Field experiences

The study of the future production profile and the evaluation of the project risk related to the production facilities

An example of sensitivity analysis (Reserves, A gas field)


The target reservoirs, “A” and “B”, in this project are located in the offshore area of Australia, and only B has a production history.
◆Review of the geological model
Reviewing the geological model and its related documents, we summarized the field characteristics. The geological model includes facies model based on the Sequential Indicator Simulation (SIS), porosity and permeability models based on the Sequential Gaussian Simulation (SGS). The model is not limited to the base model but also Low Case model and High Case model with respect to the reserves. JOE checked the integrity between the geological model and the reserves documented in the Final Field Development Plan (FFDP).
◆Study of the future production profile
To perform the study of the future production profile, the reservoir simulation model was constructed based on the geological model.
Condensate production from the A gas field was estimated from the CGR-pressure relationship, and water and dry gas flow simulation was performed. Future production profile of gas and condensate was calculated and the properness of the sales plan of gas was evaluated by the simulation. The uncertainty of the production was also evaluated through the sensitivity analysis of the recoverable reserves. The reservoir structure and the facies of the rock were revealed to have the greatest impact to the reserves, and we concluded that these properties should be estimated with a high accuracy.
Flow simulation for B gas field was performed for each hydrocarbon components. Condensate, LPG rate produced from the production wells were calculated based on the plant table (a table of distribution fractions which determine the amounts and compositions of fluid). After reproducing a production history of condensate through history matching simulation, LPG and water, future production performance was predicted. As a result, sales gas, condensate LPG volumes calculated by the simulation are not exactly equal to the operator-predicted volumes but show the same trend. This suggests that the prediction by the operator is reasonable.
◆Evaluation of the project risk
JOE evaluated the technical risk related to the offshore production facilities, the undersea pipelines and the onshore processing facilities because A gas field is at the stage of no production history. Namely, JOE reviewed the design of the surface facilities, the risk in the construction project schedule and the cost of the construction project, and extracted the possible problems and the risk in the project.
Because B Gas field has a long production history, the project risk is in the items related to the field operation. Relationship between the future production volume and the capacity of the facilities, the designed lifetime of the equipment, and the operation cost were investigated.

This project highlights features of our company that we can provide comprehensive services from subsurface to surface. In this workflow, our knowledge and experience in various technical sections are closely tied with each other, therefore all services achieved higher quality.

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