Xinchang Gas Field Shaximiao Formation Gas Reservoir Multi-fracturing Technology Research

The research of systemic multilayer fracturing technology is developed aiming at the compound gas reservoir characteristics of multilayer multisand in tight sandstone in Xinchang Shaximiao group gas reservoir. After treatment, notable stimulation effects are achieved.(1) The profile of single well stress is interpreted relying on five well log data. Generally, the stress difference between produced layer and interlayer is 2MPa to 8MPa. Considering the larger range of the thickness of tip and bottom mudstone, the manner of multi- and single fracturing exists necessarily in Shaximiao group gas reservoir.(2) The parameters of drilling, logging, testing, fracturing treatment and well testing explanation is collected. With well completion manner, well structure, well strings, electric data, test data of pre- and post-fracturing and so on, the accounting analysis is made. So the criterion of selecting layer is further improved in multilayer fracturing in Shaximiao group gas reservoir.(3) The manner of multilayer fracturing is fixed on according to different stress distribution and magnitude, formation mechanics property, interface property, tip and bottom layer thickness and mechanics property difference with produced layer, layer intervals, interlayer distribution , fluid characteristic and so on. Then perforation parameters and strings structure is optimized and designed by different multilayer fracturing manner.(4) Four types of layered fracturing downhole tools adapting to geology characteristics of Xinchang Shaximiao group gas reservoir are discussed, and the improvement and selecting type research of multilayer fracturing downhole tools is made. On the basis of two-layer separate fracturing downhole tools, three-layer ones are developed.(5) Depending on reservoir physics characteristics and multilayer fracturing technology needs at Shaximiao group, fracturing fluid system is developed. The formula has good capability of transporting sand, low friction resistance and damage, few residue and complete broken gels and hydration.(6) Through simulating effects of different work fluids, geology mechanics characteristics, perforation parameters, multilayer / layered manner and treatment technology on fracture extending by three dimension fracturing software, it can contrast analysis the effect of multi / single layer fracturing and make sure optimal fracturing scale of Xinchang gas field. The optimal hydraulic fracture half length is between 100 and 250m, and optimal sand ratio is between 20% and 25%.(7) It practises 9 multilayer fracturing treatment, ratio is 100%, and effective success ratio by well number is 100%. Average production fold reaches 25.61, the effect of increasing production is obvious.