基于岩石力学参数评价火山岩裂缝发育程度

Evaluation of fracture development in volcanic rocks based on rock mechanical parameters

裂缝性油气藏研究中,裂缝识别一直是测井解释的一个难点,常规测井方法识别裂缝的精度不能满足油气勘探开发的需求。而岩石力学参数揭示了地质历史时期裂缝成因类型、空间分布和形成的力学机理,从一定程度上反映了裂缝的发育程度。在对准噶尔盆地40块岩样进行岩石力学参数室内试验的基础上,利用弹性模量、体积模量、剪切模量等岩石力学参数来构建能够较好反映裂缝发育程度的岩石完整性系数、裂缝发育程度指标、岩石稳定系数3个计算模型,并将模型程序化,利用此3个评价指标来对火山岩的裂缝发育程度进行逐点自动处理识别。识别结果与岩心描述、成像测井对比表明,该方法能够较准确地对火山岩的裂缝进行识别且精度较高、实用性强,能满足火山岩地层裂缝测井识别精度的要求。

Identification of fractures has always been challenged in logging interpretation of fractured reservoirs.The accuracy of fracture identification with conventional logging techniques can not meet the requirements of exploration and development in oil and gas fields.Rock mechanical parameters can reveal the genetic types,spatial distribution and genetic mechanism of fractures in geologic history,thus can reflect,to some extent,the level of fracture development.Based on laboratory testing of rock mechanical parameters with 40 samples from the Junggar Basin,three computational models,including rock integrity coefficient,fracture development index,rock stability coefficient,are built up by use ofvarious mechanical parameters such as elastic modulus,bulk modulus and shear modulus,for which the programs are designed.These three appraisal indexes are used in point-to-point automatic identification of fractures in volcanic rocks.Comparison of the results with core description and image logging indicates that this method is highly accurate and practical and can meet the requirements of logging identification of fractures in volcanic rocks.