Brazil’s HRT advances Amazon exploration with new gas discovery

PETER HOWARD WERTHEIM and DAYSE ABRANTES

At the beginning of January, Brazilian independent upstart HRT O&G announced a new gas discovery, resulting from the drillstem test of a cased hole in the Tucumã prospect (1-HRT-192/02-AM), on the SOL-T-192 Block, in the Solimões basin, Amazonas State.

Referring to the new discovery, HRT CEO Milton Franke said, ‘‘A positive test in Tucumã confirms the existence of a new structural trend in our blocks, to the south and southwest of this well.’’

Fig. 1. HRT has drilled eight wells in the Solimões basin.

Two intervals were selected for the drillstem test, achieving the following results: — 01: Interval 2,254.0 m to 2,260.3 m–Juruá Formation lower member – expected to reach a stable production rate of 520,456 cmgd (18.38 MMcfgd), with a choke of 40/64 in. The estimated re-testing of this gas well (AOF) is 1.60 MMcmgd
(56.50 MMcfgd). And — 02: Interval 2,208.0 m to 2,217.0 m, also in the Juruá Formation Lower Member, expected to produce 143,092 cmgd (5.05 MMcfgd), with a choke of 40/64 in.

The drilstem test results, together with the gas findings in wells 1-HRT-5-AM and 1-HRT-9-AM, confirm the gas trend to the south and the potential for gas in the SOL-T-191 and SOL-T-192 Blocks. It will open a new exploratory play fairway for the SOL-T-214, SOL-T-215 and SOL-T-216 Blocks, where the company has identified several prospects for future wells to be drilled.

“We will announce new findings in the Amazon Rainforest,” HRT’s founder, chief executive and geologist Marcio Mello said. HRT expects production of some 47,000 bopd in the Solimões basin by 2014. Currently, the company has over 1,000 employees in the region, working round-the-clock shifts to drill exploratory oil wells and overcome logistical challenges to build infrastructure.

After showing positive results, last year HRT successfully concluded the farm-in/farm-out of Solimões areas with Petra and TNK-Brasil. The National Petroleum, Gas and Biofuels Agency (ANP) approved the transfer of a 45% share of all rights and obligations that HRT O&G owned in 21 blocks in the Solimões basin (3,025 sq km) to TNK-Brasil, a company formed by British and Russian partners. The new $1-billion venture contract is being paid in six parts up to 2014.

INNOVATIVE SATELLITE SOLUTIONS

HRT O&G plans to have five stations to access the Global Navigation Satellite Systems (GNSS). Three were already built, equipped with antennae connected to 25,000-km-high satellites capable of transmitting precise image readings.

The first was BATE-1, and the BATE-2 base is at the Amazon State University in Carauari town (24,000 inhabitants). BAJU is a smaller base by the Jurua River. There is a fluctuating port terminal, the first of the type to be employed in the area. All bases have restaurants, offices, dorms, fuel tanks, heliports, etc.

In the beginning, it was a very difficult task to install four logistical bases in Solimões, due to long seasons of bad weather, and the very long time it takes to transport material on barges via sinuous rivers.

It was worth the effort, since operational efficiency has greatly increased due to logistical bases now assisting exploration in a 49,000-sq-km area of the Solimões region. However, by mid 2012, HRT had already concluded the drilling of eight wells. Six of them revealed the existence of hydrocarbons including the 1-HRT-6-AM oil and gas well.

“We are currently working in larger areas, with one-sq-km cells, on the process of confirming volumes for planning the alternatives for the monetization of oil and gas,” said HRT’s technical director and geologist, Nilo Azambuja.

All data acquired are used to undertake geodesic and topographic studies, to support environmental licensing, agrarian licensing, seismic data acquisition, the opening of lines for long duration tests (LDTs), the building of roads, and many other activities. Due to precision, all operations can be faster and more economical, explains the executive.

With increased capacity to analyze the basin’s chosen areas down to each millimeter, due to satellite readings, HRT has the data processed and transformed into RINEX format, which is known worldwide and allows interface with partners, contractors, plus any Global Navigation Satellite Systems (GNSS) equipment.

Mello said that, “this is a remarkable achievement for HRT and shows a commitment to maximize results for our shareholders.” Considering that the last quality study undertaken on the area was by the Brazilian Army during the 1970s, this is a considerable improvement, showing that innovation has brought a huge leap to cartographic data acquisition.

HRT O&G has a portfolio of 36 blocks onshore (21 at Solimões basin) and 12 blocks offshore Namibia, with estimates surpassing 7.9 Bboe. HRT has already guaranteed extensions for its exploration periods in both countries.

Due to encouraging results at Solimões, nine blocks had exploration periods extended. Overall, prospective resources are forecast to reach 449 MMboe and 515 “contingent” MMboe, which means that they were discovered but have not yet been declared commercial. The company forecasts that it may hold between 4 Bbbl and 6 Bbbl of light oil, and between 10 Tcf and 20 Tcf of natural gas.

THE HEART OF THE FOREST

Fig. 3. HRT operates several rigs in the Solimões basin.

Running from south to north, the Tefe River turns into a lake, near the Tefe airport, right before reaching the giant Amazon River. From the airport, all bases are reached by helicopters. There are hardly any roads, because the whole area is formed of small- and medium-sized sinuous rivers, islands and other smaller lakes, which causes a very complex logistical challenge.

Other important references for oil and gas exploration in the region are the giant Jurua River, west of Tefe, and the Coari River, on the east side of the state. Both rivers have been used to access exploration/production areas by Petrobras.

Recently, Petrobras announced the signing of a memorandum of understanding with HRT O&G and TNK-Brasil Exploração e Produção de Óleo e Gás Natural Ltda. (TNK) to conduct studies in the companies' concession areas. HRT’s blocks in the Solimões basin are near some Petrobras blocks. Petrobras found 41° API oil in an exploration block near the Urucu River.

The weather is a major factor, and the volume of water dictates the rhythm of work in the area. All equipment must be transported by helicopter, including drill towers! It takes about 590 chopper trips to transport a drilling unit and, if the weather is good, it may take 35 days. On average, a small chopper will carry 3.1 tons.

For HRT operations, most of the heavy material comes from Manaus to Tefe by boat. Some material also goes from Tefe to the Solimões port base by barge, and then to the well location by helicopter.

THE GEOLOGICAL FACTOR

The Solimões basin is a vast east-west-trending, Paleozoic cratonic depression in the middle of the Amazon rain forest, covering 450,000 sq km (175,000 sq mi). It is separated from the Acre basin to the west by the Iquitos arch and from the Amazon basin to the east by the Purus arch, explained Azambuja, citing a study published in PetroGeo on May 2008. Azambuja has a PhD and has worked for 31 years at Petrobras, also developing technologies at Cenpes, the Petrobras world-renowned R&D center.

The geologist cited the contrasts between the exploration of a basin onshore and offshore: “To obtain a good reading of 2D seismic, our main tool, is much more difficult in the onshore basin, because the terrain is irregular, while the bottom of the ocean is mostly plain and we can use vessels.”

When recalling the first stage of work in the exploratory phase at Solimões, he said HRT used existing data from the 1970s and upgraded it with the new technology. “With new 2D seismic reprocessing, we can see many more signal details of the same area, and we did that in 30,000-km 2D seismic lines that are more spaced from each other. The 3D lines are closer, averaging 25 m in-between the lines. This gives the advantage, through processing data, to see surfaces in three dimensions, and it is also possible to ‘clean the noise,’ just like in the radio waves. When the signal is stronger you have less noise. On the surface, we have a geophone that takes the noise to a signal processor that will amplify and reprocess it to eliminate interference. It is called ‘seismic reprocessing,’” explained Azambuja.

“In addition, in areas where some prospects were identified, HRT acquired new seismic lines and also improved lines.” Here he was referring to the Jurua reservoir formation, closer to the Jurua River. “With more seismic lines, and with deeper explosions that we call cargo tests, we have more signals but also have to drill deeper. Thus, we have to calculate the cost benefits, because more equipment has to be removed to the areas for drilling deeper wells, if we want to explode and acquire data. The question of logistics is for our technical people and financial departments: how to improve seismic imaging? Will we drill deeper and get a better seismic image, or will we clean the signals via computer technology to improve it? All of this increases our confidence in new data acquisition, which is less expensive, because we avoid dry wells,” Azambuja said.

The density of rocks in the soil varies, and thus the attraction exerted by atmospheric pressure also varies, and that can be measured. For this, high-resolution gravimetric and magnetometric sensors were installed in airplanes and helped to measure the gravity force being exerted over the rocks and soil, as well as magnetic reading. The important aspect is that rocks contain magnetic minerals that can also be captured by sensors installed on airplanes. This reading is cheaper than 2D or 3D,” affirms Azambuja.

“By measuring through gravimetric and gradiometric surveys, we first researched by flying on lines 500 m distant from each other, and in other parts 2 km distant from each other, during three months in 2011. It was easier and cheaper to make a magnetic map, and locate great structures, faults, which helps to diagnose the area. After computer processing, if it proves to be interesting enough, we then proceed to acquire more seismic lines,” he added.

Another technology being applied is geobotanic observation, added Azambuja. “With the observation via satellite, we can also locate exudation that interferes in vegetation by segregating and creating areas with different plants. It is done by spectral analyses, and HRT uses all this info to really specify the cause of the stress on the vegetation. We can identify it by superposing images, reading layers of maps through Geographic Information System (GIS).”

DIABASE DETECTED

“There is a phenomenon that we detected, called intrusion (diabase) that happened in the Devonian era that brought some volcanic rocks to the area. These rocks surged with high temperatures up to 800°C, and besides crystallizing slowly, it also cracks gas and shows where the oil may be. We also get this reading by analyzing well samples. The farther from the intrusions, the better chance to have oil,” revealed Azambuja.

“Also, well samples shown by maturation of gas based on isotopic analyses produced a map of maturation of gas reaching Devonian source rocks associated with the thermal effect of diabase intrusions,” added Azambuja.

“Now, with an even higher sophistication, we analyze the isotopes of pre-selected diamondoids, a nano structure that is similar to the diamond shape,” explained Azambuja, while showing graphs of diamondoid marker parameters. “Sometimes, we even find two source rocks of different maturation, and the oil is shown migrating together with different thermal readings. And with graphs we make more maps, adding another layer to the analysis."

“All data are contained in the reports being prepared by the HRT/INPE (National Institute of Space Research) association,” said the executive while showing geochemical analyses marked over the lines in one of the region’s maps along the rivers.

TECHNOLOGY PARTNERSHIP

Fig. 2. Prospective resources are expected to reach 449 MMboe and 515 “contingent” MMboe in the Solimões basin.

The partnership helped to overcome the difficulties brought on by the cartographic blank that HRT found in the Solimões area and is allowing the joint effort to establish new and higher standards of operations and for logistics, explained INPE’s cartographic engineers, Edgar Souza and Mariana Silveira. Luiz Sguissardi from the Cartography Group of the Governmental Relations and Data Bank Management (GRG) supervised the work published by the engineers last year, entitled, “Installation of GNSS stations in the Solimões project area.”

Ms. Silveira explained that the activities are administrated by the Brazilian Foundation of Geography and Statistic Institute (IBGE), which also formed a partnership with the National Institute for Colonization and Agrarian Reform (INCRA).

In this context, the Brazilian Continuous Monitoring GPS System Network, or Rede RBMC , in Portuguese, which is an active geodesic network, is also taking part in the HRT/INPE partnership, established in the second half of 2011. Thus, HRT and partners will participate with all these institutions in an effort to implement the geodesic structure in that part of the Brazilian territory and link it to international geodesic networks.

This means that horizontal and vertical relative movements that occur between tectonic plates, and in provinces within the plates, will be observed by geologists working on HRT’s block projects. Besides being used by HRT and partners, the study of deformation in the crust of the region, associated with tectonic and non tectonic events, will generate data that will be provided for the Brazilian community.

For comparison, first, map legends were quoted at 1:1,000,000 m, as required for aviation purposes. Later, the resolution was improved to 1:500,000 m. Now it is further being improved by the government’s Geographic Services Department through SIVAM and SIPAM military surveillance programs.

As explained by Azambuja, by using airplanes equipped with specific sensors, many types of readings are used to enhance local images, especially those capable of analyzing the soil through the dense vegetation of the Amazon Rainforest. The continuous monitoring system provides a tridimensional reference structure involving latitude, longitude and ellipsoidal altitude that results in the geometrical model that creates representations of the Earth, delivering precise locations to users at the millimeter level of detail.

Due to heavy rain seasons followed by severe droughts, the region that mostly looks like a never-ending sequence of trees, rivers and lakes is actually moving.

The stations nearest to the Solimoes basin concession, that were already operating before the HRT/INPE partnership, were in the capital, Manaus. This is more than 600 km from the Solimões basin, and in the capital of neighboring Rondonia State, Porto Velho, more the 430 km distant. Nationwide, there are 122 points of observation and data acquisition linked through the Internet.

LAST YEAR’S DISCOVERIES

According to HRT’s office in Manaus, without the aid of the HRT/INPE satellite stations that were just built, formation tests were concluded by mid-2012 in both the 1-HRT-4-AM well, where gas and condensates were found, and in the 1-HRT-5-AM, a gas-prone well.

The acquisition of more than 3,500 km of 2D seismic since 2011 opened the opportunity for more than 60 prospects, which gives an idea of the amount of work planned to take place for the next two years in this area. Six new wells were drilled last year. Two of them, the 4-HRT-7D-AM and 1-HRT-8-AM, produced oil and gas.

South of the logistical support base, BATE-1, is on the SOL-T-169 Block. Samples were collected by the chopper and sent by airplane to be analyzed at a laboratory in Rio de Janeiro (IPEX) in mid-July. This resulted in new findings. On July 30, HRT O&G sent a notification to the National Petroleum Agency (ANP) regarding the discovery of natural gas in the 1-HRT-8-AM well on the SOL-T-169 Block. Reservoirs were found with two gas intervals in this formation, between 3,045 m (9,990 ft) and 3,130 m (10,270 ft). Last year, HRT also completed well formation testing on 1-HRT-8-AM, and confirmed natural gas production of 262,000 cmd. Production was possible on a 40/64-in. choke setting, with the capacity to produce between 4.9 Bcm and 8.2 Bcm of recoverable gas.

The drilling of the well was conducted by the QG-VIII rig, owned by Queiroz Galvão, reaching a final depth of 3,345 m (10,975 ft). The announcement confirmed the gas potential east of  Juruá field. There, the 1-HRT-5-AM and 1-HRT-2-AM wells, located 32 km and 22 km from Juruá, respectively, also were discoveries. These results were disclosed last August.

HRT IN NAMIBIA

HRT has claimed a 6% increase in its resource estimate for four of its Namibian prospecting licenses.

In its 2012 report, prepared by consulting firm D&M, HRT said there has been a significant improvement in the analysis of the volumes previously reported by D&M. This follows a study performed, using the excellent quality 3D-seismic volumes that HRT acquired and processed during 2011 and 2012.

More detailed information gained by the international oil industry on the geology of deposits offshore South America and Africa indicates their similarity and shows that the early stages of the break-up between the two continents of the previous large continental land mass occurred in the Early Cretaceous (130-140 million years ago) with the creation of rift valleys and lake deposits, explained geologist Mello.

Geological records also indicate further break-up and separation of the two sides, the deepening of marine areas and that some of the sediments overly the basalts of the oceanic floor, i.e. the early Atlantic Ocean. Rift basins and the salt basins are from the early stages of separation, before full opening of the Atlantic Ocean.

That is why the industry is so keen to invest offshore West Africa and South America, concludes Mello.

HRT says the new volumes represent an increase of 0.5 Bboe to its portfolio, reported in 2011. As a result, the company’s reserves have now increased to 7.4 Bboe, including 5.1 Bboe of crude and condensate, and 2.3 Bboe of associated and non-associated gas. HRT CEO Marcio Rocha Mello told World Oil that the company believes that the Namibian offshore portfolio is analogous to the ones present in the Campos and Santos basins.

“With the support of petroleum system technology, it has been proven that there is an almost perfect similarity (duplication) between all the elements and processes of the petroleum system, such as source rocks, reservoirs, seals and traps, and oil types of the pre-salt sequences of Brazil when compared with the pre-salt systems of West Africa,” affirms Mello, who worked as a geologist for Petrobras for 24 years. 

ACKNOWLEDGMENT

This article is the result of a field trip by Peter Wertheim and Dayse Abrantes, both World Oil correspondents, to Solimões basin, Amazon state sponsored by HRT.