长岭凹陷地应力特征研究

Abstract

压裂作业时，能否压开地层是压裂施工的关键。现在的深层储层和致密储层越来越多地被发现，如长岭凹陷的深层火山岩气藏和页岩气藏，深部储层的开发使得压裂施工难度越来越大。长岭凹陷深层火山岩天然气储层埋藏深、温度高、储层非均质性强、岩层致密、岩性变化多样。其中的腰英台深层气藏钻井过程中遇到的问题是地层复杂多变、钻遇地层多、岩性变化快、压力不统一、地层研磨性强且可钻性级值很高；在深井钻井过程中，地层特别容易发生缩颈、垮塌、井斜等钻井事故。对于压裂来讲，在现有地面施工设备能力下，如何有效预测地层破裂压力显的尤为重要。本文针对长岭凹陷部分井的岩石弹性参数和地应力参数进行分析，并通过岩心Kaiser声波实验和现场压裂施工数据，对计算的参数进行校正，得到岩石弹性参数和地应力参数剖面，为现场有效施工提供保障。 The key issue in the fracturing operations is whether the pressure is suitable to fracture the formation open. As more and more deep formations were countered, the fracturing operation encounters rather more difficult in some reservoirs, such as shale-gas and deep-volcanics formations. And this kind of reservoir, in Lingchang depression, has the properties with deep, high-temperature, strong-heterogeneity, density-rocks and various-lithology. The complicated various formations have disunity pressure and very high abrasiveness and drillability, which bring much more difficulty for the drilling. And during the drilling, neck-down and collapse and declination are always occurring, so how to predict and calculate the fracturing pressure effectively has become very important for safety before operation in-site. This paper first uses the experimental results from tri-axial mechanics test, Kaiser experiments and fracturing data from in-site to calibrate the well logging information, and second, based on experimental models, we calculate the maximum formation stress, minimum formation stress, pore pressure, collapse pressure and fracturing press. And last we analyze the characteristics of the formation stress. The calculate results soundly agree with in-site data, which forcefully supports the fracturing operation of the oilfield.