Recently, steamflood and immiscible CO2 field pilots in a heavy oil reservoir in the Ikiztepe field, Turkey were successfully completed by Japan National Oil Corporation and Turkish Petroleum Corporation in collaboration with Japan EOR Research Association. The 1, 400m deep formation is a layered carbonate with 4.3-13.2°API heavy oil with a viscosity of 936mPa. s@Tres=50°C. The primary production by natural depletion was less than 1%. Though the viability of known EOR processes under such adverse reservoir conditions remained uncertain, field pilots were decided to be conducted, since the EOR technologies would give a large impact on recovery of heavy oils in southeastern Turkey. Both steam and CO2 processes employed inverted 5-spot pattern in areas of 100m×100m and 200m×200m, respectively. High pressure and temperature steam was injected through insulated tubing. After the initial cyclic steam stimulation, continuous injection and production followed. A total of 81, 400 CWEbbl steam was injected and 26, 200bbl of oil was recovered. Low injectivity of the steam and a vertical fracture created during the operation caused lower sweep efficiency. As the thermal conductivity of the insulated tubing was deteriorated with time and injection pressure, significant amount of heat was lost in the wellbore. Due to ultra high temperature, scaling of silica compound caused low operational time of the steam generator. The CO2 gas obtained from a neighbouring field was subjected to a membrane separation process to raise its purity to over 90%. The continuous injection of CO2 was preceded by three cycles of CO2 huff'n puff. A total of 340 MMSCF gas was injected which resulted in the recovery of 17, 000bbl of incremental oil. Production data indicated that the higher the CO2 gas purity and injection pressure, the higher was the oil recovery due to increased gas solubility into the reservoir oil. A good simulation history match has been obtained for each process. Additional post-pilot simulation studies included various approach, such as utilizing horizontal wells and injection strategy including a combined steam-CO2 process.
Construction of a natural gas pipeline from Niigata to Sendai was completed in March 1996. Pipeline construction consists of engineering works such as civil engineering, material technology, welding technology and so on. This lecture presents the following items regarding the engineering works to be overcome and some technical skills associated with the project are introduced. i) Seismic design ii) Material technology, welding technology, field bending iii) Bridge design, tunnel design iv) Leak detection
“Russia” is recognized as an imporant investment opportunity by the international oil industry. One of the momentous events in the recent Russian oil industry is the adoption of the Law on the PSAs (PSL) in December 1995. In June 1996, the two PSAs for the Sakhalin-1 and Sakhalin-2 project became effective based on the grand-fathering clause in the adopted PSL. The opportunities to be pursued under the PSAs in the future, on the other hand, need the adoption of so-called Enabling Law. Further, the number of PSA projects will be restricted. The upstream investment opportunities in Russia, therefore, will be pursued in the from of PSA and conventional Joint Venture (JV). This paper discusses the recent developments of the Russian upstream industry from the view point of PSA and conventional JV.
Among the hot latin American countries, Venezuela is one of the most attractive nations in the oil industry. It is known for it's huge hydrocarbon reserves and the Orinoco Belt has future potential. Venezuela's oil resources have been nationalized since 1976, however, several new programs related to upstream business have been put into schedule recently without amending the nationalization scheme. Opening the Venezuelan oil industry to foreign investors has been accelerating since 1992, starting with the First Marginal Field Reactivation Program (3 projects), followed by Second Marginal Field Reactivation Program (11 projects), Profit Sharing Contract for New Area Exploration (8 projects), and Third Operation Agreement (in process). Additionally, other foreign investments have been involved in Strategic Association projects for LNG and heavy oil (6 projects). This lecture will outlines the Venezuelan oil industry, particularly in the upstream. Also some important issues in conducting operations and in making investments are discussed. First, social and economical uncertainties including local currency's unstableness, corruption, high inflation rate, and safety issues, second, very protected labor unions and other problems related to human resources, third, strict environmental regulations and time consuming approval process are summarized. These are not unique issues in this country, however, the overall investment environment can be considered to be fair. Due to the country's geographic position, Venezuela has kept a close relationship with the U.S., however, it is worth considering Venezuela as a key country that we should keep a close eye on for future business possibilities.
The sulfur content and sulfur isotopic composition of crude oils have been determined for 82 samples from the oil-field region of northeastern Japan. The sulfur content of crude oils lies in the range of 0.01 to 0.56wt% with a mean value of 0.28wt% and the sulfur content of condensates is usually less than that of oils. The δ34S value of crude oils ranges from -4.6 to +13.3‰ relative to CDT. The δ34S values in the Akita district show a bimodal pattern and those in the Niigata district are divided into three groups. Oils from the Iwafune-oki oil field have the heaviest δ34S value, while crude oils from the West structure of the Aga-oki oil and gas field have the lightest. Crude oils from each field are characterized by a narrow range of δ34S values, although both sulfur content and δ34S value of crude oil are affected by secondary alteration processes such as water washing and biodegradation. The δ34S value of each field shows both regional and local variations which may be attributed to the heterogeneity of sulfur in source rock. These facts suggest that the δ34S value of crude oil is useful for oil-to-oil correlations.
The author discusses and stresses the applicability of heavy mineral composition as a useful marker to characterize or identify the individual turbidite sandstone bodies based on the detailed and systematic heavy mineral analysis of many Neogene turbidite sandstone bodies in the Neogene Niigata oil basin, central Japan. Main results are summarized as follows: 1) Each turbidite sandstone body, corresponding to a formation or member, yields the same or common characteristics of the heavy mineral composition, that is, each body can be represented by the specific, but generalized heavy mineral composition. However, the different sandstone bodies are often composed of different heavy mineral composition. 2) Based on the combination of specific heavy minerals, heavy mineral composition of these sandstones are classified into several types. Each turbidite sandstone body is represented by one type or closely related two types. 3) The heavy mineral analysis of turbidite sandstones often yields a very important key or a new information in disclosing their sedimentary process, especially when its results are combined with results by sedimentological analysis such as facies analysis, paleocurrent analysis and so on. 4) As a conclusion, the analysis is very valuable not only as a conventional tool to estimate the provenance, but also as a strong measure to estimate the original relationship of several sandstone bodies neighboring each other, to disclose their sedimentary process with other sedimentary data, and to predict the three-dimensional extents of turbidite sandstone bodies both on the surface and subsurface by using samples from outcrops and from boring cores or cuttings.
Underbalanced drilling is one of the quickly developing technologies in the world. It enables to lower the development cost by increasing the oil production per well and by avoiding the possibility of drilling hazards such as lost circulation, differential sticking. Further, production impairment reduction is significant in underbalanced drilling because no fluid invasion occurs. This paper introduces the outline of underbalanced drilling in its history, advantages and disadvantages of the technologies, various fluid systems used with, etc.