Use of Microbial DNA Probes as a Potential New Tool in Oil Exploration and Characterization

In early 80's, while reassessing some old gravel pack sands from a well, we noticed some sludge in the samples. The sludge had plugged formation and the gravel pack pores. The permeability was so low that the owner of the oil property thought of abandoning the well and consequently stopped all workover measures. The owner stated that there was no more oil left in the reservoir. This observation and the previous ones in early 70's, in addition to the laboratory studies conducted at a later date, suggested the existence of bacteria in the oil. In the current study we implemented a novel, sensitive technique for bacterial DNA fingerprinting; that is, denaturing gradient gel electrophoresis of PCR amplified 16S rRNA genes. This approach allowed us to identify and classify bacteria found in the oil. The research enabled us to evaluate the application of our technique to evaluate the origin of oil in the reservoirs. To prove the hypothesis that bacteria were present in oil, we requested an operating company to provide us with 6 samples taken from 2 separate wells, but drilled in the same reservoir or at least the operator believed both wells were drilled in the same reservoir. To characterize the oil and subsequently the reservoir, we implemented our procedure of fingerprinting bacteria DNA as follows: (1) DNA extraction from oil, (2) DNA concentration, (3) Making 0.7% and 1% Agarose gel, (4) Electrophoresis of total DNA isolated from oil, (5) PCR amplification of 16S rRNA gene fragment from DNA isolated from oil, (6) Running gel on the PCR product, (7) Running Denaturing Gradient Gel Electrophoresis (DGGE), and (8) Cycle Sequencing DNA. The result from DNA concentration using our technique proved the existence of the bacteria DNA in all crude oil samples, which was not possible to find previously. Using the governmental open source data from offshore Louisiana and the results of researchers work available in the literature, we conducted a detailed geological and petroleum engineering study of the field in our study area. Furthermore, in order to find petroleum engineering applications for our discovery of DNA in crude oil we classified the bacteria and found the origin of the crude oil produced from each well in the reservoir. Based on our results, we found that Well B drained oil from a grassland, lacustrine, fresh water environment, whereas Well A drained oil from a very shallow marine environment. From the results, we concluded that, these two wells are not drilled in the same reservoir, implying that there may be enough oil left in both reservoirs to be drained by one or more wells.

show abstract

Mature Fields - Optimizing Waterflood Management Through DNA Based Diagnostics

Sawadogo

Ursell

Reeve

et al. 2020

Day 1 Mon, November 09, 2020

View full text Add to dashboard Cite

Maximizing the recovery factor achieved through water flooding depends on acquiring a detailed understanding of the vertical and areal sweep efficiency. DNA diagnostics can monitor changes in oil contributions from multiple zones and from injectors, becoming a leading indicator for the potential of water breakthrough, loss of injectivity, and the overall advancement of the water front when combined with subsurface information. This allows for proactive management of injection rates and timing to maximize recovery rates for green fields and brownfields alike. DNA diagnostics use DNA markers acquired from microbes. DNA markers of produced fluids are compared to the DNA markers of injected fluids to establish relationships and shared fluid flow. This paper will cover the end to end workflow for long term waterflood monitoring:Establishing end members, even for a mature field, with the use of new samples from offset wells, properly stored samples from existing wells, and the analysis of commingled samples in combination with the subsurface model.Establishing the level of similarity between injectors and producers as an indication for the progression of the waterflood front using methods including Principal Coordinate Analysis (PCoA) of DNA marker profiles.Performing time series analysis and establishing sampling periodicity for effective waterflood monitoring. A pilot project, consisting of 12 producers and 3 injectors in a conventional California reservoir, was conducted to prove the concepts and further develop the required analysis for waterflood monitoring. Fluid samples were taken weekly on each well over 3 weeks to establish the difference in DNA markers between the fluids. The DNA markers were used to determine the probability that injection fluid was being produced from the surrounding wells. These results were overlaid to temporal changes in the Total Fluid Logs. Taken together, the results correlated and confirmed previous water breakthrough information and provided insights into arial and vertical conformance changes. Additionally, the project provided new insights into strength of producer and injector connection based on geological features and with that informing future infill drilling decisions. Waterflood monitoring is a powerful application for DNA diagnostics that is deployable on new and existing waterfloods. The spatial and temporal monitoring limitations of modeling or tracer studies can be improved upon through this non-invasive diagnostic. Initial results demonstrate the insights that can be provided not just for monitoring the waterflood but also for further field development decisions.

show abstract

Use of Microbial DNA Probes as a Potential New Tool in Oil Exploration and Characterization

Cited by 3 publications

References 18 publications

Using Microorganisms as Prospecting Agents in Oil and Gas Exploration

Using Microorganisms as Prospecting Agents in Oil and Gas Exploration

Application of New Fingerprinting Bacteria DNA in Crude Oil for Reservoir Charaterization-Part II

Mature Fields - Optimizing Waterflood Management Through DNA Based Diagnostics

Contact Info

Product

Resources

About