A new method is proposed to estimate the matrix and fracture’s effective compressibilities by using the material balance equation (MBE) and production data. Assuming the behavior of naturally fractured reservoir (NFR), accordingly to the pressure tests analysis, it is then possible to replace the effective compressibilities into a MBE of double porosity to determine original oil from both systems. Due to the lack of information from cores and the problem that implies acquiring it, this method represents a useful alternative for analytical models. Generally, it is complicated to determine representative values of fracture compressibilities for the entire reservoir; especially when this is very heterogeneous. The calculated compressibility of the matrix and fractures can be compared with formation compressibility correlations when there are no core analysis or pressure tests available. This is an innovative method to obtain reliable compressibilities for the analysis of material balance of double porosity (MBDP). In addition, with this method it is also possible to obtain the original ratio of the volume stored in the fractures to the total volume in the reservoir; which is a crucial factor in the determination of the final oil recovery.

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Production records provide important information about volumes and contribution areas in oil wells. Over time, the records are also a great contribution to monitoring of oil water contacts. In adition, with these records it is possible to test production pressure without surface wellhead’s measurements. This new approach to obtain such information results from the need to determine the source of water in sime carbonate fields with channeling and / or coning problems, as well as to decide an optimum choke in the operation of the well. For this reason we have implemented a new way of obtaining production records that allows us to maximize the use of data by analysis of applied engineering.

Fractured systems are paramount to the productivity of carbonated formations; this is the main reason why the on-time appraisal of fractures behavior in High Pressure-High Temperature (HP-HT) Naturally Fractured Reservoirs (NFR) is decisive for the optimum selection of the exploitation strategy of the field. Considering the classifications for NFR proposed by R. Nelson and R. Aguilera, it is prone to apply the dual-porosity material balance to know the fractured network performance in different types of NFR during its exploitation, and to match the production history based on the discretization of the acting drive indices and its impact on the fractured system, resulting in one recovery factor for the matrix, and another for fractures. Several HP-HT Naturally Fractured Reservoirs (NFR) were analyzed and the material balance models were adjusted to the values of compressibility obtained from real saturation data observed in cores and petrophysical evaluations based on rock quality, rock typing and computed through correlations in order to obtain the performance of the fractured system, indicating the corresponding contribution of both to the total reservoir production; therefore it is possible to calculate a single recovery factor for fractures and other for the matrix only, and consequently, determine the type of NFR whose behavior is representative of the pressure-production history matching, agreeing with the numerical simulation model. Moreover, Pressure Transient Analysis (PTA) was considered as a good source of information to determine some critical data that are useful for the calibration of dual-porosity material balance models and the resultant description of fracture behavior for the optimum characterization of NFR, despite of the fact that well tests are not always available for every single well and the adverse wellbore effects involved that could cause interpretation problems. Additionally, it was possible to determine the matrix block size with applied material balance and well testing, achieving a better understanding of NFR. In this paper we present some cases of study of NFR hydrocarbon producers from Mesozoic age in the Southeast of Mexico with the applied methodology in order to reevaluate them, achieving important conclusions with the results obtained.

The objective of this work is to generate a selection matrix that contributes to the decision making, contemplating all the necessary technical criteria to ensure that the information gathering is adequate and the Pressure Transient Analysis (PTA) could be advantageous for the reservoir characterization and the determination of well productivity parameters. For this scrutiny we analyzed more than 500 well tests from 100 fields in Mexico and other parts of the world, onshore and offshore, carbonates and terrigenous, and different types of fluids (black oil – extra heavy, heavy, intermediate and light, volatile oil, retrograde gas and condensates, wet gas and dry gas), from which all the pressure responses obtained were compared in order to identify every associated problem and the causes that originated them from the design, execution and finally, during the interpretation of the PTA. The importance of this work lies in improving the PTA through the allocation of different numerical values for each of the controlling factors involved at reservoir, well and at surface level, depending on its own impact on the results, so we classify them in Well Evaluation Conditions (WEC) and Reservoir Evaluation Conditions (REC).