Pore Pressure Estimation Using TOC and Vitrinite Correction
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Solution Overview
Problem
Existing methods for estimating pore pressure in well bores, such as Bower's Method, fail to adequately account for hydrocarbon generation and maturity, leading to underestimation of pore pressure, particularly in source rocks like Jurassic calcareous mudstone, which can result in unexpected well control events.
Innovation Solution
A system and method that incorporates a density logging tool, a regional model, and a source rock model to calculate pore pressure by determining a total organic content (TOC) estimate and a correction factor based on vitrinite ratio Ro data, updating the estimated pore pressure in real-time to account for hydrocarbon maturity and generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pore pressure estimation methods (e.g., Bower's Method) are used, then the estimation process is simple and quick, but the accuracy of pore pressure estimation deteriorates due to failure to account for hydrocarbon generation and maturity
Solution Approach 1:
The invention introduces new parameters (TOC, vitrinite ratio Ro, correction factor) to the pore pressure estimation process. The system calculates pore pressure using multiple parameters including overburden gradient, compaction velocity profile, unloading velocity profile, TOC, and vitrinite ratio Ro, rather than relying on single-parameter conventional methods. This multi-parameter approach improves accuracy while the automated calculation process manages the complexity.
Solution Approach 2:
The invention introduces a correction factor as an intermediary element that bridges the gap between conventional estimation methods and actual pore pressure in hydrocarbon-bearing formations. The correction factor, calculated based on TOC and vitrinite ratio Ro, acts as a mediator to adjust conventional estimates and account for hydrocarbon generation effects without requiring complete redesign of the estimation process.
2Reliability
If conventional pore pressure estimation methods are used, then the calculation process is fast and simple, but the reliability of drilling operations deteriorates due to underestimation of pore pressure
Solution Approach 1:
The system performs preliminary calculations of TOC and vitrinite ratio Ro before final pore pressure estimation. By pre-calculating these parameters and the correction factor, the system ensures that all necessary data is prepared in advance, improving reliability without significantly impacting overall calculation speed during drilling operations.
Solution Approach 2:
The invention implements a feedback mechanism where the correction factor, derived from TOC and vitrinite ratio Ro, continuously adjusts the pore pressure estimation. This feedback loop ensures that the estimation accounts for hydrocarbon generation effects, improving reliability while the automated nature of the feedback maintains calculation efficiency.
3Object-affected harmful factors
If conventional pore pressure estimation methods are used, then the operational procedure is simple, but the safety of drilling operations deteriorates due to unexpected well control events
Solution Approach 1:
The system applies preliminary anti-action by calculating the correction factor based on TOC and vitrinite ratio Ro before drilling operations proceed. This pre-calculation anticipates potential overpressure conditions in hydrocarbon-bearing formations and adjusts the pore pressure estimation accordingly, preventing well control events while maintaining operational simplicity through automated calculations.
Solution Approach 2:
The correction factor serves as an intermediary that protects drilling operations from harmful effects of underestimated pore pressure. By introducing this intermediate calculation layer based on TOC and vitrinite ratio Ro, the system safely bridges conventional estimation methods and actual formation conditions without significantly complicating operational procedures.
Data Source
AI summary
Systems and methods to estimate a pore pressure of source rock include a pore pressure estimation processor, an executable, or both, and are operable to (i) calculate an estimate pore pressure based on overburden gradient data, a compaction velocity profile, hydrocarbon maturity, and an unloading velocity profile, (ii) determine a total organic content (TOC) estimate of the source rock based on a bulk density at a vertical depth measured using the density logging tool, (iii) determine a correction factor based on (a) the TOC estimate and (b) vitrinite ratio Ro data, and (iv) update the estimated pore pressure in real-time based on the correction factor.