Experience has shown that hydraulic fracturing operations can introduce and/or stimulate microbial populations in the wellbore that in turn may lead to undesired corrosion, souring or other production issues. Biocides are applied to prevent the establishment of problematic microbes. Characterizing and quantifying which microbes will be introduced to a well using molecular techniques allows for optimized or even proactive treatment and prevention strategies to be implemented, whereas, traditional microbial testing methods have proven insufficient.
Once the standard for microbial assessments in the oil and gas industry, culture media bottles are now just one of many available tests. Tests vary by their resolution (culturable, active and living, total microbes), and the information they yield. Some tests target very specific microbial subgroups of concern (culture media, qPCR), while others evaluate all microbes within the sample (ATP, qPCR, 16S rRNA sequencing). In the case studies presented, water and produced fluids were collected from all pertinent frac sample points (source waters, pre- and post-chem and post completions) and were assessed using the suite of microbial methods stated above.
Three case studies are presented with several noteworthy observations regarding the value microbial tests provide to frac operations. First, culture media-based testing consistently resulted in incoherent and confusing data that failed to correlate with the remaining testing technologies. Second, ATP technology provided efficient and timely testing which lent itself well to on-site, evidence-based decision making. During one of the fracs, ATP results were used to modify and optimize a microbial control program on-the-fly. Third, DNA-based testing (qPCR and 16S rRNA sequencing) provided the most comprehensive insight into the microbial communities exposed to the well, and those that established post-completions.
Overall, holistic microbial testing offers the user key information required to design and implement successful microbial control programs for frac. Without it, microbial issues plagued production efforts. Culture media tests provided limited and unreliable information and were deemed not suitable for frac operations. ATP provided a useful microbial load in real-time but could not elucidate the types of microbes present. DNA testing filled this gap by providing quantities and types of microbes present.
Apart from assessing microbial control programs during the frac, monitoring the production fluids is essential to assuring continued well performance. The acknowledgment of the role microbes play in well completions, and the testing technology to evaluate oilfield microbes is rapidly advancing. Here we present some of the first case studies highlighting the use of molecular, DNA-based technology for assessing hydraulic fracturing operations and showing the fallacy of culture media-based testing which is the current industry standard.
SPE's publication for the Projects, Facilities, and Construction (PFC) technical discipline, Oil and Gas Facilities (OGF), has recently launched a monthly section which will feature synopses of editor-picked SPE technical papers on PFC topics. OGF Selection Editor Gerald Verbeek will pick three papers each month that are then synopsized by SPE editorial staff and published on the OGF website. Verbeek was previously the executive editor for peer-reviewed papers in OGF and was recognized as "A Peer Apart" honoree for peer-review of more than 100 technical papers. He has picked Corrosion and Scaling for the first selection, a topic that affects all involved in oil and gas facilities. "Early in my career I spent about a year as a corrosion engineer to learn the fundamentals, only to discover that without keeping scaling and corrosion in mind, it is impossible to a be a good facilities engineer," said Verbeek in his introductory article about the new section.
In the upstream production systems, the external corrosion management typically does not affect the definition of the whole gathering network system design. However, its role is crucial for the integrity of any steel structure.
The external corrosion is generally managed with external coatings or cathodic protection systems designed to provide a durable protection against corrosive environments (either onshore or offshore). Typical external coating materials are polypropylene, polyethylene (in case of polyolefin coating), fusion bounded epoxy (FBE) or, in specific applications, thermal sprayed aluminium (TSA).
In High Pressure and High Temperature (HP/HT) reservoir applications, usually located in deepwaters offshore where the ambient temperatures are low (i.e. high temperature gradient between inside the pipelines and external environment), the selection of a specific external coating material might have significant impact on the design specification of the installed hardware, with special focus on the pipelines. In fact, depending on different physical properties of the external coating technologies, those may introduce stronger or weaker insulating capabilities and will modify the pipelines U Value, which describes the capacity of the pipelines to exchange heat with the external environment (and consequently the design specification of the production network).
A Case Study is here presented where impacts on the pipeline design specifications based on the selection of different external coating technologies have been described. In particular, it is here shown how the application of coating materials with lower insulating performance, e.g FBE coating, can increase the heat exchange between the hot production fluid and the cold external environment, leading to faster cooldown of production fluid.
In this case, reduction in operating fluid temperature has been used to prevent internal corrosion issues (generally linked to top of the line corrosion), however it may also be used as mitigation of HP/HT related issues, e.g. lateral buckling. Main pros and cons of FBE applied as a standalone external anticorrosion coating have been described in this paper.
Over 20 percent of major oil and gas (O&G) incidents reported within the European Union (EU) since 1984 have been associated with corrosion under insulation (CUI) [
Using bayesian networks (BNs) Oceaneering has developed a decision support system for effective CUI risk management. The Bayesian model can be incorporated into existing risk-based assessment (RBA) systems. A key feature of the model is the ability to predict corrosion hotspots while quantifying uncertainties. The model uses probabilities based on objective data as well as subject matter expertise, which makes analytical techniques in business accessible to a wide range of users.
With a case study we illustrate how BNs can be used to assess the risk of a fuel gas line on a live asset in the North sea. The most likely estimated remaining life (ERL) is forecasted in the range of 13 to 24 years, with a worst case of 6.7 years and best case of 40 years. By comparison, the customer CUI tracker reported an ERL of 9.7 years. BNs increase flexibility for scheduling inspection intervals, enabling more targeted inspection planning. This is a significant advancement from current RBA methodologies.
Microbial-influenced corrosion (MIC) has been implicated in few corrosion-related challenges in the well-service industry in the past. DuPont is ramping up the commercial-scale implementation of its microbial enhanced oil recovery (MEOR) method after nearly a decade of development and testing of what it says is a low-risk way to improve production from mature fields.
This paper presents a methodology to estimate the probability of failure of every individual corrosion defect and the residual likelihood of failure of an overall corroded pipeline segment after selected repairs, using structural probabilistic analysis. In this paper, a data-driven model is applied to derive optimum maintenance strategy for a petroleum pipeline. The model incorporates structured expert judgment to calculate the frequency of failure, considering various failure mechanisms.
The criticality of above-water riser hull piping requires frequent inspections. Traditional manual inspection methods present safety and efficiency concerns, but work is being done to see if robotic technologies—such as drones and crawlers—can do the job as good as, or even better than, humans. It is rare that businesses selling equipment to the oil and gas sector can benefit from lower oil prices. But that is the case for CRA pipe manufacturers, which are comfortably outperforming 2014 levels. The laboratory will be used primarily to test the sulfide stress cracking resistance of carbon steel alloys for oil wells and offshore drilling applications.
This course will help attendees develop the awareness of the cost of corrosion and how it can be managed and mitigated. It teaches the skills of dealing with chemicals, techniques to evaluate their performances, chemical applications and design to control corrosion. It will also help attendees learn corrosivity monitoring and the efficiency of the treatment. This course will help broaden your general knowledge around oilfield corrosion and its impact and control options. Participants will familiarize themselves with the various lab techniques used for evaluation of corrosion inhibitors.
Corrosion inhibitors are often the first line of defense against internal corrosion, and effective mitigation relies on proactive monitoring and management of these inhibitors to allow for regular feedback and dose adjustment. This paper describes a novel method of chemical dosage based on time-resolved fluorescence (TRF) that allows a simple, accurate, and efficient quantification of chemicals below parts-per-million ranges, even for double (scale/scale, scale/corrosion) quantification. A study done to find the root cause of coiled tubing string failures in Montney indicated microbial-induced corrosion, leading the CT service provider to create a biocide treatment program. Rigless coiled-tubing-unit (CTU) interventions can be effective in returning to production wells that have lost electrical-submersible-pump (ESP) efficiency because of organic, inorganic, or mixed scale deposits. Sour gas is being produced from a number of carbon-steel-completed wells in the US, Canada, France, and Saudi Arabia.
With these synopses of technical papers from OnePetro you can join the author for conferences in Kuala Lumpur, New Orleans, and Lagos, all while sitting in your chairs and without any travel expenses. This paper reviews the mechanisms of initiation and the prevention of top-of-the-line corrosion (TLC). Recent research and developments are highlighted and validated to arrive at best practices for control of this significant corrosion manifestation. Water condensation and/or hydrate formation at the top of pipelines are serious design/operation considerations in pipelines. This paper reports the results of tests conducted in a new experimental setup constructed for investigating gas-hydrate risks in varied operational scenarios.