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Wells in deepwater reservoirs show significant rate decline with time as the result of various causes. A diagnostic tool for quantification of factors influencing well-productivity decline is presented in this paper. One of the frustrating aspects of well-productivity analysis is identifying the causes of lower-than-expected production/injection during initial well lifetime. Our task is to evaluate the multivariate aspects of well design. The success of water-conformance operations often depends on clear identification of the water-production mechanism.
Fiber-optic technologies—distributed temperature sensing and distributed acoustic sensing—have been experiencing an ever-increasing number of applications in the oil and gas industry as monitoring systems. This paper covers the 7-year history of drilling-fluids application in a reservoir drilling campaign offshore Abu Dhabi, from the early use of a solids-free, brine-/water-based mud to the recent application of nondamaging, nonaqueous fluids (NAFs) with micronized acid-soluble ilmenite. This study focus on the design and evaluation of a customized water-based mud (NP-WBM) using silica oxide nanoparticles (SiO2-NPs) and graphene oxide nanoplatelets (GNPs). Recent research has put extensive focus on the magic of graphene in drilling fluids. Graphene, because of its thermal, electrical, chemical, and mechanical properties, improves mudcake stability and minimizes fluid loss that eventually reduces formation damage.
Recent research has put extensive focus on the magic of graphene in drilling fluids. Graphene, because of its thermal, electrical, chemical, and mechanical properties, improves mudcake stability and minimizes fluid loss that eventually reduces formation damage. Not all friction reducers are created equal. With dozens of varieties on the market, industry research suggests that oil and gas companies be choosy. Twelve organizations—universities and private technology companies—will conduct research and development on emerging shale plays and technologies covering everything from digital pressure-sensing to smart microchip proppant.
Thank you for attending the SPE Workshop. Thus, it is crucial to design and conduct well completions in such a manner to protect workers, minimize risks to the environment, and effectively partner with local communities. This workshop engaged experts and attendees to better understand and enhance the best HSE practices for well completions. Well completions, especially hydraulic fracturing, continue to be a significant topic of interest for the public. Thus, it is crucial to design and conduct well completions in such a manner to protect workers, minimize risks to the environment, and effectively partner with local communities.
To introduce attendees to the types, properties and applications of brine-based Completion and Reservoir Drill-in Fluids. Completion brines are much more than ‘salt water’. Although their compositions appear to be simple chemistries, their properties are quite complex. Gaining the fundamental knowledge of these fluids and the applications described in the course provides the basis for proper decision making. Properly formulated and applied Reservoir Dril-In Fluids can make the difference between a highly productive completion and one that does not meet expectations.
Tariq, Zeeshan (King Fahd University of Petroleum and Minerals) | Kamal, Muhammad Shahzad (King Fahd University of Petroleum and Minerals) | Mahmoud, Mohamed (King Fahd University of Petroleum and Minerals) | Hussain, Syed Muhammad Shakil (King Fahd University of Petroleum and Minerals) | Abdulraheem, Abdulazeez (King Fahd University of Petroleum and Minerals) | Zhou, Xianmin (King Fahd University of Petroleum and Minerals)
During well completion operations, the wells are killed with specific fluids to control the well. These fluids can invade and damage the formation because of fluid/rock interactions. Fluids such as fresh water, brines, and weighted fluids (e.g., barite weighted, calcite weighted, and bentonite weighted) are used to control the formations during completion operations. These fluids can invade and interact with clays and damage the formation. In addition, these fluids may alter the near-wellbore wettability and make them more oil-wet, thereby affecting the production from these formations. In this work, polyoxyethylene quaternary ammonium gemini surfactants with different types of spacers are proposed as clay swelling additives in completion fluids to mitigate the formation damage in unconventional reservoirs. Adding the new surfactants will maintain the in-situ permeability and avoid the formation damage. The novel gemini surfactants are tested on unconventional tight sandstone formation enriched with high clay content to mitigate the formation damage during well completion. The process involved a complete stabilization of clays using gemini surfactants added in deionized water (DW). Coreflooding experiments were carried out on Scioto sandstone rock samples with an average porosity of 15.6% and average absolute permeability of 0.25 md. Several coreflooding experiments were carried out with different fluids, such as potassium chloride (KCl), sodium chloride (NaCl), and different classes of gemini surfactants. Coreflooding experiments were designed in a way that the cores were preflushed with the subjected fluid and then post-flooded with DW. Results showed that the cores saturated with KCl and NaCl solutions lost permeability significantly when flooded with water while gemini surfactant solutions maintained the same permeability even after being treated with DW. Conditioning with the KCl solution resulted in a 38% reduction of permeability and that with NaCl solution resulted in an 80% reduction of permeability when treated with DW. No significant change of permeability was found for the case of gemini surfactants. This indicates that the synthesized surfactants can be used for well completion operation without any side effects.
This paper and its presentation provides an overview of an innovative way to treat zinc-contaminated water that might, for example, result from the use of completion fluids with extremely dense zinc bromide—up to 19.2 pounds (8.7 kilograms) per gallon—in high-pressure wells. Traditional approaches to treating zinc from completion fluid flowback and produced water are cumbersome and costly, with potential for perpetual liabilities associated with onshore in-ground disposal. Discussed will be a simpler, highly effective system that can save as much as 25 percent or more in zinc treatment and disposal costs.
The patented system combines two technologies—reverse osmosis (RO) membrane and ion exchange (IX) resin—to minimize zinc waste volumes. It works without chemicals and has a relatively low residence time. By selectively removing zinc, the remainder of the salts and most of the water can be discharged to the ocean. The zinc-removal system is available in two options: (1) RO with IX and (2) IX only. Both components arrive in a skid-based, offshore package. The entire system is fully compliant with API RP 14C safety standards and can operate as a standalone or integrated with pre-treatment systems that separate oil and other contaminants from completion fluid flowback or produced water.
In a 2019 efficiency test with a large independent E&P operator in the Gulf of Mexico, the system treated 36,387 barrels of water using five pairs of IX resin columns that together averaged 5 barrels-per-minute flow rates, with four total backwash cycles. Because the TDS of the produced water was already high, RO was not needed as part of the treatment system. Ultimately, the operator was able to discharge 35,400 barrels of water overboard instead of being collected and sent ashore. Only 900 barrels of zinc water from the IX resin columns needed to be sent ashore for disposal, although that amount was reduced by 75 percent to just 225 barrels upon the system's second deployment a month later.
As part of an Equinor technical efficiency program that was initiated in 2015 to deliver savings and improvements, bridging particles were removed from the drilling fluids of 15 wells in Oseberg Main and instead loss control material (LCM) was used, as required, in some but not all the wells. These long, horizontal wells were a combination of open hole (OH) and sand screens with and without inflow control together with cased and perforated (C&P) completions, producing from typical Brent Group sandstone formations with permeabilities varying from approximately 10 md to darcy sandstones, and which were depleted by as much as approximately 280 bars. In 2018, an extensive study was performed on these wells to determine the impact on inflow performance of drilling without bridging particles. It was realized that the 15 wells offered a worst-case scenario to study in the field rather than laboratory the significance of formation damage on well productivity. The data set generated offered a unique opportunity to challenge conventional formation damage assertions, especially for long, horizontal wells.
The influence of different parameters, including LCMs, lower completion design, loss type, mud penetration depth, dynamic overbalance while drilling, length of production interval, net to gross (NTG) and kh were considered for those wells drilled without bridging particles. One of the surprising findings was that there was no clear evidence that losses were detrimental to the productivity of these long horizontal wells; i.e., it would appear that the Brent reservoir sections, despite being depleted, were more resistant to the influence of formation damage on inflow performance than first thought. Furthermore, for this example bridging particles appear to be of less importance in the avoidance of formation damage but are important in preventing excessive increases in fluid costs due to losses.
After a thorough review of all the data obtained from this study, together with the conclusions drawn, it was realized that these had direct implications for Equinor’s approach to fluid qualification, and especially coreflooding. The most important conclusion that influenced this change in approach was that the long reservoir sections (approximately 1 km or more) within typical Brent heterogeneous formations appear to tolerate more formation damage without impairing the productivity index (PI). A direct consequence of this was the conclusion that more emphasis should be placed on fluid compatibility, mobility, screen plugging and stability along with particle-size distribution (PSD) design, while the importance of coreflooding to fluid qualification was downgraded for Brent and reservoirs of similar characteristics. This is not to say that coreflooding will not be performed, but rather it will be targeted toward situations where the influence of formation damage on well productivity is more significant; e.g., high-pressure and high-temperature fields where special drilling and completion fluids are required, low-permeability formations without mechanical stimulation, and shallow reservoirs with low reservoir temperature.
In this paper, we will perform an evaluation of the significance of formation damage on well productivity and use this to demonstrate Equinor’s revised approach to formation damage laboratory evaluation based on field experiences.
Well preparation includes many activities to ensure that the well is completed properly. Some of these items and activities include appropriate drilling practices, cleanliness, completion fluids, perforating, perforation cleaning, acidizing, and/or specifications for rig and service company personnel. The productivity of a cased- or openhole gravel-packed completion is determined in part by the condition of the reservoir behind the filter cake, the quality of the filter cake, and the stability of the wellbore. Given this, it can be said that the completion begins when the bit enters the pay. Thus, it follows that the goal of drilling is to maintain wellbore stability while minimizing formation damage. But, for whatever reason, instability affects both cased- and openhole completions because it can cause loss of the wellbore. Thick cement sheaths in washed-out sections result in poor to no perforation penetration and the lack of cement can make sand placement difficult. Hole collapse can prevent running screens to the bottom of the hole. Failure, in the form of fracturing or collapse, can stop an openhole gravel pack, should failure occur while the pack is in process.