A Study On Low Damage Fracturing Fluid In Coal Bed

Professor Denghongwen. Associate Professor Heshunli.Coalbed methane is a kind of nature gas produced during the long geology times that coal bed changed into the coal. The coalbed methane is also a strategic reserved resource. With the surrounding protection was being taken serious, the coalbed methane was being begun to develop. Because of American's technology and experience accumulated in the course of more than ten years that they explored and developed the coalbed methane, and more because of their economy was succeed, all of this accelerated the development of coalbed methane industry all of the world.At first, The aim of exploring coalbed methane was to ensure the safety in the coal mine. The coalbed methane was as a kind of economic industry in America at the time. Since 1950's, In the San Juan Basin and Black Warrior Basin of the American have been developing. The production from the basin takes about 96% of total coalbed methane in America. The development of the coalbed methane in another coal fields is also going on. Recently the development of coalbed methane had been made a good progress in the Australia.The commonly used method of development of coalbed methane well is hydraulic fracturing. In outworld, Fracturing fluid applied in the coalbed methane include water, gel, boron crosslinked gel and foam fracturing fluid. When fracturing fluid is pumped into the coalbed seam, it would reduce permeability of the coalbed seam. The reason include fracture liquid's adsorption course coal seam and block cleats, and block cleats will limit the coalbed methane desorption. In abroad, the coalbed seam usually had high permeability. So the research reports on fracturing fluid damage in coalbed seam is very limited. Usually, the following factor can increase the damage of fracturing fluid to the coalbed seam: The first is the distance that fracturing fluid come into vertical fracturing. The second is unilateral flow bring about the pore press lower, cleats close, and fracturing fluid deeped in it will settle.Comparing with oil field, the exploration and development of coalbed well is quite new in our country. Fracturing fluid is important in fracturing engineering. But our research work on fracturing fluid used in the coalbed well is not in a series, and further job should be done. In addition, the research work about adsorption and damage between the coalbed seam and fracturing fluid containing polymers, surfactants, biocides, and some other chemical additions has not been done in our country. This kind of reports in outside is also quite limited. While following the tracks of the fracturing fluid used in the coalbed well in our country or outside, wehad experimenting to connected with the characteristic of JINCHENG 3# coalbed seam. In this paper it concentrate on the fracturing fluid in the coalbed well. This paper sift out some fracturing fluid additions; optimize fracturing fluid system (include: water, gel, and crosslinked fracturing fluid); study the damage of fracturing fluid to the coalbed seam. In specially, experimental method had set up that can estimate the fracturing fluid's damage to the coalbed seam, and realized basic reasons that damage the coalbed seam, and then found a base rule.