为探索玛湖地区致密油藏多层系立体井网整体压裂效果,提高油藏采出程度,在构建三维地质模型和地应力模型的基础上,通过地质工程一体化方法,开展了地应力参数三维空间展布特征研究,分析井间、簇间的应力相互干扰对整体压裂效果的影响,确定了最优簇距、缝长、布缝方式及作业顺序,确定了小井距水平井立体井网开发整体压裂优化参数.研究表明:采用立体井网模式开发,优化簇距、单簇裂缝规模,采用拉链式交叉布缝的方式,能够显著提高储层改造效果,研究区缝控储量动用程度由70％提升至90％.该研究为油层厚度大、连续性较好的叠置储层区块开发提供了借鉴.

Large-scale hydraulic fracturing is the essential technology for cost-effective and efficient development of tight sandy conglomerate reservoirs. Gravel parameters are considered the key factors that influence the hydraulic fracture geometry. The existence of gravels can make it even harder to complete fracturing stimulation. The complex fracture geometry,high tortuosity,and shorter supporting fracture length make it difficult to achieve the designed fracture conductivity. In this research,the continuous-discontinuous element method（CDEM）was applied to establish a 2D full fluid-solid coupling fracture propagation model to explore the influence of stress difference,gravel content,and flow rate on the fracture propagation geometry. The numerical simulation results show that:the multi-phase media hydraulic fracturing model based on the CDEM method can accurately simulate the overall fracture propagation geometry under the influence of gravel;the fractures will divert and generate a tortuous fracture when meeting high strength gravel;in reservoirs with high stress,hydraulic fractures tend to pass around the gravel and then divert to the direction of the maximum horizontal principal stress;in the presence of gravel,the fracture propagation will shape a high-pressure zone and generate more micro-fractures,thus increasing the stimulated reservoir volume. This study lays a theoretical basis for optimization of the fracturing design of conglomerate reservoirs.

水平井限流压裂中存在携砂液冲蚀射孔孔眼现象,导致段内多簇改造不均衡,不利于地质储量的充分动用,亟需认识清楚孔眼冲蚀过程.基于孔眼摩阻公式,推导了段内多簇多孔的孔眼冲蚀模型,考虑初始孔径差异和簇间应力差,采用孔径、流量分配和孔眼摩阻的变化来量化分析孔眼冲蚀规律.研究结果表明,平均初始孔径较大、应力较小的射孔簇易产生过度冲蚀;随着孔径的增大,孔眼摩阻迅速减小,限流作用减弱,不利于缝控储量均衡动用;单纯地提升排量并不能明显减小簇间的孔眼冲蚀差异;在相对较低的携砂液浓度下,簇间孔眼冲蚀和流量分配更均匀.这说明初始孔径差异和簇间应力差是导致孔眼冲蚀不均匀的主要因素,在限流压裂设计中可通过采用等孔径射孔工艺、适当增加前置液量、优化布孔位置和数量等方法,改善施工段携砂液分配.本研究为优化水平井限流压裂设计提供了支撑.

针对致密气藏储层改造效果不理想、产量低等问题,开展了液氮伴注压后不同因素对水平井产能影响程度的研究.以临兴气田压裂水平井为研究对象,对影响单井产能的地质及工程因素进行计算分析,首先利用主观分析方法中的信息量分析法确定各参数的信息量,然后使用客观分析方法中的灰色关联分析法确定各参数之间的关联度,最后通过对比分析确定各因素的影响程度.结果表明:液氮量、水平段长度、有效厚度、压裂级数是影响水平井单井产能的主要因素;基于2种方法的分析结果整体排列具有一致性,可实现准确快速评价水平井产能,对致密气藏现场生产具有重要的指导和借鉴意义.在临兴气藏后期开发方案设计中,从主要因素中的液氮量为切入点,根据其他影响因素产能的规律来调整参数,可有效提高水平井产能.

重点研究了致密砂岩、碳酸盐岩、煤岩、页岩等非常规油气储层的储层响应特征,并对不同岩性储层的微地震监测结果进行了描述.结合压裂、地震地质等实际情况对微地震监测结果进行综合解释,取得了较好的效果.

前置酸液加砂压裂是提高致密储层有效动用的技术之一.注入酸液能有效降低储层破裂压力、清洁地层、提高压裂效果,但酸液同时也会与裂缝中的支撑剂接触而发生化学反应,从而降低支撑剂抗压性能,不利于维持较高的导流能力.文中模拟现场压裂施工方案,进行支撑剂酸溶解度测试实验,评价了酸液溶蚀作用对支撑剂抗压强度、导流能力的伤害程度.结果表明:酸液配比对酸溶解度影响最大,其次为接触反应时间;大粒径支撑剂酸溶解度较小,但酸溶蚀作用对大粒径支撑剂抗压强度、导流能力伤害较大;受酸液作用时,石英砂性能相比陶粒支撑剂稳定性好.实验结果为支撑剂的优选、合理控制酸液用量及注入时间等提供了依据.

昌吉油田吉7井区八道湾组油藏开发过程中直井水力压裂的储集层改造效果有限,产能受到限制,需要开展水平井多级压裂.针对吉7井区八道湾组的地质力学特征,采用扩展有限元法编制了非平面人工裂缝扩展模型,模型考虑了多簇裂缝同时扩展时的缝间干扰和分段压裂时邻近段的段间干扰,表征了吉7井区八道湾组水平井非平面裂缝扩展特征.结果显示,段内缝间干扰会抑制中间簇裂缝半长,使得外侧裂缝的缝宽更大、裂缝半长更长;缝间干扰和簇间干扰使得裂缝扩展呈现非平面特征,在几何形态上具有一定曲率.通过与压裂施工数据和微地震监测数据对比,认为裂缝数值模拟结果与现场数据拟合程度较好,模型在目标区域的应用效果较好.在吉7井区八道湾组开展水平井多级压裂实验,单井日产油量达到了同井区直井的7.8倍,取得明显成效.

致密砂岩气作为重要的非常规天然气资源,需经过压裂改造才能实现有效开发.压裂施工中由于毛管力作用压裂液的渗吸现象会造成储层渗透率降低,从而降低采收率,因此开展压裂过程中压裂液渗吸伤害机理研究对储层保护和提高压后产能具有深刻意义.以临兴致密气区块为研究对象,通过室内渗吸实验模拟从压裂到返排整个过程中压裂液与储层之间的渗吸作用机理,探究了渗吸液相、压裂液黏度、岩心渗透率以及渗吸时间四种因素影响下的压裂液渗吸伤害规律,并利用灰色关联法量化分析各因素对渗吸伤害的影响程度.研究结果表明:压裂液黏度和压后焖井时间与储层伤害率呈正相关关系,与返排率呈负相关关系;岩心渗透率与伤害率呈负相关关系,与返排率呈正相关关系;压裂液渗吸对储层的伤害率较地层水大,返排率则低于地层水;各因素对致密砂岩气储层渗吸伤害的影响程度大小排序为:压裂液黏度>压裂液渗吸时间>岩心渗透率.研究结果为压裂施工现场的压裂液体系优选及焖井时间控制提供参考.

Shale oil reservoirs are usually developed by horizontal wells completed with multi-stage hydraulic fractures. The fracture interference between clusters in a single stage and between consecutive stages has an impact on the stimulation quality in terms of fracture geometries and fracture widths. This study introduces a non-planar hydraulic fracture model based on the extended finite element method and its use in quantifying the effects of relevant parameters on multi-stage fracture quality in a realistic shale oil scenario. The numerical model is validated with field diagnostics based on vertical seismic profiling. Relevant parameters including stress contrast, fracturing fluid viscosity, cluster density, and fracturing in consecutive stages are quantitatively analyzed in the numerical study. Results show that effects of stress contrast on fracture quality are greater than those of fracturing fluid viscosity, while the effects are more significant in outer fractures instead of the inner fracture. Denser cluster design leads to greater inhibition for the growth of inner fractures which eventually divert them transversely. In fracturing for consecutive stages, the opening of fractures in the subsequent stages is inhibited and the fracture geometries are also altered by the inter-stage interference caused by the previous stage. Based on field data and numerical modeling, this study identifies key parameters and quantifies their effects on inter-fracture and inter-stage interference in multi-stage hydraulic fracturing in horizontal wells.

大规模水力分段压裂是页岩气等非常规资源高效开发的关键技术.页岩气井返排率一般较低,大量的压裂液长期滞留地层对储层岩石、支撑剂强度等造成一定的伤害,影响页岩储层压裂改造长期效果.针对该问题,通过室内试验模拟研究现场压裂前后气测导流的变化规律,对压裂液伤害程度进行表征.结果表明:压裂液侵入降低了支撑剂、页岩岩石强度,导致支撑剂破碎率、岩石嵌入程度加剧,导流能力伤害达到60％以上;使用大粒径支撑剂、较高铺砂浓度,优选破胶性能好、低残渣、防膨性强的压裂液,能有效提高导流能力,降低压裂液伤害程度.研究结果对页岩地层压裂设计,降低压裂液伤害提高产量提供参考.

细分切割体积压裂技术已在玛湖11个致密砾岩油藏应用118井次,验证了工艺的针对性和可操作性,压裂工程参数指标不断取得突破,水平井生产效果显著提升,但合理压裂工程参数与最优生产效果间的匹配关系仍不确定.为了优选合理的工程技术参数范围以指导后续水平井压裂设计,也为了提高致密砾岩油藏开发综合效益,开展体积压裂技术适应性研究.通过数据统计和趋势预测等分析手段,将水平井压后产量、压力等生产数据与体积压裂方式、完井压裂工艺、裂缝参数、压裂规模、压裂材料选型等压裂工程参数相对应开展分析.研究表明,针对物性较差的常压油藏,合理的压裂裂缝间距为25～35m,合理改造规模为加砂强度1.2～1.5m3/m、砂液比(1∶17)～(1∶20);针对物性较好的异常高压油藏,合理的压裂裂缝间距为40m左右,合理改造规模为加砂强度1.0～ 1.2m3/m、砂液比(1∶15)～ (1∶17).同时证明,精准定点有控压裂可在同等条件下将改造效果提高20％以上;在油藏埋深小于3500m、闭合应力低于55MPa的区块,石英砂可有效替代陶粒,具备进一步扩大应用规模的条件.

新疆油田Ma18井区百口泉组砂砾岩储层多为横向变化较大且厚度不均的薄互层,其间存在2～3个不等厚泥岩隔层.目前开发中存在压裂效果差,压窜现象突出的问题.为了能更有效地改造这类储层,开展了压裂有效隔层的界限划分研究.利用压裂软件技术,结合该井区实际压裂情况,分析地质及工程因素对缝高的影响,筛选出影响缝高的主控因素,然后将主控因素作为参数,建立了该区该类储层有效隔层识别图版.通过实例井的验证表明,该图版能够模拟不同施工情况下的有效隔层界限,对该区后续的储层改造具有重要意义.

As the construction displacement and sand amount of overlong horizontal well are increased continuously,the erosion wear of ball seat of pitching sliding sleeve is increasingly serious.There are many researches on the erosion wear of liquid?solid two?phase flow,but the influence of solid particles with mixed particle sizes to the erosion wear is not consid?ered at all.The erosion wear of ball seat by the prop?pant mixed with different particle sizes was studied.Based on the Euler two?fluid theory,the numerical simulation of the erosion wear of ball seat by mixed particle sizes was carried out with Flu?ent software.The results show that the erosion wear rule of ball seat is different caused by the solid particles with mixed particle sizes and the solid particles with single particle size.The erosion wear rate of ball seat by solid particles with single particle size is in inversely proportional to the particle size,while the erosion wear rate of ball seat by the solid particles with mixed particle sizes is related to the particle size and the volume ratio of the solid particles with different particle si?zes.With the increasing of the volume ratio of the solid particles with small particle sizes,the erosion wear rate of ball seat presents a trend of decreasing first, and then increasing. The simulated result provides a reference for the selection of staged fracturing material of horizontal well.

The staged fracturing technique for the horizontal well has become the main technique for efficient development of the tight oil and gas.The new trend of the horizontal well fracturing technology is the multiple staged fracturing and stimulated reservoir volume(SRV).Techniques for factory work have applied to lowcost development of the tight oil and gas.Along with the technical progress and updated fracturing equipments,horizontal well drilling,large-scale fracturing and real-time microseismic fracturing monitoring have become three key techniques for exploitation of the tight oil and gas.Staged fracturing technique for the horizontal well has become an important means of improving oil field recovery and comprehensive benefit.After research and analysis on the staged fracturing technique for the horizontal well at home and abroad,we know the present situation of the application and technical limitations of the staged fracturing through mechanical packer,hydraulic jetting,open hole packer,drillable bridge plug and liquid gel plug.Developing trend of the staged fracturing technique for the horizontal well is predicted so as to provide reference for the selection of the techniques in each oilfield of China.

针对低温、低压力系数气藏压裂存在的压裂液破胶时间长、返排效率低,压裂效果差等问题,研究开发了低温水基交联液氮增能泡沫压裂液体系。通过优化裂缝长度,采用低温活化破胶技术、液氮增能技术、多级支撑剂段塞等多项压裂工艺优化技术,探索出一条适合低温、低压力系数气藏压裂增产改造的工艺方法和配套技术.经现场应用取得了良好效果。

应用地层测试资料绘制的压裂选层图版,结合地层测试曲线形态以及电测解释等资料,综合分析判断是否选择压裂改造,在准噶尔盆地的应用效果比较理想,选层附和率达到91.89%。

根据新疆油田抽油井系统效率的测试结果,分析了影响新疆油田抽油井系统效率的因素.简要讨论了新疆油田近几年来在提高抽油井系统效率上所做的研究,提出了如何进一步提高抽油井系统效率的措施.