EAGE GeoTech 2022 First EAGE Workshop on Reservoir Management of Mature Fields

tight gas reservoir; multilayer co-production; interlayer interference; production characteristics; numerical simulation

A key challenge in management of mature fields is maintaining the economics balance as reservoir conditions change over time. Artificial lift methods is a key component on both sides of the equation as it “lifts both the revenue and cost”. Hence the importance of having a clear understanding of the reservoir dynamics and selecting the AL method that will perform optimally under these conditions. The objective of the work presented here is to apply a novel reservoir modeling technique called Data Physics to optimize production under the existing pump conditions and then get recommendations for pump rightsizing when required.

Filtration of a hydrocarbon gas through an oil-saturated tight core sample is investigated under reservoir conditions. Core sample permeability to the oil phase is 0.004 mD. In situ X-ray scanning is applied as the main method for the oil recovery coefficient determination. The distribution of hydrocarbon gas within the core sample is observed during the entire experiment. The displacement coefficient of reservoir oil by the hydrocarbon gas is found to be 70–75%. The obtained value allows proposing that the chosen hydrocarbon gas is an optimal agent for oil recovery for similar tight oil reservoirs.

This paper describes how Interwell Tracer Tests (IWTT) was utilized in a mature field in North Sea to extract tangible knowledge about flow pattern and swept volume in a water flood process. These are key information required for an informed water flood management and for identifying unswept reservoir areas that can be targeted for IOR/EOR applications.

We first briefly explain the so-called Residence Time Distribution (RTD) concept used to quantify the existence and magnitude of flow paths from injectors to producers in a reservoir. We also explain how the relative fraction of mass produced, in addition to interwell travel times and injection rates give quantitative information on the volumes swept by the traced water and demonstrate how this can be compared to volumes illustrated in reservoir models. By means of simple interpretation of tracer curves we show how this data can then in turn be used to identify targets for e.g., improved oil recovery in mature fields, such as the ones located in the North Sea.

The use of 3D printing provides high flexibility in the production of images of rocks of various pore space structures. A 3D-model can be made in a CAD software or created from data collected with a 3D-scanner. 3DP has great promise in the field of laboratory study of oil and gas flow, EOR, as well as petrographic characterization of rocks. 3DP-models are an ideal material for verification of fundamental analytical and numerical models of oil and gas flow in laboratory studies. Dependences of rock permeability on effective pressure with use of 3DP-models is another promising area of research. The studies on creating the 3DP-models for flow laboratory experiments are being performed.

In a mature basin, a significant challenge of managing fields in late life is locating and unlocking the bypassed oil pockets. This work describes a novel digital workflow integrating 4D seismic data to identify and quantify bypassed oil targets. The workflow leverages an innovative hybrid physics-guided data-driven, constrained by 4D time-lapse data, generating historical phase saturation maps, forecasting future fluid movements, and locating infill opportunities. This new workflow was applied to a giant mature oil field located in the North Sea. Twenty-four different static and dynamic realizations were defined to capture a wide range of uncertainties. A range of movable oil in place maps (P10/ P50/ P90) was calculated in full compliance with the 4D interpreted saturation distribution uncertainties. This process allowed to generate alternative infill targets to that originating from the traditional ‘4D attic’ deterministic maps. A total of 12 infill targets were generated, with their probabilistic production forecast. It has been proved that the new workflow can unlock the remaining potential of mature fields in a shorter time frame and generally very cost-effectively compared to the advanced dynamic reservoir modelling and history-match workflows.