The pdf file of this paper is in Russian. To purchase the paper in English, order SPE-115643-MS.
The wells in the Tuscaloosa trend in South Louisiana are high-pressure high-temperature (HPHT) wells reaching as deep as ±23,000 ft, with a bottomhole static temperature (BHST) as high as ±400°F. In the past these wells were completed using conventional cementing techniques. In some cases, soon after the wells were put on production, the intermediate casing annulus would show an increase in pressure. Historically, this pressure is manageable and can be easily reduced through current procedures and practices. However, a project was undertaken to understand the underlying cause and then subsequently deploy a solution to prevent pressure on the annulus side.
The first task was to make sure that the annulus pressure was not caused by other problems such as wellbore stability, hole cleaning, and cement slurry placement. Then the next possible cause was damage to the cement sheath during subsequent well operations and production. A detailed study was done to investigate this possibility. Mechanical and thermal properties of the formation were derived from the log data and drilling data. Additionally, this data was evaluated to identify the depths and formations associated with significant gas shows at surface.
Possible failure mechanisms in the previous conventional cement sheath were identified. The cement system was modified to prevent such failure and the new cement system was designed and tested. The modified cement system was deployed in the field in April 2006, and the well was put on production a few months later, and since then has been on line and producing without annular pressure problems.
The techniques and solutions discussed in this paper can be applied to wells around the globe that have related problems. These solutions may help prevent annular pressure and improve the safety and economics of operating these wells.
The definition of oil displacement mechanism is one of major questions in problem of reservoir processes: or as mixed oilwater flow, when oil and water phase relative permeability (kro and krw) of water flood zones are specified; or as piston flow, when takes place frontal drive of oil by stream of approaching water.
Phase relative permeability for water and oil are usually defined on the basis of learning filtering of oil-water mixtures through a core. Just on the basis of such experiments the curves of phase relative permeability to oil and water are performed, which then used in the different design documents and projects of field development.
At the same time it is known, for example, that using modern methods of engineering inclusive reservoir simulation model are large difficulties at history matching with applying of such relative permeability curves of filtered fluids. Frequently forced variation of parameters of filtering at history matching results in concurrence of calculated and actual indexs to development at final parameters of filtering much distinguished from source, obtained in laboratory conditions.
It is necessary to mark also, that in the literature last years many papers have appeared that the core is a poor material that only on its basis to plan field development because of unrepresentative of coring, as a result of which it does not mirror property of all reservoir system; high created gradients of stresses at studies in laboratory conditions as contrasted to actual; strictly oriented directivity of flow of fluid through a core with impossibility of an estimation of anisotropy of formations on permeability and etc.
In a paper the features of extraction of oil reserves on some fields of Western Siberia are reviewed. Is shown, that as a whole on fields there are complex processes of fluid flow, where are formed as regions of water inrushes with consequent catastrophic watering out of individual wells, and zones of oil displacement with waterless wells, working a long time, and recovery of reserves in such zones much greater, than initial oil reserves in drained areas of these wells. It is impossible to explain by widespread assumptions about influencing reformative phase relative permeability or complex heterogeneity of oil reservoir. Formed zones of oil displacement to durable waterless operation of wells, as a rule, are connected with frontal drive. The examples of operation of some horizontal wells with high oil recovery factor (more than 0.5) in area of their
drainage. The results of numerous production and injection well testing and conducting of hydrolistenings testify to such nature of water-oil displacement.
The concrete offers on rational field development methods are made, when the piston condition of water-oil displacement is organized predominantly.
The pdf file of this paper is in Russian. To purchase the paper in English, order SPE-117087-MS.
This paper is devoted to the issues related to the strategy of development of an oil-and-gas accumulation of Cenomanian age. Vanyogan field is taken as an example (West Siberia).
Results of the conducted well tests and pilot work to develop a thin and highly-viscous oil rim in PK1-2 reservoirs at Vanyogan field demonstrate that it is impossible to develop this oil accumulation without its separation from the gas cap. Gas breaks through immediately from the gas cap to the producing wells.
One of the possible ways to develop this oil rim is barrier waterflooding.
The system of development via the barrier waterflooding (water injection into the gas-oil contact) may enable conditions preventing gas coning movement towards producing wells. However, to create the water barrier will require significant overcompensation (200-250 %).
Controlled gas production from the gas cap is a possible way to produce oil reserves at immovable GOC (gas-oil contact) and lower voidage replacement ratio. Decrease in initial oil-and-gas reserves ratio by a quarter, may provide lower level of compensation (about 150%) required for barrier forming.
Based on the projected system of development (barrier waterflooding) it is possible to use thermal methods by injecting hot water into a reservoir.
Analysis of simulation results manifests a significant loss of heat during the process of barrier forming due to dominating filtration of the working agent into a gas saturated part of the reservoir that is an evidence of low efficiency of the thermal stimulation.
Results of the steam injection lab studies (fresh water) demonstrate significant swelling of clay in the rock, multiple reduction of permeability and thus impossibility of using these methods in practice.
The optimal way to retain rheological properties of oil is to inject water heated up to the reservoir temperature.
The pilot program is underway to test the barrier waterflooding at the field and assess the efficiency of the thermal method on the representative areas of the accumulation.
Implementation of the program will enable to evaluate technological efficiency of the barrier waterflooding in combination with the thermal stimulation and prepare the object for the commercial development.
Institute of oilfield chemistry under Russian State University of oil and gas named after I.M. Gubkin in cooperation with BelNIPIneft, RUE «Production Association
«Belorusneft» have developed the technology of formation hydrochloric acid hydraulic fracturing combined with water shut-off in producing wells, exposing carbonate reservoirs.
It is known that during interaction of hydrochloric acid solutions and oil, containing big quantity of tars and asphaltenes sludging and formation of emulsions colmataging porous space of reservoir take place.
In our work we have used the ability of generating such compounds when hydrochloric acid contacts hydrocarbon gel, composed using gelling complex "Khimeco-H?? based on ferric salts of organic orthophosphoric ethers and stock (commercial) oil.
Hydrocarbon gels based on ferric salts of organic orthophosphoric ethers are obtained by dissoluting in hydrocarbon fluids gelling agent (mixture of alkylphosphoric ethers, mainly diakylphosphoric ethers) and activator based on ferrous compounds. As a result of interaction between gelling agent and activator we ontain ferric salts of organic orthophosphoric ethers which in their turn create associated complexes of molecular weight in hydrocarbons.
The pdf file of this paper is in Russian. To purchase the paper in English, order SPE-117372-MS.
This paper summarizes practical results of oil fields development by multilateral horizontal wells. By the example of Severo-Yangtinskoe and Chatylkynskoe oil fields the whole cycle of works from well-planning to development monitoring is described.
Severo-Yangtinskoe is one of the newest oil fields operated by the Company. Field Development Project regulating its development was drawn up and approved in Central Development Commission in 2006 after that production drilling of the main object began. All project decisions are based on reservoir simulation model. According to FDP, development scheme involves irregular placement of horizontal and subvertical wells.
Severo-Yangtinskoe reserves may be classified as difficult to recover; in practice it is problematic to involve such a deposit into development by conventional subvertical well schemes. During the two-year period of field development 8 horizontal wells have been successfully drilled and put on production, of which 3 are multilateral, that is the latest well completion technology probe-tested in the Company. This technology has been put into practice on the other Company's oil fields. Present work demonstrates and proves the advantages of complex reservoirs development by dual horizontal wells.
Chatylkynskoe oil field is also one of the newest Company's assets. FDP regulating the development was composed and defended in Central Development Commission in 2006. The pilot project specifies horizontal wells application as well as marginal waterflooding by deviated wells for the field development. The main reservoir has significant thickness, but its geological structure is complicated by tectonic disturbances and heterogeneity. All the decisions worked out are based on a reservoir simulation modeling. During the period 2006 - 2008 7 horizontal wells have been successfully drilled, 5 of which are dual wells.
General oil fields description
Severo-Yangtinskoe oil field belongs to Purovskij district of Yamalo-Neneckij autonomous okrug, Tyumen region, and is situated in the territory with well-developed infrastructure. (Fig.1)
In immediate proximity to Severo-Yangtinskoe field Umseyskoe and Muravlenkovskoe oil fields, operated by the Company, are situated. The area is located 32 kilometers south of Muravlenko town.
The pdf file of this paper is in Russian. To purchase the paper in English, order SPE-116905-MS.
This paper is the first in a series describing results and lessons learned from longer run life across 13,176 Electric Submersible Pump (ESP) systems in TNK-BP. ESP artificial lift is the dominant method for producing approximately 90% of TNK-BP's oil volume, which averages more than 200,000 tons (1.5 million barrels) per day.
A sustainable economic benefit for TNK-BP was defined during 2006, and this benefit directly results from increased ESP run life. The 5-year value was estimated at $350 million and long-term forecast was $1 billion. An indirect benefit from longer run life was better HSE performance due to reduced exposure to oil field hazards from fewer rig days pulling ESPs.
Since 2006, TNK-BP has gradually changed the way it thinks about ESP run life and lessons learned are provided in this paper as a case history.
ESP run life was about 300 days MTBF when the project started and the 5-year goal was set at 600 days MTBF by year end 2011. Elements for success included leadership structure, coordinated teamwork across multiple internal business segments and continuous equipment improvement using root cause failure analysis. Reducing frequent failures was a basic priority as was technical equipment innovation and pilot project expansions.
Results have been impressive with run life steadily increasing each month. Run life improved to 410 days MTBF during August 2008 from 296 days in January 2006. This 114 day run life increase has already prevented 550,000 tons (4 million barrels) of deferred oil, reduced $50 million of operating costs and saved rig time. The $350 million project value did not include redeployment of rigs to complete other oil enhancing work such as hydraulic fracturing and acid stimulations.
During 2004, TNK-BP joined the ESP-RIFTS Joint Industry Project. The ESP-RIFTS System allowed TNK-BP to further develop and implement a unified way to classify and analyze ESP data for a huge well stock. The result was strategic operating changes, one of which was stopping the purchase of the lowest reliability equipment. Failure analysis was fundamental in helping TNK-BP with its initiative to get the right equipment into the right well.
Kozin, A.A. (RN-SakhalinNIPImorneft) | Kuznetsov, M.A. (RN-SakhalinNIPImorneft) | Khamitov, I.G. (RN-SakhalinNIPImorneft) | Igumnov, V.I. (RN-SakhalinNIPImorneft) | Mukminov, I.R. (RN-UfaNIPIneft) | Azimov, T.A. (RN-Sakhalinmorneftegaz)
The pdf file of this paper is in Russian. To purchase the paper in English, order SPE-114436-MS.
The paper deals with the unique experience of Odoptu-more (Northern dome) field development by Rosneft. The field is located 5-7 km from the Shore of Sakhalin Island under the Sea of Okhotsk waters. Onshore extended-reach wells (ERW) with horizontal section are drilled in severe arctic conditions.
Similar ERD technology is used worldwide: in the North Sea (BP, Wytch Farm) , for example, on South China Sea shelf, at Tiera del Fuego coast (Total, Hidra field) . The successful experience of extended-reach drilling (ERD) gained by Rosneft since 1998 was adopted in 2003 by Exxon Neftegaz Ltd. - Sakhalin-1 Project consortium operator - who revised his initial plans of using expensive fixed sleetproof offshore platform and started Chayvo field development applying onshore ERW .
The paper describes the results of geosteering of ERW with up to 800 m long horizontal section in 3-4 m layer at 1500 m TVDSS. Horizontal displacement of 6000 m is typical for this wells. ERD in such geological conditions is a very delicate job considering geological uncertainties related to structure dip angle variation and reservoir discontinuity. It is the first successful application of ERD on the Russian shelf.
Moreover, paper touches upon the optimal object development pattern reasoning. Main design solutions that helped to avoid a number of problems connected with subsurface geology and technological restrictions are described.
The pdf file of this paper is in Russian. To purchase the paper in English, order SPE-117430-MS.
The information on the horizontal borehole geometry (size and shape) is needed in well logging interpretation and solving engineering tasks, for example, choosing a place for mounting a casing pipe seal. Direct application of mechanical driven logging devices such as used in a wire line caliper tool is impractical in horizontal boreholes. The borehole geometry can be determined by ultrasonic caliper operating in a pulse-echo pattern. Such techniques have been successfully used in wireline logging for borehole imaging and cement bond evaluation, but meet some obstacles in horizontal wells. A rugous borehole wall and low difference in acoustic impedances of formation and drill mud are the reasons of acoustic pulse high attenuation. In horizontal boreholes the logging tool is always decentralized and consequently the pulse travel time may be less than transducer ringing duration. These concerns with ultrasonic measurements lead to a task of finding a reflected signal amid overwhelming noise.
Using transducers similar to those of wireline scanners and applying robust algorithm to data processing can solve the task. The principal procedure of processing includes regular noise extraction by compiling waveforms of the neighboring depth steps in time domain. The search of reflected pulses in waveforms is provided by time windowing and finding the first reflections in frequency domain.
Application of described techniques in memory logging tool and data processing discovered a durable method of caliper measurements in horizontal boreholes. Field tests have demonstrated the capabilities of proposed logging method in borehole shape determination. Actually in more than a hundred boreholes average diameters were measured without discontinuities. The error of diameter determination was in the range of ±2 mm.
The results of field tests gave a hope for the ultrasonic caliper application to both borehole shape measurements and stress direction determination.
Abstract. This work shows the first experience of cyclic steam stimulations of vertical wells with radial horizontal bores in the deep heavy oil carbonates of the Usinsk Permian - Carboniferous reservoir.
In the end of 2006, more than 30 radial horizontal bores of approximately 100 m length each were drilled in 8 vertical wells, 5 of which were then stimulated by steam injection.
Radial drilling in low productivity carbonates without the following cyclic steam stimulations were ineffective because it did not resulted in significant increase in the well productivity.
Integrating radial drilling and cyclic steam stimulations proved highly effective by reducing oil viscosity. The average growth of oil rate was about 15.0 tones per day.
Introduction. Because of the rapid extraction of light oil, the problem of active development of heavy oil and bitumen reserves is becoming one of the most pressing for the petroleum industry in the new millennium.
Heavy oil and bitumen relate to unconventional sources of hydrocarbons which world's resources have already exceeded the resources of light oil and gas and equivalent to 600 - 800 billion tons of oil. It is expected that by 2025 unconventional sources of hydrocarbons will provide more than 20 % of the world oil production .
According to various estimates, Russian recourses of heavy oil and bitumen range from 30 to 75 billion tones.
The purpose of the paper is to propose a vessel design that could work in clear water open-sea and in ice-covered arctic environments with least ice-management requirement. With that aim, a state of the art non-ship-shaped circular FPSO design concept is described here that provides the capability for round-the-year drilling and production operations within Arctic Frontier Regions. The vessel is purposely sized with storage capacity to make it massive and to provide an inherent inertia and momentum to break ice effortless and to provide an economic solution to the industry.
The proposed arctic-class floating vessel has several advantages over fixed arctic-structures and over the existing floating designs proposed for arctic applications. The proposed vessel is independent of water depth in its operation, functions well both in ice-infested and clear water, is compliant to ice/ridges loads, and has ice-breaking capability by vessel induced swing. The vessel thus has both active and passive icebreaking mechanism built into the design concept.
The key vessel design challenges for the arctic applications are considered in developing the concept including ice- structure interaction, stability, storage, constant draft, motion, moon pool resonance, moorings and station keeping, flexible riser systems, disconnectable turret system, offloading operation, fabrication, transportation, and installation. The vessel hull with most of its topside load is designed such that it could be fabricated elsewhere and dry-transported on transportation vessel. During its operation, the oil /water ballast storage may be adjusted to maintain the same draft.
The capability to withstand and break the ice and ice ridge forces are built into the design more efficiently. This arctic class vessel is designed with a dis/re-connectable turret to support flexible risers and vessel moorings. Thus, dual mooring system is utilized. In the case of the very harsh environment beyond control, say with the threat of ice-bergs, the vessel could be disconnected & moved away, if needed, effortless with the help of the turret buoy system. The re-attachment of the turret is feasible. Overall, the proposed floating vessel is considered suitable for water depths ranging from shallow to deep water, suitable for harsh environment with/without ice. This paper presents the design of a non-ship-shaped FPSO adapted to deep arctic fields. For this study, the condition of the Russian Barents Sea and Sakhalin-V are selected. The vessel is designed to resist the first and second year sea ice and the large and deep ridges. The predominant and most innovative features of the vessel design are presented. Wave tank model test with 1:45 scale model was carried out to ensure the hydrodynamic properties of the vessel and its sea-keeping performance in waves for severe summer condition in the arctic sea. Innovative damping system is designed to control the near resonant response of the heave and the roll behavior of the vessel. Conical shaped moon-pool used is first of the kind in the technology to increase the heave natural period without spoiling the stability of the vessel.