On the eve of the opening of the 14th international conference "Oil and Gas of Sakhalin", Exxon Neftegas Limited organized a press tour to the Odoptu field. “By the end of this year, Odoptu is planned to be put into operation. During the trip, we want to show and tell journalists on the spot about what has been done and the degree of readiness of the field for the start of production,” said the invitation from the company’s press service.

On the morning of September 27, a group of 20 Russian and foreign journalists took a charter flight from SAT Airlines from Yuzhno-Sakhalinsk to Okha. The 12-hour trip, most of which consisted of a flight and a trip in a passenger KAMAZ from Okha airport to the Piltun Spit, provided only a brief acquaintance with the field, but nevertheless provided an idea of ​​​​the scale of work carried out there over the course of about a year and a half.

Under the wing of the Dash-8-200 is the main highway of Sakhalin.

Bear Lake. We are approaching Okha airport.

A Sakhalin Airways charter flight is the usual method of delivering Exxon Neftegas Limited employees to this field in the Okha region. Just like the orange KAMAZ that is waiting for us in front of the airport building.

The path to Odopta lies first through the village of Ozerny and the village of Tungor - along a short asphalt section of the Yuzhno-Sakhalinsk - Okha highway, then along a dirt road among dwarf cedar and other low tundra vegetation.

Rosneft drilling rig.

The presence of the Russian oil company is visible all along the sand spit that separates Piltun Bay from the Sea of ​​Okhotsk. Odoptu-Sea is the first field that began to be developed on the Sakhalin shelf. Using its ultra-deep directional well, the company produced more than 5 million tons of oil from the northern dome of the field.

Since 1995, the central dome of Odoptu has been included in the second stage of the international project "Sakhalin-1", carried out on production sharing terms. To date, the project participants are ExxonMobil, Rosneft, Japanese SODECO and Indian ONGC.

Entrance to the territory of Exxon Neftegas Limited. Checkpoint.

Odoptu.

Administrative building.

The building is designed for personnel who will service the field after it is put into operation. It has everything to make work comfortable in the harsh conditions of the Sakhalin north - from a conference room, to relaxation rooms, a gym and a sauna.

Dining room.

In the summer, against the backdrop of mass diseases of Sakhalin residents with intestinal infections, several dozen workers at Odoptu and Chaivo became infected. Rospotrebnadzor and the prosecutor's office found violations in the canteens of workers' settlements. Obviously not in this dining room...

After lunch we will receive a safety briefing. It is not much different from the same mandatory procedure at, say, the Chayvo oil and gas plant and the Korsakov LNG plant. The presenter, Andrei Vasko, warns that equipment adjustment at Odopta continues, gas leaks are possible, so in addition to the usual ban on using cell phones, a warning is added to operators - the cameras can only be turned on after checking the air with a gas analyzer.

Wearing orange overalls with the word “Visitor” on the back, we first head to the “central control room.”

Today, the Odoptu field is operating in test mode, says Pavel Gorkin. Six wells have been drilled and are ready for operation, an 80-kilometer pipeline has been built to the Chayvo onshore complex, from where oil will be supplied via pipeline to the port of De-Kastri. The second phase of the Sakhalin-1 project is close to completion.

Meanwhile, the site is busy and quite crowded. It is still surrounded by buildings made of iron containers. During the most active phase of the project, at least four thousand people worked here - from various contracting companies. With the commissioning of the field, the number of personnel will be significantly reduced, and 70 percent of it will be Russian employees.

We go on a tour of the site. The first stop is at the production module, where the extracted oil will go through purification stages before entering the oil pipeline. But the first thing journalists photograph, as soon as Andrei Vasko allows them to turn on the cameras, is a torch in which associated gas and a reservoir of water are burned. The torch is slightly smaller than in Prigorodny...

The Hawk rig for drilling extended reach wells was built about eight years ago in Louisiana specifically for ExxonMobil. In disassembled form, it was delivered through the port of Korsakov to the Chayvo field, where by the end of 2008, with its help, the required number of wells was drilled, including one or two of record length. Then they dismantled it again and transported it on trucks 80 kilometers north - to Odopta. The reserves of this field do not lie as deep as at Chayvo, however, one of the wells drilled here is still the second longest in the project. "Hawk" is still considered one of the largest drilling rigs in the world. Odopta has been upgraded to operate and now uses ExxonMobil's patented accelerated drilling method.

Introduction

The Odoptu-Sea (Northern Dome) oil field was put into development in 1998.

In the section of the field, 4 productive layers have been identified (XIX 1, XX 2, XX 3 and XXI 1); for the first three of which oil reserves are calculated according to category C 2.

Technical and economic calculations for the development of the Northern Dome of the field determined the drilling of the XXI 1 layer deposit with six production wells, based on the directional drilling capabilities that existed at that time.

Basic provisions of the period of pilot industrial operation:

It is recommended to carry out drilling using a directional method with a two-hole completion; location of the faces from each other at an angle of 120º; maximum deviation of wells from the vertical is 6390 m with a vertical of 1587 m (well No. 208);

well drilling - cluster; number of bushes – two;

accumulated production over the profitable development period is 4.2 million tons;

The design development period is 27 years.

Provide for simultaneous and separate exploitation of XIX 1 +XX 2 +XX 3 layers in the well. 208.

All wells are characterized by a decrease in the productivity coefficient over time, which is associated with a drop in reservoir pressure, the development of a dissolved gas regime, a possible gas breakthrough from the gas cap and a deterioration in the condition of the bottomhole formation zone. So, according to well. 204, located near the gas cap, over 5 months of operation the productivity coefficient decreased from 5.4 to 1.62 10 m 3 /(day MPa); by well 202 over 3.5 years of operation it changed from 9.4 to 4.9 10 m 3 / (day MPa)

Hydrotesting was carried out twice on the area in 2001, during which it was established that there was a possible hydrodynamic connection between some of the wells under study.

The deposits of the field are subject to a single natural regime for the creation of reservoir energy - elision, that is, closed-elastic.

1Geological and field characteristics of the Odoptu deposit

1.1 General information

The Odoptinskoye oil and gas condensate field is located on the shelf of the Sea of ​​Okhotsk, at the latitude of the northern end of the Piltun Bay, 6-10 km east of the coast of Sakhalin (Figure 1). The sea depth within the western wing of the Northern Dome of the field is about 18 m.

Administratively, the field is located in the Okhinsky district of the Sakhalin region. The area is located 40 km southeast of the regional center of Okha, which is connected with the regional center (Yuzhno-Sakhalinsk) by air and railway. The nearest developing field on land of the island is Odoptu, located 7 km to the northwest.

The subsoil user is OJSC Rosneft-Sakhalinmorneftegaz on the basis of a license for the right to use subsoil in the Northern Dome of the field (SHOM, No. 10429 dated November 2, 1993), issued by the Committee of the Russian Federation on Geology and Subsoil Use until 2013. The license has the right of mining allotment , limited in depth by the roof of the foundation. The main condition of the license agreements: geological exploration work for the XXVII layer and trial operation; drawing up a project document.

The climate of the deposit area is monsoon type with short and cool summers and long and cold winters. The winter period lasts from 220 to 240 days (November-April). The average annual temperature is negative minus 5 °C. Maximum temperatures in July-August range from minus 40 to plus 35 °C. Summer is usually rainy. The periodic occurrence of tropical cyclones (typhoons) in the summer is accompanied by heavy torrential rains, and in winter – by snowstorms. The maximum precipitation during the passage of typhoons is up to 100 mm per day, the height of waves at sea reaches 13 m.

Ice in the Sea of ​​Okhotsk off the coast of Sakhalin sets in in December. The fast ice breaks up periodically. The cold Sakhalin Current moves broken ice and ice fields along the coastal part of the island from north to south at a speed of up to 1.6 m/sec. In this case, ice hummocking occurs, which leads to the formation of stamukhs up to 7 m high above sea level, and the underwater part - up to 20 m. "Stamukhi" in loose sediments plow furrows up to 0.5-0.6 m deep. The sea area is freed from ice ice in June. Offshore drilling with jack-up rigs can be carried out from late June to October, however, due to the shallow sea depth within the western flank of the structure, offshore drilling rigs cannot be used.

According to seismic zoning, the northeastern shelf of Sakhalin belongs to the zone of moderate seismic activity with the maximum possible amplitude of earthquakes up to 8 points.

The topography of the sea bottom is composed of silty-sandy rocks of the Upper Nutovsky subhorizon, partially overlain in some areas by loose, predominantly sandy sediments of Quaternary age (up to 15 m thick).

The Odoptu-Sea (Northern Dome) field (Figure 2, 3) was discovered in 1977 as a result of oil and gas exploration work carried out by Rosneft-Sakhalinmorneftegaz OJSC on the Sakhalin shelf and includes the Northern and Southern well clusters. Development of the field began in the Northern bush in 1998.

Study area

Figure 1 – Overview map of the area

Figure 2 – Map of thicknesses of the XXI-1 formation with the location of wells

Figure 3 – Map of thicknesses of the XXI-2 layer with the location of wells

1.2 Stratigraphy

The stratigraphic section of the field area is represented (from bottom to top) by the following deposits:

chalk "foundation"

Machigarian Horizon (Oligocene)

Daekhuri horizon (Oligocene)

Uininsky-Daginsky-Okobykay horizon (Upper-Lower Miocene)

Nutovian horizon (Upper Miocene-Pliocene)

Quaternary deposits

Deep prospecting and exploration wells at the field revealed a section of Miocene-Pliocene sediments of Neogene age.

The most ancient exposed part of the stratigraphic section (well 1) is the Upper Okobykai subhorizon (N 1 ok). The upper boundary of the Okobykai horizon is drawn conventionally along the top of the XXVII layer. The exposed deposit thickness is 350 m; according to seismic survey data in the western direction, the thickness of sediments increases to 1000 m, to the east of the field (within the East Odoptinskaya zone) it is about 500 m. Lithologically, the horizon is represented by alternating layers of sandstones (20 to 40 m thick) fine- and medium-grained, dense clays and siliceous, dense mudstones.

Nutovo Horizon (N 1 nt) – Upper Miocene-Pliocene. The horizon deposits were exposed by all drilled wells. The thickness of sediments is 2100-2300 m, reaching 3000 m in the southwest and decreasing eastward to the East Odoptinskaya zone to 1800-2000 m. In the regional plan, the horizon changes from an almost entirely sandy section in the west and northwest (East Nutovo, Eastern Osoy, Goromai) to clayey in the east (Dagi-sea).

The Nutovo horizon is divided into two subhorizons: the Nizhnenutovo (IX-XXVI layers) and the Upper Nutovo (“M”, “N”, “O”, I-VIII layers).

The Nizhnenutovsky subhorizon (N 1 nt 1 - upper Miocene) is lithologically represented by alternating complex layers of sandstones (from 2 to 60 m thick), clays and siltstones. The maximum content of sand rocks is characterized by the middle part of the section XII-XXIV layers (sand rock content 40-55%). Sandstones are gray and light gray, medium- and fine-grained, well sorted, often silty and clayey. The clays are predominantly gray and dark gray, soft and slightly sandy in the upper part of the section, dense, mudstone-like in the lower part. Siltstones are gray, light gray, inequigranular, dense, sometimes grading into fine-grained sandstones. The thickness of subhorizon deposits in the area is 1000-1300 m, in troughs it increases to 1800 m, decreasing eastward (towards the East Odoptinskaya zone) to 400-500 m. Simultaneously with the decrease in the thickness of sediments, their claying occurs.

All established hydrocarbon deposits in the field are confined to the middle part of the section of the Nutovsky subhorizon (XX-XXI 2 layers). In the process of detailed correlation of well sections, taking into account the interpretation of 3D seismic materials, four productive formations XX 1 2, XX 2, XXI 1, XXI 2 with proven industrial oil and gas potential were identified in the field; in the XX 3 formation, an oil deposit is assumed based on GIS materials. All productive layers are combined into a common pack - XX and XXI layers; for the convenience of field nomenclature, each of them is called a “layer”.

Verkhnenutovsky subhorizon - N 2 nt (Pliocene)

The deposits of the Upper Nutovsky subhorizon are composed of sand layers “M”, “N”, “O”, I-VIII. The subhorizon sediments were deposited in the basin at depths of 50-150 m. At the top of the structure, the thickness of the subhorizon sediments is 750 m.

1.3 Tectonics

In tectonic terms, the Odoptinskaya anticlinal fold is confined to the Odoptinskaya meganticline, the dimensions of which are 326.5 km. The structure has a submeridional strike and is slightly asymmetrical. In the near-axial part of the structure, the rock dip angles are 2-3˚, ​​as they move away from the axis to the western wing, the dip angles change from 5˚ to 17˚, on the eastern flank – 3-7˚. The meganticline hinge undulates to form three domes: Northern, Central and Southern. The Northern Dome, through a saddle, articulates with the Central Dome, which is part of the licensed area of ​​the Sakhalin-1 project. The dimensions of the Northern Dome are 11  4 km. In the latitudinal section, the structure is asymmetrical: the western wing is slightly steeper than the eastern one. The rock dip angles on the eastern flank are about 5˚, on the western flank - up to 10˚.

Within the Northern Dome, three fault zones are identified in the depth range from 500 to 2000 m. These faults are of the graben-forming type and very few of them cut the main oil reservoirs. Within the first zone, the largest fault-slip fault is identified - fault No. 1. The fault extends from southwest to northeast through the arch of the dome and can be traced throughout the section. The vertical amplitude of the disturbance is beyond the capabilities of seismic resolution. Discharge 1 was not intercepted by wells, but in the process of hydrodynamic studies of wells. 204, the possible presence of an impenetrable screen was established at a distance of 30-40 m from the well. The fault screens the oil deposit of the XX 1 2 layer in the southeast, as evidenced by the lack of oil saturation in the wells of the adjacent block (wells 1, 209).

Fault No. 2 was established by seismic materials; it has an insignificant amplitude, but its screening properties are confirmed by the difference in the productivity boundaries of blocks 2 and 3, as well as the existence of a gas cap of the XXI 2 layer deposit in block 3.

Zones weakened by disturbances could be filled with impermeable sediments, creating lithological screens separating sand bodies into separate hydrodynamically unconnected deposits.

1.4 Properties and composition of oil, gas, condensate and water

The physical and chemical properties of the oil in the field were determined based on the results of the analysis of deep and surface samples taken during well testing.

Within the Odoptu-Sea field (Northern Dome), the XXI 1 layer (oil inflows were obtained in all wells) and the XIX 1 layer (oil inflows (well 1) and water with an oil emulsion (well 3) were obtained). According to the area of ​​deposits, changes in oil properties are insignificant.

In general, separated oils from the Odoptu-Sea field are light (density up to 0.870 g/cm3), low-sulfur (up to 0.5%), low-resin (resin up to 6.3%), low-paraffin (up to 2.4%); oil with a high yield of gasoline fractions (up to 31%).

Reservoir oil samples were taken during well testing using samplers included in the reservoir testers. The quality of the samples was controlled by the coincidence of the opening pressure of the sampler valve with the pressure at the sampling depth. In case of poor sampling, oil samples were recombined by saturating the separated oil with gas collected at the wellhead. Below is a brief physical and chemical characteristics of oil from productive formations.

XXI 1 reservoir. The physical and chemical properties of separated oil were characterized using 14 samples taken from 4 wells in the Southern, Central and Northern domes of the field. In the Southern and Central domes (wells 5 and 11), compared to the Northern dome (wells 1 and 3), the oil becomes heavier from 0.838 (well 3) to 0.862 g/cm 3 (well 11). Accordingly, the resin content increases from 3.49 to 5.38%. Oil viscosity increases from 2.5 to 5.01 mPa s; the content of light fractions decreases from 74 to 59.5%. On average, the density of oil in the Northern Dome is 0.838 g/cm 3, viscosity is 2.52 mPa s. The oil contains 0.62% asphaltenes and 6.30% silica gel resins.

In the process of testing the horizon in well 3 (interval 1671-1676 m), oil and gas samples were taken from the separator at a separation pressure of 11.95 kgf/cm 2 and transferred for analysis to a laboratory in Dallas (USA). When recombining the sample to an operating gas factor equal to 379 m 3 /m 3, a sample with a saturation pressure of 351 kgf/cm 2 was obtained. Such a sample could only be obtained if the phase equilibrium at the bottom of the well was disturbed with a slight decrease in reservoir pressure, i.e. at full saturation of oil with gas in initial reservoir conditions. This assumption was confirmed when sampling in other wells.

Due to the similarity of the properties of separated oils, reservoir oils are also similar in physical and chemical parameters. The gas content in the oil deposit of the Northern dome is 102 m 3 /t, in the Central and Southern domes - 100 m 3 /t. The volumetric coefficient of oil is 1.224 and 1.215, respectively. The viscosity and density of oil are also respectively equal to 0.74 mPa*s; 0.751 g/cm 3 and 0.81 mPa*s; 0.768 g/cm3.

Due to insignificant oil inflows from the XIX 1 formation (wells 1 and 3) and the lack of testing of the oil and gas-bearing XX 2 and XX 3 formations, the physicochemical parameters of oil and dissolved gas for these objects are not given.

Associated gas sampling during well testing was carried out after the separator and analyzed in the laboratory of the SakhalinNIPImor-Neft Institute and gas laboratories in Dallas (USA) using gas-liquid and gas adsorption chromatography methods.

The gas from the Odoptu-Sea field dissolved in oil is of the “dry” type with a methane content of 90.45-94.80%; tu - 4.15-8.99%; relative density in air 0.5848-0.6176. Hydrogen sulfide not detected, helium<0,001 %; аргона - 0,001-0,030 %.

According to the commercial characteristics, gas dissolved in oil contains a small amount of ballast gases (N 2 + CO 2 in the range of 0.53-1.75%), has a high calorific value (8220-8710 kcal/nm 3 (lowest) - 9120-9640 kcal /nm 3 (highest), indicating the profitability of the field's exploitation.

In hydrochemical terms, the Odoptu-Sea deposit, like the Odoptu and Eastern Ekhabi deposits located closely on the coast, is confined to the development zone of the most complex zonality with the distribution of waters with maximum mineralization for the North Sakhalin basin (20-35 g/l). At the same time, a distinctive feature of the groundwater salinity in the field is its inversion throughout the studied section.

The upper, predominantly sandy, stratum of the first aquifer complex is characterized by a zone of development of waters of marine origin with a salt concentration of up to 35 g/l.

The zone of saline waters with a salt concentration of 27 g/l is inherent in the zone of slow water exchange and partially extends to the upper part (XIX 1, XX layers) of the main productive complex III. Within the zone confined to the intermediate II complex, there is no clear dependence of water mineralization on the stratigraphic and hypsometric depth of its occurrence. But, for the XIX 1 productive formation, there is a slight decrease in water salinity along the strike and in the eastern direction, to 22.3 g/l, table. P.3.6. The composition of groundwater in this zone is chloride, sodium with a sodium to chlorine ratio of 0.931.00. Waters of the calcium chloride type (according to the classification of V.A. Sulin) have a predominant development. Waters of the magnesium chloride type are less common. The waters are enriched with sulfates - 64-422 mg/l with rSO 4,100 / rCl = 0.32.08. Increasing the sulfate coefficient to 4.2 in the well. 9 is apparently due to the admixture of technical water.

Within the III hydrogeological complex, where the water pressure system is subject to conditions of difficult water exchange, a decrease in salinity is observed with the spread of slightly saline waters of zone B 20. In the area of ​​XXI 1, XXI 2 layers, the mineralization of formation waters decreases from 19.1-19.9 g/l to 13.3-16.1 g/l in the area of ​​XXIV 2 layers.

According to actual data on the composition of the waters of the III complex of the Odoptu-Sea field, the content of chlorides decreases with stratigraphic depth (from 10.511.5 g/l in the waters of the XXI 1st layer to 7.08.5 g/l in the waters of the XXIV 2 layers) and sulfates and the content of hydrocarbonates increases (from 0.51.0 g/l to 1.52.5 g/l). More detailed information on the Odoptu-Sea Field (Northern Dome) is given in Table 3

Table 3 - Physico-chemical properties and fractional composition of degassed oils of the Odoptu Sea Field (Northern Dome)

Name			Layer XXI 1
			Number of studied				Range of change		Average value
Volume yield of fractions, %
Oil classification									I.1Sm 1 Wed 1 Pr 1

Table 3 - Physico-chemical properties and fractional composition of degassed oils of the Odoptu Sea Field (Northern Dome) (Continued)

Layer XXI 1 -XXI 2
Density kg/m3
Dynamic viscosity, mPa*s
Kinematic viscosity,  m 2 /s
Pour point, 0 C
	Silica gel resins
	Asphaltene
	Paraffin
	Fur. impurities
	Chloride salts
Melting point of paraffin, 0 C
Volume yield of fractions, %

Exploration of the Northern Dome of Odoptu was almost completed by drilling the exploratory directional well 202. Subsequently, all exploration tasks were solved by production horizontal wells. It is obvious that the complex of geological and geophysical research is limited by the technical and economic capabilities of the customer. At the same time, the research program during the OPE period has been largely completed. Almost all drilled wells ended up in the oil-bearing contour

In the process of drilling horizontal wells, a certain set of well logging was carried out, limited mainly to the productive part of the section and a set of research methods, which made it difficult to quantify the indicators of filtration-capacitance and reservoir properties of productive formations.

To study the properties of formation fluids, deep samples and recombination samples were taken from the XX, XXI 1, XXI 2 layers, which made it possible to study the necessary indicators of the properties of formation fluids.

Thus, the necessary and sufficient amount of information was obtained to build a geological model of the field and calculate oil and gas reserves. ,

2 Analysis of the field development scheme

The operating method used is ESP. The pumps used are DN1600, DN1300, DN300 and DN 1750 from Shlumberger, suitable for operating wells with horizontal completion. There were no losses of operating time due to pump failures.

Well downtime is associated only with power outages and is insignificant.

The production from the wells of the Odoptu-Sea field (Northern Dome) is supplied to the oil separation unit (OSN), located in the area of ​​the northern cluster of wells, where oil is separated from gas. Part of the gas after separation is supplied for production and economic needs, and the main part is supplied to the Tungor GSU through a DN 300 mm gas pipeline. Pre-separated oil is supplied through existing pipelines to the Tungor central oil pumping station.

The northern cluster of wells is located 200 meters from the USN, the Southern cluster of wells is located 4.6 kilometers south of the USN.

2.1 Analysis of the Yastreb drilling rig

The Hawk is an earthquake-resistant drilling rig capable of operating in temperatures of -40°C (-40F). This rig uses extended reach drilling (ERD) technology, which significantly reduces capital and operating costs for large offshore structures and significantly reduces the negative impact on environmentally sensitive coastal areas.

Parker Drilling designed, custom built and installed the Hawk (Figure 4) in 18 months. Test assembly and commissioning took place in June 2002 in New Spain, Louisiana. The installation was then dismantled, packed into transportable blocks and sent by three cargo ships to the port of Korskakova on the island. Sakhalin and arrived at the beginning of August.

Yastreb has drilled record wells in length, including 7 that are among the 15 longest in the world. The deepest hole drilled by Hawk has a total length of 11,134 m (36,529 ft) with a horizontal section of 10,088 meters (33,098 ft). The total vertical depth is over 2,600 m (8,530 ft).

Key components of the Hawk project include a fully enclosed rig, automated pipe storage with a guillotine door and double wall with two inches of insulation. The enclosed derrick and pipe storage facility allow the team to carry out drilling operations in temperatures as low as 21 degrees Celsius (70 degrees Fahrenheit) throughout the year.

The rig's main features include a 1.5 million lb (680,389 kg) hook load, a 3,000 horsepower (2,206.5 kW) winch, and a top drive system. To service extremely deep wells, Yastreb is also equipped with 4 7500 hp mud pumps, 9000 barrels of drilling mud tanks and 6 generators. The 40-41 m (130-134 ft) pipe warehouse has a seven meter working height. The drill pipe stands and 20-inch diameter, 30 m (98 ft) long casing string are screwed together and moved horizontally in a pipe yard instead of the drill site as required by earthquake safety regulations. Top drive systems, diesel engines and other equipment can transmit real-time data off the well site to assess maintenance needs and recommend adjustments and repairs.

Figure 4 - Yastreb drilling rig

2.2 Justification for the choice of well design at the Odoptu-Sea field (Northern Dome).

The design of directional wells was chosen based on the conditions for preventing complications during the drilling process (Figure 5)

Figure 5

The upper unstable part of the wellbore (sands), where seawater can enter the well, is blocked with a conductor to a depth of 100-150 meters. The wellbore for the conductor is drilled with a bit with a diameter of 660.4 mm to a depth of 90 - 130 meters, the conductor with a diameter of 508 mm is lowered and cemented to the same depth. To prevent gryphon formation, an intermediate column is lowered into the 444.5 mm diameter shaft, which is cemented to the mouth. The depth of descent (1300 m) is determined by excluding the possibility of rupture of weakly cemented sands under the conductor shoe after complete replacement of the drilling fluid in the wellhead sealing well.

In wells with large inclination angles, drilling a long open hole is accompanied by significant gouging with subsequent possible sticking of drill strings during their descent. To avoid this, the exit from under the shoe of the previous column is limited to 4400 m, which is achieved by running a second intermediate column with a diameter of 244.5 mm into the shaft, drilled with a bit with a diameter of 311.2 mm to a depth of 4000 - 6400 m. Running a second intermediate column increases the guarantees successful running of the production string (liner) to the designed depth in a horizontal wellbore.

2.3 Rationale for choosing flushing fluid

The choice of the type of drilling fluid when drilling directional wells on Sakhalin was determined not by the peculiarities of the geological conditions of drilling, but by the configuration of the wellbore. Large inclination angles (up to 85 - 90 degrees) and horizontal waste (up to 6 km) require drilling fluids, first of all, to have high lubricity, providing a friction coefficient of less than 0.3.

To the greatest extent, these requirements are met by a hydrocarbon-based invert emulsion drilling mud, the formulation of which, as well as recommendations on the list and volumes of chemical reagents and materials, were developed by Sakhalinmorneftegaz specialists together with USPTU scientists.

On the eve of the opening of the 14th international conference "Oil and Gas of Sakhalin", Exxon Neftegas Limited organized a press tour to the Odoptu field. “By the end of this year, Odoptu is planned to be put into operation. During the trip, we want to show and tell journalists on the spot about what has been done and the degree of readiness of the field for the start of production,” said the invitation from the company’s press service.

On the morning of September 27, a group of 20 Russian and foreign journalists took a charter flight from SAT Airlines from Yuzhno-Sakhalinsk to Okha. The 12-hour trip, most of which consisted of a flight and a trip in a passenger KAMAZ from Okha airport to the Piltun Spit, provided only a brief acquaintance with the field, but nevertheless provided an idea of ​​​​the scale of work carried out there over the course of about a year and a half.

Under the wing of the Dash-8-200 is the main highway of Sakhalin.

Bear Lake. We are approaching Okha airport.

A Sakhalin Airways charter flight is the usual method of delivering Exxon Neftegas Limited employees to this field in the Okha region. Just like the orange KAMAZ that is waiting for us in front of the airport building.

The path to Odopta lies first through the village of Ozerny and the village of Tungor - along a short asphalt section of the Yuzhno-Sakhalinsk - Okha highway, then along a dirt road among dwarf cedar and other low tundra vegetation.

Rosneft drilling rig.

The presence of the Russian oil company is visible all along the sand spit that separates Piltun Bay from the Sea of ​​Okhotsk. Odoptu-Sea is the first field that began to be developed on the Sakhalin shelf. Using its ultra-deep directional well, the company produced more than 5 million tons of oil from the northern dome of the field.

Since 1995, the central dome of Odoptu has been included in the second stage of the international project "Sakhalin-1", carried out on production sharing terms. To date, the project participants are ExxonMobil, Rosneft, Japanese SODECO and Indian ONGC.

Entrance to the territory of Exxon Neftegas Limited. Checkpoint.

Odoptu.

Administrative building.

The building is designed for personnel who will service the field after it is put into operation. It has everything to make work comfortable in the harsh conditions of the Sakhalin north - from a conference room, to relaxation rooms, a gym and a sauna.

Dining room.

In the summer, against the backdrop of mass diseases of Sakhalin residents with intestinal infections, several dozen workers at Odoptu and Chaivo became infected. Rospotrebnadzor and the prosecutor's office found violations in the canteens of workers' settlements. Obviously not in this dining room...

After lunch we will receive a safety briefing. It is not much different from the same mandatory procedure at, say, the Chayvo oil and gas plant and the Korsakov LNG plant. The presenter, Andrei Vasko, warns that equipment adjustment at Odopta continues, gas leaks are possible, so in addition to the usual ban on using cell phones, a warning is added to operators - the cameras can only be turned on after checking the air with a gas analyzer.

Wearing orange overalls with the word “Visitor” on the back, we first head to the “central control room.”

Today, the Odoptu field is operating in test mode, says Pavel Gorkin. Six wells have been drilled and are ready for operation, an 80-kilometer pipeline has been built to the Chayvo onshore complex, from where oil will be supplied via pipeline to the port of De-Kastri. The second phase of the Sakhalin-1 project is close to completion.

Meanwhile, the site is busy and quite crowded. It is still surrounded by buildings made of iron containers. During the most active phase of the project, at least four thousand people worked here - from various contracting companies. With the commissioning of the field, the number of personnel will be significantly reduced, and 70 percent of it will be Russian employees.

We go on a tour of the site. The first stop is at the production module, where the extracted oil will go through purification stages before entering the oil pipeline. But the first thing journalists photograph, as soon as Andrei Vasko allows them to turn on the cameras, is a torch in which associated gas and a reservoir of water are burned. The torch is slightly smaller than in Prigorodny...

The Hawk rig for drilling extended reach wells was built about eight years ago in Louisiana specifically for ExxonMobil. In disassembled form, it was delivered through the port of Korsakov to the Chayvo field, where by the end of 2008, with its help, the required number of wells was drilled, including one or two of record length. Then they dismantled it again and transported it on trucks 80 kilometers north - to Odopta. The reserves of this field do not lie as deep as at Chayvo, however, one of the wells drilled here is still the second longest in the project. "Hawk" is still considered one of the largest drilling rigs in the world. Odopta has been upgraded to operate and now uses ExxonMobil's patented accelerated drilling method.

The famous installation is shown to us from afar - the drillers from Parker Drilling do not like guests.

According to K. Cotton, drilling supervisor for Exxon Neftegas Limited, it takes about 60 days to drill one well. Now "Yastreb" is finishing work on the seventh well out of ten, which are planned for the first half of 2011. Then, it is possible that the installation will again continue to operate at the Chayvo field, where it will drill gas wells.

At the end of the press tour, we make an attempt to get acquainted with gray whales. We peer through the mesh fence into the Sea of ​​Okhotsk and sometimes notice low fountains among the waves. We, of course, did not see Steller's sea eagles, another object of protection by the developers of the Sakhalin shelf. But along the sandy road we noticed traces of foxes, of which, according to oil workers, there are many here.

Already late for the plane, we stop for a minute to photograph the torch and the drilling rig, which from a distance looks like a space rocket.

Odoptu deposit

Location of the deposit:

The Odoptu field is an oil and gas field located on the territory of the Russian Federation. It is located on the continental shelf of Sakhalin Island, at a distance of six to ten kilometers from the coast of the island. The Chayvo field is located 75 kilometers to the north. This field belongs to the Okhotsk oil and gas province. Administratively, it is part of the Okhinsky district in the Sakhalin region. It was at this oil and gas field that the first oil was obtained from this Sakhalin shelf. The oil and gas field consists of three domes – Southern, Northern and Central. The field is quite shallow, which creates certain difficulties during the drilling process. The operator at the Odoptu field is the large Russian company Rosneft-Sakhalinmorneftegaz.

Inventory data:

The level of initial recoverable oil reserves at the Odoptu field is estimated at 20 million tons. In 2008, oil production amounted to 1 million tons. Odoptu's 33 wells provide 50 percent of the daily production of Rosneft-Sakhalinmorneftegaz.

Field development history:

The Odoptu oil and gas field was discovered in the summer of 1998 by drilling well number 202. Deposits in the field are located at a depth of 1.3 to 1.5 kilometers. When developing this Odoptu field, directional wells were used for oil production. In 2009, the Odoptu field project entered a new phase of its development. Since 2010, industrial production of gas and oil has begun here. To date, thirty-three wells have been drilled on the northern dome of the Odoptu field, with column diameters ranging from 4348 to 7005 meters. At the beginning of 2011, a well was drilled here at an acute angle, which became one of the longest in the world - its length is 12,345 meters. It is called the deepest Kola superdeep well.

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