For offshore wells requiring sand control, Open Hole Gravel Packing (OHGP) with or without shunted screen technology is a common completion technique. Prior to this paper, there has been no application of shunted screen OHGP in High-Pressure High-Temperature (HPHT) environment due to lack of a viscous fluid availability in high-density divalent brines (> 14.6 lbm/U.S. gal). For the case study, the fluid requirements in terms of density and temperature were 15.4 lbm/U.S. gal and 265°F, respectively. The only brine option at this density was a blend of calcium chloride/bromide and zinc bromide. In this brine and density, none of the existing fluids work hence a novel polymer-based fluid had to be developed. The fluid had to pass the following tests a) rheology before and after subjecting to high shear of both uncontaminated and contaminated fluids at 3 different temperatures b) sand settling tests at 4 different temperatures c) Production Screen Tester to ensure the fluid does not plug the screens during the job. System Integration Tests (SIT) were performed to ensure the mixing equipment would be able to batch mix the fluid and actual pumping equipment would function properly with the fluid. The field trial planning included simulations, pre-job meetings, and fluid management plan. The job was executed as per the procedure outlined during pre-job meetings. This paper discusses laboratory development, yard test qualification, and successful shunted screen OHGP case history of a novel 15.4 lbm/U.S. gal viscous gravel pack carrier fluid.

High-temperature water-based drilling fluid systems hold several advantages over synthetic based systems from financial and environmental viewpoints. However, most conventional water-based systems start to become unstable at temperatures above 300 degF. This paper details the design and implementation of A Novel Water-Based Drilling Fluid that meet these temperature stability requirements. The newly developed high-temperature water-based system discussed in this paper utilizes a custom-made branched synthetic polymer that exhibits superior rheological properties and fluid loss control as well as long term stability above 400 degF. The branched synthetic polymer is compatible with most oilfield brines and maintains excellent low-end rheology necessary for hole cleaning and solids suspension under high-temperatures and pressures. Under static conditions, the high-temperature fluid shows no gelation resulting in lower swab surge pressures while the stability of the highly branched synthetic polymer and enhanced rheological profile minimize sag. To drill a challenging exploration well, a Middle East client required a cost-effective drilling fluid system which remains stable under static temperatures expected to exceed 375 degF. The long-term stability of the system was critical for successful wireline logging operations. In addition, the system was required to provide shale inhibition, hydrogen sulfide suppression and sufficient density (above 16.5 lbm/galUS) to maintain well integrity while drilling through anticipated high-pressure zones. The challenging intermediate (12.25-in and 8.375-in) and reservoir (6-in) sections were successfully drilled and evaluated using this new branched synthetic polymer-based system. Fluid property trends and system treatments will be detailed alongside thermal stability data for extended periods required for wireline logging (up to 9 days static). This paper will discuss how proper laboratory design of the high-temperature water-based system was translated to excellent field performance and will indicate how this technology can be utilized for future campaigns in the region and worldwide.

The conventional drilling fluid to drill the high-temperature wells are non-aqueous fluid. ADNOC used high-temperature water-based drilling fluid instead of nonaqueous fluid to drill the well successfully. High-temperature water-based drilling-fluid systems hold several advantages over non-aqueous systems from financial and environmental viewpoints. However, most conventional water-based systems start to become unstable at temperatures above 300 degF. This paper details the design and implementation of specially designed water-based drilling fluids based on custom-made branched synthetic polymer that meet these temperature stability requirements. The branched synthetic polymer exhibits superior rheological properties and fluid loss control, as well as longterm stability above 400 degF. Under static conditions, the high-temperature fluid shows no gelation, resulting in lower swab surge pressures while the stability of the highly branched synthetic polymer and enhanced rheological profile minimize sag. ADNOC required a cost-effective drilling-fluid system that remains stable under static temperatures expected to exceed 375 degF. The longterm stability of the system was critical for successful wireline logging operations. In addition, the system was required to provide shale inhibition, hydrogen sulfide (H2S) suppression and enough density to maintain well integrity while drilling through anticipated high-pressure zones. The challenging intermediate and reservoir sections were drilled and evaluated using high temperature water-based system. This paper will discuss the successful execution of high temperature water-based system in one of high-temperature well in ADNOC field.

The development of deep oil and gas reservoirs requires high temperature stable drilling fluid systems. The properties of conventional polymers in water-based systems decline above 300°F which led to the development of the new high temperature water-based system. The high temperature water-based system, featuring a newly developed synthetic polymer, has been developed to provide enhanced rheological profiles and fluid loss control, along with long-term stability under elevated temperature and pressure conditions. The system has been designed to minimize formation damage by forming a thin and ultra-low permeable filter cake. The versatility of the developed polymer allows the new system to be formulated at a wide range of densities using most conventional oilfield brines including monovalent and divalent halide and formate brines. The clay-free high temperature drilling fluid has stable rheological properties, no gelation and low sag tendencies which are ideal for high temperature logging applications. Also, the highly branched nature of the polymer provides a rheological profile suitable for coil tubing applications. A new breaker package was developed along with the high temperature water-based system to slowly and uniformly clean-up its deposited filter cake, reducing near wellbore damage and maximizing production when the system is used to drill open-hole completion wells. This paper summarizes the fluid design in the lab and recent field applications, where the new high temperature polymer-based system was successfully deployed in different locations around the world.

Non-aqueous gravel pack carrier fluids (GPCF) have been introduced into the industry to eliminate the risks associated with the water-based carrier fluids in the presence of reactive shale interbeds in the reservoir. However, non-aqueous GPCF pose a significant barrier to the effective deployment of post-gravel pack filter cake breaker (FCB) application because all FCB systems are water-based. Therefore, a novel approach was developed for FCB application in non-aqueous GPCF environment to improve the efficiency of the FCB and the overall well performance. The non-aqueous GPCF was redesigned from ground up to promote the better diffusion of the FCB. This was accomplished by introducing a reversible emulsifier package into the non-aqueous GPCF design which allows the gravel to change wettability from an oil-wet state to a water-wet state when a low pH solution i.e., breaker is spotted inside the sand screens after the open hoel gravel pack (OHGP). To complement this, the FCB design was deconstructed, and the in-situ breaker component was blended with the gravel. The concept was to incorporate the in-situ breaker component into the gravel pore space which would promote better diffusion of FCB through the reversible non-aqueous GPCP. The in-situ breaker component is inert to the carrier fluid until it is activated by the temperature and water posing no threat to the stability of the carrier fluid while pumping. The innovative approach was tested in the laboratory setting using ceramic disks and return to flow method to prove the concept before conducting an elaborate return permeability testing with the reservoir core plugs for the final validation. Return to flow method indicated that the novel approach could improve the results by at least 10% compared to the baseline test with no breaker application. In the return permeability tests with reservoir core plugs, the novel approach resulted in 76% of the initial permeability whereas the baseline test was only 50%. Both the tests with ceramic disks and full-sequence formation damage tests with actual reservoir cores highlighted the benefits of the novel approach for gravel packing with non-aqueous GPCF and post-gravel pack FCB scenario. Non-aqueous GPCFs are relatively new to the industry and no record of the filter cake breaker application in such environment exists. This novel approach makes the filter cake breaker application possible in non-aqueous environment and pushes the existing boundaries of filter cake breaker chemistries.