This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 22110, “Digitally Transformative U-WISE Software Technology,” by Nasser M. Al-Hajri, Syed Gilani, and Mohammed Saloojee, SPE, Saudi Aramco, et al. The paper has not been peer reviewed. Copyright 2022 International Petroleum Technology Conference. Reproduced by permission.


In the complete paper, the authors introduce a model that provides risk-based financial optimization for surveillance programs. The model balances risk with financial investment to provide the asset owner with several optimization scenarios (at low risk and low investment) and ensures that surveys are not overdone. The example used to explain the model is one involving well-integrity surveillance. This example allows the oil operator to obtain a return on past investment made into collecting historical well-integrity data.

Well-Integrity Surveys

Several different kinds of well-integrity surveys are common in the industry, including the following:

- Wellhead-integrity surveys use pressure to investigate the functionality and pressure-sealing integrity of the wellhead tree valves. The primary criterion of a successful wellhead-integrity test is that the valves are able to contain the well pressure without passing pressure outside the well to the surface flowline or the atmosphere.

- Surface- and subsurface-safety-valve surveys are another critical test. The primary criterion of a successful surface- or subsurface-safety-valve test is that the valve functions properly by sealing the well pressure when activated.

- Landing-base inspection is conducted by electronics that measure the metal loss of the landing base that seats the wellhead tree valves. The primary criterion of a successful landing-base inspection is for the landing base to have an acceptable metal loss without allowing fluid leaks from inside the well.

- Annuli surveys are conducted using pressure to investigate the integrity of the cement-filled spaces between each downhole pipe. The primary criteria of a successful annuli survey are that no pressure is measured between the pipes and that no fluid is leaking through the cement from a downhole reservoir to surface.

- Corrosion surveys measure the downhole pipes’ remaining metal loss. The primary criterion of a successful corrosion log is to record metal loss for downhole pipes lower than a minimum thickness determined by the well owner as being safe for operations.

- Temperature surveys measure the downhole temperature profile and identify possible downhole pipe leaks. Typical downhole temperature profiles are geothermal trends that increase with depth. The temperature surveys not following a typical downhole temperature-gradient profile are flagged as anomalous and are investigated further. The primary criterion of a successful temperature survey is to obtain a downhole temperature recording that conforms to the base temperature-gradient profile without significant increase or decrease of temperature readings.

In the complete paper, the authors provide a method of optimization for survey frequency. The temperature survey is used to explain the model work flow.

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