RU2171952C1 - Approach to increase efficiency of development of gascondensate-oil filed in region with underdeveloped transportation infrastructure - Google Patents

Abstract

FIELD: production of liquid and fluid gaseous media from wells. SUBSTANCE: invention specifically deals with processes of production of hydrocarbons with subsequent separation of materials extracted from wells. It can find use in process of development of gas-condensate and gas-condensate-oil fields. Technical result of invention lies in provision for inclusion of wide fraction of volatile hydrocarbons ( fraction C₂+C₃+C₄ ) in marketable products and their delivery to consumer. Stratal gaseous mixture extracted from cluster of wells and collected at cluster collection point is cleared from solid, liquid and gaseous impurities and separated into two phases: methane-ethane phase( (C₁+C₂) ) and propane- butane phase ( (C₃+C₄). Methane-ethane fraction is pumped into main gas line. Propane-butane fraction is pumped into same gas line by means of multistep cyclic treatment. On delivery to consumer gas mixture is separated into fractions and components if necessary. EFFECT: provision for inclusion of wide fraction of volatile hydrocarbons in marketable products.

Description

 The invention relates to the field of production of liquid and gaseous fluids from boreholes, and in particular to methods for producing hydrocarbons with the subsequent separation of materials extracted from wells, and can be used in field preparation and transportation of hydrocarbons in the process of developing gas condensate and gas condensate-oil fields.

 It is well known that a gas-liquid mixture (hereinafter referred to as GHS) extracted from productive formations of a gas condensate-oil field consists of a wide range of gaseous and liquid hydrocarbons and solid, liquid and gaseous impurities. In order to isolate commercial products from this mixture and deliver it to the consumer, the reservoir GHS is subjected to field processing (preparation), i.e., it is purified from solid, liquid and gaseous impurities, separated into phases and fractions, then the resulting hydrocarbon feedstock is transported to the consumer by known methods. The choice of the method of field preparation of gas and condensate for transport and the type of transport is determined by a number of factors, the main of which are the geological, geographical and climatic conditions of the field, the material composition of hydrocarbon raw materials, the presence of solid, liquid and gaseous impurities. At the same time, the maximum yield of a commercial product should be achieved and high quality and low cost of hydrocarbon raw materials should be ensured, and therefore its competitiveness in the domestic and foreign markets.

The specialized literature covers rather widely the issues of developing gas condensate and gas condensate-oil fields (hereinafter - GKN fields), production and processing of hydrocarbon raw materials, and transportation to its consumer [1, 2]. Extracted and collected from a group of wells, the reservoir GHS is cleaned of solid particles, water and other impurities. Then the methane-ethane mixture (fraction C ₁ + C ₂ ) is separated from the condensate, further purified from solid and liquid suspended particles, dried and sent to the main gas pipeline. Condensate (fraction C ₃ and higher) is first sedimented in water separators, then passed through special separators (to maintain the required pressure) and pumped into the condensate line, through which the condensate is transported to the consumer under its own pressure. If there is no condensate pipeline in the field, the condensate is delivered to the consumer by land (rail, road) or water transport. To this end, the condensate is separated into a liquid phase (fraction C ₅ and higher, i.e. a stable condensate) and a gas phase (propane-butane fraction C ₃ + C ₄ , i.e. an unstable condensate). Stable condensate is pumped into the oil pipeline, and unstable condensate is sent through condensers to storage tanks, from which tanks of land or water vehicles are loaded for delivery to the consumer.

 The described method of processing and transportation of hydrocarbon raw materials of the GKN field has a significant drawback - a prerequisite for its implementation is the presence of a condensate pipeline in the field, or the transport infrastructure must be sufficiently developed in the gas producing region. However, these conditions do not exist everywhere. Suffice it to say that in the Russian Federation over 300 GKN deposits have been explored for deposits located in regions that are unfavorable from the point of view of hydrocarbon transport to industrial centers. For example, a group of Vasyugan GKN fields in the Tomsk Region (Myldzhinskoye, Severo-Vasyugan and others) do not have a condensate line connecting these fields with consumers - the Tomsk Petrochemical Plant and TPP-3. The construction of a 530-600 km long Myldzhino-Tomsk condensate pipeline would cost Tomskgazprom about 400-500 million US dollars, which is unrealistic in the current economic conditions. There is no way to deliver condensate to Tomsk by land. This is due to the fact that the northern regions of the region are very boggy, which is why roads in the gas production region are almost completely absent. Condensate transport by water is also excluded, since the small rivers available in the deposit area are navigable for only 1-1.5 months, per year.

 In this regard, TomskNIPIneft has developed a project for the development of the Myldzhinsky GKN field, the essence of which is as follows [3]. This project was adopted by us as a prototype. Extracted from well clusters and collected at cluster collection points, reservoir GWFs are processed at integrated gas treatment plants (UKPG) and differential mixture separation units (UDSK).

In these plants, using well-known technologies, the reservoir GHS is cleaned of solid particles, water and other impurities and separated into phases and fractions: the liquid phase (fraction C ₅ and higher, or stable condensate), methane gas (C ₁ ) and fraction C ₂ + C ₃ + C ₄ or a wide fraction of volatile hydrocarbons (hereinafter - NGL). After appropriate treatment, stable condensate (fraction C ₅ and higher) is pumped into the oil pipeline, and drained gas (C ₁ ) is fed into the main gas pipeline, and NGL - due to the lack of a condensate pipeline in the field and the possibility of delivery to the consumer by land or water - are pumped into productive formations Place of Birth.

Obviously, a significant drawback of the technology developed by TomskNIPIneft is the irrational use of BFLH (fraction C ₂ + C ₃ + C ₄ ) - high-calorific fuel and valuable raw materials for the chemical industry. First, OAO Tomskgazprom suffers huge losses from the fact that about 300 thousand tons per year of valuable hydrocarbons are withdrawn from commercial products. Secondly, the injection of BFLH into the productive formations of the field is associated with significant energy consumption. Thirdly, in the event of unstable condensate falling in the bottomhole zone of the wells into the liquid phase, the production rate of production wells decreases sharply, and moreover, these wells can completely stop the production of gas condensate.

The task was set: in the absence of a condensate pipeline, land roads and waterways at the GKN field, to ensure the involvement of a wide fraction of volatile hydrocarbons (fraction C ₂ + C ₃ + C ₄ ) commercial products and their delivery to the consumer.

The problem is solved as follows. Extracted from the wellbore and collected at the cluster collection point, the reservoir GHS is cleaned of solid, liquid and gaseous impurities and divided into two phases - liquid (fraction C ₅ higher or stable condensate) and gas (methane - butane fraction C ₁ + C ₂ + C ₃ + C ₄ ). The liquid phase is subjected to degassing and pumped into the oil pipeline. The gas phase is dried and separated into two fractions: methane-ethane (C ₁ + C ₂ ) and propane-butane (C ₃ + C ₄ ). The methane-ethane fraction is pumped into the main gas pipeline. The propane-butane fraction is pumped through the same gas pipeline through multi-stage cyclonation. Upon receipt of the consumer, the gas mixture, if necessary, is divided into fractions and components.

The implementation order of the proposed technical solution is shown in the following example. GKN field is drilled by bushes of production wells. Each of the bushes consists of six peripheral production wells, opening the reservoir in the corners of the hexagon, and one central injection well. In the process of developing the field, reservoir GHS is selected from the producing wells, which is fed through plumes to the cluster assembly point. The reservoir GHS collected on the bush is processed at the integrated gas treatment unit (UKPG), where it is cleaned of solid, liquid and gaseous impurities and divided into two fractions: liquid (fraction C ₅ and higher) and gaseous (methane-butane mixture C ₁ + C ₂ + C ₃ + C ₄ ). The liquid phase is degassed and pumped into the oil pipeline. The gas phase is further purified from solid and liquid suspended particles, dried with a dew point of water vapor below the minimum operating temperature and separated into a methane-ethane fraction (C ₁ + C ₂ ) and a propane-butane fraction (C ₃ + C ₄ ). The separated methane-ethane fraction is pumped into the main gas pipeline. The propane-butane fraction is stabilized by multistage cyclonation due to thermodynamic processes occurring during cyclonation and pumped into the same gas pipeline. The gas mixture received by the consumer can be used as chemical raw materials. In this case, the mixture is separated by methane (C ₁ ) and NGL (C ₂ + C ₃ + C ₄ ) or by methane-ethane (C ₁ + C ₂ ) and propane-butane (C ₃ + C ₄ ). If the gas mixture is intended for combustion at thermal and power plants, then it is not divided into fractions.

Compared with the prototype, the proposed technical solution has the following advantages:
without exception, all hydrocarbons produced in the field are commercial products transported by pipeline;
excludes energy costs associated with the injection of BFLH into the reservoir;
the reliability and stability of producing wells increases;
there is no need to build a condensate pipeline, which significantly reduces the financial, material, labor and time costs for developing the field.

Sources of information
1. N. M. Bazlov et al. Preparation of natural gas and condensate for transport. - M .: Nedra, 1968, p. 140.

 2. N. G. Sereda and others. Satellite oilman and gasman. Directory. - M .: Nedra, 1986, p. 288.

 3. The project of pilot operation of the Myldzhinsky gas condensate-oil field. - Tomsk, TomskNIPIneft, 1996, p. 363.

Claims (1)

A way to increase the efficiency of the development of a gas condensate-oil field in a region with an undeveloped transport infrastructure is that the produced liquid mixture extracted from the wells and collected at the group collection point is cleaned of solid, liquid and gaseous impurities and separated into a liquid (fraction C ₅ and higher) and gaseous phase (methane-butane mixture C ₁ + C ₂ + C ₃ + C ₄ ), and the liquid phase is degassed and pumped into the oil pipeline, characterized in that the gas phase is further dried with a dew point of water vapor below the barrels of minimum temperature and are divided into two fractions: methane-ethane (C ₁ + C ₂ ) and propane-butane (C ₃ + C ₄ ), while the methane-ethane fraction is pumped into the gas pipeline, and the propane-butane fraction is stabilized by multi-stage cyclonation in a gas pipeline through which the gas mixture is delivered to the consumer, where, if necessary, it is separated by known methods into fractions and components.