【作者】 谢润成；

【导师】 王允诚； 周文；

【作者基本信息】 成都理工大学 ， 油气田开发工程， 2009， 博士

【摘要】 川西坳陷须家河组天然气资源丰富,已有的油气勘探开发成果表明了该气藏具有良好的天然气勘探开发前景。但由于川西须家河组地质条件复杂,地层超高压异常,泥页岩易坍塌,且天然裂缝发育,导致一系列井下复杂问题发生,严重影响钻井工程进度及压裂施工等,制约了整个须家河组气藏勘探开发评价工作。国内外已有的研究表明,井下复杂问题的产生与其地区的地应力关系密切。本论文针对研究区须家河组地层钻完井中出现的复杂井下情况,以石油地质学、构造地质学、地球物理测井、储层地质学、岩石力学、岩体力学、钻井工程、油气储层改造、油气藏工程学等多学科理论和方法为指导,从岩石基本物理特征分析入手,开展了模拟地层条件下的岩石力学参数试验、地应力解释、三大压力建立及井壁稳定性评价。研究结果表明,饱水岩样波速度大于干燥岩样波速,相同饱和流体介质条件下,波速与岩石粒度成反比,同时利用实测纵横波数据采用最小二乘法进行二项式拟合获得研究区横波时差计算公式;采用粘弹性频散方程,实现不同频率声波之间的转换,解决了岩电对应性问题,直接建立起模拟地层温度、压力及饱和流体性质下的岩石力学强度参数、弹性参数解释模型及动静转换关系式;在区分岩性的基础上,考虑泥质含量对岩石抗压强度的影响,建立起模拟地层条件下砂岩、泥岩抗压强度测井解释评价方法,解决了岩石抗压强度测井解释难的问题,同时形成了岩石力学参数试验-测井解释评价方法体系。根据试验结果,采用非线性拟合方法建立起岩石孔隙弹性系数解释方法;采用人工取点,利用等效深度法建立起研究区地层压力解释图版,并探索Eaton法、有效应力法解释地层压力;通过声发射、波速各向异性测试、粘滞剩磁试验、差应变测试、特殊测井、压裂施工资料反演,获得了须家河组地应力值的大小及方向,现今水平最大主应力方向总体上为近东西向,平面上不同构造部位略有转变;在比较各测井地应力计算模式的基础上,选用ADS法计算地应力剖面,利用压裂资料反演地应力结果校正,获得了较为可靠的地应力剖面。采用岩心刻度测井有效地识别裂缝,并利用R/S法进行单井裂缝识别,划分出完整井壁与非完整井壁,分析井壁崩落规律;选用库仑—摩尔强度准则,以实钻钻井液密度修正井壁岩石非线性应力系数,建立起地层坍塌压力评价方法;结合粘土矿物成分分析、泥页岩膨胀试验、分散性试验等开展泥页岩水化研究,讨论和评价了模拟地层条件下不同岩样尺度钻井液浸泡对岩石力学性质的影响,以及力学与化学耦合对岩石力学性质的影响;结合岩心测试、现场测试及实钻资料统计分析,对岩石力学强度解释剖面、地应力解释剖面、地层压力解释结果以及地层破裂压力、坍塌压力剖面进行验证,结果表明所建立的剖面解释精度高,与实钻情况符合程度较高,预测结果具有较高的可靠性。论文研究中形成了一套从岩石力学参数解释、岩石孔隙弹性系数评价、地层孔隙压力解释、地应力解释、破裂压力评价、坍塌压力解释、到结合实钻资料验证综合分析评价单井岩石力学、地应力及井壁稳定性的工程地质特征综合研究方法技术体系。论文研究成果为加强研究区须家河组钻完井工程工艺技术应用研究、确保钻井工程科学、高效、安全施工以及压裂改造等措施开展提供了强有力的技术支撑。论文研究方法与技术手段对同类型气藏研究具有借鉴意义。更多还原

【Abstract】 The natural gas resources of Xujiahe formation are rich in western Sichuan depression, which the achievements of oil & gas exploration and exploitation had indicated that the gas pool has the good prospect for exploring and exploiting. Because of complex geological conditions, such as super-high reservoir pressure, collapsed clay, development of natural fracture, the complicated conditions have occurred frequently in downhole, which influenced the drilling process seriously, fracturing, etc, and restricts the gas pool exploration and exploitation appraisal work.. Research results of domestic and foreign indicate that the relation between down-hole complex conditions and the local stress is close. Based on the Xujiahe formation complex drilling conditions, the rock mechanics trial, stress interpret ,reservoir pressure ,fracture pressure, collapsing pressure and wellbore stability appraisal are researched, guided by the petroleum geology, the structural geology, the geophysical well logging, the reservoir geology, rock mechanics, the rock-mass mechanics, the petroleum well drilling project, the oil gas reservoir transformation, the oil & gas pool engineering and the multi-disciplinary theories and methods.The results indicate that the wave velocity of rock water saturated is quicker than the dry rock sample’s wave velocity. Under the same fluid medium saturated, the wave velocity is in reverse proportion with the rock granularity. According the actual P-wave and S-wave data, the thesis establishes the binomial formula of transformational relation between P-wave and S-wave using the least squares method. The thesis realizes transformation of the different frequency wave velocity using the viscoelasticity frequency dispersion equation, resolving the corresponding relation of lithological-electrical parameters, establishing the elastic parameter explanation model and dynamic and static elastic parameters transformation directly basing the simulation formation temperature, the formation pressure and the fluid saturated.Basing on different lithology, the thesis establishes mudstone’s compressing strength and the new sand compressing strength formula including information of rock density, acoustic velocity and content of clay, resolving the problem of compressing strength interpretation difficulty. And the thesis forms the rock mechanics parameter experiment, well logging interpretation and the assessment method system. According to the test results, the thesis establishes the interpretation method of Biot’s coefficient using non-linear fitting. Through the artificially spot, the thesis achieves the formation pressure explanation plate basing equivalent depth method, and tries to interpret formation pressure using the Eaton method and the effective stress method. Through the sound launch, the wave velocity anisotropy test, the sluggish residual magnetism test, the difference strain test, the special well logging, and the fracturing data, the thesis obtains the stress value and the direction of Xujiahe formation, and the biggest horizontal principal stress’s direction is nearly E-W, which slightly changes at different structure position in the plane. In the foundation of comparing various logging stress computation pattern, the thesis selects the ADS method to commutate stress, and regulates the result using the fracturing results to obtain the more reliable stress section.According to the core and well logging, the thesis distinguishes the natural fracture effectively, recognizes the single well fracture basing the R/S method, thus divides the complete wellbore and the non-complete wellbore, and analyzes the wellbore collapsed discipline. The thesis establishes the collapsing pressure assessment method by selecting the Coulomb-Mohr of strength criterion and revising the wellbore non-linear stress coefficient with the drilling mud density. According to the clay mineral analysis, the mudstone inflation experiment, and the dispersive experiment, the thesis discusses and appraises the influence of drilling fluid immersion to the rock mechanical properties basing the simulation formation condition and the different rock sample criterion, as well as the rock mechanical properties influenced by the coupling of mechanics and chemistry. Basing on the core trial, the field test and drilling data analysis, the thesis verifies the rock mechanics strength section, the stress section, the formation pressure explained results, the fracturing pressure, as well as the collapsing pressure section effectively, which the results indicate that the interpretation section’s precision is high, the results and drilling data is in a good agreement, which improves that the explanation result has the high reliability.The research establishes a set of engineering geology research technique system from the experimental trial, the rock mechanics parameter explanation, the stress explanation, three formation pressure explanation, and the wellbore stability analysis synthetically. And the results of research provide the powerful technical support on drilling and well completion project processing technology enhancement, guarantee the drilling engineering scientifically and highly effective, safely as well as fracturing .The analysis methods and technological of the thesis is of a certain guiding and referable significance for research the same gas reservoirs.更多还原