35 Acidizing Technology. Cattle Research And Applications

Sandstone matrix acidizng is an important measure for reservoir stimulation. It is widely used in oil-produced countries. Aimed at the typical characteristics of low permeability reservoir, such as small pore throat, the high content of clay, the growth of minute pore etc, via a great deal of theoretical and indoor experimental study, this paper formed an practical technology for oilfield sandstone acidizing.(1) Collected the Niu-35 reservoir data, made use of scanning electron microscope to analyze the characteristics of reservoir clay mineral distribution, and developed the research of the velocity sensitivity, water sensitivity, alcali sensitivity, salt sensitivity and core flow experiment of mud acid sensitivity. All those provided a basis for the analysis of reservoir harm mechnism and the design of reservoir sensitivity experiment.(2) Analyzed the reservoir acidizng mechnism and expounded the improvement degree of the potential of the damaged-well and non damaged-well in Niu-35 block.(3) Took experiments as the foundation, appraised acidizing effect of the commodity acid such as borofluorhydric acid, low-damaging acid, organic acid, condensed acid etc, and hydrochloric acid (low concentration and high concentration ), mud acid (low concentration, and high concentration ) on the natural core in Niu-35 block. Studied the effect of acidizng treatment on the rock mineral compositions and the pore structure of the natural core via scanning electron microscope.(4) Aimed at the reservoir characteristics of Niu-35 block, based on many experiments, optimized acid additive such as theFe2+stabilizing agent, mutually soluble cleanup additive, clay stabilizing agent etc, and optimized the suitable acid compounding.(5) Took into account the wellbore temperature, reservoir temperature (included the acid-rock reaction heat), acid concentration distribution, reservoir porosity-permeability and the forecast of acidizng effect, developed a set of sandstone matrix acidizing simulating model which is comparatively self-contained. It can be used to simulate the sandstone acidizing and optimize the design of treatment parameter.(6) Aimed at the characteristics of Niu-35 block, such as too many series of strata, large permeability difference between layers, and large difference between injecting rates of layers , built the acidizing-shunt model for small layers.(7) Analyzed various means of flowback, put forward the measure of chemical aid-cleanup combined with injecting liquid-state carbon dioxide which is fit for Niu-35 block.(8) The field applications of the research achievement in Niu-35 block indicates, acidizng treatment can produce high output of single well Jong period of validity, notable economic profit and society benefit. It fully proved the acidizing technology researched in the paper is successful and reliable and formed a set of relevant acidizing technology for oilfields.