Research Of Acid Fracturing Temperature Field Model With Considering Acid-rock Reaction Heat

Acid fracturing as the stimulation of measures to build capacity after several years of development has been applicated widespread in domestic and foreign oilfield. The development got through a process of single process, single-fluid system to a multi-stage process, composite liquid system. In the stimulation process to III dense reservoir such as Jingbian gas field, the cross-linked acid sand carrying acid fracturing technology had shown a good applicability, and then made a challenge to the therotical model. People did a lot of research on reaction mechanism of acid rock and acid fracturing design mathematical model in domestic and abroad, the main idea is to increase consideration, refining assumptions, seeking a more simple solution and so on. The development got through a two-dimensional, quasi three-dimensional, full three-dimensional crack propagation simulation, single-phase, two-phase, mixed phase complex, non-steady state to steady state, continuous medium heat to the process of heat transfer in porous media.It's found a relatively small exothermic reaction into account in acid fracturing temperature field model, the software associated with is relative lack and cause the considerable error in acid fracturing design. However, the flow of cross-linking and rheological properties of acid in shear and the effect of temperature will have significant adverse effects, cross-linked acid formulation (cross-linking agent, breaker concentration) set by breaker and reasonable return time, invariably depends on the ambient temperature. The actual simulation can be seen through the reaction heat for the temperature field has great influence, in turn affect the etching effective distance, and ultimately affect the stimulation effect.This paper analyzes the cross-linked acid sand carrying acid fracturing process in Jingbian gas field, and the shortcomings of the process and the potential of point while affirming its value. Take a further laboratory studies to the acid system, screen the paid agent composition and the amount, analyzes the effects of amount of crosslinking agent to the acid crosslinking time and viscosity and the temperature to the time of cross-linking. Determine acid - kinetic equation of rock at 60℃, acid - activation energy and the acid rock reaction of hydrogen ion effective mass transfer coefficient De using SARⅢacid rock disc reactor.In the base of previous model, add the acid rock reaction releasing heat to the fracture surface energy equation, discrete and give the coupled solution combined with the continuity equation, energy equation of fluid cracking. Take a calculation and simulation to one well in Jingbian using the experiment to obtain the cross-linked Acid Rock Kinetic Parameters and cross-linked acid Jingbian field acid fracturing sand carrying construction parameters, simulation results show that the convergence of the model, reasonable and consistent with the actual situation. After considering the reaction heat, the temperature change still affect the distance of acid.This paper build three-dimensional gap of the effective distance calculation model compound with three-dimensional velocity field model of acid, and gives the lumping method. In according of the simulation to a gas well data in Jingbian field, show the model can simulate and calculate the actual distance accurately, and it's suitable for further study and application. In base of the model build, and then analysis the effect of construction emission, liquid temperature, the quatitive of surrounding rock, the original temperature gradient, porosity, casing diameter and other factors to shaft and fracture temperature field distribution in a specific time step,and then give some suggestions to the construction according to the simulation results.