Well productivity and injectivity

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Well productivity and injectivity

The area of a reservoir in the immediate vicinity of a well is subject to complex phenomena which can significantly reduce a well’s productivity or injectivity. These phenomena include the formation of emulsions during drilling, the penetration of solids into rock pores, the precipitation or flocculation of chemical species and the ingress of water.

Tackling these phenomena is essential to improve oil recovery rates. Now that they have been identified, the process of understanding them is underway. IFP is working to construct a model of the reservoir area which surrounds a well and linking it to:

a reservoir simulator,
a simulator which tracks the flow of fluids in wells and production networks.

Research areas

IFP is developing solutions to tackle the various phenomena which negatively impact a well’s productivity and injectivity.

Treating production water

On average, the production of one volume of oil results in the production of five volumes of water. In mature zones, the ratio of oil to water can be as high as one to twelve. Production water contains a variety of pollutants, such as solute oil, emulsified oil and solid particles. To satisfy increasingly stringent environmental standards, this water needs to undergo expensive treatment processes before it can be disposed of at sea.

As a result, an increasing number of water management programmes are based on the reinjection of this water. This solution reduces production costs without having a negative impact on the environment. Nevertheless, it can result in considerable losses in injectivity.

IFP is developing physical models to track injectivity behaviour in well surrounds.

Quantifying the volume of sand produced by a well

The term “ingress of sand” describes both:

massive changes in unconsolidated formations, such as the formation of wormholes in heavy crude fields,
the production of fines as a result of erosion in consolidated formations. This is liable to give rise to deconsolidation at a later date.

IFP is evaluating the quantity of sand produced by a well on the basis of reservoir rocks and production conditions. The aim is to refine the parameters of systems which warn of sand ingress. In the long term, IFP’s teams aim to find ways to prevent the ingress of sand, a development which would substantially reduce investments.

Modelling damage to reservoirs

Many gas reservoirs are only slightly permeable and can only be exploited with hydraulic fracturing techniques. The damage that these operations cause to the matrix and the fracture network is poorly understood. IFP is, therefore, conducting laboratory tests on rock samples to quantify and model the extent of this damage.

Reservoirs can also be damaged by the precipitation or flocculation of different chemical species. IFP has acquired an excellent understanding of the different physicochemical phenomena responsible for this damage. The challenge is to integrate this knowledge into a well model which would allow:

a reservoir engineer to identify the best development approach,
the producer to set the well development parameters so as to remain outside risk zones or to implement a repair programme.

Projects with industrial partners

Total

IFP is working with Total to improve forecasts of the quantity of sand which a well will produce. This research takes account of the operating conditions at the site as well as any specific constraints and pressures.

SEPPIC & LIPESA

Stargel is a line of microgels developed in partnership with SEPPIC, a chemical company. These products are dedicated to water shut off, sand control and conformance control applications with excellent tolerance to high temperature, salinity and environmental constraints. The technology has been validated through the Stargel JIP sponsored by GDF, NEXEN, STATOIL-HYDRO and TOTAL and is currently marketed by LIPESA.