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Â  RESUMO Neste trabalho foram utilizados dados BHT - Bottom Hole Temperature ou temperatura de fundo de poA§o na inversA£o de dados com o objetivo de obter a distribuiA§A£o 1-D do gradiente geotA©rmico. Antes da inversA£o propriamente dita, foi utilizado o mA©todo de correA§A£o de Horner, para determinar a temperatura correta da formaA§A£o. A inversA£o foi realizada em um modelo sintA©tico inspirado em dados reais do Campo de Pineview (Utah, EUA), no caso, com o objetivo de obter gradientes geotA©rmicos de nove formaA§Aµes utilizando dados BHT de 32 poA§os. A matriz Â do problema geotA©rmico contA©m os elementos , ou seja, a espessura da i -A©sima camada perfilada no j -A©simo poA§o. O mA©todo dos mA­nimos quadrados foi utilizado, e devido A  existAancia de ruA­do foi necessAirio o amortecimento. A implementaA§A£o numA©rica da inversA£o, ou seja, a determinaA§A£o do operador inverso Â ou Â foi atravA©s da decomposiA§A£o em valores singulares. As inversAµes iniciais nA£o geraram resultados satisfatA³rios, melhorando bastante com a introduA§A£o do amortecimento. A melhoria dos resultados A© explicada quantitativamente pelo fato do nAomero de condiA§A£o da matriz a ser inversa reduziu bastante com a utilizaA§A£o do amortecimento. Por seu turno, o amortecimento demanda a escolha de um parA¢metro A³timo, sendo que foi utilizada a curva L para esse fim. Â  Palavras-chaves: problemas inversos; gradiente geotA©rmico, bottom hole temperature . Â  ABSTRACT This study consists in obtain the 1-D distribution of the geothermal gradient from the inversion of Bottom Hole Temperature (BHT) data. Before the inversion procedure, Horner correction method was used to determine the correct formation temperature. The inversion was performed in a synthetic model based on real data from Pineview Field (Utah, USA), in this case, to obtain geothermal gradients from nine formations using BHT data from 32 wells. The Â matrix of the geothermal problem contains the elements , i.e., the thickness of the i -th layer logged in the j -th well. The least squares method was used, and, because of the occurrence of noise, damping was required. The numerical implementation of the inversion, i.e., the determination of the inverse operator Â or Â was performed by singular value decomposition. Initial inversions did not produce satisfactory results, but they significantly improved with the introduction of damping. The improvement of the results is quantitatively explained by the fact that the condition number of the matrix to be inverted greatly reduced with the use of the damping. In turn, damping requires the choice of an optimal parameter, and the L-curve was used for this purpose. Keywords: inverse problems; geothermal gradient, bottom hole temperature.

Inversion of Bottom Hole Temperatures for Gradient Determination by the Damped Least Squares Method for Noise Attenuation