Experimental Study Of Biological Enzyme Guargum Fracturing Fluid System

The biological enzyme fracturing fluid is clean fracturing fluid system developed for lack of conventional fracturing fluid.In this paper, the basic characteristics of the DB and ZL reservoir have been combined in order to analyse the damage factors of the two reservoirs.And evaluate existing fracturing fluid system to identify the existing problems of the existing system.Then according to the problem of DB and ZL reservoir, optimize the existing formula of fracturing fluid system. Failly we have studied the gel breaking mechanism and influencing factors of Nzy-1,development theguar gum fracturing fluid system of biological enzyme for DB and ZL reservoir, and study the extent of the impact of the biological enzyme to to remove filter cakea and its influencing factors. Through research the following key understandings are obtained in this paper:(1) DB reservoir rock is mainly composed of feldspar sandstone、 Lithic feldspar sandstone、feldspathic lithic sandstone; DB reservoir rock is mainly composed of Lithic feldspar sandstone and feldspar sandstone, and two reservoirs belonging to the low porosity and low permeability oil and gas reservoir.(2) DB formation damage factors in order as the water-sensitive, water lock solid-phase intrusion, acid sensitivity, stress sensitivity, alkali sensitivity, speed-sensitive ZL reservoir damage factors in order as the water-sensitive, water lock, solid-phase intrusion, acid sensitivity, stress sensitive to alkali sensitivity, speed-sensitive.(3) DB reservoir optimization six sets of formulain the original formula, and ZL reservoir optimization six sets of formula. Gel breaking time, heat and shearing resistance, debris and some other performance has improved, fracturing fluid gel breaking liquid core damage to reduce by26.7%-36.5%.(4) The effect of fracturing fluid additives on the biological activity is small, biological enzyme optimal activity temperature is45-65℃, the optimal pH range of7to7.5.(5) Optimized11sets of bio-enzyme formula on the basis of the optimized formulation in DB reservoir, and ZL reservoir optimized six sets of bio-enzyme formula. Gel breaking time, heat and shearing resistance, debris and some other performance has substantially improved, fracturing fluid gel breaking liquid core damage to reduce by26.7%-36.5%.(6) Through the filter cake damage experiment shows that, within the range of4565℃, the activity of biological is the highest, the damage of formation is small, so the biological enzymatic is apply to the fracturing process of Low-Medium temperature in DB reservoir and ZL reservoir...