Low Salinity Viscous Fluid Drilling Salt Formations
Solution Overview
Problem
Drilling in saline formations with high salinity and variable salt intercalations leads to irregular well diameters, poor cementation quality, and increased logistical challenges due to the dissolution of salts, resulting in well integrity issues and high costs.
Innovation Solution
The use of a low salinity viscous fluid, mixed with seawater in real-time, to reduce salt diffusion and maintain a homogeneous well diameter, employing viscosifiers like xanthan gum to create a laminar flow regime and improve cementing operations, allowing for efficient drilling without fluid return and reducing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high flow rates of seawater are used to drill saline formations, then drilling speed increases, but salt dissolution increases causing irregular well diameters and poor cementation quality
Solution Approach 1:
The patent changes the salinity parameter of the drilling fluid from high (seawater) to low (freshwater or brine with lower salinity than formation), which reduces the driving force for salt dissolution while maintaining drilling effectiveness through optimized flow rates and fluid properties
Solution Approach 2:
The patent uses composite drilling fluids combining freshwater/brine with viscosifiers and other additives to create a fluid system that provides both low salinity (to reduce dissolution) and adequate rheological properties (to maintain drilling performance)
2Stability of the object's composition
If saturated sodium chloride solution is used to prevent salt dissolution, then halite stability improves, but more soluble salts like carnallite and sylvinite continue to dissolve causing diameter irregularities
Solution Approach 1:
The patent changes the approach from matching formation salinity (saturated NaCl) to using lower salinity fluids, combined with reduced drilling parameters (flow rates, RPM) to minimize dissolution of all salt types regardless of solubility differences
Solution Approach 2:
The patent applies a more conservative drilling approach with lower flow rates and extended drilling times, accepting slower productivity to achieve complete prevention of salt dissolution rather than partial protection
3Manufacturing precision
If low salinity viscous fluid is used to reduce salt dissolution, then well diameter uniformity improves, but fluid viscosity increases requiring higher pumping pressure
Solution Approach 1:
The patent optimizes the viscosity parameter by using moderate concentrations of viscosifiers rather than high concentrations, achieving sufficient diameter control while limiting viscosity increase and associated pumping pressure requirements
Solution Approach 2:
The patent uses dynamic adjustment of fluid properties and drilling parameters, modifying flow rates and viscosity levels according to real-time drilling conditions and formation characteristics to balance diameter control with pumping requirements
4Reliability
If Pump and Dump technique is used to cross saline formations, then well stability improves, but logistical complexity and costs increase significantly
Solution Approach 1:
The patent extracts the core function of the Pump and Dump technique (preventing salt dissolution) and implements it through a simplified continuous drilling process using low salinity fluids, eliminating the need for complex pumping equipment and fluid disposal infrastructure
Solution Approach 2:
The patent creates a universal drilling fluid system (low salinity viscous fluid) that can be used continuously throughout drilling operations in saline formations, replacing the specialized Pump and Dump approach that requires separate equipment and procedures
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 significantly reduces salt dissolution, enhances well integrity, and decreases construction time and costs by enabling drilling with smaller, less expensive rigs, while maintaining well quality and reducing logistical complexities.
Implementation Method 1
employing viscosifiers like xanthan gum to create a laminar flow regime
Implementation Method 2
reduce salt diffusion
Implementation Method 3
low salinity viscous fluid... employing viscosifiers like xanthan gum
Data Source
AI summary
The present invention addresses to the use of a viscous fluid in continuous pumping to contain the saline dissolution in a homogeneous way (not limited to just one type of evaporite), highlighting the results of seawater with viscosifiers, due to its simplicity, and that does not have the same impact on the logistical chain as a brine supply. The increase in fluid viscosity limits the diffusion of salt into the medium and thus better contains the dissolution of the well walls, while also promoting a laminar flow regime in the annulus of the well, variables desired to achieve the quality of the operation of cementation. The employment of viscous fluid concentrates allows “on the fly” dilutions with the in-line seawater fraction mixture. The technique can also employ solutions of pre-dispersed viscosifying additives which, when added to seawater, result in a substantial increase in the volume of drilling fluid produced, no longer limited by the unit tank capacity. This allows drilling large extensions of salt. The low salinity viscous fluid is used in drilling operations without fluid return to the drilling rig (riserless) in the presence of a predominantly saline formation, aiming at preserving the phase diameter and improve well construction conditions.