川西地区钻井地质特征的测井研究

【作者】 田云英；

【导师】 夏宏泉； 范翔宇；

【作者基本信息】 西南石油大学 ， 石油工程测井， 2007， 硕士

【摘要】 “钻井地质特征因素的测井识别”技术是综合优快钻井技术集成的一个重要内容。钻井地质特征描述包括地层岩性、岩石力学参数、可钻性、研磨性和地应力及三地层压力体系等。川西坳陷发育有巨厚的侏罗系和上三叠系陆相碎屑岩地层,自上而下主要有蓬莱镇组、沙溪庙组、千佛崖组和须家河组4个气藏,上三叠系须家河组气藏以须二段为主要目的层,其井深一般为4600-5700米,该深层气藏是目前扩大储量的重要勘探目标。该区工程地质特征复杂,表现为;纵向上存在多个产层段和多套压力系统,在进入蓬莱镇后,高压气层发育、地质构造复杂,浅部地层多为不整合接触,地层破碎,泥页岩水化强,深部须家河组煤层不稳定、易坍塌,且裂缝与断裂发育,泥浆密度窗口窄,井壁稳定性差,易发生“喷漏卡塌”等钻井事故;此外在下沙溪庙和须家河组地层,地层岩性致密坚硬,以石英砂岩为主,研磨性强、可钻性差,导致钻速慢、钻井周期长,钻头选型难。由于测井资料蕴含大量的地质环境因素信息,具有高分辨率、连续性好、方便和经济等优点,可利用测井资料深入研究已钻井或待钻井的钻井工程地质特征。论文采用多矿物模型分析方法,计算地层岩石矿物成分和体积含量,建立了工区地层岩性体积剖面。基于岩石力学实验“刻度与标定”测井计算的岩石力学参数,建立工区岩石力学特性剖面,为钻头选型、地应力和地层压力计算提供了可靠的岩性、岩石力学依据。根据可钻性试验与测井计算的岩石可钻性,建立了地层可钻性剖面,结合实钻资料,采用灰色关联分析法优选与地层相匹配的钻头类型。该法克服了神经网络法建模困难、易出现判识混类等缺点,具有快速、直观、简便和符合率高等优点。基于川西深井地应力试验,开展了测井确定地应力方向和大小的研究,建立了工区地应力剖面。研究发现,工区须家河组地层地应力表现为σ_V＞σ_H＞σ_h,σ_H方向近于E-W向。鉴于川西地区须家河组的地层异常高压特性和等效深度法预测地层压力的局限,采用基于有效应力定理的层速度与有效应力关系模型来计算孔隙压力,同时借鉴经验公式并结合川西地区工程地质特点,优选出适合工区的地层坍塌压力和破裂压力测井计算模型,确定防止井壁失稳的安全钻进泥浆密度窗口。实例表明,所计算的地应力、三地层压力及泥浆密度窗口合理,能满足现场钻井工程需要。川西须家河组地层具有低孔低渗、可钻性差和研磨性强等特点,采用欠平衡钻井技术,有利于保护油气层、消除“压持效应”而提高机械钻速和避免钻井液漏失及压差卡钻事故等,采用欠平衡测井可及时获取地层信息。本文根据声电核三大类测并方法的测量原理,给出在充气介质欠平衡测井条件下可选用的电缆测井系列,分析了欠平衡状态下测井曲线响应特征及其异常现象,形成一套欠平衡测井储层参数解释方法,取得了较好的应用效果。更多还原

【Abstract】 The technology about the logging identity the geologic character of drilling is an important content of synthesizing speedily and high quality drilling. The geologic character description about drilling includes lithology, rock mechanic parameter, drillability, abrasivity, crustal stress and three stratum pressure etc. There is gigantic thick land facies clastic rock layer about Jurassic system and Upper Triassic in the sunken of Chuan-xi. From above to below there are Peng Lai-zhen group, Sha Xi-miao group, Qian Fou-ya group and Xu Jia-he group four gas reservoir. Taking T₃X² as the main aim layer in Upper Triassic, the wells depth is 4600-5700m, which is the important exploitation aim using enlarging reserves at present.The engineering geology character is complex, which showing is that there are many producing layers and many series pressure system. When drilling to Peng Lai-zhen group, the high pressure gas layers are developing, the geologic structure is complex , the shallow stratum is discortant contact, the stratum is breaked , the argillutite hydrating is easy, the coal bed of deep Xu Jia-he stratum is instability which will collapse, and the fracture and rupture are developing which will cause the windows of drill fluid become narrow and the stability become poor, all that will cause "blowout、leak、block and collapse" etc drilling accident. When drilling to below Sha Xi-miao and Xu Jia-he stratum, the lithology is very compact and hardness, which cause the abrasivity become strong and the drillability become poor, all these cause the drilling speed is slow and the drilling period is long and bit selection is difficult.Since well logging data implies large geologic environment facts information, and has the merits of high definition, fine continuance, convenient and economic etc. So we need using log information lucubrate the drilling engineering geology feature of the drilled wells or the undrilled wells.This paper adopts MMMA analysis method calculating the volume content about the rock mineral and founding the lithology volume section in work area. Based on rock mechanics test demarcates the rock mechanics of logging calculating and founding the rock mechanics parameters section. All which will offer the lithology and rock mechanics parameters about bit selection、crustal stress and stratum pressure.Based on the test of drillability and the rock drillability drawing from logging, the stratum drillability section will established. Combining the drilling practice and adopting grey relation analysis method we will optimize the bits which suit the stratum. The method overcome the defects of the neural net method of modeling difficulty and identifying confused, which has the merits of speedy, intuition, simply and high coincidence rate.Based on the crustal stress test, the crustal stress direction and value using logging information were developed and the crustal stress section was established. From researching we founded that the crustal stress valve showsσ_V >σ_H >σ_h and theσ_H direction is W-E. Whereas the stratum abnormal high pressure character in Xu Jia-he of Chuan-xi area and the limitations of predicting stratum using equivalent depth method, adopting the model between interval velocity and effective stress based on the theorem of effective calculate the pore pressure. At the same time using predecessors’ empirical formula combining the engineering geology character of Chuan-xi, optimize the logging calculation models about stratum caving pressure and break down pressure which suit work place, we will obtain the safe drill fluid density window which will prevent the destabilizing of the wall of a well. The examples manifest that the stress, the three stratum pressures and the drill mud density window are reasonable, and satisfy the need of fact drilling engineering in local.The stratum in Xu Jia-he of Chuan-xi has the traits of low porosity, low permeability, poor drillability and strong abrasivity etc. Adopting under Balanced Drilling will favor to protect hydrocarbon reservoir, remove chip hold down effect to raise the drill speed, avoid drill fluid leaking and differential pressure sticking accidents etc. Using Under Balance Logging will obtain stratigraphic information on time. This text based on the measure theory of acoustic logging, electric logging and nuclear logging offered the selection of wireline logging series in gas filled medium under the UBL condition and analyze the character of logging curve response and abnormal phenomena under UBL condition, which form a method on reservoir parameter under UBL condition. The effect is better.更多还原