A Study Of Acid-Rock Reaction Dynamic Mechanism And Deep-Penetration And Low-Damage Acidizing Fluid In Penglai 19-3 Oilfield

With the oil and gas resources developing to the deep and low efficient reservoirs, the study on the acidizing and the acid fracturing technology of the deep penetration and low damage characteristics will become more and more important. "The deep-penetration and low-damage acidizing fluid" has a series of advantages, e.g., the slow acid etching rate, the large acid etching depth, and the apparent reservoir reconstruction effect and so on. The basic of launching deep acidizing and acid fracturing are testing the kinetic parameters of acid rocks and researching acid etching mechanism. Through in-depth analysis of Penglai 19-3 oil field pollution and damage mechanism, this paper will determine formula of the deep-penetration and low-damage acidizing fluid system adapting to the reservoirs, carry out acid etching experiments for reservoir cores through a novel device, and analyze the acid etching rate, strength and deep penetration performance and other dynamic laws. It will also combine with the microscopic scanning system to perform quantitative analysis to the rock surface morphology characterization of the corrosion process and after corrosion, find the acid properties'influence on the kinetic parameters of acid rocks and corresponding laws. The main research contents of the dissertation are:(1) To study the mechanism of plugging reservoir after repeated acidizing the characteristics of selected reservoir, the geological characteristics of reservoir rock composition, and fracture distribution and filling condition, etc. Moreover, it will also test the conventional properties of natural cores, obtain the basic data of pore structure and pore permeability of the reservoir, and analyze the damage factors of reservoir caused by the acid after repeated acidizing. This paper will study on the damage mechanism of acid sludge and the influence factors, analyze the damage mechanism of reservoir on the different injected water and different injection intensity,and provide a theoretical basis for the development of the deep-penetration and low-damage acidizing fluid.(2) To test and analyze the acid-rock reaction dynamics parameters, the flow characteristics of the deep-penetration and low-damage acidizing fluid in the formation pore and fracture, the effect of the flow pattern and the flow rate of acid on the test of acid-rock reaction parameters dynamics. This paper will build a comprehensive basic theory adapt to the dynamics parameters test of acid-rock reaction of the deep-penetration and low-damage acidizing fluid.(3) To develop the deep-penetration and low-damage acidizing fluid, and to determine the mechanism of acid-rock reaction through core simulation experiment. For this, we will focus on the synthesis of the deep-penetration and low-damage acidizing fluid, the screening and preparation of acidizing fluid additives, determination of the acidizing fluid system and study on the mechanism of acid-rock reaction. Besides, the paper will study on the deep penetration and low damage characteristics with the long and short core acidification process flow, simulate the reaction behavior of deep-penetration and low-damage acidizing fluid in the near wellbore area with the long sand-filling tubes, its microstructure will be observed by scanning electron microscope, determine the deep penetration performance and influencing factors of the deep penetration and low-damage water shutoff agent. This paper will compare the differences in core section microstructure images of the deep-penetration and low:damage acidizing fluid and conventional acidizing fluid after entering the core, explore the low-damage micro mechanism of the acidizing fluid acid-rock reaction.(4) To study on the influences of acid properties on the kinetic parameters of acid rocks and corresponding laws, to analyze the changes of acid properties on the kinetic parameters of acid rocks, to study on the influence of various factors (e.g., temperature, viscosity, flow velocity) on the kinetic parameters of acid rocks, to explain the laws of the acid properties affecting the rate change of acid-rock reaction. This paper will test the kinetic parameters of acid rocks in different conditions, build a comprehensive mathematical model of new type dynamics of acid-rock reaction applicable to the deep-penetration and low-damage acidizing fluid, determine the mechanism of dynamics of the deep-penetration and low-damage acidizing fluid reaction. And this research has an important meaning to select the field application of the deep-penetration and low-damage acidizing fluid.The research will fill the gaps in failing to meet acidification test after repeated acidizing of traditional methods, it has an important meaning to prefer the deep-penetration and low-damage acidizing fluid, to analyze the acidizing mechanism, to create repetitive acidification and predict the productivity.