Qualification of Gravel Packing in HP/HT Wells

Abstract

For HPHT wells it appears that the only industry practice for open hole sand control has been Stand Alone Screens (SAS), even for wells that should have been gravel packed. For North Sea HPHT field developments, SAS has been chosen as the open hole sand control method. However, according to company best practice, these wells should have been gravel packed. General skepticism around gravel packing for these wells is primarily based on the risk of losses. A study was initiated to look closely at potential losses during gravel pack pumping when compared to SAS in HPHT environment. Key issues:a. Narrow margin between pore pressure and fracturing gradient b. Well control risks, technical risks and cost c. Fluid selection The basis for the study was to perform gravel packing with conditions as close as possible to the planned low well angle SAS wells solution. The screens were to be run in screened reservoir drilling fluid. This fluid contains filtercake repair particles. It became natural to evaluate this fluid also as a carrier fluid for the gravel, thus mitigating the risk of losses. Due to small margin between pore pressure and fracture gradient, the gravel pumping operation would have to be planned to be performed at low rates. To qualify the HPHT gravel placement, yard testing was performed in a mini-scale gravel pack model. Gravel was placed successfully at low rates with screened reservoir drilling fluid. Very little degree of settling in horizontal surface lines was observed at low pump rates, hence no practical consequences is expected for this in high angle well sections. Furthermore, flowback testing in lab was performed on the particle containing carrier fluid. The major findings in this study were: --Gravel can be placed effectively at low rates, minimizing ECD impact in a narrow pore/frac operational window.--Gravel can be placed using screened formate based Reservoir Drilling Fluid (RDF) maintaining the filtercake intact and with minimum risk of losses. --The particle containing carrier fluid has no adverse effect on gravel pack permeability.

Sand screens application and performance for sand control: A review of selection criteria, screen materials, and causes of failure

“…For example, Gillespie et al [ 48 ] suggested that 2D 50 serves as the maximum aperture size for wire-wrapped screens, based on slurry SRT across various sand types. Ballard & Beare [ 49 ] integrated findings from pre-packed and slurry SRT analyses to propose aperture sizing based on the D 30 , indicating its superiority over the D 10 criterion. Similarly, Weatherford guidelines advocate for D 25 when selecting wire-wrapped screens.…”

Simulation and application analysis of gravel packing in deepwater HT/HP wells

“…The significant temperature change phenomenon leads to significant changes in the physical properties of carrier fluid, resulting in drastic changes in packing friction and packing pressure. So how to overcome the operation contradiction of gravel packing in deepwater horizontal wells and achieve high quality and effective packing has become a key technical problem for effective offshore oil and gas development 14–16 . According to the specific characteristics of deepwater high‐temperature and high‐pressure (HT/HP) and multichannel, a gravel packing coupling model for deepwater HT/HP horizontal well based on the α–β wave packing theory 17 is established, the influence of slurry flowing through long and multichannel and temperature alternation along flow path are considered.…”

“…So how to overcome the operation contradiction of gravel packing in deepwater horizontal wells and achieve high quality and effective packing has become a key technical problem for effective offshore oil and gas development. [14][15][16] According to the specific characteristics of deepwater high-temperature and high-pressure (HT/HP) and multichannel, a gravel packing coupling model for deepwater HT/HP horizontal well based on the α-β wave packing theory 17 is established, the influence of slurry flowing through long and multichannel and temperature alternation along flow path are considered. The packing simulation algorithm and calculation process are designed to realize the temperature-pressure simulation and multistage fine friction calculation of gravel packing in deepwater HT/HP horizontal Wells.…”