A computer-implemented method for updating a geological model of a hydrocarbon reservoir using observed data of the hydrocarbon reservoir to perform history matching using an objective function constructed using a Bayesian formulation, the method comprising: a) computing new geological realizations for a prior geological model of the hydrocarbon reservoir using a computer processor; b) computing an exact likelihood of the objective function using the new geological realizations for the prior geological model by performing a forward simulation, streamline tracing and calculation of derivatives to obtain a model response, a data-misfit and an array of data sensitivity coefficients which are used to determine the exact likelihood of the objective function; c) defining an initial state for a sequential Monte Carlo chain based on the exact likelihood of objective function; d) defining a new sample based on the initial state for a sequential Monte Carlo chain and a random sample from the prior geological model; e) computing an approximate likelihood of the objective function by using the new sample and the data sensitivity coefficients to calculate a change in forward model response; f) repeating step d), based only on another random sample from the prior geological model, and step e) until the approximate likelihood of the objective function meets an acceptance criteria; g) computing another exact likelihood of the objective function using the new sample if the new sample meets the acceptance criteria; h) repeating step d), based only on another random sample from the prior geological model, and steps e) through g) until the another exact likelihood of objective function meets another acceptance criteria; i) repeating step d), based only on another random sample from the prior geological model, and steps e) through h) until a convergence criteria is met; j) storing each new sample that meets the acceptance criteria and the another acceptance criteria, each new sample representing a respective updated posterior geological model for the prior geological model; and k) forwarding the updated posterior geological models to an operating unit for inclusion in closed-loop-reservoir-management workflows or execution of well-placement optimization campaigns. a) computing new geological realizations for a prior geological model of the hydrocarbon reservoir using a computer processor; b) computing an exact likelihood of the objective function using the new geological realizations for the prior geological model by performing a forward simulation, streamline tracing and calculation of derivatives to obtain a model response, a data-misfit and an array of data sensitivity coefficients which are used to determine the exact likelihood of the objective function; c) defining an initial state for a sequential Monte Carlo chain based on the exact likelihood of objective function; d) defining a new sample based on the initial state for a sequential Monte Carlo chain and a random sample from the prior geological model; e) computing an approximate likelihood of the objective function by using the new sample and the data sensitivity coefficients to calculate a change in forward model response; f) repeating step d), based only on another random sample from the prior geological model, and step e) until the approximate likelihood of the objective function meets an acceptance criteria; g) computing another exact likelihood of the objective function using the new sample if the new sample meets the acceptance criteria; h) repeating step d), based only on another random sample from the prior geological model, and steps e) through g) until the another exact likelihood of objective function meets another acceptance criteria; i) repeating step d), based only on another random sample from the prior geological model, and steps e) through h) until a convergence criteria is met; j) storing each new sample that meets the acceptance criteria and the another acceptance criteria, each new sample representing a respective updated posterior geological model for the prior geological model; and k) forwarding the updated posterior geological models to an operating unit for inclusion in closed-loop-reservoir-management workflows or execution of well-placement optimization campaigns.