Leading with Advanced Frac Fluid & Technologies

ii) Environmentally Crosslinked Fluid

Lab Test & Implementation

• Part of requirement of Green Completion by BP Oman
• A Green Completion is a zero-flaring concept – hydrocarbon during well test operations are "Cleaned" and then routed to processing facilities for export rather than being flared. The testing removes contaminants – proppant, frac fluid and H2S
• H2S was a byproduct of Sulphur based Hi Temp Gel Stabilizer in the frac fluid
• Gel slurry was formulated using mineral oil instead of diesel & non-Sulphur Hi Temp Gel Stabilizer
• Frac fluid requirement at 300 cP for 3 hours stability
• 13,000 bbls of AF40XLMO successfully pumped to carry ~ 1M lbs of 20/40 HSP proppant in a single job in 2020 as the 1st frac job with international client in Oman done by Local Omani Frac Service provider

Key Implementation Details:

• The field prone to self-scaling issue, from water analysis, the dominant scale is CaCO3
• Scale reduced the production rate of the well, even more lifetime of the well productivity
• Scale also create trouble on ESP, as such the costly workover for ESP maintenance needed
• Implementation of SI strategy will prolong the ESP lifetime, and maintain well production above economics threshold
• Nominated SI technology is infused inside ceramic proppant
• Client approved and successfully pumped in 5 wells

Most Popular Features of Hydraulic Fracturing:

• Degradable Particulate Diverter (AFDP), engineered shape, blend & degradation period.
• Through tubing and WHIT conveyance, eliminate pre & post workover Rig/Hoist less intervention. Alternative solution to costly mechanical diversion techniques (i.e. MSS Frac sleeves, Perf & Plugs, CT conveyance frac treatment, Pinpoint fracturing).
• Improve reservoir contact, especially important for tight rock formation fracturing.
• Enabler for multistage fracturing placement across different stress contrast.
• Far field diversion for geometry control, i.e. frac hit avoidance, height growth control.
• Improve perforation breakdown. Accommodate all possible perforation shapes.
• On-the-fly delivery, provide flexibility of real time concentration adjustment.

Design Comparison

Several candidate wells screening with target zone of Late Cretaceous tight carbonate formation

• Various well and reservoir scenario were simulated to cover uncertainty and provide fair comparison: Pore pressure depletion, YMES, Stress contrast and anisotropy, permeability and fluid efficiency, tubular friction, perforation interval
• Initially gelled acid and crosslinked Self-Diversion Acid were chosen for fluid system for contractual context. Retarded emulsified acid system were implemented on later phase of the campaign
• For comparison, equivalent budgetary job size between acid fracturing and propped fracturing were simulated
• For average candidates, the study indicate propped fracturing provide better conductive fracture penetration, therefore more flow area. However, some pre-existing completion can only be stimulated proppantless.

Execution

Series of prejob injection decline pumping were performed to include:

• BDT and DFIT with small volume brine
• SRT with brine in the case of high NWB suspected
• FET calibration injection with crosslinked fluids if excessive leak-off anticipated

• Largely, the secondary leakoff due to fissures opening is anticipated at Field L, M & S
• Some jobs with RA Tracers run confirmed the fracture height as pressure matched post job, however for the well with lack of cement isolation this can be misleading
• Acid frac treatment was performed at Field S (gel acid) & M (emulsified acid), to complement study comparison.

Post Fracture Evaluation

Master databases were collected to include critical information:

• Well & reservoir data
• Design & actual treatment parameter
• Pressure, rate data and diagnostics
• Other operational parameter

Following the fracturing campaign:

• Substantial improvement in both gross and net oil production (oil production increased by a factor of 20).
• Productivity was sustained, uptime improved from 25% to 100%.
• Propped fracturing method is preferred when applicable, while retarded acid fracturing provide more flexibility for complex pre-existing well completion