Research On Drilling Fluid Technology For Shale Gas In Biyang Sag

Nowadays, With the rising demand for coal, oil, natural gas and other resources, unconventional natural gas is an important goal for today’s resource requirements, especially the development of shale gas in recent years should not be underestimated in recent years. According to the authorities, the global unconventional natural gas, mainly distributed in Canada, Russia, the USA, China, Latin America, etc., is estimated to be2338.2bcm, being approximately4.56times of the world’s total conventional gas resources (512.6bcm) and1.65times of the world’s oil and gas resources.Shale gas was an unconventional gas, which was widely distributed throughout the world. In recent years, it took a high proportion of natural gas production. Shale gas is a kind of unconventional natural gas with enormous reserves and complex reservoir structure,low porosity, low permeability, long production life, long lead time, dramatic change of recovery and usually lower recovery than conventional natural gas. The United States is the first country to have an E&P for shale gas; so far, over35,000wells are putting into production and the annual output exceeds200×108m3,shale gas in some basins of Michigan and Indiana has been in a commercial production.There is shale gas resources within the territory of our country in geological history, The Resources of Shale gas are widely distributed in marine and continental basins, especially in southern、central and western regions of the basin as the main occurrence region in China。preliminary estimation, our shale gas resources is about100trillion cubic meters in china. In China’s Sichuan Basin, the Jung-gar Basin has industrial airflow through drilling. Therefore, the s development and utilization of shale gas has become a new bright spot of the global oil-gas exploration and development. Speeding up the exploration of the development and utilization of shale gas resources, alleviating the shortages of oil and gas resources, changed the pattern of oil and gas resources, renewable energy structure, ensured national energy security, promoted economic and social development are of great significance. The exploration of Henan Oilfield included the Nanxiang Basin biyang, Nanyang sag, Xinjiang-Yanqi Basin, southern North China Basin and the western margin of the Junggar Basin spring block and Yili Basin. According to the geological foundation data of Biyang sag shale, Referring to the constituency registration principles of the shale exploration and the three-owned assessment results, chosed an effective shale area of400km2, effective shale thickness of200m, Shale density2.7t/m3, the average gas2m3/t, Preliminary calculation:shale gas resources has large exploration prospects for432billion cubic in Biyang sag.This paper is from the exploratory of Henan Oilfield shale gas in Biyang sag, whose density is up to1.5g/cm3,anti-temperature is larger than120℃, API filter loss is less than3.5ml, HTHP(120℃,3.5MPa) filter loss is more than7ml, demulsification voltage is more than400V. To meet exploiting Henan Oilfield shale gas in Biyang sag, the target of the paper is obtaining a drilling fluid by compounding a effective HT-resistant polymer as one of composition, which can be controlled readily, is salt and pollution resisting to saturation when formation temperature being120℃and mud weight being1.5g/cm3.This thesis is done by following these steps, first selected the type of drilling fluid system, followed by optimization of various formulations of the drilling fluid system, finally, performance evaluation and the note of field application.For selecting the type of drilling fluid, taking into account the advantage of oil-based drilling fluid, resistant to high temperatures and Pollution, strong inhibition, good lubricity and performance of reservoir protection, etc. At the same time, taking into account the environmental requirements, selected the white oil as base oil in the oil-based drilling fluids.Finally, this thesis has configurated and established a line secretion of oil-based drilling fluid system, which meet the demand of application and maintenance requirement in biyang sag, the Formula:[oil-water ratio:5#White oil:20%aqueous solution CaCl2,2%MOEMUL,1%MOCOAT,3%Tianjin-dual-ruiorganic clay,2.0%alkalinity adjustment agent,3%filtrate reducer MOTEX,1%wetting agent, barite (heavier to1.5g/cm3),has good process stability sidewall, reduced downhole complication, reservoir protection, and has great promotional value, which solved necking, borehole expansion, well collapse, sticking, etc.For the exploitation of shale gas, oil-based drilling fluid could been effective protect reservoir,while improving the value of the shale gas mining, provided a strong supply for the shortage resources in our country, with good economic and social benefits.