Study Of Formation Damage And Acid Treatment Of PuTaoHua At The East Of Daqing Oilfield

Acidizing of the matrix of the sandstone is one of the technical measures to stabilize or increase the production of a oil or gas well, lower the injection pressure and enhance the injection of a injection well. The aim is to dissolve the particle and impurity in the formation near the wellbore caused by drilling, workover and water injection, through the flow of acid in the pore, cavity and microcrack in the formation, so as to relieve the formation damage, dredge the flow channel, thus recover and enhance the production. According to the statistics home and abroad, acidizing is the process with highest usage and success ratio among the stimulations of water shot off, water injection profile adjusting, paraffin clear and control and sand protection.In the eighth oil plant of Daqing oil field, there exist the flowing problems: high water injection pressure, water can not be injected of can not meet the injection demand, the effect of routine acidizing is poor and the effective period is short. In order to make clear the reason of shortfall in injection of a injecting layer, to select and evaluate the additive of acidizing fluid, to optimize the acid system with high performance and low damage effect which is fit to the acidizing process of the water injection well with low permeability in the PuTaoHua oil layer, the damage of waste water re-injection on the reservoir, the damage of sensitivity and the acidification process engineering are studied synthetically on The PuTaoHua oil layer, combining the oil reservoir's geologic feature. The laboratory flow simulation experiments on short and long rock cores are carried out to study the applicability of the acid system optimized on the reservoir, to determine the procedure of fluid injection for site operation. The process parameters are optimized for five treated wells using the model of "Two acidifications, Three minerals". The acidifications are performed on five wells on site and the results are evaluated. The technology of block-relief by acidification for sand stone reservoir is drawn in this project, which put the scientific and reliable laboratory study method with strong operability and the technique of implementation and evaluation on site together.The results of acidifications on the five injecting wells shortfall in injection show: the water injection pressure all are higher than 20 MPa, the pressures of Yong82-60# and Yong90-62# are as high as 22.4MPa. After acidification, the injection rates meet the injection requirements, and the average injection pressure has a decline of 2.84 MPa, the pressure of Yong82-60# lower to 16.6 MPa with a decline of 5.8 MPa. So, all the success ratio and effective rate are 100%. By the end of 9^th 2004, the effective period exceeds 3 months for a single well, the average...