RE: PG Update4 Aug 2025 19:05
It does seem that Jimmy is onto something here, re potential long term reservoir damage from overbalanced mud weights.
I asked ChatGPT if using overbalanced mud weights can cause permanent reservoir damage when there is high porosity and permeability:
Using overbalanced mud weight in drilling highly porous and permeable reservoirs can potentially cause permanent damage to the formation. Here's how this can occur:
### 1. **Formation Damage:**
- **Fluid Invasion**: Overbalanced drilling (where the mud weight exceeds the formation pressure) can cause the drilling fluid to invade the porous rock. This invasion can lead to the plugging of pores and fractures, reducing the permeability of the reservoir.
- **Clay Swelling and Migration**: If the reservoir contains clay, overbalanced mud can cause clay particles to swell or migrate, which can further block pore spaces and lead to reduced flow rates.
### 2. **Alteration of Reservoir Properties:**
- **Stress Changes**: Applying excessive pressure from the overbalanced mud can change the stress regime within the reservoir, potentially leading to rock fracture or collapse, altering reservoir characteristics and reducing productivity.
- **Damage to Hydrocarbon Pathways**: The advent of mud filtrate into the reservoir can damage the pathways through which hydrocarbons flow, creating skin damage around the wellbore.
### 3. **Costly Remediation:**
- **Workover Operations**: The damage caused by overbalanced mud might necessitate expensive workover operations to restore the production capability, including methods such as acid stimulation or other remedial treatments.
### 4. **Long-term Production Impacts:**
- Even if initial flow rates appear satisfactory, reservoir damage from overbalanced mud can lead to long-term declines in production, impacting the overall economics of the well and the field.
### Best Practices:
To minimize risks, engineers often consider using managed pressure drilling (MPD) or underbalanced drilling techniques, especially in formations that are highly porous and permeable, to maintain formation pressure and protect reservoir integrity.
In conclusion, while overbalanced mud weight can be necessary in some drilling scenarios, careful management and consideration are crucial to minimize the risk of permanent damage to highly porous and permeable reservoirs."
My concern is that after 4/5 successive overbalanced mud weight drills at Guercif, is the potential long term damage cumulative as well as more and more likely?
And why no mention of this aspect of the drilling snafus, rather than focussing on the relief shown in PG's face and answers in the interview that they have now proved the problems come from formation damage.
I suspect ONHYM, when they fully consider the implications of this technical wrong approach at Guercif, will not be best pleased with Predator, at least behind closed doors.
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