Ageing Resistance of Bi-Layer Coating Systems for Dry Lubrication of Premium OCTG Connections

The latest dope-free configuration combines an electrodeposited zinc-nickel (ZnNi) plating, which provides anti-galling and most of anticorrosion properties, and an organic topcoat which provides lubrication through its low friction coefficient. This dry lubrication constitutes an alternative to storage and running dope meanwhile it improves running performances, reduces operational costs on the yard and rig and avoids dope discharge to the environment. Since the technology is "rig-ready", it must withstand the different risks of degradation occurring along its whole lifecycle. The present study aims at assessing the robustness towards ageing along storage on yards, transportation to the rig and or service life in well conditions. The performances of the different layers were checked stepwise, first assessing the ZnNi plating alone, and then considering the additional protection brought by thermoset topcoat. Regarding atmospheric corrosion, the characterization path involved both accelerated laboratory tests (such as the VDA 233-102 cyclic corrosion test) and outdoor exposures, under plastic protectors and after their removal, in different climates: temperate, desertic and tropical. The specimens were inspected regarding at: (i) efficiency of cathodic protection provided by the metallic coating; (ii) paint blistering, (iii) propagation of corrosion from a scribe down to substrate. Regarding rig operations, some examples of rig-return were reported and the compatibility with completion fluids, encountered in case of misrun and subsequent pull-out of the column, was checked though immersion in alkaline brines. In respect to the service in simulated well conditions, the resistance to Stress Corrosion Cracking (SCC) in brines were carried out to complete the former autoclave tests to assess resistance of carbon and stainless steel to well conditions. Both the ZnNi plating and the bi-layer system revealed lifetimes in storage conditions ranging from 3 to more than 5 years before any sign of significant degradation such as red rust, paint blistering or disbonding. According to cyclic corrosion tests results, higher lifetimes could be even expected thanks to the additional anticorrosion protection of the topcoat. Regarding exposure to completion fluids, the bilayer coating was shown to withstand 3000h exposure with no more than scarce rust indications. These results testify of the technology robustness from storage on yards to rig operations. In the multiple service conditions in wells, it was shown that the corrosion and cracking resistance of the substrate was not deteriorated by the plating presence, but instead improved in the multiple assessed well service conditions. The present communication updates the results of atmospheric corrosion compared to the former one [1] and it details new results after rig-return and regarding the risks of cracking.

Produced Water Reuse for Drilling and Completion Fluids Using Ion Exchange Resins

Produced water is considered one of the largest by volume waste streams and one of the most challenging effluents in the oil and gas industry. This is due to the variety of contaminants that make up produce water. A variety of treatment methods have been studied and implemented. These methods aim to reduce the hydrocarbon content and the number of contaminants in produced water to meet the disposal, reuse, and environmental regulations. These contaminants can include dispersed oil droplets, suspended solids, dissolved solids, heavy metals, and other production chemicals. Some of those contaminates have value and can be a commodity in different applications such as bromine (Br). Bromine ions can be used to form calcium bromide, which is considered one of the most effective drilling agents and is used extensively in drilling and completion operations. This paper aims to highlight the utilization and the new extraction method of bromide ions from produced water to form calcium bromide (CaBr2). The conventional preparation of calcium-bromide drilling and completion fluids involves adding solid calcium-bromide salts to the water, which can be relatively expensive. Another method can involve the handling of strong oxidants and toxic gas to form solid calcium bromide. The novel method outlined in this paper is a cost-effective and environmentally friendly way of generating calcium bromide from produced water. The method includes processing the produced water to recover bromide ions. This is done by first passing the produced water through a resin bed, including bromine-specific ion exchange resin, where the bromide ions will adsorb/absorb onto the resin, as shown in Figure-1. The second step involves regenerating the resin with regenerant having calcium cations and water to form calcium bromide. The final stage is generating the calcium bromide in the water from the bed of resin by introducing concentrated CaCl2, forming a concentrated solution of water and calcium bromide. The developed solution will be further processed to give drilling and completion fluids. This novel method constitutes a good example of produced water utilization in different applications to minimize waste and reduce the costs of forming highly consumable materials.

Identification of Breakout Behind Casing: Methodology to Obtain Openhole-Equivalent Caliper Measurements Through Slotted Liner Using the Density Tool

Growth in the coal seam gas industry in Queensland, Australia, has been rapid over the past 15 years, with greater than USD 70 billion invested in three liquified natural gas export projects supplied by produced coal seam gas. Annual production is of the order of 40 Bscm or 1,500 PJ, with approximately 80% of this coming from the Jurassic Walloon Coal Measures of the Surat Basin and 20% from the Permian Coal Measures of the Bowen Basin. The Walloon Coal Measures are characterized by multiple thin coal seams making up approximately 10% of the total thickness of the unit. A typical well intersects 10 to 20 m of net coal over a 200- to 300-m interval, interbedded with lithic-rich sandstones, siltstones, and carbonaceous mudstones. The presence of such a significant section of lithic interburden within the primary production section has led to a somewhat unusual completion strategy. To maximize connection to the gas-bearing coals, uncemented slotted liners are used; however, this leaves fluid-sensitive interburden exposed to drilling, completion, and produced formation fluids over the life of a well. External swellable packers and blank joints are therefore used to isolate larger intervals of interburden and hence minimize fines production. Despite these efforts, significant fines production still occurs, which leads to the failure of artificial lift systems and the need for expensive workovers or lost wells. Fines production has major economic implications, with anecdotal reports suggesting up to 40% of progressive cavity pump artificial lift systems in Walloon Coal Measures producers may be down at any one time. The first step in solving this problem is to identify the extent and distribution of fines production. The wellbore completion strategy above, however, precludes the use of mechanical calipers to identify fines-production-related wellbore enlargement. A new caliper-behind-liner technique has therefore been developed using a multiple-detector density tool. Data from the shorter-spacing detectors are used to characterize the properties of the liner as well as the density of the annular material. This is particularly important to evaluate as the annulus fill varies between gas, formation water, drilling and completion fluids, and accumulated fines. The longer-spacing detector measurements are then used in conjunction with pre-existing openhole formation density measurements to determine the thickness of the annulus, and hence hole size, compensating for liner and annulus properties.

Inhibiting Calcium Chloride Heavy Brines to be Used as Drilling Fluids: Hurdles Encountered in Treatment, Application, Corrosion Mitigation, Solubility, and Foaming Tendencies for Drilling Sites in Canada

A need for more economic drilling fluids has been addressed by repurposing heavy brines typically used as completion fluids. Heavy brine corrosion inhibitors have been designed for stagnant systems. Drilling fluids are subjected to both heavy agitation and aeration through recirculation systems and atmospheric exposure during the various stages of the drilling process. This paper documents the development of heavy brine corrosion inhibitors to meet these additional drilling fluid requirements. Multiple system scenarios were presented requiring a methodical evaluation of corrosion inhibitor specifications while still maintaining performance. Due to the high density of heavy brine, traditional methods of controlling foaming were not feasible or effective. Additional product characteristics had to be modified to allow for the open mud pits where employees would be working, higher temperatures, contamination from drill cuttings, and product efficacy reduction due to absorption from solids. The product should not have any odor, should have a high flash point, and mitigate corrosion in the presence of drill cuttings, oxygen, and sour gases. Significant laboratory development and testing were done in order to develop corrosion inhibitors for use in heavy brines based on system conditions associated with completion fluids. The application of heavy brine as a drilling fluid posed new challenges involving foam control, solubility, product stability, odor control, and efficacy when mixed with drill cuttings. The key to heavy brine corrosion inhibitor efficacy is solubility in a supersaturated system. The solvent packages developed to be utilized in such environments were highly sensitive and optimized for stagnant and sealed systems. Laboratory testing was conducted utilizing rotating cylinder electrode tests with drill cuttings added to the test fluid. Product components that were found to have strong odors or low flash points were removed or replaced. Extensive foaming evaluations of multiple components helped identify problematic chemistries. Standard defoamers failed to control foaming but the combination of a unique solvent system helped to minimize foaming. The evaluations were able to minimize foaming and yield a low odor product that was suitable for open mud pits and high temperatures without compromising product efficacy. The methodology developed to transition heavy brine corrosion inhibitors from well completion applications to drilling fluid applications proved to be more complex than initially considered. This paper documents the philosophy of this transitioning and the hurdles that were overcome to ensure the final product met the unique system guidelines. The novel use of heavy brines as drilling fluids has created a need for novel chemistries to inhibit corrosion in a new application.

Optimized Multi-Zone Dynamic Reservoir Evaluation in the Middle Caspian

Caspian offshore is reach for hydrocarbon reserves. The fields are made of multi-zone carbonate and sandstone reservoirs with significant variation of properties having high pressure (HP), high temperature (HT) and high H2S concentration in reservoir fluid. These challenges pose significant challenges to conduct the formation and multi-zone reservoir testing in a safe and informative manner. The dynamic reservoir evaluation program consists of formation pressure and its profile measurements, fluid pump-out for confirming the fluid type and sampling performed with wireline formation testers (FT) in open-hole and multi-zone well test for productivity estimation with drill-stem test (DST) designed for offshore environment with HP and high H2S. The project was planned and executed in an integrated manner, where the well construction design and selection of drilling and completion fluids has to improve the chance of success for FT and DST by taking into accound the downhole tool sizes and complex geological conditions. The open-hole formation testing and well testing in cased-hole were combined to provide enough information for characterizing multi-zone reservoirs by minimizing the drilling rig time. The well testing program was optimized in terms of number of zones for testing and necessity to acidize the reservoir based on formation testing data. The given methodolgy allowed to efficiently conduct the formation testing and well testing at two recently drilled offshore wells with multi-zone reservoirs. It was the first integrated dynamic reservoir evaluation project for such complex geological conditions in Middle part of Caspian offshore. This paper demonstrates the lessons learnt from two wells and offers the methodology for planning the evaluation for similar fields.

Drilling and Completion Waste Reutilization and Zero Discharge Technology Used in China Bohai Bay

With the increasingly stringent national environmental rules, waste produced in drilling and completion process is forbidden to be discharged into the Bohai Bay or reinjected into the formation. The current disposal method of drilling and completion waste in Bohai Oil field has some problems such as high cost, low efficiency and high HSE management and control risk. Faced with these problems, drilling and completion waste reutilization and zero discharge technology has been developed and applied in this region. In order to reutilize drilling and completion waste which include cuttings circulated from formation, wasted drilling and completion fluids, the following aspects are carried out: Firstly, drilling platform is upgraded to meet the zero discharge requirement: solid control system is modified, cuttings closed transfer system and cuttings treatment system are equipped on the platform to collect and dispose the waste. Meanwhile, recovery and disposal capacity to support different spud drilling are assessed: cuttings transport capacity is up to 15m3/h, which can meet the highest requirements of 12-1/4″ hole drilling when ROP is up to180m/h. Secondly, the well profile is downsized to reduce the production of cuttings, mud and other wastes from the root, which can also improve efficiency and yield cost. The field application shows that the amount of the waste has been reduced by 41.39%, 39.86% and 41.52% in first, second and third spud drilling, and average ROP is 35%, 28%, 42% higher than similar wells drilled before. Lastly, in drilling and completion fluids system optimization and reutilization aspects, environmentally friendly drilling and completion fluids with low solid content are developed. The experiment shows that the properties of the liquid phase after solid-liquid separation can be reused, and the solid phase with low water content is easy to pack and transport back to land. Drilling and completion waste reutilization and zero discharge technology introduced in this paper has been successfully applied in more than 40 wells, and the volume of waste drilling fluid is reduced by 80%, which is a trade-off between zero discharge and well construction cost. This technology can also be applied in other offshore oilfield which is inevitable as the environmental rules become more and more strict.

Boosting Production in the Llanos Orientales Colombia Basin, with an Approach to the Usage of the Completion Fluid. A Recent Case Study

This arcticle highlights the importance of a systematic step change approach to the formulation of completion fluids in the Llanos Basin (LLAB), Colombia, when formation-freshwater is to be used as control - completion (C&C) fluid. The results demonstrate that the process used reduced the formation damage statistics from 41% of the wells drilled to only 16%, boosting production and establishing a best practice for future drilling and completion (D&C) campaigns in the region. An initial sample of 19 wells was considered to evaluate the damage caused by using formation-freshwater as C&C fluid. Formation-freshwater was selected only considering the fluid density (wellbore pressure), ignoring the negative effects it can have on formation damage. 41% of the wells were damaged, as evidenced by pressure build up. Some of the main damages on the pay-zone in an oil well are due to emulsion blocking, change in wettability, swelling and migration of clays, incompatibility of fluids, and scale formation. A detailed design of completion fluids has a positive influence over well productivity by mitigating formation damage before starting the production stage. The methodology used was aimed at designing the C&C fluid through a step-by-step approach, consisting of: 1) Laboratory tests supported with mineralogical data and oil and formation water properties and 2) Physical-chemical analysis of reservoir fluids and water for mixing purposes. The process involved testing different formulations and then their implementation in the field. The initial tests were conducted in a total of 5 wells in 4 fields. Changes were identified in the formulation to achieve optimal fluid design for each field and then the selected fluid was extended to a total of 24 wells. This was the first time a thoroughly designed completion fluid was used in the region. The results point towards the need to include surfactants, mutual solvents, and brines to substantially reduce formation damage. The application of new completion fluids enabled the operational teams to optimize the process by steps. The implementation of customized completion fluid reduced the formation damage as evidenced through productivity analyses and pressure build up tests. Only 16% of the wells presented formation damage. The process applied to reduce formation damage of the Llanos Basin led to a systematic approach for the analysis stage, which may be applied in other areas, where the utilization of formation-freshwater is an issue. The particularly short time frames and best practices derived from the learning curve of this case are worth to be shared with other operators.

Evolution of P-Wave Velocity in Settling Drilling Fluids

Drilling and completion fluids (muds) are complex suspensions that typically contain weight material (such as barite) to increase the density, and clay particles to increase the viscosity and provide yield stress. In a static column of fluid, barite will inevitably settle. The density of the mud column gradually increases, from free fluid at the top to a compact, and possible gas tight solid at the bottom. The separation mechanism into different phases is complex, thus detailed, systematic fluid experiments is needed to fully understand the properties of settled barite. Wave velocity, commonly used to determine the condition of the borehole (and annulus), could be used to characterize, and possibly identify the different sediment phases in a mud column. The current study investigates the evolution of acoustic wave velocity during compaction/gravity separation of mud. A laboratory setup which allows for a controlled drainage of fluid was used to resemble the sedimentation process. The study was performed on three drilling fluids: two synthetic and one commercial polymer, and three compacted barite samples using two test procedures. The first procedure focuses on investigating acoustic properties during settling. The second procedure was used to investigate the behavior of compacted barite. The result shows a decrease in the wave velocity during settling, whereas increase in the wave velocity in consolidated barite with compaction. The increase or decrease of velocity with compaction can be explained by the relative changes of modulus/stiffness and density of the studied material.

Laboratory Formation Damage Test Data Upscaled With Computational Fluid Dynamics

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 199268, “Upscaling Laboratory Formation Damage Laboratory Test Data,” by Michael Byrne, SPE, Lesmana Djayapertapa, and Ken Watson, SPE, Lloyd’s Register, et al., prepared for the 2020 SPE International Conference and Exhibition on Formation Damage Control, Lafayette, Louisiana, 19-21 February. The paper has not been peer reviewed. Through several case histories, the complete paper demonstrates applications of computational fluid dynamics (CFD) modeling to upscaling of laboratory-measured formation damage and reveals implications for well and completion design. The value of laboratory testing is quantified and interesting challenges to conventional wisdom are highlighted. Introduction Laboratory formation damage testing is often used to help select optimal drilling and completion fluids. Test procedures such as sand retention and return permeability represent an attempt to simulate near-wellbore conditions during well construction and production. To determine what degree of permeability impairment is allowable, further interpretation that cannot be provided using classical nodal analysis or reservoir simulation methods is required. The complete paper describes the evolution of, and potential for, more-comprehensive upscaling and outlines the importance of consideration of full well geometry when designing and interpreting coreflood tests for formation damage. CFD simulations provide a means to upscale suitable laboratory test data to predict effect on well performance. Methods CFD simulations use a relatively simple, steady-state, static damage model that takes endpoint data from laboratory core tests and translates the data into parameters that are used for input into well geometry. Although this method has its merits and is a considerable advance on previous, more-simplistic upscaling attempts, it does not necessarily present the full picture of damage evolution in the near-wellbore. A transient model of damage with data again derived from laboratory coreflood data could reveal more about well cleanup and progressive damage removal. Steady-State Modeling. No API recommended practice for return permeability testing exists. Laboratories have their own procedures that comply broadly with recommended procedures developed some time ago. Operators and consultants, too, have their own procedures, which they often ask laboratories to follow. Although no recommended practice exists, evaluation of drilling and completion fluids usually involves measurement of a base permeability and remeasurement of a return permeability—or several—after application of the test fluid or fluids. In many cases, the laboratory removes the external mud cake or trims a slice of the end of the plug to measure return permeability without mud cake (Fig. 1).