低渗页岩储层难以自然形成工业油气流,常采用水平井和水力压裂建立人工缝网以保证商业化开采.然而,随着大规模加密布井和压裂,水平井间距缩小、储层改造体积增加,井间出现人工裂缝导致的干扰,影响邻井的井口压力和产量,甚至诱发井控、套损和支撑剂侵入等问题,严重时导致水平井报废,极大地影响生产效率.此外,老井亏空会导致储层地应力在原位地应力的基础上发生动态演化,形成复杂地应力状态,继而影响加密水平井和重复压裂井的储层改造效果,限制井平台产能表现.我国准噶尔盆地、四川盆地、鄂尔多斯盆地等地的页岩油气资源开发已进入小井距和加密布井阶段,井间干扰已对正常生产产生明显影响,急需开展针对性研究.本文对国内外页岩油气藏的井间干扰现象、机理以及诊断方法进行全面、详细的介绍,并提出干预对策.研究认为:准确表征与预测压裂水平井井间干扰需要在地质工程一体化的框架下展开;对天然裂缝、断层、原位地应力和储层岩石力学特征的准确认识是评价井间干扰的前提;地层亏空诱发的动态地应力和复杂人工缝网的建模与表征是定量评价井间复杂缝网交互与连通的关键手段,也是定量预测井间干扰对于井平台最终可采储量(EUR)影响的有效方法;关井、老井注液、重复压裂、优化井距和压裂优化都是干预或减小井间干扰的手段.

Commercial production from hydrocarbon-bearing reservoirs with low permeability usually requires the use of horizontal well and hydraulic fracturing for the improvement of the fluid diffusivity in the matrix. The hydraulic fracturing process involves the injection of viscous fluid for fracture initiation and propagation, which alters the poroelastic behaviors in the formation and causes fracturing interference. Previous modeling studies usually focused on the effect of fracturing interference on the multicluster fracture geometry, while the related productivity of horizontal wells is not well studied. This study presents a modeling workflow that utilizes abundant field data including petrophysical, geomechanical, and hydraulic fracturing data. It is used for the quantification of fracturing interference and its correlation with horizontal well productivity. It involves finite element and finite difference methods in the numeralization of the fracture propagation mechanism and porous media flow problems. Planar multistage fractures and their resultant horizontal productivity are quantified through the modeling workflow. Results show that the smaller numbers of clusters per stage, closer stage spacings, and lower fracturing fluid injection rates facilitate even growth of fractures in clusters and stages and reduce fracturing interference. Fracturing modeling results are generally correlated with productivity modeling results, while scenarios with stronger fracturing interference and greater stimulation volume/area can still yield better productivity. This study establishes the quantitative correlation between fracturing interference and horizontal well productivity. It provides insights into the prediction of horizontal well productivity based on fracturing design parameters.

材料力学是石油工程专业的一门必修课,保证此课程的教学质量对于学生学习后续开设的石油工程主干课程十分关键.材料力学与机械、土木等行业关系较为紧密,教学中缺乏石油工程行业相关案例,很可能导致学生在学习时理解困难.为了提高教学质量,该文探索了一种基于仿真数值模拟平台的石油工程专业材料力学教学改革方法,选取与石油工程相关的简化力学案例,结合数模工具可视性、互动性强的特点开展教学.这种教改方法使抽象的力学概念具象化,能调动学生的学习积极性,引导学生活学活用,最终达到提升石油工程专业本科生材料力学课程教学质量的目的.

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.

Secondary catalytic reactions of primary volatiles from oil shale pyrolysis were characterized by using a two-stage reactor to study the effects of different catalytic materials, reaction atmospheres and residence time on oil/gas yield and quality. The results showed that comparison with FCC catalyst as bed materials in the 2nd stage, the shale ash possessed relatively moderate activity for adjusting the secondary reaction of pyrolysis volatiles in the applied range of residence time. Using steam as the reaction atmosphere could further enhance the liquid yield by 5% and suppress the C2—C3 hydrocarbons in the cracked gas. The heavy oil fractions, such as vacuum gas oil (VGO, >350℃), could be converted into light oil fractions by the catalytic effects of shale ash, and correspondingly the boiling range of pyrolysis oil tended to be lighter with higher residence time. Oil components analyzed with GC-MS demonstrated that steam could effectively inhibit the over-cracking of aliphatic hydrocarbons at shorter residence time (<3 s), and thus increase the gasoline and diesel fractions by over 20% compared with the N2 atmosphere. However, at higher residence time (3—5 s) the VGO fractions were prone to be condensed as coke, and as a result profoundly decreased the pyrolysis oil yield.

The development and application of high temperature gas dust removal technology makes great sense to the energy utilization and cleaner production in industrial processes. Granular filtration technology which shows a balance between efficiency and pressure drop,better economy and good adaptability in harsh environment,has provided an effective way to settle issues involved in efficient synthetically utilization of solid fuels,clean electricity generation and utilization of residual heat,etc. The principle and forms of granular bed filters(GBFs)were introduced in this paper. Special emphasis was placed on the structure type and improvement research of GBFs,including fixed GBFs,moving GBFs and other forms of GBFs. The influence factors and present studies on engineering application of GBFs were then summarized,and the development trend of GBFs was discussed at last. There are many control factors in moving GBFs and the filtration efficiency of moving GBFs still needs to be improved compared with fixed GBFs,but moving GBFs are more appropriate for industrial application and are the first choice,because moving GBFs can be operated continuously at a steady efficiency and pressure drop. In addition,uniform flow and high utilization efficiency of granular layer,optimization of dirty gas inlet modes and pertinency and integration design are the future directions of research for moving GBFs.