Study On Optimization Of Steam Huff-puff Thermal Efficiency Improvement Technology For Horizontal Wells

Heavy oil reservoirs are widely distributed and abundant in the world,and their reserves account for more than 70% of the world’s total oil reserves.Efficient development of heavy oil has very urgent practical significance for solving the contradiction between energy supply and demand.Compared with vertical wells,horizontal wells have a large drainage area,which is an effective technology to increase the single well production of heavy oil reservoirs.However,during the steam injection development process of heavy oil reservoirs,due to the length of the horizontal section and the heterogeneity of the reservoir,etc.Due to the influence of factors,the steam enters the horizontal well section and the local burst phenomenon occurs,and the reservoir production is seriously uneven.After multiple rounds of huff and puff,the newly injected steam is repeatedly heated and cleaned in the formed large pores,forming steam channeling or forming drainage With the extension of the period,the radius of impact will no longer be enlarged,the effect of steam huff and puff is greatly reduced,and the improvement of steam thermal efficiency is an urgent problem in the development of heavy oil thermal recovery.This paper first simulates the heterogeneous reservoir through the double-pipe parallel experiment,studies the influence of the heterogeneity of the reservoir on the steam absorption profile,and obtains the temperature change law of the heterogeneous reservoir,and then carries out the parallel core gel plugging control and In the experiment of foam regulating and blocking steam channeling,the regulation law of gel and foam on temperature profile and split flow was obtained.Combined with the geological parameters of the oilfield,a numerical simulation study of multi-round steam stimulation thermal field regulation under formation conditions was carried out,and the effects of gel and foam on the thermal field regulation of the reservoir were analyzed,and then the horizontal well section after multiple rounds of stimulation was studied.The law of uneven steam absorption and the adjustment method of horizontal well steam injection screen.The research results show that as the permeability difference increases,the heat transfer distance of steam in the low-permeability core is gradually shortened.When the permeability difference increases to 5.39,the entire section of the low-permeability core cannot absorb steam and heat up;gel plugging and steam flooding experiment Under the medium and low injection rate,the gel is severely washed by steam,and the high injection rate is easy to block the formation.Under the experimental conditions,0.3 PV shows the best plugging ability;the parallel core plugging test results show that the heterogeneous layer is resistant to temperature condensation The main function of the glue is to block the seepage channel of steam in the high-permeability layer and make the steam enter the low-permeability core.The main function of the foam is to promote uniform steam absorption in the high-and low-permeability core and adjust the steam absorption profile.Numerical simulation results show that the effective period of gel plugging is short,and the subsequent steam injection with foam can prolong the effective period of gel,adjust the temperature field,and improve uneven reservoir production.Under the combined action of gel plugging and foam profile control,steam thermal efficiency An increase of 13.43%.For steam injection in horizontal wells,this paper proposes the concept of temperature variation coefficient of horizontal well sections to evaluate the degree of uneven steam absorption in steam huff and puff wells,and compares the influence of adjusting the position of steam injection screens at different stages on steam huff and puff.When the temperature variation coefficient reaches its minimum value,It means that the high-permeability section has a higher specific heat capacity,the water saturation of this section is large,and the high-permeability section has been effectively used.At this time,the position of the steam injection screen should be adjusted to the low-permeability section,and the steam thermal efficiency can be increased by 24%.