Hydrothermal geothermal development method of multilateral well closed circulation
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Solution Overview
Problem
Current geothermal development modes in China face challenges with low production per well and difficult recharging due to complex geothermal reservoir conditions, particularly in medium-low temperature systems with low water temperature and permeability.
Innovation Solution
The hydrothermal geothermal development method employs a multilateral well closed circulation technique, dividing the reservoir into distinct layers for recharge and production, drilling radial horizontal holes, and using a guiding pipe to create a geothermal fluid circulation passageway, allowing for efficient heat recovery and recharging without the need for separate wells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If direct geothermal fluid exploitation is used, then heat recovery power is maximized, but production per well is low and recharging is difficult due to complex reservoir conditions
Solution Approach 1:
The geothermal reservoir is segmented into multiple layers based on geological conditions, with each layer having different permeability and temperature characteristics. This allows selective exploitation of high-permeability layers for production while using low-permeability layers for recharging, thereby improving overall production per well while maintaining heat recovery power.
Solution Approach 2:
Different regions of the reservoir are assigned different functions based on their local properties: high-permeability zones are designated for fluid production, while low-permeability zones are used for recharging. This local differentiation enables each zone to contribute optimally to the system, increasing overall productivity without sacrificing heat recovery capability.
2Productivity
If hydraulic fracturing is performed to improve reservoir permeability, then geothermal fluid production increases, but development cost increases and underground water resources are polluted
Solution Approach 1:
The method exploits the natural local quality differences in reservoir permeability without artificial enhancement. By identifying and utilizing naturally high-permeability zones for production and low-permeability zones for recharging, the system achieves improved fluid production without the need for costly hydraulic fracturing operations.
Solution Approach 2:
The reservoir's natural permeability structure is utilized to self-organize the production and recharging functions. The system leverages existing geological features rather than requiring expensive artificial modifications, thereby improving productivity while avoiding increased development costs and environmental pollution.
3Device complexity
If heat recovery without water is used, then recharging difficulty is avoided and process is simplified, but heat recovery power is limited and energy utilization rate is low
Solution Approach 1:
The system segments the thermal exploitation process into two distinct functional zones: a production layer for extracting high-temperature geothermal fluid and a recharge layer for injecting cooled fluid. This segmentation enables full utilization of geothermal fluid for power generation while maintaining a simplified recharging process through natural layer differentiation.
Solution Approach 2:
The invention transitions from horizontal heat exchange (conduction through pipes) to vertical multi-layer fluid circulation. By utilizing the vertical dimension and creating a closed circulation system between production and recharge layers, the system achieves both high heat recovery power and simplified recharging with high energy utilization rate.
4Adaptability or versatility
If medium-low temperature geothermal systems are exploited, then geothermal resources are utilized, but water temperature is low and flow rate is small resulting in poor quality
Solution Approach 1:
The geothermal system is segmented into multiple temperature zones, with deeper layers providing higher temperature sources and shallower layers serving as recharge zones. This vertical segmentation allows the system to utilize medium-low temperature resources effectively by creating temperature gradients that drive circulation and improve overall water temperature and flow rate quality.
Solution Approach 2:
The system utilizes the vertical dimension to create temperature gradients, drawing hot fluid from deeper layers and injecting cooled fluid into shallower recharge layers. This vertical circulation approach transforms low-temperature, low-flow resources into a high-quality system with improved water temperature and flow rate by leveraging the thermal energy from deeper geological formations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases heat recovery efficiency, reduces development costs, and enhances the recharge capability, enabling more effective exploitation and sustainable use of geothermal resources by utilizing the geothermal fluid's thermal gradient for circulation.
Implementation Method 1
The geothermal fluid circulation passageway enables efficient heat recovery and recharging
Implementation Method 2
utilizing the geothermal fluid's thermal gradient for circulation
Implementation Method 3
utilizing the geothermal fluid's thermal gradient for circulation
Data Source
AI summary
The present disclosure provides a hydrothermal geothermal development method of multilateral well closed circulation, comprises the steps of: dividing a geothermal reservoir into single layers according to geothermal reservoir geological conditions, wherein an upper single layer with a lower water temperature and a higher permeability is taken as a recharge layer, and a lower single layer with a higher water temperature is taken as a production layer; tripping a production casing, and injecting cement for well cementation; performing casing lateral windowing in a vertical hole corresponding to the recharge layer, and drilling several branch radial horizontal holes into the recharge layer; performing casing lateral windowing in the vertical hole corresponding to the production layer, and drilling several branch radial horizontal holes into the production layer; tripping a guiding pipe into the production casing of the vertical hole, with a depth thereof reaching a well section between the recharge layer and the production layer; tripping a packer at a guiding shoe to isolate the guiding pipe and an annulus of the casing from each other, so as to prevent geothermal fluid of the recharge layer and the production layer from being communicated with each other in the vertical hole.