Real-time Microseismic Monitoring Research Articles

A Real-Time Microseismic Monitoring System Based on Virtual Instruments

Many geologic hazards, such as rock burst coal and gas outburst, have an inevitable connection with microseismic phenomena in rock mass. In order to provide accurate evidence of underground safety monitoring, inspecting microseismic signal is a good way to make sure the range and the level of underground rock breaking. Previous microseismic system using DSP or singlechip can’t obtain the desired data collection, neither for the achievement of advanced algorithm. The real-time microseismic monitoring system realizes the acquisition of multiple microseismic signals and uses wavelet transform algorithm, which gives full scope to the advantages of virtual instruments. The monitoring result was very similar to actual rock burst and the error of orientation results was minor to prescriptive upper limit, which means this new system completes the monitoring of real-time microseismic emission effectively.

Using Real-Time Downhole Microseismic To Evaluate Fracture Geometry for Horizontal Packer-Sleeve Completions in the Bakken Formation, Elm Coulee Field, Montana

Summary Multistage fracturing in the Bakken formation, Elm Coulee field, Williston basin, Montana, has been performed using hydraulic packers for zonal isolation with ball-actuated fracture sleeves to improve performance of horizontal wells. Optimizing development drilling and fracture-treatment designs for horizontal wells requires an estimation of the fracture geometry (azimuth, height, and half-length, with respect to lateral orientation). A fracture treatment designed under the assumption of a longitudinal fracture (along the length of the borehole) will be entirely inadequate if the actual fracture propagates in a transverse orientation (perpendicular to the length of the borehole) and vice versa. Recovery factor and reserves estimation, interference, drainage, and well spacing require an understanding of the created fracture geometry from multistage completions. This paper describes how real-time downhole microseismic monitoring, fracture-treatment pressure interpretation, and subsequent production evaluation were used to better understand the created-fracture geometry, completion staging efficiency, and fracture-stimulation effectiveness in a project with two parallel 4,000-ft middle-Bakken treatment horizontal wells 2,000 ft apart with a horizontal well in between. The following topics will be discussed as part of this paper: Success and failure in achieving proper stage isolation, diversion, and fracture-stimulation coverage using hydraulic packers for zonal isolation with ball-actuated fracture sleeves in two 4,000-ft laterals.Fracture azimuth and half-length as related to entry-point spacing and intersections with nearby wells.Fracture-height growth up into the Lodgepole limestone and down into the Three Forks formation as related to microseismic location uncertainties and use of this information in fracture-model calibration.Discussion and comparison of the production response for past completion strategies to the current approach, as well as discussion about production interference between horizontal wells. The integration of fracturing-mechanics studies that began with the initial vertical wells and concluded with current-day horizontal applications in concert with detailed reservoir-engineering evaluations has resulted in significant production improvement in the Bakken formation, Elm Coulee field, Williston basin, Montana. Detailed reservoir engineering led to optimized multistage fracturing that was applied using hydraulic packers for zonal isolation with ball-actuated fracture sleeves to improve performance of horizontal wells. Using a calibrated/customized fracture model that had been developed from evaluation of hundreds of wells in the basin, the fracture-treatment pump schedules were designed to minimize fracture complexity and optimize lateral proppant placement to attempt to create an ideal transverse-fracture geometry within a horizontal well. Microseismic imaging was used to confirm the historical information in the basin, fracture mechanics studies, and customized models relative to the azimuth, height, and half-length with respect to lateral orientation.

Improving Well Completions by Use of Real-Time Microseismic Monitoring: West Texas Case Study

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 137996, ’Improving Well Completion by Use of Real-Time Microseismic Monitoring: A West Texas Case Study,’ by E.A. Ejofodomi, SPE, M.E. Yates, SPE, R. Downie, SPE, T. Itibrout, SPE, and O.A. Catoi, Schlumberger, prepared for the 2010 SPE Tight Gas Completions Conference, San Antonio, Texas, 2-3 November. The paper has not been peer reviewed. Hydraulic-fracture-stimulation treatments that were performed on a vertical-well completion in the Spraberry/Wolfcamp formations in Midland County, Texas, are reviewed. Real-time microseismic hydraulic-fracturing monitoring (HFM) was used to “track” development of the hydraulic fractures as they propagated through the formation, thereby allowing implementation of corrective actions to improve the completion efficiency of the well. Introduction The “Wolfberry play” is the local name given to wells with commingled production from the Wolfcamp through the Spraberry formations. This low-permeability oil play extends over 2,500 sq miles in 11 counties in the Midland basin of west Texas. Typical porosity and permeability ranges for the Spraberry are 5 to 18% and 0.01 to 3.0 md, respectively. With new hydraulic-fracturing technologies developed in the late 1980s, operators in the basin began to explore and develop the potential of the deeper Wolfcamp interval. The trend contains pockets of high porosity and permeability, but most of the reservoir interval is lower quality, with porosity and permeability ranges of 5 to 8% and 0.001 to 1.0 md, respectively. By identifying and completing the productive Wolfcamp trend in addition to the Spraberry, operators have reduced payout times and increased returns on investments. In recent years, HFM has become relied upon to understand the propagation behavior of stimulation treatments. This technology enables the quantification and evaluation of the induced fracture. It also has been vital in observing and analyzing the interaction or communication of the created hydraulic fractures with potential geohazards such as faults and natural fractures. In this study, the operator evaluated the effectiveness of typical Wolfberry-completion designs and practices. Thus, in addition to use of good petrophysical and rock-mechanical properties for the completion and fracture design, real-time microseismic HFM was used to obtain information about the fracture length and height to improve the fracture model, validate stress profiles, and determine the major fracture orientation for future well spacing and infill-drilling programs. The real-time application of microseismic HFM identified unwanted fracture behavior and enabled making necessary modifications to optimize the overall well completion. Wolfberry-Completion Considerations Typical Wolfberry wells penetrate up to 3,000 ft of gross interval. Typically, the wells are completed with five to ten fracture-stimulation stages during which a single or multiple wireline runs are made into the well to perforate and then isolate between stages. Each stage can have up to seven pay targets. While the best method of stimulating each zone is selective pinpoint perforation and stimulation of individual pay targets, this technique can prolong the overall completion time severely, and increase the well-completion costs. To ensure coverage of the stimulation treatments over the target intervals and manage completion costs, operators rely on two main perforation strategies—conventional limited-entry and single-cluster.

Management of Post-mining Large-scale Ground Failures: Blast Swarms Field Experiment for Calibration of Permanent Microseismic Early-warning Systems

In France, decades of coal and iron-ore mining have left extensive underground cavities beneath or in the vicinity of urban areas. This poses an environmental challenge for society. To ensure post-mining risk management and public safety, wherever remediation is not possible, numerous real-time microseismic monitoring systems are being installed. The objective is to detect remote rock mass fracturing processes, precursory events and acceleration phases for appropriate and timely action. Although no consistent collapse has occurred in any of the monitored areas yet, single 3-D probes record many microseismic events of very low amplitude which create difficulties in the quantitative data analysis. The development of specific quantitative processing has therefore become a major issue in our research work. For that purpose, a field experiment was carried out on six of the instrumented sites. It consisted of sequences of small blasts in mine pillars which were accurately controlled in terms of the location, orientation and energy of the explosive source. The data analysis was used to calibrate parameters (velocity model, 3-D sensor orientation, etc.) for reliable 3-D localization and to develop an empirical law to estimate the source energy from the sensor energy. This work now enables us to analyze real microseismic events with a considerably better level of accuracy and to obtain enough information and confidence to discuss these data in terms of site stability.