冀中坳陷霸县地区现今温压场及其与地热资源的关系

渤海湾盆地冀中坳陷霸县地区是地热资源富集区,其以"雄县模式"为示范引领,成功打造了中国第一个"无烟城"。为指导下一步地热能的勘探开发,基于大量油田钻井实测温度和压力数据,对该区现今地温梯度及温度、压力平面分布特征进行了系统研究,探讨了温压场与地热资源的关系。结果表明:(1)该区现今地温梯度介于21.8~73.5℃/km,平均值为33.5℃/km;(2)霸县地区地层温度随着深度的增加而逐渐升高,其平面变化特征与地温梯度展布特征相似,两者都与基底起伏形态具有很好的对应关系——对于同一深度,牛驼镇凸起温度最高,而廊固凹陷和霸县凹陷则较低,牛驼镇凸起北部、霸县凹陷中部及廊固凹陷中东部普遍存在高异常温度区,是潜在的地热资源有利开发区;(3)霸县地区现今地层压力以常压、弱超压为主,其平面分布规律随深度变化而存在着一定的差异,廊固凹陷南部和霸县凹陷南部在深度4 000 m处普遍发育中—强超压带,在开展下一步的地热能开发时需要格外注意。

Present-day temperature–pressure field and its implications for the geothermal resources development in the Baxian area,Jizhong Depression of the Bohai Bay Basin

The Baxian area in the Jizhong Depression, west of the Bohai Bay Basin, is rich in geothermal resources, where Xiong County was built as the first smokeless city in China and the Xiong-county Model has become the geothermal resources demonstration model in China. In this study, the present-day geothermal gradient and the horizontal distribution characteristics of the temperature and pressure at different depths in the Baxian area were studied based on massive measured temperature and pressure data of the boreholes, and then the relationship was also discussed between the temperature–pressure field and the geothermal resources. The following findings were obtained. (1) The present-day geothermal gradient of the Baxian area is within the range of 21.8–73.5 ℃/km, averaging 33.5 ℃/km. (2) Its strata temperature increases as the depth increases. The horizontal variations of the geothermal gradient and strata temperature correspond to the basement relief very well. As the abnormally high temperature areas, the northern Niutuozhen Uplift, the Central Baxian Depression and the central East Langgu Depression possess huge geothermal resources and will be the most favorable exploration targets. (3) The formation pressure of the Baxian area is characterized by normal pressure and weak overpressure, and its horizontal distribution varies at different depths. The middle–strong overpressure generally developed at the depth of 4 000 m in the southern Langgu Depression and southern Baxian Depression. This study is of important guiding significance for the exploration and development of geothermal resources in the Baxian area.