Simulation method and device for stripping and transporting hydrate reservoir sediment during depressurization

Abstract

The invention discloses a simulation method and device for stripping and transporting hydrate reservoir sediment during depressurization. The simulation device comprises a reservoir simulation module,a supply module, a pressure control module, a temperature control module and a recovery module. The reservoir simulation module is used for loading loose deposits, forming a hydrate reservoir and observing a sediment stripping initiation process and comprises a microscopic visual module, a pure radial flow reservoir simulation module and a non-radial flow reservoir simulation module. The influences of the different streamline patterns and a hydrate distribution law on the initiation and migration process of hydrate reservoir sands are considered, hydrate reservoirs under different hydrate saturations and different hydrate distribution patterns are prepared through the reservoir, that the hydrate is in an undecomposed state in a subsequent sand production mechanism analysis experiment is guaranteed, a critical pressure drop condition of sand production and an sand production pattern evolution law are discussed, and a technical support is provided for the prediction of a sand productionlaw in an actual production well.

Description

technical field [0001] 本发明属于海洋天然气水合物开发领域,具体涉及能够模拟不同流场条件下水合物降压开采过程中泥砂剥落、泥砂运移细观过程的可视化模拟方法及系统。 Background technique [0002] 随着我国首次海域天然气水合物试采成功,海域天然气水合物开采过程中的出砂及其影响因素的评价模拟迅速成为国内研究热点。目前的关注点主要是通过数值模拟或实验模拟的手段回答降压过程中储层泥砂的产出规律。由于缺乏现场实际出砂测试数据,实验模拟成为天然气水合物开采出砂机理分析、出砂规律预测的主要手段。青岛海洋地质研究所(专利公开号:CN106950153A;CN106353069A)、中国海洋石油集团有限公司(专利公开号:CN108316913A)、中国石油大学(华东)(专利公开号:CN106680435A)、中国科学院力学研究所(专利公开号:CN104950074A)等单位分别针对不同的水合物开采工况提出了水合物分解产出过程中的出砂规律模拟实验系统及实验方法,这些方法的重点是考虑水合物开采产气产水过程与产砂过程间的规律,无法从微观机理的角度描述水合物开采过程中泥砂在储层中的剥落、运移过程。 [0003] 实际上,天然气水合物开采过程中的出砂过程与储层的力学性质弱化密切相关,水合物储层的出砂机理与储层的力学性质演化密切相关。 为此,青岛海洋地质研究所(专利公开号:CN107121359A)考虑了水合物开采出砂与力学性质的耦合关系,提出了基于三轴力学基本测试原理的水合物出砂量-抗剪强度联合探测 method. 但该方法从宏观角度解释出砂过程对力学性质的影响,对水合物储层砂粒的剥落机理有一定的帮助,但仍然无法从微观尺度验证水合物分解过程与泥砂启动运移的关系。 为了解决上述问题,专利公开号CN109254137A试图应用X-CT技术揭示水合物储层的出砂过程对储层孔隙的影响。 [0004] 这些有益的探索都对水合物的开采出砂过程、出砂机理的研究提供了基础,但是大都是在一维条件下开展的,即没有考虑储层流场对储层泥砂剥落、启动运移过程的影响,也很难实现可视化的模拟。 [0005] 综上可见,从天然气水合物出砂模拟研究的角度,仍然存在如下问题: [0006] (1)目前存在重规律、轻机理,重出砂结果、轻泥砂在储...

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Problems solved by technology

[0007] (2) Although some schemes have realized that the sand production mechanism of reservoirs should be explained from the microscopic scale, it is still impossible to discuss the influence of hydrate decomposition on the exfoliation and migration process of mud and sand particles from the perspective of visualization;

[0008] (3) The influence of special reservoir streamline pattern on sand migration in hydrate reservoirs is not considered, which cannot meet complex mining methods, such as sand spalling and start-up pattern description in special seepage areas around hydraulic slots

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