基于临界流量的深水探井测试关键技术与实践——以琼东南盆地深水区为例

深水探井测试对于深海油气田的勘探发现和开发方案的制订起着至关重要的作用。为此,针对琼东南盆地陵水凹陷深水测试面临的海床温度低、管柱压力大,以及地层水或凝析水具有生成天然气水合物(以下简称水合物)堵塞测试管柱等技术难题,在分析总结南海北部珠江口盆地多口深水探井与国外合作测试作业成功经验的基础上,研究形成了该区测试期水合物形成区域预测及水合物防治方法;建立了基于临界测试流量设计测试工作制度;结合地质录井、MDT测井等资料.建立了可视化数值试井模型并对压力恢复时间进行合理设计;通过对深水测试管柱结构的优化,提出了深水测试一开一关的测试程序,从而达到多开多关测试程序的功能;通过对地面测试流程的模块化方案设计,增强了深水测试的安全性和高效性。实践结果表明:测试期间水合物和地层出砂得到了有效防治.测试管柱及模块化地面流程经受住了高产气流的考验,获得了完整的测试资料,节省了测试时间,达到了准确评价储层的目的,并基本形成了我国的深水油气井测试技术。

Key techniques and practices of critical flow based tests for deep water exploration wells:A case study of deep water area in the Qiongdongnan Basin

The test of a deep-water exploration well plays a vital role in the exploration discovery and development planning of deep sea oil and gas fields. However, in the Lingshui sag of the Qiongdongnan Basin, such tests face many technical problems like low seabed temperature, high string pressure and plugging of test string by hydrate formed from formation water or condensate water confronted. In this paper, through an analysis of the successful testes of a number of deep water exploration wells in the Pearl River Mouth Basin of the northern South China Sea, a method for predicting and preventing the hydrates formed at the test stage, and a working system for designing the test based on the critical test flow rate was established. Moreover, combined with geologic mud logging and MDT logging data, a visualized numerical well test model was built and rational design was conducted on buildup time. By means of optimizing the deep water test string structure, a one-open and one-close test program was proposed for a deep water well test in order to achieve the function of multiple-open and multiple-close test program. In addition, by means of modularized program design of surface test workflow, the security and efficiency of deep water test are strengthened. It is shown by practices that, during the well tests in deep water, the hydrate and formation sand flow can be effectively controlled, that the test string and modularized surface workflow withstand the test of high rate gas flow, that complete test data are obtained and test time is saved, and ultimately the objective of accurately evaluating the reservoir is achieved. As a result, testing techniques for deep water oil and gas wells in China are basically formed.