摘要:
2006年TheLeadingEdge第一期详细介绍了磁力梯度张量的理论、仪器与野外试验结果,磁力梯度张量技术已成为磁力勘探新的热点之一。笔者介绍了磁力梯度张量的概念及优点;利用频率域与空间域方法把井中三分量磁测资料换算磁力梯度张量;根据联合反演原理与欧拉反褶积方法,推导了磁力梯度张量的联合反演方程,该方程通过权函数矩阵可以灵活对一个或多个分量反演,比文献[14]方法更具普遍性。理论模型结果表明,磁力梯度张量反演方法对井底异常的定位准确,对于3D模型,一口钻井的资料也能较好确定空间位置。将该方法用于湖北大冶铁矿18-2井三分量磁测资料的解释,得出磁力梯度张量的欧拉解集中在100~180m与500~550m两个深度,与钻探结果十分吻合。该结果证实了地质上关于铁矿体分布具两个台阶的推论,对大冶铁矿的深部找矿具有实际意义。
Abstract:
SincethepaperpublishedinTheLeadingEdge(No.1issueof2006)describedindetailthetheory,equipmentsandout-doortestresultsofmagneticgradienttensor,thistechnologyhasbecomeoneofthehottopicsofmagneticprospectingmethods.This paperdescribestheconceptsandadvantagesofthemagneticgradienttensor.Bothfrequencyandspatialdomainmethodsareusedto transferboreholethree-componentmagneticdatatomagneticgradienttensor.AccordingtothejointinversionprincipleandEulerde-convolution,thejointinversionequationsformagneticgradienttensorarededuced,whichenableustoflexiblyinverseoneormore componentsbasedonaweightedfunctionmatrix,andthetechnologyismorecommonthanthemethodmentionedinReference[14]. Thesimulatedresultsofsyntheticmodelsrevealthatthemagneticgradienttensorinversionmethodcanbeaccuratelyemployedtolocate themagneticbodyaccordingtoboreholebottomanomalies.Concerning3Dmodels,onlyoneboreholemagneticdatacancalculatethe locationsaccurately.Moreover,themethodwasappliedtointerpretingthethree-componentmagneticdataofNo.18-2drillinDayeiron miningarea,Hubeiprovince,andtheresultsindicatethatthedeconvolutionsolutionsofmagneticgradienttensorareconcentratedon the100to180mand500to550melevationsthatareinaccordancewiththedrillingresults.Theresultconfirmsthegeologicalinfer-encethattherearetwostepsofironorebodies,whichhaspracticalsignificanceinsearchfororebodiesatdeeperlocationsinDayeiron miningarea.
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