Brand: Variperm

The role of fouling materials strength on unplugging sand control devices using electrohydraulic stimulation

Previous studies showed that the fouling materials strongly affect the plugging of sand control devices during the oil production, thereby reducing oil productivity index drastically. In this study, we investigate how the compressive and tensile strengths of fouling materials affect the cleaning performance of shock waves generated by an electrohydraulic stimulation (EHS) tool.

First, we synthetically plug wire-wrapped screens using different class G cement slurries widely used in oil fields. Silica, calcite, clay, and organic carbon powder as additives are mixed with the cement at different concentrations. Next, we evaluate the compressive and tensile strengths of the cured cement samples by performing uniaxial compressive strength (UCS) and Brazilian tests. Finally, the cleaning performance of the EHS tool is evaluated for plugged wire-wrapped screens.

The UCS and Brazilian tests results show that the presence of additives changes the mechanical properties of cement samples. The compressive and tensile strengths of cement samples prepared with silica are found to be higher than those prepared with calcite and clay. Besides, the results of the pulsing stimulation treatment performed by the EHS tool show that the cleaning performance of the EHS tool for the wire-wrapped screens plugged with cement and carbon powder is the highest among all samples as cement samples with carbon powder represent the weakest mechanical properties (UCS and tensile strengths) among all samples. This study provides valuable insights into understanding the effect of shock waves on cleaning the plugged wire-wrapped screens. The results also enable production engineers to better plan for the treatment of damaged wells.

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Data-driven well pad development performance review: Role of liner design

Steam Assisted Gravity Drainage (SAGD) is the dominant in-situ method for oil production in Western Canada. The current study analyzed the relative performance of various well-completion practices using data from 4,000 well pairs that were drilled over a decade. The data analysis provided a unique opportunity to find best operating practices. The scope of this paper is to review the performance of major thermal projects in Canada and investigating the effect of liner design and Flow Control Devices (FCDs) on well pair performance and development.

Cumulative oil production and cumulative steam oil ratio (cSOR) were used as the key metrics in comparing the well performance in a SAGD operation. However, to compare different pads and different projects, it was critical to normalize the data with geological variation, well length, well spacing, and with consideration to the well failure rate, remedial completion and re-drills. In this paper we review seven thermal projects of four key operators with almost 3,500 wells and 1,200 well pairs in operation as early as 1996. All geoscience, and production/injection data have been extracted from public databases and utilized to develop a data-driven model.

The reservoir thickness variation for each well was determined using available geoscience data, and through the development of a geological model based on the available core data and well logs. The model was used to define the drainage volume for each well pair, which in turn was used to assign a geological ranking to the well. The cumulative oil production and cSOR were then normalized with the geological ranking and the size of the net drainage volume. The number of well pairs in each pad and the cumulative pad production were normalized against the number of days in production and their relative decline, which allowed for comparison between pads within the same project, as well as pads from other projects. The cumulative production of the active pads in each project was used to compare the relative performance of different projects. Also, we separated the projects and wells based on their use of FCDs in the producer and injector to compare the relative performance of each technology in the field.

This paper is the initial phase of the study on the role of completion design on relative well and well pad performance. The results will help completion and production engineers to better understand the well pair and pad relative performance and how to normalize the oil production data against geological variation to compare performance.

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Evaluation, Implementation, and Operations of an FCD for SAGD Producer Wells

The goal of this paper is to present the philosophies for the qualification and flow loop testing of FCD nozzles as well as the macroscopic implementation and operations of FCDs in SAGD producer wells. A quantitative methodology to evaluate FCD nozzles to choke back steam will be presented. Flow loop testing data will be shown to illustrate the qualification process. We will also discuss if sand control screens should be put on the tubing deployed inflow control devices. Some modeling and field examples will be shown. In the end, field data of the SAGD producer wells installed with the FCDs will be presented. Experience to manage and operate the wells will be shared.

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An Investigation into Current Sand Control Testing Practices for Steam Assisted Gravity Drainage Production Wells

Sand control screens (SCD) have been widely installed in wells producing bitumen from unconsolidated formations. The screens are typically designed using general rules-of-thumb. The sand retention testing (SRT) technique has gained attention from the industry for the custom design and performance assessment of SCD. However, the success of SRT experimentation highly depends on the accuracy of the experimental design and variables. This work examines the impact of the setup design, sample preparation, near-wellbore stress conditions, fluid flow rates, and brine chemistry on the testing results and, accordingly, screen design. The SRT experiments were carried out using the replicated samples from the McMurray Formation at Long Lake Field. The results were compared with the test results on the original reservoir samples presented in the literature. Subsequently, a parametric study was performed by changing one testing parameter at a test, gradually making the conditions more comparable to the actual wellbore conditions. The results indicate that the fluid flow rate is the most influential parameter on sand production, followed by the packing technique, stress magnitude, and brine salinity level. The paper presents a workflow for the sand control testing procedure for designing the SCD in the steam-assisted gravity drainage (SAGD) operations.

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A dual-directional flow control device for cyclic steam stimulation applications

Cyclic steam stimulation (CSS) is one the most effective thermal recovery methods. It is widely used as the primary thermal recovery method to recovery heavy oil fields in Middle East, Asia Pacific, North and South America. In this paper, a novel dual-directional flow control device (FCD) will be introduced. This FCD technology can allocate accurate steam outflow into the reservoir formation and improve steam quality during steam injection period and can mitigate steam breakthrough from the neighboring wells during production period.

In the first section, we will give a brief introduction on CSS and the main issues encountered in the field operation. A multi-directional flow control nozzle specifically designed for CSS application will be presented. Design philosophy in thermodynamics and hydrodynamics of the nozzle will be discussed in detail. Field performance results, Computational Fluid Dynamics (CFD) and flow loop testing data will be shown to evaluate the performance of the technology. The application of the technology in steam assisted thermal applications will be introduced. Well-known issues such as erosion and scaling on the FCD tools will be studied in the end.

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An intelligent system for multi-label classification based on particle size and shape features

Intelligent systems are becoming more and more popular in the petroleum industry. Particle Size Distribution (PSD) based on sieve size is a key signature of the unconsolidated/weakly consolidated sandstone formations and is commonly the main parameter in the sand control design.

With available extensive PSD measurement techniques and a large number of measurements, especially for horizontal wells, it is necessary to classify the PSDs prior to further analysis for the sand control design. On the other hand, PSD analysis is not enough for sand control design, and particle shapes need to be taken into account as well. A successful clustering algorithm for the mentioned purposes needs to be a cascade, multi-label, unsupervised and self-adaptive approach since the particles can be assigned to more than one group and there is no prior idea on how many clusters should be formed after the clustering process. Besides, due to the differences between sieve size and shape features, they should be used separately for clustering the particles.

In the current study, a cascade approach is used for clustering the particles. In the first level of the cascade, an unsupervised and self-adaptive algorithm is introduced based on the sieve size features. The algorithm optimizes the number of clusters through a self-adaptive and incremental approach. The proposed clustering method uses a minimum similarity threshold (δ) as the only input parameter to start the clustering and tries to minimize the number of clusters during the clustering. In the second level of the cascade, the similarity between all particles in each cluster with their corresponding cluster-center is measured, and those particles that do not respect the δ in terms of the shape similarity, are moved out of the cluster.

The novelty of the proposed method is in three folds. The first one is to provide a particle clustering algorithm, which works based on the whole range of the sizes and shape descriptors rather than focusing on certain points in the size graph (D-values). The second one is the dynamic nature of the clustering, which tends to optimize the number of clusters during the clustering process. The third one is that we have used a cascade approach for involving both size and shape parameters for the clustering. Our proposed method can be applied in field application for downhole monitoring and sand screen design.

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Optimization of Slotted Liner in Rubiales Field: Trade-Off between Sand Control, Flow Performance, and Plugging Tendency

Authors: Morteza Roostaei (RGL Reservoir Management Inc.) | Edgar Alberto Mayorga Cespedes (Ecopetrol) | Alberto A. Uzcátegui (RGL Reservoir Management Inc.) | Mohammad Soroush (RGL Reservoir Management Inc. and University of Alberta) | Seyed Abolhassan Hosseini (RGL Reservoir Management Inc. and University of Alberta) | Hossein Izadi (University of Alberta) | Brad Schroeder (RGL Reservoir Management Inc.) | Mahdi Mahmoudi (RGL Reservoir Management Inc.) | Dionis M. Gomez (Ecopetrol) | Edgar Mora (Ecopetrol) | Javier Alpire (Ecopetrol) | Joselvis Torres (Ecopetrol) | Vahidoddin Fattahpour (RGL Reservoir Management Inc.)

Designing and selecting the proper sand control mechanism for horizontal wells in unconsolidated heavy-oil reservoirs tend to be underlooked in some cases. Standalone completions pose some sand control challenges, which could jeopardize the oil production or even lead to critical problems. Massive sand production, screen/formation plugging, hot spots, and mechanical integrity failures are some of the well-known issues. This study attempts to optimize the slotted liner design for horizontal wells in a heavy-oil field in Colombia.

A careful selection of representative core data was made to study the variation of sand particle-size distribution (PSD) within the development area. Reservoir fluid properties were analyzed. Based on PSD variation and current design criteria in the industry, several seamed slotted-liner configurations were proposed as an alternative completion for testing. Later, a series of large-scale sand retention tests (SRTs) were performed to assess the selected alternatives under typical field production conditions. The effects of aperture size and open-to-flow area were investigated to evaluate flow and sand control performance.

This investigation started with a detailed study of the PSD, particle shape variation, and composition of fines in the development area. The PSD then classified into four distinct minor and major sand facies, ranging from medium to very coarse sand with different fines content. Further investigations have shown that current design is only suitable for a limited number of the PSDs, while the overall PSD classes indicate the requirement for wider slot aperture sizes. The results of the SRTs indicated that the flow performance of the screen is mainly controlled by the slot aperture. Choosing the optimized aperture size avoids unacceptable sanding even for the multiphase flow scenarios with gas. Results also indicated that by increasing the aperture size and application of the seamed slots for the studied formation, plugging could be mitigated.

A comprehensive sand control design workflow for cold primary heavy-oil production in horizontal wells is presented in this work. The current study is one of the first that investigates and compares conventional straight slotted liners with seamed slotted liners at a larger scale for this field. Moreover, this study helps to better understand the effect of design parameters of seamed slotted liners on sand control, flow performance, and plugging tendency.

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Numerical investigation of the hydraulic fracturing mechanisms in oil sands

Authors: Siavash Taghipoor, Morteza Roostaei, Arian Velayati, Atena Sharbatian, Dave Chan, Alireza Nouri

This paper presents a numerical investigation of hydraulic fracturing in oil sands during cold water injection by considering the aspects of both geomechanics and reservoir fluid flow. According to previous studies, the low shear strengths of unconsolidated or weakly consolidated sandstone reservoirs significantly influence the hydraulic fracturing process. Therefore, classical hydraulic fracture models cannot simulate the fracturing process in weak sandstone reservoirs. In the current numerical models, the direction of a tensile fracture is predetermined based on in situ stress conditions. Additionally, the potential transformation of a shear fracture into a tensile fracture and the potential reorientation of a tensile fracture owing to shear banding at the fracture tip have not yet been addressed in the literature. In this study, a smeared fracture technique is employed to simulate tensile and shear fractures in oil sands. The model used combines many important fracture features, which include the matrix flow, poroelasticity and plasticity modeling, saturation-dependent permeability, gradual degradation of the oil sands as a result of dilative shear deformation, and the tensile fracturing and shear failure that occur with the simultaneous enhancement of permeability. Furthermore, sensitivity analyses are also performed with respect to the reservoir and geomechanical parameters, including the apparent tensile strength and cohesion of the oil sands, magnitude of the minimum and maximum principal stress, absolute permeability and elastic modulus of the oil sands and ramp-up time. All these analyses are performed to clarify the influences of these parameters on the fracturing response of the oil sands.

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Experiments with Stand-Alone Sand-Screen Specimens for Thermal Projects

Authors: Vahidoddin Fattahpour (RGL Reservoir Management Inc.) | Morteza Roostaei (RGL Reservoir Management Inc.) | Seyed Abolhassan Hosseini (University of Alberta) | Mohammad Soroush (University of Alberta) | Kelly Berner (RGL Reservoir Management Inc.) | Mahdi Mahmoudi (RGL Reservoir Management Inc.) | Ahmed Al-hadhrami (Occidental Petroleum Oman) | Ali Ghalambor (Oil Center Research International)

Most of the test protocols developed to evaluate sand-screen designs were based on scaled-screen test coupons. There have been discussions regarding the reliability of such tests on scaled test coupons. This paper presents the results of tests on wire-wrapped screen (WWS) and slotted liner (SL) test coupons for typical onshore Canada McMurray formation sand.

A unique sand control evaluation apparatus has been designed and built to accommodate all common stand-alone screens that are 3.5 in. in diameter and 12 in. in height. This setup provides the capability to have a radial measurement of pressure across the sandpack and screen for three-phase flow. Certain challenges during testing such as establishing uniform radial flow and measuring the differential pressure are outlined. Produced sand is also measured during the test. The main outputs of the test are to assess the sand control performance and the mode of sanding in different flow directions, flow rates, and flow regimes.

It was possible to establish uniform radial flow in both high- and low-permeability sandpacks. However, the establishment of radial flow in sandpacks with very high permeability was challenging. The pressure measurement at different points in the radial direction around the screen indicated a uniform radial flow. Results of the tests on a representative particle size distribution (PSD) from the McMurray Formation on the WWS and SL test coupons with commonly used specifications in the industry (aperture sizes of 0.012, 0.014, and 0.016 in. for WWS and 0.012, 0.016, 0.018, and 0.020 in. for SL) have shown similar sanding and flow performances. We also included aperture sizes smaller and larger than the common practice. Similar to previous tests, narrower apertures are proven to be less resistant to plugging than wider slots for both WWS and SL. Accumulation of fines close to the screen causes significant pore plugging when conservative aperture sizes were used for both WWS and SL. In contrast, using the test coupon with a larger aperture size than the industry practice resulted in excessive sanding. The experiments under linear flow seem more conservative because their results show more produced sand and smaller retained permeability in comparison to the testing under radial flow.

This work discusses the significance, procedure, challenges, and early results of physical modeling of stand-alone screens in thermal operation. It also provides insight into the fluid flow, fines migration, clogging, and bridging in the vicinity of sand screens.
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Characterization and corrosion behavior of electroless Ni-Mo-P/Ni-P composite coating in CO2/H2S/Cl− brine: Effects of Mo addition and heat treatment

Authors: Jiankuan Li, Chong Sun, Morteza Roostaei, Mahdi Mahmoudi, Vahidoddin Fattahpour, Hongbo Zeng, Jing-Li Luo

The electroless Ni-Mo-P/Ni-P composite coating was applied on N80 carbon steel, and the effects of Mo addition and heat treatment on the corrosion resistance enhancement in CO2/H2S/Cl− brine were studied by electrochemical measurements and surface analysis techniques. The Mo addition in the as-deposited Ni-P coating causes the microstructural transformation from amorphous to crystalline due to the reduced P content, thereby suffering severe corrosion. The impaired corrosion performance of as-deposited Mo-incorporated coating is also originated from the absence of the oxide film on the coating surface. Nonetheless, the heat-treated Ni-Mo-P/Ni-P coating exhibits desirable corrosion resistance, which is reflected by the outstanding corrosion inhibition efficiency (η = 96.1%). Heat treatment facilitates the formation of Ni4Mo phase and more importantly, the growth of an oxide film consisting of nickel and molybdenum oxides (H2S-immuned MoO3) with better passivation properties, which accounts for the remarkable corrosion resistance improvement.

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