Review of Artificial Lift in Egypt

One of the real challenges facing the oil industry in Egypt now, is to keep up production and maximize reserves especially in mature oil fields. The application of artificial lift systems to improve the productivity, whilst ensuring the most effective use of the existing reserves, should optimize the petroleum resources. A total of 137 oil and gas fields were placed on production since the oil industry in Egypt started in 1910. Currently there are 122 oil and gas fields on stream, among which 9 are gas production fields and the other remaining 113 are producing oil from 1311 oil wells. The natural producing wells are representing 15%, while the gas lifted wells are 24% and the pumped wells are 61%. This paper presents the philosophy and the methodology of applying artificial lift system in the Egyptian oil fields. Pending on the production forecast and the expected well behavior and also the effects of applying the secondary recovery mechanism either by water flood or gas injection. Also the problems encountered on well behavior are analyzed and solutions are suggested. Special emphasis is given to the marginal oil fields artificial lifting systems, because of the economical limitation accompanied with such field’s development costs. The concept is not only to equip a well with a cost effective means of artificial lift to be able to continue production, but also to manage the reservoir behavior for the maximum oil recovery. Introduction The decision of which artificial lift system to use, depends on many factors such as: the reservoir pressure, well depth and potential, type of the produced fluid. The most updated technology is being applied in the Egyptian oil fields, such as equipping oil wells with the suitable Artificial lift system: whether it’s gas lifting or submersible pumps operated electrically, mechanically or hydraulically. This decision is very important to the long-term profitability. An improper selection of artificial lift choice can reduce production and increase the operating costs substantially. Once a decision was made on the type to install on a well, it rarely can be altered whether the method selected was and still is the best choice for existing conditions. Of course a starting point in any selection process is to review the current practices. Fig (1) shows the spread of the oil and gas fields in Egypt. The map describes the seven major areas of the oil production as follows; The Gulf of Suez (GOS), Sinai, Eastern desert (E.D.), Western desert (W.D.), Upper Egypt, Nile Delta and Mediterranean sea. Fig. (2-A) and (B) shows the distribution of the natural flowing wells compared to artificial lifted wells; either by gas lift or pumping. A statistical survey for the Egyptian oil fields shows that: 28 % are gas lifted wells characterized as high rate wells, Electrical submersible Pumping system (ESP’s) are 31 %, about 38 % are on beam pumping and 3 % on Hydraulic and Jet pumps. Generally, the majority of the offshore wells in Egypt are on continuous gas lift or ESP. The major oil companies such as GUPCO, SUCO and PETROZEIT are using gas lift as a preferable system in offshore wells due to the abundance of gas and low operating cost. PETROBEL has used ESP in SINAI and offshore fields in the Gulf of Suez. This company is using also rod pumping system in the land wells, Agiba is utilizing all various kinds of pumps on its fields in the western desert. During the last year Agiba used the cavity pump driven by sucker rod in one well as a first trial and this application succeeded to reduce workover frequency and increase run life for one year. Table (1) represents the oil production companies in Egypt and statistics of the different types of artificial lift used in the different location of the oil fields. Table (2) represent a summarized comparison study between all types of artificial lift. Gas lift system Gas lift is one of the major artificial lift systems used extensively around the world and the most common system of artificial lift used in offshore fields in Egypt. It is Favorable for offshore fields due to flexibility in its production rates, ability to handle corrosive fluids, suitable for high temperature SPE 64508 Review of Artificial Lift in Egypt M. A. Naguib, SPE, SUCO, S.E. Shaheen, SPE, GEMPETCO, A. El-Wahab Bayoumi, N.A. El-Emam, Al-Azhar University 2 M.A. NAGUIB, S.E. SHAHEEN, A.BAYOUMI, N.A. EL-EMAM SPE 64508 and high gas oil ratio wells and compatibility with sand production. For all the above, the gas lift is the preferable technique for artificial lift in offshore fields in the Gulf of Suez. The Gulf of Suez contributes over 80% from the total oil production rate in Egypt. Most of the oil production from this area comes via gas lifted wells. The majority of these wells undergoes continuous gas lift. The continuous gas lift is recommended for high rate and high static bottom hole pressure wells and it is an excellent application for offshore classic type formations with water drive, or water flood reservoirs with good productivity. Also, the gas lift is very attractive especially in case of high pressure gas availability or where gas is low in cost. There are three major oil production companies in Egypt using gas lift in the Gulf of Suez area; these are GUPCO, SUCO and PETROZEIT. All GUPCO fields in the Gulf of Suez use gas lift as the most suitable technique for artificial lifting since 1965 and uptill now. Also SUCO used gas lift in the two main fields, RAS BUDRAN and ZEIT BAY fields since 1985. GUPCO has some fields in the Western Desert in Egypt, Abu El Gharadig field started with hydraulic pumping system as initial artificial lift and then converted to gas lift in order to maximize production with minimum operating cost. This process was done via rigless workover by making a port in the production string which was followed by installation of the proper gas lift equipment. Also, BAPETCO is using gas lift in two wells on its fields on W.D. area. Two case histories are available in this paper describing the advantage and limitations of the gas lift and describing analysis of the problems encountered and suggested solutions. Ras Budran field “SUCO” case history Ras Budran (R/B) Offshore field is one of the mature fields in Egypt “cumulative production over 200 MMSTB” consisting of massive Nubian sandstone. The field is producing from saturated reservoir where the production is maintained by gaslift while the pressure is supported by a combined water flooding and limited aquifer drive. The production started on April 1983 and the gas lift was introduced in 1985 as the most suitable technique for the field in order to maximize production. Fast depletion rate was observed, so water injection support started on November 1985 to maintain the reservoir pressure, improve the sweep efficiency, and support the lifting efficiency. Big efforts and engineering work were carried out in order to improve the lifting efficiency and maintain the production via continuous monitoring of the wells performance and optimization of the gas injection volumes. Many gas lift optimization studies were carried out either in-house or via consultants. SUCO stuff used special softwares for gas lift design and optimization like SAM and PIPE SIM. A routinely static and flowing bottom hole pressure and temperature surveys (SFPT) were used as a tool for monitoring and evaluating the lifting efficiency and to detect the point of injection (P.O.I.). According to the interpretation of these surveys, a suitable action was taken to improve the lifting efficiency according to the reservoir pressure and gas lift valves status. Fig (3) shows the temperature profile for a gas lift survey. Increasing water cut is considered as the main problem affecting the lifting efficiency and gas lift performance. This problem was encountered after the water break through has been occurred. SUCO made some modifications in the gas lift valves design in order to increase the gas injection volumes via using the ORIFCE or DOWEL ORIFICE valves as a (P.O.I.). However, these trials made a slight improvement but the problem is still not solved completely. A production logging tool was used to detect the watered out zones (gas lift string is open system). Through tubing bridge plug was used to isolate the watered out zones, most of all down hole jobs and recompletion were carried out via rigless workover. Later observations, following breakthrough of the injected sea water, revealed deposits of Calcuim, Barium and Strontium sulphate which resulted in plugging or partially plugging of the production strings and add a difficulty for retrieving the gas lift valves. Effective tubing cleaning job was carried out using preflush (diesel & xylene) followed by scale dissolver spotted at the gas lift mandrel. A new technique is also applied to use a coated gas lift valves in some wells and it is showed a good results in the changing out of the gas lift valves. Zeit Bay “SUCO” field case history The Zeit Bay field “ offshore and land wells” reservoir consists of sandstone and carbonates with a complex drive mechanism. The production commenced in 1984 A secondary recovery scheme of gas re-injection into the original gas cap was initiated to maintain reservoir energy and minimize pressure decline. Some wells in this field producing naturally and others are subjected to gas lift according to its productivity and reservoir pressure. According to the same reasons above and the availability of gas there are two system of the gas lift. The first is high pressure gas comes from gas plant after compression and the other is low pressure gas lift which comes from gas producers, Also the gas injection into gas cap comes via high pressure gas system. A successful conversion from natural flowing to gas lift by using concentric gas lift valves via rigless workover has been done. The most serious problem in this field is a severe corrosion was happened in the comple