Alternating Cased Openhole Wellbore for Multi-Reservoir Monitoring
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Solution Overview
Problem
Current well construction practices that run casing across upper reservoirs interfere with saturation monitoring, limiting the ability to effectively measure saturation in multiple reservoirs through a single wellbore, and often require dedicated observation wells for each reservoir, increasing costs and complexity.
Innovation Solution
A method of constructing a wellbore with alternating cased and openhole sections to allow for openhole saturation logging and pressure monitoring of multiple reservoirs via a single wellbore, using real-time and memory gauges to record pressure data and openhole logs to measure saturation, thereby reducing the need for multiple wells and enhancing surveillance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If casing is run across upper reservoirs in current well construction practices, then wellbore structural integrity is improved, but saturation monitoring capability deteriorates
Solution Approach 1:
The wellbore is segmented into alternating cased and openhole sections, allowing different functions in different zones. Cased sections provide structural integrity while openhole sections enable saturation monitoring, resolving the contradiction by spatial segmentation of functions.
Solution Approach 2:
Different sections of the wellbore are given different properties: cased sections for structural support and openhole sections for measurement capability. This local differentiation allows both structural integrity and saturation monitoring to be achieved in appropriate locations.
2Measurement precision
If dedicated observation wells are constructed for each reservoir, then saturation monitoring accuracy is improved, but well construction cost and complexity increase
Solution Approach 1:
A single wellbore is designed to serve multiple reservoirs simultaneously by incorporating alternating cased and openhole sections at different depths. This multi-functional design eliminates the need for separate dedicated observation wells for each reservoir, reducing complexity while maintaining monitoring capability.
Solution Approach 2:
Multiple observation functions for different reservoirs are merged into a single wellbore structure. The wellbore combines cased and openhole sections to monitor both upper and lower reservoirs, consolidating what would traditionally require multiple separate wells.
3Measurement precision
If multiple separate wells are constructed for monitoring multiple reservoirs, then saturation logging accuracy is improved, but development cost increases
Solution Approach 1:
The wellbore is designed as a universal monitoring structure that can log saturation data from multiple reservoirs through its alternating cased and openhole sections, eliminating the need for multiple separate wells and reducing development costs.
Solution Approach 2:
The patent merges multiple saturation logging functions into a single wellbore, combining what would traditionally require multiple separate wells. This consolidation reduces the quantity of wells needed, thereby reducing development costs while maintaining logging accuracy.
Data Source
AI summary
A system and method for monitoring a subterranean formation including conducting openhole saturation logging, via a single wellbore, of both an upper reservoir of hydrocarbon and a lower reservoir of hydrocarbon.