Pre-Salt Well Completion With Two-Casing 2R-PAC Architecture
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Solution Overview
Problem
The high costs and time consumption associated with constructing wells in pre-salt fields due to complex drilling and completion processes, which involve multiple phases and casings, pose a challenge for economic project implementation.
Innovation Solution
A simplified well drilling and completion system (2R-PAC) that reduces one phase to three drilling phases, using only two casings, with one casing exposed to the saline formation, and employs seawater-based drilling fluids and optimized completion methods to expedite the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional four-phase drilling with three or four casings is used, then well construction reliability and safety are improved, but construction time and costs increase significantly
Solution Approach 1:
The patent merges phases 3 and 4 into a single drilling phase, and reduces the number of casings from three or four to two. Specifically, the production casing and intermediate casing are combined into one production casing, and the conductor casing and surface casing are maintained as the second casing. This consolidation reduces construction time by approximately seven days while maintaining well integrity through proper casing shoe positioning and cementation procedures.
Solution Approach 2:
The patent extracts and eliminates the intermediate casing from the conventional four-phase process, reducing the total number of casings to two. The production casing directly replaces both the intermediate casing and production string function, while the second casing (conductor or surface casing) provides the necessary structural support and isolation. This extraction reduces material costs and construction time without compromising safety when proper engineering controls are applied.
2Reliability
If conventional four-phase drilling with multiple casings is used, then well construction safety is improved, but overall project costs increase
Solution Approach 1:
The patent merges the functions of the intermediate casing and production string into a single production casing. This production casing is designed with appropriate wall thickness and material properties to withstand both the structural loads previously handled by the intermediate casing and the production requirements. This consolidation reduces material procurement, handling, and installation costs while maintaining well safety through proper casing design and cementation.
Solution Approach 2:
The patent removes the intermediate casing from the material list, reducing the total quantity of steel and cement required. The production casing is engineered to directly contact the formation and provide necessary structural support, eliminating the need for the intermediate casing. This extraction of unnecessary materials directly reduces project costs while maintaining safety through careful engineering of the remaining two-casing system.
3Productivity
If simplified two-casing system is used, then construction time and costs are reduced, but exposure to saline formation increases
Solution Approach 1:
The patent positions the shoe of the second casing (conductor or surface casing) at a depth that ensures it extends below the saline formation before drilling begins. This preliminary positioning establishes a protective barrier in advance, preventing saline formation exposure during subsequent drilling operations. The production casing is then drilled through the saline formation to the reservoir, with the second casing already in place to contain any potential exposure issues.
Solution Approach 2:
The second casing acts as an intermediary protective barrier between the drilling operations and the saline formation. By positioning this casing to extend below the saline zone, it mediates the interaction between the drilling process and the harmful saline environment, containing any potential exposure within the cased section and protecting the production equipment from direct contact with saline formations.
4Reliability
If conventional completion equipment is used, then completion reliability is improved, but complexity and cost of the system increase
Solution Approach 1:
The patent merges the completion string and production string into a single production string configuration. The production casing serves dual purposes as both the structural wellbore component and the completion conduit. This consolidation eliminates the need for separate intermediate casing and completion string assemblies, reducing system complexity while maintaining completion reliability through proper selection of production casing specifications and completion equipment designed for direct installation in the production casing.
Data Source
AI summary
The present invention refers to a system and method for construction and completion of wells in the pre-salt production and injection fields. The application of the present invention allows a reduction in well construction time of approximately seven days considering the drilling and completion of the well. The system comprises string accessories, cement, AMB, production string, casings, HFIV, fluid, wellhead system, subsea equipment, DHSV and packer. The method aims at reducing one well phase, resulting in three drilling phases, with the running in of only two casings and the completion in an open well with part of the same exposed to the saline formation, herein called 2R-PAC.