Three significant areas of advance in horizontal well technology are in drilling, production and reservoir characterization. Both reservoir engineer and geologists are interested in reservoir description for better well placement and flow simulation. It is only through the co-operation of the earth scientists that includes the geologist, geophysicist, petrophysicist, geostatisticians, reservoir simulation engineers, drilling and production engineers etc. that optimized results can be achieved. The current challenge is development of models that propel forward the oil and gas technology by reducing, if not eliminating, the time it takes to react to new inforrilation. Also important is the advance in non-linear geostatistics that allows for risk assessment in horizontal well planning.

Why Characterize Reservoirs?

Advanced 3D reservoir modelling translates directly into better placements of vertical and horizontal wells. Other benefits of the reservoir characterization are risk reduction, revenue enhancement and better recoveries of the in-place volume. These can be categorized as pre-drill field studies. While-drilling characterization has all the advantages the pre-drill process provides, in addition to cost savings associated with potential reduction of drilling time. Real time reaction to the (ultimately variable) reservoirs has the opportunity to reduce risk and take advantage of additional data.

Geologists are most familiar with the concept of variability at every scale of detail. In fact, very few geologists will take a picture of a core or outcrop without a scale such as a hammer or a person because it is nearly impossible to tell the size of the features otherwise. While the complex strata that we see in the form of vertical and horizontal logs, outcrops, cores, seismic x-sections etc., reveal a seemingly chaotic pattern, it can be mathematically shown that within distinct facies the characteristics of data has power law characteristics, otherwise known as fractal properties. Since most current interpolation methods such as kriging are linear and tend to average the results, we tend to lose the variability that is inherent with the data. The measured variability in fractal interpolation is added back into the model and that is why the characteristic of the fractal interpolation is better characterization of flow through solute transport, resulting in smoother history matching.

Just as geological interpretations vary for each geologist or geophysicist, new technologies need to honour their interpretation and not to run wild to merely develop a 3D interpretation.

Several processes are responsible for the intense interest and advances in 3D or 4D technologies. These include advances and understandings in:

  1. Multi-disciplinary co-operation barriers for field development studies are gradually coming down.

  2. Geostatistic methods are becoming more acceptable. These dous potential for solving some of the very difficult problems in cementing. The CEA99 project is a fundamental investigation of the inflatables while the objective of the PEA-91 project is to determine operational considerations for improvement of inflatables.

Later that same month the CEA-90 project joined with the PEA-91 project to share data. All inflatable manufacturers were asked to submit information on all jobs conducted worldwide between 1994 and 1996.

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