三角函数热流模型与EASY%Ro法结合恢复古地温梯度史

EASY%Ro法是一种能与现今Ro垂向分布达到最佳匹配的古地温梯度的反演热史分析法,涉及到重要环节是约束条件的最优化计算。计算发现,EASY%Ro得到的地温梯度史有一定的不确定性；这种不确定性发生在反演地质时间段的早期。根据三角函数古热流模型简化而来的三角函数古地温梯度模型,将该模型用于EASY%Ro法求解古地温的约束条件中,使求得的古地温梯度称为—连续函数,可以更好的反映地温梯度在地史上的连续起伏变化,克服了以往单独用EASY%Ro求解古地温梯度时多解性问题或不确定性,具有唯一性,有效避免多解性,得到的古地温梯度为连续可导函数,更符合古地温在地史的变化特征。经在松辽盆地王府断陷使用得出王府断陷地温梯度史大致分成3个阶段,断陷期(火石岭组~营城组)的由高地温梯度到低地温梯度的下降阶段；拗转换期至坳陷期(登娄库组至嫩江组的)的地温梯度缓慢上升阶段；反转期的稳定地温梯度阶段。

Trigonometric functions and EASY % Ro method combined with heat flux model to restore the ancient history of geothermal gradient- to wangfu sag of songliao basin city deep 1 well as an example

EASY%Ro is a kind of inversion thermal history analysis method that can find the paleogeothermal gradient matching the present Ro vertical distribution best. An important part of the involved is the optimization calculation of oonstraint condition. Calculation, found that EASY % Ro which get history of geothermal gradient has certain uncertainty; The uncertainty happens in the early inversion of geological time.Trigonometric function paleogeothermal gradient model is based on a simplified trigonometric function palaeo-heat flow model. When this model is used in the constraint condition of the palaeogeothermal solving by EASY%Ro, the paleogeothermal gradient obtained can be a continuous function. And the result can reflect the change continuous rolling of geothermal gradient in the geologic history better This method solves the problem of multiple solution and uncertainty by the progress of EASY%Ro solving paleogeothermal gradient. And this method has been used in Wangfu sag of Songliao basin and good results are obtained.Through the application in Wangfu sag of Songliao basin, it is got that history of geothermal gradient of Wangfu sag can be divided into three stages: The decline stage that the geothermal gradient falling from high to low in the fault depression period (Huoshiling group ~ Yingcheng group), the slowly rising stage of geothermal gradient from Distinctive quality fist to depression period (Denglouku group to Nenjiang group) and the stable stage of geothermal gradient in reverse epoch.