Research On The Prediction Method Of Inflow Performance For Low Permeability Reservoirs

With the increasing proportion of low permeability reservoirs in the new proved reserves, it has become the main type of future reserve replacement, and how to produce these reserves effectively becomes more important. The seepage characteristics of low permeability reservoirs are much different from mid high permeability, such as the existence of starting pressure gradient, deviation from the Darcy's law, etc, the conventional inflow performance relationship is no longer applicable.By analyzing seepage characteristics, single-phase inflow performance relationship is improved with a new non-linear flow model. The relationship between mobility function (kro/μoBo) and reservoir pressure is established by numerical simulator. Effects of average reservoir pressure, bottomhole pressure, skin factor, pressure-sensitive factor are investigated. Combined with pressure-sensitive effect, mobility function is extended, a new equation which can reflect the impact of bottomhole pressure is established through the fitting method. The inflection point of inflow performance relationship curves are found in the current low permeability reservoir production, the main causes of the inflection point are investigated. Then according to the nonlinear seepage law, two-and three-phase inflow performance relationships for low permeability reservoir are established with the new mobility function, considering starting pressure gradient and pressure-sensitivity. simulator results are used to investigate the validation of the analytical relationships, on this basis, the future inflow performance relationship is given. Application results show that the accuracy of new IPR equation meet the engineering needs.