Experimental Research On Sensitivity Of Gas Bearing Coalbed

With the increasing decrease of normal natural gas resource and the sharp increase of natural gas demand, coalbed gas as a kind of nonnormal natural gas resource is valued by more and more people.In order to decrease the damage to conventional reservoirs,great many studies have done on the stress sensitivity flow rate sensitivity water sensitivity acid sensitivity alkali sensitivity and diversified chemic substance sensitivity. Comparing with oil field, the exploration and development of coalbed well is quite new and the research work about protecting the coalbed seam from damage has not been done in our country.Because of special physical property special chemistry property and special pore structure, the permeability of the coalbed seam is easier reduced than oil field when stress is changed or outer liquid flowed in. Considering that coring in coalbed gas well are difficult, powdered coal packs are usually choosed to do flowing experiment apparently this packs are quite different from the true coalbed cores in pore structure. Moreover,the majority of sensitivity study have be done on the stress sensitivity and the permeability damage which caused by drilling fluid and fracturing fluid. This kind of reports in outside is also quite limited,the studies also only have done on the stress sensitivity and the polymer sensitivity.The majority of gas-bearing coalbed in our country have low porosity (Φ <10%) low permeability(K-3 μ m²)and low pressure(buried not very deep).So the commonly used method of development of coalbed methane well is hydraulic fracturing.For providing the basis of how to prepare low damage foam fracturing fluid,we have done this coalbed'sensitivity experiments. Blind coal from JinCheng and soft coal from Hancheng are used and cores are prepared in this experiment. Considering the specific characteristics of gas-bearing coalbed,we put forward the experimental methods that suit gas-bearing coalbed with reference to the methods of normal sandstone statas.We have done systemic studies of coalbed seam on the stress sensitivity flow rate sensitivity water sensitivity and working...