The Practice Of Acidification Technology Of Zhongba Shoudi Gas Reservoir

Zhongba Xutwo gas reservoir is a heterogeneous, low porosity, low permeability gas reservoir, which processes a large number of natural fractures and faults. The gas reservoir was put into operation in 1973, and its total gas production was 93.42×108m3. The water invasion of Zhongba Xutwo gas reservoir was serious, and the output of the single well was low. In the present, it's an urgent problem to improve the output of single well. Hydraulic fracturing was easy to communicate with the water layer, so acid fracturing technology would be the main acid stimulation technology of this gas reservoir. A comprehensive analysis of gas reservoir structures has been made, and the supporting stimulation method and acid fluid system was determined. The acid fracturing fracture parameter optimization model was built, and the acid fracturing parameters were optimized, which provided a theoretical basis.A comprehensive analysis of reservoir structures, faults distribution, sedimentary facies and fluid distribution was made. According to the growth of fractures, the reservoir was divided into Class ?, ?, ? and ?. With the development of reservoir, Class ? and ? would be the main body of development, and the supporting stimulation method was acidizing and acid fracturing technology, respectively.Single well dynamic reserves, single well remaining reserves, single well production, single well pressure, water production characteristics and other factors had significant impact on the productivity of single well. According to the comprehensive analysis, a total of 15 wells of Class ?, ? were chosen for acidizing or acid fracturing.Effective acidizing stimulation process of Class ? was deplugging acidification and temporary plugging acidification. For Class ?, the effective acid fracturing stimulation process was deep retarded acidizing technology and multistage alternating injection acid fracturing. Suitable acid systems for the reservoir of Class ? and Class ? were the turning mud acid and gelling mud acid, respectively.Based on the characteristics of the reservoir of Class ?, vertical wells acid fracturing fracture parameter optimization model was built, and utilizing meshing principle, seepage differential equation and outside the boundary treatment to calculate the optimal fracture parameters. The half-length of acid fracturing fracture and acid etched conductivity of Class ? reservoir was 120m and 15D cm respectively. The construction parameters were optimized by Meyer software. The optimal acid displacement was 2m3/min, the optimum acid dosage was 290 m3.The acid fracturing parameters optimization software of Zhongba Xutwo gas reservoir has been programmed. The software optimization result and actual acid result was highly conforms. The software provided effective support for the stimulation development of Zhongba Xutwo gas reservoir.