Dual Purpose Observation and Production Well Design
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Solution Overview
Problem
Current methods for monitoring pressure and saturation in subterranean oil and gas wells are inefficient, as they require dedicating drilling slots for either production or observation, leading to costly and restrictive practices that hinder continuous pressure measurement and simultaneous production from separate reservoirs, especially in offshore fields with limited slots.
Innovation Solution
A dual-purpose well design featuring a vertical lateral for observation and a horizontal lateral for production, allowing continuous pressure measurement and flexible intervention, while eliminating the need for additional drilling slots by utilizing a single well with straddle packers and a Y-tool for logging and production logging tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a vertical well is drilled for production and pressure monitoring in the same reservoir, then pressure monitoring is possible, but the pressure readings are not representative of the general area due to pressure drop around the well bore
Solution Approach 1:
The well is segmented into two distinct laterals: a vertical observation lateral and a horizontal production lateral. This segmentation allows the observation well to remain closed and isolated from production activities, enabling representative pressure measurements while the production lateral maintains continuous hydrocarbon production. The packer system further segments the wellbore to isolate fluid flow paths between the two laterals.
Solution Approach 2:
A packer system acts as an intermediary mechanism to isolate the observation lateral from the production lateral. The packers create sealed zones that prevent cross-contamination of pressure regimes, allowing the observation well to accurately reflect reservoir pressure while the production well maintains its production-induced pressure drop.
2Measurement precision
If additional wells are drilled for observation purposes, then representative pressure data can be obtained, but drilling costs and slot utilization increase significantly
Solution Approach 1:
The invention merges the functions of production and observation into a single well infrastructure. By drilling one well with two laterals instead of two separate wells, the system achieves representative pressure monitoring while eliminating the need for additional drilling slots and reducing overall drilling costs. The shared wellbore and surface facilities further reduce resource requirements.
Solution Approach 2:
The dual-lateral well structure provides multi-functionality: the vertical lateral serves as an observation well for pressure and saturation monitoring, while the horizontal lateral serves as a production well. This universal design allows a single well to fulfill multiple reservoir management functions that traditionally required separate wells.
3Adaptability or versatility
If multiple reservoirs are perforated for production from different zones, then production diversity is achieved, but logging access is hindered by tubing and casing strings
Solution Approach 1:
The wellbore is segmented into isolated zones using packers, creating separate sealed compartments for different reservoirs. This segmentation allows logging tools to be run through the observation lateral to access formation properties in multiple zones without the interference of production tubing and casing, while each reservoir maintains its own production capability through the horizontal lateral.
4Ease of manufacture
If vertical wells are used for production, then drilling is simpler, but production rates are low compared to horizontal producers
Solution Approach 1:
The well design employs asymmetric laterals with different orientations optimized for their specific functions: a vertical observation lateral for measurement accuracy and a horizontal production lateral for maximum production rate. This asymmetric configuration allows each lateral to be optimized independently, achieving both drilling simplicity and high production capability.
Data Source
AI summary
A method for producing hydrocarbons in a subterranean well useful for observing properties of one or more subterranean zones, includes the steps of: (a) installing a lower straddle packer in a vertical well section below a junction with a lateral well section; (b) installing an upper straddle packer in a vertical well section above the junction with the lateral well section; (c) conveying hydrocarbons from the lateral well section to the surface with a tubing; (d) observing pressure information in at least one zone with a pressure gauge located in the vertical well section below the lower straddle packer; and (e) obtaining information in the at least one zone with logging equipment run through the tubing. A sidetrack window may be installed in the tubing between the lower straddle packer and the upper straddle packer for providing access to the lateral well section.