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The Hassi R'mel field is a gas condensate reservoir with a rather significant oil rim on the eastern and southern peripheries. Producing wells were confronted by a severe salt deposit problem, more or less related to the exploitation regime, which severely reduced oil production or caused the well to shut in totally. The presence of sodium chloride inorganic precipitate in the well is undoubtedly influenced by:The type and quantity o water influx;Operating procedure; and,Reservoir characteristics, such as temperature and pressure. A permanent fresh water injection under a packer did not improve the performance of these wells. A large volume of water injection is required for particular wells, tubing intervention. This treatment tends to become a cost factor and these wells are then shut in. A study was undertaken in collaboration with the Research and Development Centre (CRD) at Sonatrach to solve the salt deposit problem in production due to the effect of temperature change. It consists of analyzing a sample of the formation water in order to understand the phenomenon of the salt deposit, to test the anti-deposition product efficiency, and to optimize its concentration under surface and bottom conditions, keeping in mind the reduction of the amount of injection water. Laboratory testing was undertaken first of all, in order to assess chemical water injection compatibility with formation water to ensure that the two fluids will not produce precipitates. It has shown that the alkylamide aqueous solution is used to prevent precipitation of sodium chloride crystals from high chloride brines from the bottom of the hole, changing crystal growth from symmetrical cubic orientation to a non-symmetrical dentritic type. Independently of entation to a non-symmetrical dentritic type. Independently of the temperature, its efficiency will also depend on the presence of other salts in the brine and the pH. The purpose of this paper is to show:The problem created by sodium chlorite salt deposits which impede the performance of a well; and,Solution adopted to improve the Productivity Index, by using chemicals to reduce deposits of salt. Introduction The Hassi R'mel field demonstrates well performance problems due to salt deposits. During production, when the temperature in the tubings charges, water cools abruptly and salt deposit are formed(1). Several studies were carried out to remedy and reduce these deposits of salts. In this study, we want to further examine methods to treat salt deposits in oil well production. The Hassi R'mel field is a gas condensate reservoir located 500 km south of Algiers. The field extends 80 km from north to south and 60 km from east to west, with a rather significant oil rim in the eastern and southern peripheries(Figure 1). The significance of the oil rim was highlighted with the drilling of well 8, which confirmed the existence of a significant accumulation of oil with good petrophysical characteristics and a great extention. The first producing well was drilled in 1979, and encountered a series of sandstone at an approximate depth of 2,200m.

The field of Hassi R' Mel is a gas condensate reservoir with a rather significant oil rim in the Eastern and Southern peripheries. Producing wells were drilled to develop the oil zone, unfortunately these wells are confronted to a severe salt deposit problem more or less related to exploitation regime perturbing oil rim production or shut in the well totally.The presence of sodium chloride inorganic precipitate is undoubtedly influenced by:-the type and quantity of water influx -operating procedures -reservoir characteristics such as temperature and pressure.A permanent fresh water injection under packer does not give improvement for these wells.A large volume is required for particular wells; the rapid salt deposition needs then a daily Coil tubing intervention. The treatment becomes a cost factor and these wells are then shut in.A study was undertaken in collaboration with the research and development center ( CRD ) to solve the salt deposit problem in the column of production due to temperature change effect . It consists to analyse a sample of the formation water in order to understand the phenomenon of the salt deposit, to test the anti-deposition product efficiency and to optimise its concentration under surface and bottom conditions; keeping in mind the reduction of the amount of the injection water.Laboratory testing was first of all undertaken, in order to assess chemical water injection compatibility with formation water to ensure that the two fluids will not produce precipitates. It has shown that the alkyl amide aqueous solution is used to prevent precipitation of sodium chloride crystals from high chloride brines from bottom of the hole, changing crystals growth from symmetrical cubic orientation to non-symmetrical dentritic type. Independently of the temperature, its efficiency will also depends on the presence of other salts in the brine and the pH.The purpose of this presentation is to show: Problem of sodium chlorite salt deposit which penalizes the good performance of a well.Solutions to adopt to improve the Index of productivity, by using chemicals to reduce deposit of salt.

Water flooding and gas coning are potential problems in the horizontal wells drilled to penetrate the oil column in the channel sands of the Hassi R'Mel field. This field is operated by Sonatrach, the Algerian National Oil Company. High Definition Induction Logging (HDIL) in such environments has been used to build a reliable geological model along the wellbore, identify potential problem intervals, and minimize the risk of perforating and producing gas and/or water. The new generation of induction tools - array induction tools - has an advantage of acquiring unfocused data that can be numerically focused to any part of the formation at the post-acquisition stage. Operating at low frequencies with relatively large transmitter-receiver spacings, the wireline array induction measurements can provide reliable information from geological targets up to a 6-m (20 ft) distance from the borehole, depending on resitivity contrasts. In horizontal wells, the induction data may be influenced by adjacent layers located above or below the reservoir. In such cases, when evaluating the water saturation in the near wellbore region, we must, firstly, correct for the influence of the remote layers. Secondly, after correcting the deep HDIL measurements for the presence of the borehole and invasion, we use them to determine both the distance to and the resistivity of remote beds. To integrate the HDIL results into the geological model, a number of issues must be considered. First of all, in the Hassi R'Mel field remote conductive shoulder beds may be either conductive shales or water-bearing horizons. Therefore, to distinguish between the two, their resistivities must differ and, in the interpretation stage, be compared with that of the remote shoulder bed interpretation. In addition, as the measurements do not have a sense of direction, they cannot distinguish between remote beds above or below. Interpretation of the location of an identified remote layer must therefore be based on the geological model for the field as well as other log data. Finally, although an interface between two resistive layers is more difficult to resolve, remote oil-gas contacts may in some cases be found from the interpretation. Presently, every logging job in Hassi R'mel includes an HDIL tool in a string, and the data are usually processed within 48 hours. Providing the geological model and perforating recommendations prior to well completion improves the economics of the well due to increase in oil production and the reduced cost of well recompletion. Introduction More than seventy years after formation resistivity logs were first recorded to identify the presence of hydrocarbons they have lost none of their importance. A particular challenge we face today is to interpret the response of resistivity instruments in deviated and horizontal wells, where formation layering is at a high relative angle or parallel to the wellbore.1,2 Horizontal and highly deviated wells have significantly increased our ability to efficiently produce hydrocarbons from formations where oil recovery otherwise would not be economical. For example, horizontal wells allow us to access the hydrocarbons in thin stratigraphic intervals or where they are sandwiched between an expanding gas cap and an active aquifer. Interpreting the response of today's modern array resistivity tools in these situations is critical to the drilling and formation evaluation process. In horizontal wells, the response of resistivity tools in even a simple layered formation is complicated and may differ significantly from our vertical well-based intuition. However, forward modeling and inversion techniques, from the simplest to the most sophisticated, can assist us with extracting the required information.

The objective of this study is to analyze the experience of drilling horizontal wells in Hassi R'Mel oil rim, Algeria. The excepted results are: higher well productivity, better oil recovery, lower water and gas coning, minimum cost of production operations and maximum profit. For the Hassi R'Mel oil rim, recovery of the oil using only vertical wells is difficult because water and gas coning result in low oil production rate and high cost of production operations. Then using only vertical wells exhibit a drilling of a large number of wells which could affect the profitability of the development project especially in the presence of thin oil thickness. A field development of Hassi R'Mel oil rim is needed, the technique of drilling horizontal wells is chosen as an alternative to some vertical wells, since horizontal wells provide options whereby pressure drawdown can be minimized, coning tendency can be minimized, high oil production rate can be achieved and consequently the cost of production operations can be reduced. The first horizontal well HRZ-01 in Algeria was drilled in 1991 in Hassi R'Mel oil rim. Since, many horizontal wells have been drilled based on the optimization simulation study of the Hassi R'Mel oil rim development. Eight horizontal wells were chosen for this study with the objective to analyze their performance and assess their profitability. Introduction The Hassi R'mel field is located approximately 500 kilometers South of Algiers in the Northern Grand Erg occidental of the Algerian Sahara. Early evaluations of the discovery by the drilling of well HR-1 in November 1956 revealed it to be one of the largest gas fields in the world which has an oil rim existing primarily along the Eastern and Southern margins of the field. Hassi R'mel oil rim is a thin oil thickness reservoir sandwiched between a large gas cap support and a bottom aquifer throughout the entire oil rim. The gross thickness of the oil column ranges from 3 to 12 meters with an average permeability of 500 md. All those factors made the necessity to develop the Hassi R'mel oil rim by implementing horizontal wells, in addition to vertical wells (Mixed Development Strategy), to improve the oil recovery in one hand, and to reduce water and gas coning problems. One of the main reasons for coning is pressure drawdown. A vertical well exhibits a large pressure drawdown near the wellbore, whereas horizontal well exhibits minimum pressure drawdown, thus horizontal wells provide options whereby pressure drawdown can be minimized, coning tendencies can be minimized, and high oil production rates can be achieved. For a vertical well, the majority of the pressure drawdown is consumed near the wellbore. Therefore, there is a big drawdown around the wellbore in a vertical well. In the case of horizontal wells, the pressure drop is fairly uniform throughout the reservoir near the wellbore, an extra pressure drop is observed. This pressure drop is, however, very small as compared to that around a vertical wellbore. For horizontal wells, due to low pressure drawdown, one expects a high oil production rate without water coning. In a reservoir with bottom water or top gas, rising water and downward movement of the gas cap can be controlled to obtain the best possible sweep of the reservoir. This is also called water cresting. With proper operating procedure, the bottom water drive for horizontal wells behaves very similar to a water-flood for vertical wells, resulting in very high recovery. A horizontal well provides an option not only to enhance initial oil-production rates, but also to obtain maximum possible ultimate reserves in a shorter time than a vertical well. The develoment and application of horizontal wells drilling thechnology is causing a revolution in the petroleum exploration and exploitation industry.