南海珠江口盆地钻井BHT温度校正及现今地温场特征

2016-09-29唐晓音黄少鹏杨树春姜光政胡圣标

地球物理学报 2016年8期

关键词：深度

唐晓音，黄少鹏，杨树春，姜光政，胡圣标

1 西安交通大学人居环境与建筑工程学院，西安　710049 2 岩石圈演化国家重点实验室，中国科学院地质与地球物理研究所，北京　100029 3 中海油研究总院，北京　100027

南海珠江口盆地钻井BHT温度校正及现今地温场特征

唐晓音1，2，黄少鹏1，杨树春3，姜光政2，胡圣标2

1 西安交通大学人居环境与建筑工程学院，西安710049 2 岩石圈演化国家重点实验室，中国科学院地质与地球物理研究所，北京100029 3 中海油研究总院，北京100027

温度是盆地现今地温场研究最重要的基础参数之一，针对钻井井底温度(BHT)一般低于地层真实温度的情况，本文对珠江口盆地16口钻井的BHT数据进行了校正，并根据校正后的温度数据采用最小二乘法新增计算了16个地温梯度及大地热流数据.结合前人发表数据，本文绘制了珠江口盆地最新地温梯度等值线图及大地热流等值线图.除此之外，系统收集整理了盆地钻井大地热流、生热率以及热导率等参数，利用一维热传导方程计算了盆地1～5 km深度处的温度，并绘制了盆地深部温度等值线图.在此基础上，分析了盆地现今地温场特征及其成因，以期为珠江口盆地地球动力学背景研究及油气资源评价与勘探提供地热学参数.

BHT校正;地温梯度;大地热流;温度;珠江口盆地

In this paper,two correct methods that is the Horner-plot method and the Waples method have been chosen for BHT correction.The new thermal gradient data have been calculated by the least square fitting based on the corrected BHT data,and the deep temperature have been acquired by the 1-D heat conduction equation.

Thermal gradient of the Pearl River Mouth Basin ranges from 24.7 ℃/km to 60.8 ℃/km,with the average value of 37.87±7.35 ℃/km,and the heat flow ranges from 24.2 to 121.0 mW·m-2,with the average value of 71.5±13.4 mW·m-2.The temperature at the depth of 1 km,2 km,3 km,4 km,5 km ranges during 22.2～70.4 ℃,43.6～117.4 ℃,64.4～164.0 ℃,84.4～209.9 ℃,and 103.7 ℃～254.9 ℃,respectively,and with the average value of 46.5±7.9 ℃,78.3±10.9 ℃,109.5±15.6 ℃,139.8±20.7 ℃,and 169.6±26.2 ℃,respectively.

After comparison between the corrected BHT with the DST data,we found that the corrected BHT data by the Horner Plot is still much lower than the DST data,while the data corrected by the Waples method is very close to the DST data;From the view of the geothermal gradient and heat flow,the Pearl River Mouth Basin belongs to the classical “hot basin”;The counter maps of the geothermal gradient,heat flow and deep temperature generally show the increase trend from the shelf area to the slop area,but display two abnormal areas with high value,that is the Shunde sub-sag and the Yangjiang sub-sag;The overall characteristics of the present geothermal field of the Pearl River Mouth Basin is under the control of geology background.The increase trend is in consistence with the decrease trend of the crust thickness of this basin,and the high value of the Shunde sub-sag is likely to be caused by igneous activities while the high value of the Yangjiang sub-sag might be the result of fault activities.