度低,效果差,措施成功率低。为此,本文深入研究了苏德尔特区兴安岭群和布达特群复杂岩性储层有效压裂技术,这对苏德尔特区的有效开发具有重要意义和实用价值。首先,系统研究了兴安岭群和布达特群储层的沉积、构造、储层和岩性等特征,并详细分析了储层的注采能力。结果表明,兴安岭群沉积岩储层凝灰质及蒙脱石和高岭石等粘土矿物含量较高,敏感性较强。布达特群变质岩潜山储层多为碎裂的含钙中砂岩、细粒长石岩屑砂岩和碳酸盐质砾岩。两套储层均属低孔特低渗透储层,排驱压力较高,中偏强水敏,弱速敏到中等偏强速敏。断层均十分发育,布达特群储层裂缝和孔洞相对比较发育。两套储层的自然产能和吸水能力都非常低,多数层试油时不出油,采油指数和吸水系数都很低。其次,基于已有地应力计算模型,建立了考虑构造应力和热应力影响的地应力计算新模型,并设计了相应的地应力剖面解释软件,进而,利用实际测井资料,分区块进行了地应力解释,计算出沿深度的连续地应力剖面数据、岩石力学参数、柱状剖面图及分层数据等,得到苏德尔特区地应力的纵向和平面分布规律,为苏德尔特区压裂开发提供了理论依据。第三,基于储层岩性认识和地应力等研究成果,给出了布达特群储层裂缝起裂和延伸准则及裂缝开启的数学模型和求解方法,并且,分析了含凝灰质兴安岭群储层压裂的起裂和延伸机理。同时,还测定了两套储层的岩石力学参数,结果表明,布达特群变质岩基质致密,裂缝和孔洞发育,且储层厚度较大,纵向上无明显应力差,压裂时压裂液滤失量大,易垂向延伸,裂缝较窄且缝高不易控制,压裂施工难度大,需要降低滤失和优化压裂施工设计,建议采用合层压裂以减少裂缝窜层,也可采用液体控缝高剂控制裂缝高度。含凝灰质兴安岭砂岩储层是粘土含量高、具有较强塑性的硬地层,水力压裂时裂缝起裂机理与常规砂岩硬地层相同,但由于岩石塑性较强,且因粘土吸水膨胀应力而使裂缝内有效净压力降低,导致裂缝变窄,加砂困难,采用能够抵制岩石水化的低滤失压裂液,可以控制裂缝的起裂和延伸。第四,针对兴安岭群含凝灰质储层易水化变软和滤失大及布达特群复杂介质储层滤失大的问题,研制了低滤失交联冻胶乳化压裂液体系,并从配方优化、性能表征、降滤失机理、滤失和压裂模型等方面,系统地研究了交联冻胶乳化压裂液的应用性能。结果表明,该乳化压裂液体系具有良好的岩石配伍性、乳化液稳定性、降滤失性能、流变性能、破胶性能及携砂能力,且储层伤害低,可适用于兴安岭群含凝灰质强水敏储层及布达特群缝洞发育复杂介质储层的压裂施工。乳化压裂液的降滤失机理主要是贾敏效应、高粘度、对凝灰岩吸水的抑制作用、油水两相流动效应及滤饼的形成。计算结果表明,乳化压裂液可明显改善裂缝的几何形状。第五,根据储层的地应力和岩性等特点,开展了兴安岭群含凝灰质储层压裂的施工参数和施工工艺的优化研究。设计了乳化压裂液的配液装置及配液流程,确定了有效的乳化压裂液施工参数,进行了现场试验,分析了现场压裂应用效果。同时,研究了布达特群储层的人工控缝高、变排量施工、测试压裂和地应力分析等压裂优化设计方法及提高压裂砂比和加砂强度的系列技术,形成了布达特群储层现场压裂施工控制技术,进行了现场试验,分析了布达特群储层的现场压裂应用效果。最后,对本文研究的复杂岩性储层压裂技术的措施效果进行了经济评价。室内实验分析和现场试验结果表明,本文研究的复杂岩性储层压裂技术可有效的开发动用苏德尔特区含凝灰质兴安岭群储层和复杂介质布达特群储层,现场压裂施工的压裂液平均返排率高,砂比和加砂强度大,施工成功率高(达到80%~90%),投入产出比分别达到1:5和1:8以上,技术效果和经济效益非常显著,解决了苏德尔特区复杂岩性储层压裂的难题。更多还原

【Abstract】 Xinganling sedimentary tuff formations and Budate metamorphic formations with fractures and dissolved pores/caves are the main formations with low pororsity and extra low permeability of Sudert region in Hailaer Oilfield. Only limited oil could be produced by unartificial method. Hydraulic fracturing technology which is potential to stimulate such formations can provide more estimated and recoverable reserves. However, the structure and lithology of the formations are so complexed and unconventional that conventional fracturing technologies are noneffective because it is difficult to forecast and control fracture splitting and extending with large loss of fracturing fluid. As a result, sand plug is encountered at lower proppant concentration, limited stimulation is obtained, only a few wells are stimulated and improved. In this work, researches on effective hydraulic fracture technologies were carried out to improve the hydraulic fracturing effect and stimulate the formation.First, the sediment, structure, formation and lithology characteristic of the formations were investigated, and injection and production capabilities were researched in detail. It is shown that, Xinganling sedimentary tuff formations are sensitive to water and flow rate for their higher contents of montmorillonite and kaolinite. And Budate metamorphic hidden mountain formations are comprised of fractured calcic medium sand rocks, sand rocks with fine feldspathic rock crumbs and carbonate conglomerate rocks. With lower porosity and permeability, higher drainage pressure, medium/large water sensitivity, weak/medium/large flow rate sensitivity were observed in laboratory. Faults are found in both kinds of formations. More fractures, pores and caves are found in Budate formations. Both kinds of formations were tested with much lower oil production and water injection capabilities. There was almost no oil produced from most formations in the test for oil. The oil productivity index and water injectivity index were extra lower.Second, new earth stress models in view of structural and heat stress were established based on the existing earth stress models, and the earth stress profile interpretation software developed with these models. Then the earth stress of some regions were interpreted with the practical well logging data, continuous earth stress profile data, rock mechanic data, column profile chart and layered data obtained. Then longitudinal and tabulate rules of the earth stress were concluded. These technologies and theories are significant for development of Suderte region effectively.Third, based on the achievements of formation lithology and earth stress etc., the earth stress and hydraulic fracture models of Budate were discussed, the splitting and extending guidelines were presented, the splitting models and solving methods were provided furthermore. At the same time, the splitting and extending principles of Xinganling sedimentary tuff formations were investigated. Whereafter, rock mechanic parameters of both kinds of formations were measured. It shows that matrix of Budate formations is compacted and tight. There are developed fractures, pores and caves in it. The earth stress difference is unconspicuous between the formation and up/under isolated layers because its large thickness. As a result, fracturing fluid loss is large, the splitted fracture inclined to extend vertically, fracture with limited width were obtained, the height of fracture was difficult to control, and it is hard to implemented effective hydraulic fracture. It could be improved by means of reducing fracturing fluid loss and optimizing design of the hydraulic fracture execution. It is advised to fracture the formations combined to restrain the unexpected fracture extension, and/or use fluid additives to control fracture height. Xinganling tuff sand formations belong to elastic rigid formations with large clay content. Their fracture splitting and extending principles are similar to the conventional sand formation, but the width of the fracture and sand added is limited for the effective net pressure decrease in the fracture derived from the plasticity and expanding stress of the rocks adsorbing water. Emulsified crosslinking jelly glue fracturing fluids is potential to restrain water adsorption to the rocks, control fracture splitting and extending effectively.Forth, emulsified crosslinking jelly glue fracturing fluid with lower fluid loss was developed to decrease fluid loss in hydraulic fracture of the formation with complex lithology. Its technological and ecnomics feasibilities are evaluated in terms of prescription optimization, performance characterization, principles of decrease in the fluid loss, models of fluid loss and hydraulic fracturing, and so on. It shows that the fracturing fluid has favorable compatibility, emulsion stability, capability to reduce fluid loss, rheological and glue breaking characteristics, sand carrying capability, and lower damage to the formation. The system is applicable to hydraulic fracture of Xinganling tuff sand formations with strong water sensitivity and Budate formation with fractures, dissolved pores and caves. The principles of its decrease in fluid loss are researched in detail, mainly Jamin’s effect, high viscosity, inhibition of the adsorption of water to the tuff rock, flow effect of water and oil phases, and filter cake formed the fracturing fluid involved to decrease the fluid loss. The simulation calculation indicated the emulsified crosslinking jelly glue fracturing fluid is significant to improve the fracture geometry.Fifth, optimization and design of the parameters and technics for hydraulic fracturing of Xinganling tuff formations were carried out according to the earth stress and lithology of the formations. The confecting facility and technological process designed. The effective implementing parameters were determined, The field tests were carried out. The field application results were analyzed. At the same time, some methods and technologies are provided to optimize and design hydraulic fracturing implementation and enhance proppant concentration, which include fracture height controlling artificially, operation with different injection rates, testing hydraulic fracture, and earth stress analysis, etc. And field implementing control technologies for Budate formations also provided, then the field application results are introduced. In the end, the commercial effects of the hydraulic fracturing technologies for the complex formations in Sudert region are introduced.Laboratory and field researching results show that the hydraulic fracturing technologies are feasible and practical to develop Xinganling sedimentary tuff formations and Budate metamorphic formations with fractures and dissolved pores/caves in Sudert region. Large ratio of fracturing fluid flowed back to that injected, higher proppant concentration, higher success rate (up to 80% ~90%), and higher input-output ratio (1:5 and 1:8 respectively) were obtained.更多还原