Development of a Modified Dummy Gas Lift Valve for Subsurface Depth-Resolved Microbiological Sampling and 3D Mapping

Objectives/Scope: This study outlines the development and use of a modified dummy gas lift valve designed to obtain subsurface microbiological samples from a defined depth series across a production well. An overview of the initial field pilot is presented wherein microbiological data from the modified valve will be contrasted with topside samples to evaluate the information yielded from sampling downhole biofilm communities in place of planktonic populations from the well head. Methods, Procedures, Process: In this approach, the modified dummy gas lift valve, preloaded topside with carbonate plugs and coupons, is deployed at various depths in the well's completion for downhole incubation. This modification allows production fluids to wet the payloads, enabling in situ biofilm colonization by reservoir communities across depth and temperature gradients. Post retrieval using a slickline tool, sample DNA is extracted for metagenomic sequencing, assessing microbial composition and metabolic capabilities (including souring and MIC-related activities). Concurrent production fluid samples from the wellhead will be analyzed for comparison to evaluate any information gained from biofilm over planktonic population sampling. Results, Observations, Conclusions: Samples from the modified valve are expected to provide sufficient yields of DNA, uncontaminated by non-resident microbes from outside of the producer. Microbial data from downhole biofilms is anticipated to provide a more diverse community makeup than production fluid communities sampled at the wellhead, with a corresponding increase in problematic species associated with MIC and souring. Corrosion coupon analyses will enable conclusions regarding proactive decision-making enablement and extrapolations of 3D projections of microbiological communities between modified valves across the completion column will provide the relationship between in situ conditions, microbial colonization in the context of pore space and risks of unfavourable microbiological activities with potential correlations to known zones of souring and corrosion. Understanding these microbial profiles can directly inform targeted interventions in reservoir management for more efficient and sustainable operations. Novel/Additive Information: This paper presents a novel approach to in situ microbiological sampling at specific reservoir depths, a procedure not commonly practiced due to significant constraints associated with existing subsurface sampling approaches (such as side wall coring and core drilling operations). The resulting data can provide valuable insights for practicing engineers into the actual communities residing downhole and spatial microbiological heterogeneity of reservoirs, enabling more accurate proactive assessment for reservoir water management and maintenance.