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割理是广泛存在于煤层中对煤层气的产出具有重要意义的内生裂隙系统，是煤层经过干缩作用、煤化作用、岩化作用和构造压力等各种过程形成的天然裂隙。由于在煤层气勘探中，割理及割理渗透率形成与保存对煤层气高富集区预测有着重要重要，所以了解割理的成因和分类及相应的研究方法对煤层气地质选区评价至关重要。本次研究结论如下：①割理形成既有外生成因，也有内生成因。煤层割理是干缩作用、煤化作用、成岩作用及古构造应用等内外

EVALUATION METHOD OF CLEATS IN COAL RESERVOIR BED

Cleats are the endogenetic fracture systems which are widely distributed in the coal bed and are of great sig nificance for the coal-bed gas to be produced, being the natural fractures formed by desiccation, coalification, lithification and tectonic force. Because, in coal-bed gas exploration, the forma tion and preservation of cleats and deat permeabilities have great significance for predicting coal-bed gas high-production accumu lation zones, it is very important for geological region selection e valuation to understand the genesis and classification of cleats and their research methods. The main conclusions are as fol lows : ① the formation of cleats results from both exogenic and endogenetic effects and they are the result of the coaction of in ternal and external geological agents such as desiccation, coalifi cation, li thification and palaeotectonic stress, etc., so that a dual genesis hypothesis is much more appropriate; ②a set of methods of studying cleats and cleat systems in coal-bed in detail are pro posed and the method of evaluating permeability by cleats is per fected;③through analyzing the internal factors influencing the growth of cleats,it is thought that the cleats are formed by the external geological agents (coalification and tectonic stress, etc. )in combination with the internal attribution of coal-bed (coal thickness, coal petrologic composition and ash content, etc. ), being a comprehensive reflection of various geological a gents in coal reservoir bed. Not a single one of both the internal attribution of coal-bed and the external geological agent can be dispensed with and they are the necessary conditions of forming cleats and improving the permeability of coal-bed.