UNITED STATES DEPARTMENT OF INTERIOR GEOLOGICAL SURVEY COAL RESOURCE ASSESSMENT OF THE JHERRUCK AREA, SONDA COAL FIELD, SINDH PROVINCE, PAKISTAN by John R. SanFilipo , Shafique A. Khan2 , and Altaf H. Chandio2 , Open-file report 93-523 Prepared jointly by the Geological Survey of Pakistan and the U.S. Geological Survey, under the auspices of the U.S. Agency for International Development -' U.S.Geological Survey, 956 National Center, Reston VA 22092 2 Geological Survey of Pakistan, 42-R, Block-6, PECHS, Karachi This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. Any use of trade names is for descriptive purposes only and does not imply endorsement by the USGS. 1994 CONTENTS page ABSTRACT.................................................. 1 INTRODUCTION.............................................. 2 Project background.................................... 2 Purpose and scope..................................... 4 Responsibilities and acknowledgements................. 8 Geographic setting.................................... 14 Location, access, and infrastucture............... 14 Topography........................................ 16 Field operations.................................. 17 GEOLOGY OF THE SONDA COALFIELD............................ 22 Geologic setting...................................... 22 Stratigraphy.......................................... 24 Depositional environments......................... 32 Structure......................................... 34 Coal geology...................................... 41 Coal zone nomenclature........................ 41 Coal bed correlation.......................... 42 Coal bed descriptions......................... 46 COAL RESOURCES............................................ 48 Definitions........................................... 48 Thickness and extent of coal beds..................... 55 Depth to coal......................................... 60 Resource estimates.................................... 63 Methodology and uncertainty....................... 63 Discussion of the results......................... 67 Main Sonda bed................................ 67 CONTENTS (cont'd) page Other beds.................................... 69 Comparison with previous estimates............ 70 COAL QUALITY.............................................. 71 Introduction.......................................... 71 Sampling procedures............................... 73 Previous work..................................... 75 Statistical methods............................... 77 Results of standard analysis.......................... 78 Moisture.......................................... 82 Rank.............................................. 84 Ash............................................... 86 Sulfur............................................ 89 Other standard analysis........................... 91 Results of oxide and trace element analysis.......... 100 CONSTRAINTS ON MINING.................................... 103 Hydrology............................................ 104 Roof and floor conditions............................ 105 Surface impacts...................................... 107 Marketability........................................ 108 CONCLUSIONS AND RECOMMENDATIONS.......................... 109 REFERENCES CITED......................................... 112 APPENDICES............................................... 119 Appendix 1. GSP drilling proposal, Jherruck Block... 120 2. Coal bed intercepts and sample numbers.. 125 3. Detailed coal resource estimates........ 143 4. Conversion factors and statistical formulae................................ 145 11 CONTENTS (cont'd) page Appendix 5. Statistical summaries of coal quality, low-rank U.S.coals...................... 146 FIGURES Figure 1. Index map; coal fields of Pakistan............ 3 2. Drill-hole location map....................... 7 3. Geologic setting.............................. 23 4. Generalized stratigraphic column.............. 25 5. Generalized geologic map...................... 26 6. Typical geophysical log....................... 31 7. Index map, structure sections................. 36 8 . Triangle-zone backthrusting................... 38 9. Index map, stratigraphic sections............. 43 10. Coal-bed correlation by gamma-neutron logs.... 44 11. Examples of qualifying coal................... 53 12. Flow chart, coal analytical procedures........ 72 13. Classification of coal by rank................ 85 TABLES Table 1. Summary of drilling activities.................. 9 2. Schedule of TDY's and report preparation activities..................................... 12 3. Surveyed drill-hole coordinates and elevations. 18 4. Core-loss statistics........................... 21 5. Coal bed thickness statistics.................. 56 6. Coal resource estimates by depth and reliability categories......................... 68 7. Coal resource estimates by thickness and reliability categories......................... 69 8. Coal resource estimates by thickness and overburden categories.......................... 75 111 CONTENTS (cont'd) page Table 9. Index of previous coal quality reports......... 76 10. Statistical summary of selected coal quality parameters, as-received basis.................. 79 11. Statistical summary of selected coal quality parameters, equilibrium-moisture basis......... 80 12. Statistical summary, ash values, dry basis..... 88 13. Coal quality statistics, main Inayatabad bed... 92 14. Coal quality statistics, main Sonda upper bed.. 94 15. Coal quality statistics, main Sonda bed........ 96 16. Coal quality statistics, Sonda lower main bed.. 98 PLATES Plate 1. 1:50,000 base map showing location of drill holes... pocket 2. Structure contour map of the main Sonda coal bed.....pocket 3. Structure section A-A'...............................pocket 4. Structure section B-B'............................... pocket 5. Structure section C-C'...............................pocket 6. Correlation diagram A-A'.............................pocket 7. Correlation diagram B-B'.............................pocket 8. Correlation diagram C-C'............................. pocket 9. Isopach map of the thickest Inayatabad coal bed......pocket 10. Isopach map of the thickest Sonda upper coal bed.....pocket 11. Isopach map of the main Sonda coal bed...............pocket 12. Isopach map, thickest Sonda lower main coal bed......pocket 13. Overburden map of the main Sonda coal bed............pocket 14. Coal resource map, main Sonda coal bed...............pocket 15. Geologic assurance categories........................pocket 16. Composite isopach map, thickest projected coal bed...pocket IV CONTENTS (cont'd) page Plate 17. Ash isopleth map, main Sonda coal bed...............pocket 18. Sulfur isopleth map, main Sonda zone................pocket 19. Percent sandstone map, 3 m roof above the main Sonda zone..........................................pocket COAL RESOURCE ASSESSMENT OF THE JHERRUCK AREA, SONDA COAL FIELD, SINDH PROVINCE, PAKISTAN by John R. SanFilipo U.S. Geological Survey and Shafique A. Khan, Altaf H. Chandio Geological Survey of Pakistan ABSTRACT Between 1985 and 1989, the Geological Survey of Pakistan, in cooperation with the U.S. Agency for International Development and the U. S. Geological Survey, drilled 55 exploratory boreholes in the northern part of the Sonda coal field. The latest program of 20 holes drilled on 3 km centers has enabled individual coal beds to be correlated, and has led to the identification of a contiguous area of about 500 sq km where at least one coal bed exceeds 1 m in thickness. Seven coal zones containing multiple coal beds have been identified in the upper part of the Paleocene Bara Formation at Jherruck. The thickest and most persistent coal bed occurs in the Sonda zone, and lies at depths of 80 to 400 m in the 530 sq km study area, where it ranges in thickness from 0 up to 6 m. Total in-place coal resources for this bed, considering a minimum thickness of 30 cm and a maximum dry ash yield of less than 50 percent, are estimated to be 900 million tonnes, 40 percent of which is in the demonstrated category. The average thickness of the main Sonda bed within the study area is 1.3 m, but 53 percent of the total resources estimated for this bed occurs within a 150 sq km subarea where the coal is thicker than 1.5 m and less than 300 m deep. The area is relatively undeformed structurally, but mining could be constrained by other factors such as poor roof conditions, potential mine flooding, and limits to acceptable subsidence in irrigated areas which overlie some of the thickest coal. The coal is subbituminous C in rank. Analyses of 66 samples from the main Sonda bed yield thickness-weighted averages of 8 percent ash and 1.4 percent sulfur, which compare favorably with most Pakistani coals, but the average heating value is a relatively low 7933 BTU/lb and the average moisture content is a relatively high 32 percent. Relative to typical U.S. coals of equivalent rank, the Sonda coals appear to be enriched in chlorine, bromine, strontium, and some heavy metals. The uppermost part of the Bara Formation contains numerous marine faunal and glauconitic zones and appears to intertongue with the overlying shallow marine Lakhra Formation. Coal-bed geometries suggest that a variety of coal-forming environments were present in a generally oscillatory paralic depositional setting, and that the main bed of the Sonda zone probably formed in