Significant advances has been made in the exploration and development of deep gas reservoirs in the southeastern Chongqing

especially the deep shale gas. While the shallow gas exploration is on the contrary

especially the shallow fracture-matrix limestone gas reservoir

Maokou Formation

with low porosity

low permeability

low fracture development

low reservoir temperature

low pressure coefficient

and mediocre fracture development. During the acid fracturing process

as the gel is hard to break by acid and the flow back is difficult

then the effect is poor

and it is difficult to make breakthrough. Taking the characteristics of carbonate reservoir

Maokou Formatio

n in well-Dashi-1HF

as the example

the difficulties in reservoir acid fracturing have been analyzed

the self-degradation gelling acid has been synthesized

the mechanism of degradation has been introduced

and the optimization of the acid-liquid system has been carried out. The horizontal well acid fracturing pipe string has been optimized to form acid fracturing technology of self-degradation gelling acid and multilevel packer

at the same time

the segmented acid fracturing parameters have been optimized. 4 stages acid fracturing of well-Dashi-1HF has been completed

and the total acid dosage is 2 129.2 m

3

. The test gas production after acid fracturing is 22.6×10

4

m

3

/d. The results show that this new technology has a good effect in the shallow limestone of southeastern Chongqing

and provides useful reference for the acid fracturing of similar layers in the future.