On the topic of XOM's decision, I’d like add that engineers from many corners are studying the data from the Makó trough, including Hungarian engineers.

Here’s an analytic report in the Hungarian Engineers Journal.

http://mernokujsag.hu/index.php?szam=11&ev=2009&n=80

The unconventional hydrocarbon occurrence located in the Makó trough is classified as a basin-centered gas accumulation – or BCGA. These BCGAs’ typically spreads over large geographical areas, several 100, even several 1000 km2 in size. Characteristically they occur in the deep sedimentary basins, mostly in depths greater than 3000 m.

The BCGA occurrences are constituted of cells, for which the boundaries not necessarily tied to a well defined stratigraphic or structural boundary. Consequently, the qualification methods for conventional hydrocarbon research – such as traps, reservoir size and strata identification, and reserve estimate etc. – in the case of basin-centered gas accumulations not employable. Instead, in the case of the BCGA-cells, a comprehensive genetic research approach takes place, where the creation of the hydrocarbons, the short distance migrations and accumulations (trapping) can be viewed as part of a diversified, but coherent process. In optimum cases, the BCGA-cells becomes fully gas-saturated, which results in a very significant geological resource; of course this depends on the size of the cells and the porosity of the layers in the formation.

The basin-centered gas accumulations have numerous characteristically common features, based on those features; the area can be qualified with certainty whether it is a BCGA. The following diagnostic features are the most important ones:

– Predominantly low permeability of the layers (<1 mD),

– Abnormal pressure (under or overpressure),

– Gas accumulation in the vicinity of the source rock, short distance migration,

– Usually, the water-gas boundary develops above the gas,

– Spreads over large region, very large geological resource,

The BCGA cells are usuallyconstituted of very low permeability formations, this have both advantages and disadvantages. To be considered as an advantage is that the gas migrates only a short distance and accumulates in the source rock or directly above it in the cap rocks. The gas retention potential is very high, therefore very high gas concentrations can be found in the target zone. However at the same time, an advantage can be a disadvantage: the testing of these wells in general results in weak flow and low yields. Accordingly, the basin-centered gas accumulations typically very large (several 100 or several1000 billion m3) initial geological resource extraction are faced with significant technological challenges. Often, because of the relatively low yield factor, the commercial assets can be much smaller than the geological resource. The exploitability of hydrocarbons, or rather the yield rate, depends on the production method. This is a very serious engineering challenge, which is summarized as follows.

Earlier researches have proved that the hydrocarbon research of interdisciplinary background now exists: 3D seismic measurement acquisition and interpretation of scientific and technological data allows the researcher to pinpoint optimal settings for drilling locations. The technical characteristics of the obtainable drilling equipment, its instrumental and automation capability, drilling crew dedication and various service reliability due to the 6 -- 7 thousand meters of drilling, the implementation time does not exceed two hundred days, despite the fact that the drilling rig has to transverse through ultra-high temperatures and high pressured formations. The planning and implementation of this type of well drilling constitutes a challenge to such an extent that the relevant Standards include specific subchapter of Standards, the so-called. HTHP (HighTemperature High Pressure) Chapter. In context with the origins of hydrocarbon, during the drilling of HTHP wells, hazardous concentrations of hydrogen sulphide and carbon dioxide gas can be a major risk factor, also corrosion can occur.

It is worthwhile to take an engineer’s view on what kind of important knowledge has slowly arose from the half decade of drilling activity in the Makó trough area. In review of the lessons learned, it is worthwhile to pose the problems that arose, for which hopefully the solutions will be found in the near future.

1) The gas bearing rock layers can be opened with the fracing method. However to extract considerable amounts of gas from the gas accumulation, the selection of appropriate fracing fluids is critically important. For the time being it is unknown that the up to now used water-based fracing fluids properties what kind of capillary pressures resulting in the target formation. It will be necessary to test a variety of (oil based) fracing fluids.

2) The fracing requires large amounts of energy input, in the order of 10-50 thousand hp hydraulic power is needed. To illustrate the magnitude of energy is demanded for fracturing: in 1969 and 1973 nuclear energy was used by the United States for the purposes of rock fracturing. However the big question is that how much of the injected energy converts into volumes of work to stimulate the formation and its impact on the efficiency of production.

3) A considerable amount of hydrocarbon production can only be achieved with significant number of drillings, geometrical arrangements, and the application of appropriate type and rate of fracing still to be determined. This - taking into account the very deep targets, also the extreme temperatures and pressures – promise to be a costly process, which is one of the key questions of this project.

4) It is prominently vital to gain a higher resolution knowledge of the hydrocarbon-cell’s physical parameters (eg pressure and temperature conditions), Without an acceptable level knowledge of rock matrix stress conditions for example, the currently available results of fracing models can only be accepted with serious criticism.

The above described research-development tasks were determined on the basis of observation derived from the fracing carried out in Makó trough-1 mining area. In the following, a series of fracing is presented to illustrate, where the deficiencies can be found in the modeling, which consequently gave rise to serious contradictory results. In particular, the fact that the deployment of the most modern equipments - from the fracing technology point of view the successful formation fracturing and stimulation resulted in no significant amount of hydrocarbon flow from the opened formation.

In this example, the objective for this well was to open the formation at several levels in the Szolnok Formation, the implementation of this task required 20 thousand horsepower hydraulic total capacity, working pressure of 1038 barbattery of pumps, fracing and well fluids, in and out storage capacity of 1600 m3 of storage space have been created. The operation took place a total of 3 stages, during which 1800 m3 frac fluids and 210 tonnes of propant for the target formation. The hydraulic fracturing followed by the technology phase - the start up and production - the well produced variable gas-to-water ratios of natural gas and first flowback liquids then underground waters with gradually decreasing wellhead pressure.

The applied technology provided us with the following lessons:

- The Szolnok formation has been successfully opened at 3 different levels, the inflow surface multiplied in the total volume of 1800 m3 fracture system.

- The fracture and the production have shown extremely high formation pressure and the presence of hydrocarbons in the Szolnok Formation.

- However, the yield of the produced gas was much lower than the expected level would be based on the above conditions, which indicates the development of physical factors (blocking effect) in the fracturing process that is substantially impedes the inflow.

- In the development of blocking effect, the applied frac fluids capillary pressure is fundamentally determinable.

Solutions to these problems seem to have key importance in the economical extraction of hydrocarbons in the Makó trough. These are the challenges that require innovative basic and applied research, for which the cost is to difficult to estimate today. The hope for success is promising: it is about our country’s long-term energy supply. To relate to the near future energy-related research topics - such as the Szeged, Prague and Bucharest cities implementation of the first European large laser equipment – it can be said that the Makó trough research is comparable in magnitude and importance to the ELI- Super Laser project. If that is not a dream, then the Makó gas is a reality.

Dr. Gilyén Elemér

dr. Szabó Imre