An Expanded Study of Proppant Distribution Trends from a Database of Eroded Perforation Images

This paper further develops an analysis of proppant distribution patterns in hydraulically fractured wells initially presented in SPE-199693-MS. A significantly enlarged database of in-situ perforation erosion measurements provides a more rigorous statistical basis allowing some previously reported trends to be updated, but the main objective of the paper is to present additional insights identified since the original paper was published. Measurements of the eroded area of individual perforations derived from downhole camera images again provide the input for this study. Entry hole enlargement during limited entry hydraulic fracturing provides strong and direct evidence that proppant was successfully placed into individual perforations. This provides a straightforward evaluation of cluster efficiency. Perhaps more importantly the volume of proppant placed into a perforation can also be inferred from the degree of erosion. Summing individual perforation erosion at cluster level allows patterns and biases to be identified and an understanding of proppant distribution across stages has been developed. Outcomes from an analysis of a database that now exceeds 50,000 eroded perforations are presented. Uniform reservoir stimulation is a key objective of fracture treatments but remains challenging to measure and report. The study therefore focused on understanding how uniformly proppant is distributed across more than 1,800 measured stages. Results demonstrate how proppant distribution within stages is influenced when treatment parameters change. Our approach was to vary one parameter, for example the stage length, while all other parameters were maintained at a consistent value. We investigated multiple parameters that can be readily controlled during treatment design and show how these can be manipulated to improve proppant distribution. These included stage length, cluster spacing, perforation count per cluster and perforation phase. Hydraulic fracturing is a complex, high energy process with numerous input parameters. At individual cluster and stage level outcomes can be unpredictable and diagnostic results are often quite variable. The approach taken here was to complete a statistical analysis of a sufficiently large dataset of in-situ measurements. This allowed common trends and patterns to be confidently identified and conclusions reached on how proppant distribution is affected by varying specific design parameters. This should be of interest and value to those designing hydraulic fracture treatments.

Advancement of Hydraulic Fracture Diagnostics in Unconventional Formations

Multistage hydraulic fracturing is a technique to extract hydrocarbon from tight and unconventional reservoirs. Although big advancements occurred in this field, understanding of the created fractures location, size, complexity, and proppant distribution is in its infancy. This study provides the recent advances in the methods and techniques used to diagnose hydraulic fractures in unconventional formations. These techniques include tracer flowback analysis, fiber optics such as distributed temperature sensing (DTS) and distributed acoustic sensing (DAS), tiltmeters, microseismic monitoring, and diagnostic fracture injection tests (DFIT). These techniques are used to estimate the fracture length, height, width, complexity, azimuth, cluster efficiency, fracture spacing between laterals, and proppant distribution. Each technique has its advantages and limitations, while integrating more than one technique in fracture diagnostics might result in synergies, leading to a more informative fracture description. DFIT analysis is critical and subjected to the interpreter’s understanding of the process and the formation properties. Hence, the applications of machine learning in fracture diagnostics and DFIT analysis were discussed. The current study presents an extensive review and comparison between different multistage fracture diagnostic methods, and their applicability is provided. The advantages and the limitations of each technique were highlighted, and the possible areas of future research were suggested.

Application of Interventionless Single Point Entry Technology to Improve Proppant Placement Control and Well Production

The hydraulic fracture treatment (HFT) and its effectiveness to enhance wellbore drainage directly correlate with each well’s overall production performance and underlining economics. This paper will discuss the potential of ultra high stage count Single Point Entry (SPE) sleeves and their ability to increase control over proppant placement and isolation during the HFT as a method for optimizing well performance, economics, and reduce non-uniformity between treatments and wells. To address the limitations of current completion methods, full ID single point entry systems have been developed for open hole and cemented applications. These systems provide unlimited frac stage count with lower frac tortuosity, provide increased control over proppant placement and well production, reduce or eliminate over- flush and formation damage, and achieve higher efficiency during and after frac stimulation than previous conventional plug-and-perf (PnP) and sleeve systems, thereby reducing costs. While the ball-and-seat completion technique revolutionized the efficiency of multi-stage single point entry fracturing, its vast array of limitations (primarily ID restrictions), limited stage count, and compatibility with cemented liners quickly sidelined it in place of PnP. PnP offers increased surface area contact through additional entry points compared to sleeve systems of the past and remains the accepted method for achieving zonal isolation and initiation during stimulation. However, the time intensive operations of PnP present challenges in maintaining efficiencies due to variability in wireline during deployment and coiled tubing during millouts. The increase in number of clusters per stage and number of stages per well achieved with PnP often results in higher stimulated rock volumes (SRV) however, due to the number of multiple clusters open simultaneously, this method gained a "pump-n-pray" reputation due to the uncertainty of cluster efficiency and its unpredictability. The lack of cluster control over the years has created a series of challenges in terms of parent-child well relationships and spacing, economical asset development, and loss of potential production. With over 4,000 stages fracture stimulated across US, Canada, and Asia, some wells containing 220 individual stages, this paper will address the differences in production in terms of bbl of oil equivalent (BOE) for direct and indirect offsets in trials, compare capital efficiency with spud to put on production (POP) timelines, demonstrate economical completion optimization for lower commodity pricing of oil, and carbon intensity reduction measures to lower greenhouse gas emissions.

The impact of smart specialization strategies on sub-cluster efficiency: simulation exercise for the case of Mexico

Purpose This paper aims to evaluate whether the integration of smart specialization strategies (S3) into clusters significantly impacts their efficiency for countries that still do not implement this policy. This study tests three effects: whether the kind of policies envisaged through an S3 strategy impacts cluster’s efficiency; whether this impact changes with the technological intensity of the clusters; to determine which S3 is more suitable for sub-clusters at different levels of technological intensity. Design/methodology/approach The Mexican economy is taken as case of study because it has a proper classification of its industries intro Porter’s cluster’s definition but still does not adopt the S3 policy. Through data envelopment analysis (DEA), this study evaluates the cluster’s efficiency increment when variables representing the S3 elements are included. Findings The results show that strategies following the S3 had a significant impact in all clusters, but when clusters were classified by technological intensity, the impact on efficiency is higher in clusters in the medium low-tech group. Practical implications According to the results in the DEA, it can be concluded that these S3 strategies have the potential to increase the clusters’ productivity significantly. These results make convenient the adoption of the S3 policy by countries that already count with a properly cluster definition. Originality/value These findings contribute to the lack of studies that analyze the join implementation of S3 on clusters.

Determination of the Machine and Tractor Fleet Optimal Composition for a Model Cotton­Textile Cluster

The authors showed that the cotton-textile cluster efficiency (the capacity of the machine-tractor fleet, cotton yield, the production profitability) largely depended on the use of the optimal number of tractors and agricultural machines. The existing methods (theoretical, graphic, economic and mathematical) were difficult for practical use and did not take into account the specifics of mechanized cotton growing processes. Therefore, it was important to develop a simple normative method for determining the optimal composition of the machine and tractor fleet for clusters, corresponding to the technological map for the production of raw cotton. (Research purpose) To calculate the required amount of agricultural machinery based on the established standards. (Materials and methods) The authors developed an algorithm for determining the standard coefficients of the equipment necessity per 1000 hectares of arable land. These coefficients for each type of equipment were established in the context of technological operations of growing cotton: plowing, soil preparing for sowing, sowing seeds, cultivating the soil between cotton rows, mechanized removal of growth points of the main stems and side branches of plants, defoliation with chemicals, machine harvesting and transportation of harvested cotton – raw. (Results and discussion) The authors proposed the term “model cotton-textile cluster”. They calculated the required amount of equipment for such a cluster with an area of 13,732 hectares. They determined the percentage of the machine and tractor fleet: the share of tractors – 28 percent, cultivators – 22, trailers – 19.8, cotton pickers – 13.8, the rest – 16.4 percent. They emphasized that the machines fleet could expand with the arrival of new modern machines produced by machine-building plants of the republic and imported from foreign countries. (Conclusions) The authors accepted the machine and tractor fleet of the cotton-textile cluster with the number of equipment 1660 units as rational. They proved that it ensured the implementation of all technological operations within agrotechnical terms.

Proppant Placement in the Barnett Shale When Perforations are Selected in Like-Rock

In previous frac designs, proppant tracer logs revealed poor proppant distribution between clusters. In this study, various technologies were utilized to improve cluster efficiency, primarily focusing on selecting perforations in like-rock, adjusting perforation designs and the use of diverters. Effectiveness of the changes were analyzed using proppant tracer. This study consisted of a group of four wells completed sequentially. Sections of each well were divided into completion design groups characterized by different perforating methodologies. Perforation placement was primarily driven by RockMSE (Mechanical Specific Energy), a calculation derived from drilling data that relates to a rock's compressive strength. Additionally, the RockMSE values were compared alongside three different datasets: gamma ray collected while drilling, a calculation of stresses from accelerometer data placed at the bit, and Pulsed Neutron Cross Dipole Sonic log data. The results of this study showed strong indications that fluid flow is greatly affected by rock strength as mapped with the RockMSE, with fluid preferentially entering areas with low RockMSE. It was found that placing clusters in similar rock types yielded an improved fluid distribution. Additional improved fluid distribution was observed by adjusting hole diameter, number of perforations and pump rate.

A Shot in the Dark: How Your Post-Fracture Perforation Imaging can be Misleading and How to Better Understand Cluster Efficiency and Optimize Limited Entry Perforating

With recent advances in downhole imaging technology, it has become evident that surface perforation testing does not directly translate to downhole conditions. A total of 279 pre- and 595 post- fracture treatment perforations were imaged in this analysis. Pre-treatment perforation hole size was highly variable, even with oriented equal-entry charges. Because of high pre-fracture treatment variability, it is not recommended to use an average diameter of unstimulated perforations to evaluate cluster efficiency of perforations post-fracture treatment. Ideally, perforations should be individually imaged before and after treatment for direct comparison. However, since pre-treatment imaging is costly, an alternate methodology is presented. The findings in this paper will challenge current understanding of actual pre-treatment hole sizes, their variability, and their implications on cluster efficiency. Cluster efficiency cutoff limits have historically been subjective and promoted a false confidence in the ability of Completions Engineers to extend stage lengths and adjust perforation designs. A more stringent and calculated method of determining cluster efficiency is presented. Utilizing both wireline pumpdown for pre-treatment measurements, and coil tubing for post-treatment measurements, downhole imaging technology was deployed to measure perforations from four separate perforation charge manufacturers for pre- and post- treatment erosional analysis. Additionally, while understanding the strike/slip stress state of the Anadarko basin, perforations were oriented at 90° and 270° (degrees from top of wellbore), parallel to the maximum rock stress, promoting a shorter and less tortuous path to the fracture initiation point. Perforating at 90° and 270° reduced tortuosity and surface treating pressure, promoted a less variable pre-treatment perforation hole size due to its symmetry, and resulted in a significant increase in cluster efficiency verses pervious designs. This project effectively optimized a perforation design utilizing pre- and post- fracture treatment perforation imaging and a thorough understanding of pre-treatment perforation hole size to evaluate the effectiveness of stress-targeted, oriented perforating and its effect on cluster efficiency, tortuosity, and pre-treatment hole size variability. The optimized design resulted in 84%-97% cluster efficiency and reduced surface treating pressure by 770 psi. This workflow can be applied by Completions Engineers to any unconventional basin where plug and perf design is utilized.

Novel Near-Wellbore Fracture Diagnosis for Unconventional Wells Using High-Resolution Distributed Strain Sensing during Production

Summary The characteristics of hydraulic fractures in the near-wellbore region contain critical information related to the production performance of unconventional wells. We demonstrate a novel application of a fiber-optic-based distributed strain sensing (DSS) technology to measure and characterize near-wellbore fractures and perforation cluster efficiency during production. Distributed fiber-optic-based strain measurements are made based on the frequency shift of the Rayleigh scatter spectrum, which is linearly dependent on strain and temperature changes of the sensing fiber. Strain changes along the wellbore are continuously measured during the shut-in and reopening operations of a well. After removing temperature effects, extensional strain changes can be observed at locations around the perforation cluster during a shut-in period. We interpret that the observed strain changes are caused by near-wellbore fracture aperture changes caused by pressure increases within the near-wellbore fracture network. The depth locations of the measured strain changes correlate well with distributed acoustic sensing (DAS) acoustic intensity measurements that were measured during the stimulation of the well. The shape and magnitude of the strain changes differ significantly between two completion designs in the same well. Different dependencies between strain and borehole pressure can be observed at most of the perforation clusters between the shut-in and reopening periods. We assess that this new type of distributed fiber-optic measurement method can significantly improve understanding of near-wellbore hydraulic fracture characteristics and the relationships between stimulation and production from unconventional oil and gas wells.

Clusters in the regional economy, their effectiveness and organizational approaches

В статьи рассмотрены теоретические подходы формирования кластерной экономики. Выявлены основные критерии эффективности кластеров. Рассмотрен опыт организации кластеров в странах мира и регионах России. The article discusses theoretical approaches to the formation of a cluster economy. The main criteria of cluster efficiency are revealed. The experience of organizing clusters in the countries of the world and regions of Russia is considered.