New techniques of coal seam panels' pre-drainage - based on project experience

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1 New techniques of coal seam panels' pre-drainage - based on project experience Janusz Makówka, Jacek Skiba, Bartłomiej Jura Central Mining Institute Jerzy Król JSW S.A., Marian Zmarzły- JSW SA Kwakow, 28 th February 2018

2 Basic facts: Realisation time: July 2015 June 2018 Budget: 3.8 mln Partners: GIG (Poland) project coordinator, JSW (Poland) INIG-PIB (Poland), RWTH (Germany), INERIS (France), Imperial College (UK), HUNOSA (Spain)

3 Structure of the project : WP0: Project Coordination and Reporting (GIG) WP1: Characterisation of Coal Seams and Surrounding Rocks: Field Site Characterisation (RWTH) WP2: Development of Borehole Stimulation Technologies for Coal and Rock Formations (GIG) WP3: Numerical Modelling and Design of Field Scale Stimulated Methane Drainage Processes (Imperial College, INIG) WP4: Field Scale Implementation of Improved Methane Drainage Systems at Mine Sites (JSW SA) WP5: Long-term Monitoring and Assessment of Improved Methane Drainage Efficiency (GIG) WP6: Conclusions, Recommendations and Dissemination (INERIS)

4 Imputs and outputs of WPs cores/samples, geol. info existing equipment param. WP1: Characterisation of coal seams Lab/field test data WP3: Numerical Modeling and Design theoretical drainage range/parameters reports, publications, experience WP2: Development of Borehole Stimulation empirical drainage range/parameters WP4: Field Scale Implementation boreholes layout WP5: Long-term monitoring and Assessment drainage long-term characteristic WP6: Conclusions, Recomendations and Disseminations SAFER AND MORE EFFECTIVE MINING

5 apparent ky (m²) Effective porosity, MIP (%) 2 Laboratory experiments to define the baseline reservoir properties The laboratory experiments aimed at defining the baseline reservoir properties for numerical simulations. Petrophysical data comprise permeability and porosity. Physico-chemical data comprise methane sorption isotherms and gas uptake kinetics determined on different particle sizes. The database is complemented by organic petrological information and petrography of the bedrock samples. 1.00E :1 line 1:1 line 1.00E Confining pressure MPa 1.00E MPa MPa MPa 1.00E coals, JSW, seam E bedrocks, JSW, seam E E E E E apparent kx 10.0 (m²) Total porosity, He-pycnometry (%) Gas (N 2 ) permeability coefficients in x- and y-direction (ZOFIOWKA, seam 412). Stress dependence of apparent permeability coefficients of four JSW coal samples Normalized pressure decline curves for gas uptake by different grain sizes of Porosity coefficients ZOFIOWKA of ZOFIOWKA seam coals 412 (seam coal (semi-logarithmic 412) determined by plot). mercury injection (MIP) and He-pycnometry (unconfined, standard conditions). Error bars represent the standard deviation determined from the set of 3 sub-samples

6 Assessment of the prevailing stress state at different mine layouts The main objective of this task was to implement both numerical and empirical methods to define the state and magnitude of stresses around working longwall and sublevel caving coal faces at JSW and HUNOSA to assist the initial design of field experiments in the project. Location of extracted panels in seam 412 and surrounding seams Vertical stress distribution in seam 412 in Zofiowka colliery Vertical stress distribution around longwall panel D-2 isosurfaces of 15 MPa (green), 20 MPa (orange), 25 MPa (grey) and 30 MPa (red). 2

7 In-situ measurements of coal and surrounding rock properties This task aimed at drilling and instrumenting a number of boreholes at selected JSW and HUNOSA sites to carry out field experiments to establish the in situ stress and reservoir properties of the coal seams and surrounding rocks that are affected by coal production. S h =16 S H =59 log pd vs. time curve A B C Directions and values of horizontal stresses obtained from Pressure gauge developed by measurements INiG-PIB Diagram of the coal permeability measurement A).Hydrostatic pressure balance in seam 412. the reservoir pressure in coal, B) Removal of some fluid volume from the well, C) Monitoring the fluid table behaviour.

8 Development of the equipment and tools for the stimulation Task 2.1 aimed at the development and construction of the equipment and tools for the hydraulic/mechanical slotting and stimulation by blasting. Due to specific underground coal mine conditions, the equipment had to be designed and manufactured with the required specifications and certifications. A schematic diagram of integrated parts assembled for hydro-fracturing/cutting of coal seams. 2

9 Laboratory investigations into stimulation techniques Laboratory experiments to characterise fracture growth, frac fluid and proppant behaviour in coal seams Baseline permeabilities Permeabilities with sand proppant The newly constructed 100mm hollow cylinder testing triaxial cell during pressure testing. Large cell size and weight requires lifting and stabilising tools. Permeability behaviour of a sand propped fracture in coal comparing baseline (un-propped) and propped N2 permeabilities. Fractured coal samples treated with Mesh sand proppant (left) and InterProp 30/50 ceramic proppant (right).

10 Laboratory investigations into stimulation techniques Laboratory experiments to develop new blasting techniques for fracturing coal and rock masses Characteristics of the pressure changes during explosion of the 10 g METANIT SPECJALNY E7H charge (Initial pressure = 1.3 MPa). Test chamber for determining the explosive characteristics. Relationship between combustion rate in the intermediate period of the course, and initial pressure for 50% time of pressure increase.

11 Numerical modeling to assess the performance of stimulated wellbores Numerical modelling of hydraulic stimulation Numerical modelling of stress relief and fracturing induced around slotted wellbores Numerical simulation of cavity completions Numerical simulation of the use of explosives (a) n // σ2 (b) n // σ3 The effect of varying dip direction and dip angle on failure zone geometry. (a) Permeability profiles along the (a) coal seam strike and (b) vertical direction. (b)

12 Field testing and development borehole methods Monitoring boreholes Test borehole Training of the use of stabilization-turning unit USO 1. Test boreholes used to investigate hydro cutting and hydro slotting technique. Confirmation of hydro slotting range: water and steam flow from the monitoring borehole. 2

13 drainage coefficient [-] Numerical modelling of multi-seam mining layouts and gas flow patterns around longwall faces for enhanced methane drainage at JSW mines no slots slots every 6m slots every 4m slots every 2m Variation of methane production rate with time in stimulated and unstimulated 3D distribution Data availability of effective distance and the along vertical development the borehole stress of a in [m] structural the model framework representing for a 3D part of the Horizontal cross section D-2 of longwall the D-2 showing part Data geological of the sets the 412 used location model coal wellbores. for of the of seam the the petrophysical Zofiówka model stimulated Colliery. with modelling. horizontal a single borehole borehole stimulated and Drainage coefficient in the vertical cross section planes B-B' of 2 parallel hydraulic to the fractures. borehole axis, cm from the the plane borehole of the axis. borehole. by a uniform set of jet slots of separation distance of 2 m. The distribution of the drainage coefficient in

14 GŁÓWNY INSTYTUT GÓRNICTWA Application of large scale stimulated drainage of methane layouts at JSW Results of aerometric tests in the experimental borehole G180c (2016) before and after slotting Layout of boreholes with slots and measurement system Location of test boreholes drilled from the testing tail gate D-2 in the seam Exemplary results of methane intake from borehole G180c

15 GŁÓWNY GŁÓWNY Map of the INSTYTUT INSTYTUT research area GÓRNICTWA GÓRNICTWA

16 GŁÓWNY INSTYTUT GÓRNICTWA Placement of the machinery underground

17 GŁÓWNY Outline INSTYTUT of the site test GÓRNICTWA

18 GŁÓWNY INSTYTUT GÓRNICTWA Outline of the hole in the coal seam

19 GŁÓWNY Positioning INSTYTUT the USO equipment GÓRNICTWA

20 GŁÓWNY Fixing INSTYTUT rod elements GÓRNICTWA together

21 GŁÓWNY INSTYTUT GÓRNICTWA Rod entering into stabilizing pipe

22 GŁÓWNY Drainage INSTYTUT instalation GÓRNICTWA

23 GŁÓWNY Methane INSTYTUT flow sensors GÓRNICTWA on the pipe

24 GŁÓWNY INSTYTUT GÓRNICTWA Long-term Monitoring of Improved Methane Drainage Efficiency Example of methane drainage system with measuring equipment. Components of integrated methane drainage sensor ZCO Block diagram of the ZCO sensor adjusted to operation with a measuring orifice plate

25 GŁÓWNY INSTYTUT GÓRNICTWA Findings and conclusions from Zofiowka tests Conducted experiments and data obtained during the research in Zofiowka mine enabled the following: to confirm the results we came across in EM Barbara to confirm the possibility of applying hydroslotting system undergound to determine the possible dangers and safety measures to discover the most important elements of this technology to find solutions to the problems that might appear during operating to find the correlation in the parameters in order to optimize the technology

26 Thank you for your attention