A waxy shale oil and gas dual-pipe gathering and transportation system and process

Abstract

The present invention relates to the field of oil and gas transportation technology, and discloses a waxy shale oil and gas dual-pipe gathering and transportation system and process. This system adopts a dual-outlet oil gathering and transportation pipeline from the well site / platform to the centralized processing station to adapt to the full life cycle production. In the early stage of waxy shale oil production, high-pressure and low-pressure oil and gas transportation paths are not distinguished. The first oil and gas transportation path and the second oil and gas transportation path are produced in parallel to adapt to the maximum production capacity scale to reach the flat peak; in the stable production period of waxy shale oil, the oil and gas produced by the high-pressure single well and the low-pressure single well are separated for production, thereby improving the oil and gas transportation efficiency from the well site / platform to the centralized processing station, and setting an intermediate two-way connecting path to guide the high-pressure oil and gas into the low-pressure oil and gas transportation path to avoid the low flow rate of the low-pressure oil and gas transportation path and easy wax precipitation. The system makes full use of the good low-temperature flow properties of waxy shale oil to improve the efficiency of the gathering and transportation pipeline and save energy consumption, thereby achieving energy consumption reduction and cost reduction in the full life cycle of the waxy shale oil gathering and transportation system.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas transportation, and in particular to a waxy shale oil and gas dual-pipe gathering and transportation system and process, which is suitable for the collection and processing of shale oil and gas produced by large platform well groups. Background Art

[0002] At present, foreign shale oil is mainly light oil and condensate oil, while domestic shale oil is mostly heavier medium crude oil and heavy crude oil. For example, the density of Jimusar shale oil in Xinjiang Oilfield is 0.875~0.940g / cm 3 The pour point is low and the maximum wax content is 12.4%. The density of Qingcheng shale oil in Changqing Oilfield, Ordos Basin is 0.85g / cm 3 The freezing point is low, the viscosity is low, and the gas-oil ratio is 90-110m 3 / t. The density of most shale oil in Jiyang, Shengli Oilfield, Bohai Bay Basin is 0.85-0.91g / cm 3 The density of Gulong shale oil in Daqing Oilfield, Songliao Basin is 0.8337g / cm 3 , low viscosity (15.6cp@50℃), pour point 35.8℃, wax content 24% and gas-oil ratio low 67m 3 / t. The average density of shale oil in Sinopec's Fuxing area is 0.774g / cm 3 , solidification point 24 ℃, wax content maximum 22.4%, and gas oil ratio average 1000m 3 / t, which is a waxy, high-pour point, light shale oil containing condensate. Domestic waxy, high-pour point shale oil gathering and transportation processes typically use single-tube heating or dual-tube liquid mixing (oil or water) gathering and transportation processes, with three-tube heating processes being less common. Using normal temperature, non-heating, or cold transportation gathering and transportation processes is more difficult, and currently, single-tube normal temperature gathering and transportation processes have only been achieved under conditions of high water content and low gas-oil ratio. Currently, the main waxy shale oil gathering and transportation processes at home and abroad are:

[0003] 1) Single-pipe oil closed gathering and transportation process

[0004] This waxy shale oil single-pipe gathering and transportation process is used at home and abroad, such as Figure 1 As shown, the process flow is often divided into heated and unheated gathering and transportation. This is often due to the crude oil's favorable physical properties, with a pour point near or above ground temperature, or favorable natural conditions in the oilfield, resulting in high oil well temperatures, a high gas-oil ratio, and a high water content. For example, crude oil from the Qingcheng shale oilfield in Changqing generally has a pour point of around 20°C and a viscosity of approximately 4.5 mPa.s at 50°C. When the water content is greater than 60%, a single-pipe unheated gathering and transportation process is employed. When the water content is less than 60%, platform-integrated heating facilities are employed to ensure that the terminal temperature of the gathering and transportation pipeline is 3°C above the pour point. A single-pipe heated gathering and transportation process is employed.

[0005] a. Waxy shale oil single-pipe unheated closed gathering and transportation process, such as Figure 1 shown

[0006] The gathering and transportation process involves single wells, single well metering, oil gathering manifolds, and centralized processing stations. Both the single well and the oil gathering manifold, and the oil gathering manifolds and the centralized processing station, are single-pipe oil gathering and transportation. Hot-wash interfaces and ball-drop wax removal facilities are installed on the platform's oil gathering trunk pipeline. Key technical parameters include a maximum oil gathering radius of 4.5 km, a single well production of 15 t / d, and a gas-to-oil ratio of 100 m³ / s. 3 / t, crude oil freezing point 20℃, wellhead oil temperature 10~20℃, wellhead oil pressure 1.0~1.5Mpa, gathering and transportation self-consumption gas 5m 3 / t. Advantages: Simple system, minimal energy consumption; low investment. Disadvantages: Pipeline wax removal relies on ball pigging, which requires daily pigging and heavy operational and management workload. In low-temperature conditions, heating equipment must be operated intermittently seasonally to maintain terminal gathering and transportation temperatures.

[0007] b. Single-pipe heating and closed gathering and transportation process for waxy shale oil

[0008] The process uses single-pipe oil gathering, platform heating, centralized metering, and a single-pipe oil gathering trunk pipeline to transport oil and gas to a centralized processing station. The oil and gas from the oil well (temperature less than 20°C) are first metered by single well selection and heated by the platform's integrated heating equipment before entering the centralized processing station through the oil gathering trunk line. A wellbore hot wash interface is installed at the wellhead, and a ball-dropping pigging device is installed on the oil gathering trunk line. The oil gathering pipeline from the wellhead to the heating furnace is insulated with an electric heating belt. Main technical parameters: Single well production return period 30m 3 / d~50m 3 / d, water content 100% to 50%; normal production in the first year is 35m 3 / day, water content below 50%; 15m 3 About 30% water content, gas-oil ratio 200m 3 / t, wellhead pressure 0.1MPa~2.0MPa, wellhead oil temperature 10℃~20℃, average oil gathering radius 4~5km, maximum oil gathering radius 8~9km, oil gathering terminal temperature 20~25℃, gas gathering and transportation consumption less than 10m 3 Advantages: Simple gathering and transportation system, low energy consumption; safe flow in the gathering and transportation pipelines. Disadvantages: High investment; complex system.

[0009] The single-pipe gathering and transportation technology is used in the development of shale oil in Changqing Oilfield, Xinjiang Oilfield and Shengli Jiyang. It is suitable for the gathering and transportation system from a single well to a centralized processing station. The oil wellhead pressure does not change much, and the gas-oil ratio is within 200m 3 / t of shale oil and gas, there are single-pipe gathering and transportation technologies such as single-pipe annular and single-pipe branch.

[0010] 2) Double-pipe water and liquid mixing (one oil pipeline + one water or liquid mixing pipeline) gathering and transportation technology, such as Figure 2 shown

[0011] In addition to the single-tube heating process, the Daqing Oilfield Gulong shale oil adopts a double-tube water injection process. This process is mostly a two-level station, namely a metering station and a centralized processing station (oil transfer or dehydration station). There are two pipelines from the wellhead to the centralized processing station, one is an oil gathering pipeline and the other is a water injection pipeline. The gas-liquid separation, sedimentation buffering, dehydration heating and water injection functions are completed in the centralized processing station. Main technical parameters: the water injection outlet temperature is 70°C, the temperature at the end of the gathering and transportation pipeline is 5°C higher than the freezing point of crude oil, the wellhead back pressure is not more than 1.0MPa, and the average single well water injection volume is 1.2m 3 / h~l.5m 3 The oil gathering radius is 2 to 5 km, and the station manages about 100 oil wells, with a maximum of 200.

[0012] Advantages: This process is highly adaptable, safe and reliable for waxy shale oil with high freezing point in cold regions. This process is widely used in Daqing Oilfield. Disadvantages: High investment and energy consumption, self-consumption gas is greater than 12m 3 / t oil.

[0013] Waxy shale oil fields currently in production are characterized by high initial liquid and oil production, followed by a decrease of over 50% in both oil and liquid production during the stable production period. This results in a lower gas-to-oil ratio and reduced gas production. This leads to significant excess capacity in the oil gathering and transportation pipelines for single- or dual-pipe water-blended gathering and transportation, resulting in reduced pipeline flow rates and increased wax deposition rates, making waxy shale oil transportation unfavorable and resulting in wasted investment. This is particularly true for condensate shale oil wells with initial pressures exceeding 20 MPa and later dropping below 12 MPa.

[0014] Therefore, in order to improve the efficiency of the gathering and transportation pipelines, save energy consumption, and make full use of the good low-temperature flow properties of waxy shale oil, the development of a gathering and transportation process with two oil-producing gathering and transportation pipelines for waxy shale oil can achieve energy consumption and cost reduction throughout the life cycle of the waxy shale oil gathering and transportation system, which is of great significance to the efficient development of shale oil and gas resources. Summary of the Invention

[0015] In response to the above-mentioned defects in the existing technology, a waxy shale oil and gas dual-pipe gathering and transportation system and process is provided. By utilizing dual oil gathering and transportation pipelines, the system can meet the production of outputs throughout the entire life cycle from the shale oil wellhead to the centralized processing station, thereby solving the problems of rapid production decline, short stable production time and large wellhead pressure changes in shale oil blocks, which in turn bring difficulties to the determination of ground gathering and transportation scale, the subsequent rolling development of high and low pressure oil and gas wells on the same platform for production, and the construction of oil and gas mixed transportation pipelines.

[0016] The technical solution adopted by the present invention to solve the above technical problems is:

[0017] A waxy shale oil and gas dual-pipe gathering and transportation system includes a well site or platform, and a centralized processing station, and is characterized in that: a first oil and gas transmission path and a second oil and gas transmission path connected in parallel are provided between the well site and the platform, and an intermediate two-way connecting path connecting the first oil and gas transmission path and the second oil and gas transmission path, both ends of the first oil and gas transmission path and the second oil and gas transmission path are respectively connected to the well site or platform, and the centralized processing station; the first oil and gas transmission path and the second oil and gas transmission path are respectively used as high-pressure oil and gas transmission and low-pressure oil and gas transmission, and according to the pipeline layout requirements, the first oil and gas transmission path or the second oil and gas transmission path is designated as the path for high-pressure oil and gas transmission; the intermediate two-way connecting path is opened according to demand to guide the oil and gas part of the high-pressure oil and gas transmission path into the low-pressure oil and gas transmission path.

[0018] According to the above technical solution, a number of single wells are provided in the well site or platform, and the output pipelines of the single wells are simultaneously connected to the first oil and gas transmission path and the second oil and gas transmission path; a pressure detector is provided in the output pipeline of each single well, and the single well is selected to be connected to the first oil and gas transmission path or the second oil and gas transmission path according to the oil and gas pressure produced by each single well.

[0019] According to the above technical solution, the first oil and gas transmission path consists of several first oil outlet lines, a first oil gathering manifold, and a first gathering trunk line. The output pipeline of each single well is connected to a first oil outlet line. The other end of all first oil outlet lines is connected to one end of the gathering trunk line through the first oil gathering manifold. The other end of the first gathering trunk line is connected to the centralized processing station.

[0020] The second oil and gas transmission path consists of several second oil outlet lines, a second oil gathering manifold, and a second gathering trunk line. The output pipeline of each single well is connected to a second oil outlet line. The other end of all second oil outlet lines is connected to one end of the gathering trunk line through the second oil gathering manifold. The other end of the second gathering trunk line is connected to the centralized processing station.

[0021] The output pipeline of a single well is connected to the first oil outlet line or the second oil outlet line according to demand, and the intermediate two-way communication path is connected between the first oil collecting manifold and the second oil collecting manifold.

[0022] According to the above technical solution, valves are provided at the connection between the first oil outlet line and the single-well oil outlet pipe, and at the connection between the second oil outlet line and the single-well oil outlet pipe. The valves open or close the valves at the connection between the first oil outlet line and the single-well oil outlet pipe, and at the connection between the second oil outlet line and the single-well oil outlet pipe according to the oil and gas pressure produced by the single well, and the situation of high-pressure or low-pressure oil and gas transported by the first oil and gas transmission path and the second oil and gas transmission path.

[0023] According to the above technical solution, skid-mounted well selection and metering skids are provided at the ends of the first and second oil gathering manifolds close to the single wells. The first oil outlet line is connected to the inlet of the skid-mounted well selection and metering skid, and the first oil gathering manifold is connected to the outlet of the skid-mounted well selection and metering skid; the second oil outlet line is connected to the inlet of the skid-mounted well selection and metering skid, and the second oil gathering manifold is connected to the outlet of the skid-mounted well selection and metering skid.

[0024] According to the above technical solution, a heating structure and a throttling structure are also provided in the single-well output pipeline, and the throttling structure is located after the pressure detector; the heating device is used to heat the output pipeline with a production oil and gas pressure of aMPa and above, where the value range of a is above 10, and the throttling device is used to throttle the oil and gas in the output pipeline to reduce the pressure.

[0025] According to the above technical solution, after heating, the temperature of the oil and gas output flowing out of the output pipeline is between 35°C and 45°C; it is necessary to ensure that the inlet temperature of the oil and gas output on the first oil and gas transportation path and the second oil and gas transportation path is controlled to be 3°C higher than the freezing point of shale oil.

[0026] A waxy shale oil and gas dual-pipe gathering and transportation process, characterized by comprising the following steps:

[0027] In the initial stage of production, each single well is connected to the closest path between the first oil and gas transmission path and the second oil and gas transmission path;

[0028] Heat the output pipeline of a single well with a production oil and gas pressure greater than aMPa, and adjust the heating temperature so that the temperature of the oil and gas output entering the centralized processing station is 3°C higher than the pour point of shale oil;

[0029] Throttle the oil and gas output of all single wells, and maintain the pressure at 4MPa to 5MPa after throttling;

[0030] During the stable production period, according to the pressure in the output pipeline of each single well, the optimal oil and gas transmission path is allocated according to the pressure, and the first oil and gas transmission path or the second oil and gas transmission path is set as the high-pressure oil and gas transmission path;

[0031] The output pipeline of a single well with a production oil and gas pressure greater than aMPa is heated, and the heating temperature is adjusted to match the oil and gas introduced from the high-pressure oil and gas transmission path to the low-pressure oil and gas transmission path, so that the temperature of the oil and gas output entering the centralized processing station from the first oil and gas transmission path and the second oil and gas transmission path is 3°C higher than the pour point of shale oil;

[0032] The oil and gas output of all single wells is throttled, and the pressure of the high-pressure oil and gas transmission path is maintained at 4MPa~5Mpa, and the pressure of the low-pressure oil and gas transmission path is maintained at 1.5MPa~2.0MPa.

[0033] According to the above technical solution, an electric valve is set in the middle two-way connecting path, and pressure sensors are provided in the first oil and gas transmission path and the second oil and gas transmission path. The opening and closing and opening degree of the electric valve are controlled according to the pressure in the low-pressure oil and gas transmission path detected by the pressure sensor.

[0034] The present invention has the following beneficial effects:

[0035] In the early stage of waxy shale oil production, since the oil and gas pressure in each single well is at a relatively high state, the first oil and gas pipeline diameter and the second oil and gas pipeline diameter do not distinguish between high-pressure oil and gas transmission paths and low-pressure oil and gas transmission paths, and the oil and gas produced by each single well are directly transported to the centralized processing station through the nearest first oil and gas transmission path or the second oil and gas transmission path; in the stable production period of waxy shale oil, due to the rapid production decline, short stable production time and large changes in wellhead pressure of shale oil blocks, the production oil and gas pressure of some single wells in the well site gradually fluctuates greatly, and the production oil and gas pressure of a considerable number of single wells is at low pressure. At this time, according to the distribution of all low-pressure wells and the optimal transmission path, the first oil and gas transmission path or the second oil and gas transmission path is selected as the low-pressure oil and gas transmission path, and the remaining path is used as the high-pressure oil and gas transmission path. Subsequently, the medium pressure in the low-pressure oil and gas transmission path is tested. When the pressure is too low, the intermediate two-way connecting path is opened to introduce the oil and gas part of the high-pressure oil and gas transmission path into the low-pressure oil and gas transmission path. The high-pressure oil and gas are used to disturb the flow of low-pressure shale oil and gas in the low-pressure oil and gas transmission path, avoiding wax deposition and extending the pipe cleaning cycle.

[0036] Based on the above measures, this system uses dual oil gathering and transportation pipelines from the well site / platform to the centralized processing station to adapt to full-life cycle production. In the early stages of waxy shale oil production, no distinction is made between high- and low-pressure oil and gas transportation paths. The first and second oil and gas transportation paths operate in parallel to maximize production capacity and reach peak production. During the stable production period of waxy shale oil, the oil and gas produced by high-pressure and low-pressure single wells are separated for production, improving the oil and gas transportation efficiency from the well site / platform to the centralized processing station. An intermediate two-way connecting path is also set up to guide high-pressure oil and gas into the low-pressure oil and gas transportation path, avoiding the low flow rate and easy wax precipitation in the low-pressure oil and gas transportation path. This fully utilizes the good low-temperature flow properties of waxy shale oil to improve the efficiency of the gathering and transportation pipelines and save energy. This reduces energy consumption and costs throughout the life cycle of the waxy shale oil gathering and transportation system, which is of great significance to the efficient development of shale oil and gas resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of a single-pipe gathering and transportation process for waxy shale oil in the prior art;

[0038] Figure 2 This is a schematic diagram of a double-pipe water-blending gathering and transportation process for waxy shale oil in the prior art;

[0039] Figure 3 It is a structural schematic diagram of an embodiment provided by the present invention;

[0040] Figure 4 It is a detailed diagram of an embodiment provided by the present invention;

[0041] In the figure, 1, well site or platform; 1-1, single well; 1-2, output pipeline; 2, centralized processing station; 3, first oil and gas transmission path; 3-1, first oil output line; 3-2, first oil gathering manifold; 3-3, first gathering and transmission trunk line; 4, second oil and gas transmission path; 4-1, second oil output line; 4-2, second oil gathering manifold; 4-3, second gathering and transmission trunk line; 5, intermediate two-way connecting path; 6, skid-mounted well selection and metering skid. DETAILED DESCRIPTION

[0042] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0043] Reference Figures 3 and 4 As shown, the present invention provides a waxy shale oil and gas dual-pipe gathering and transportation system, including a well site or platform 1, and a centralized processing station 2, a first oil and gas transmission path 3 and a second oil and gas transmission path 4 connected in parallel are provided between the well site and the platform, and an intermediate two-way connecting path 5 connecting the first oil and gas transmission path and the second oil and gas transmission path, both ends of the first oil and gas transmission path and the second oil and gas transmission path are respectively connected to the well site or platform, and the centralized processing station; the first oil and gas transmission path and the second oil and gas transmission path are respectively used as high-pressure oil and gas transmission and low-pressure oil and gas transmission, and according to the pipeline layout requirements, the first oil and gas transmission path or the second oil and gas transmission path is designated as the high-pressure oil and gas transmission path; the intermediate two-way connecting path is opened according to demand to introduce the oil and gas part of the high-pressure oil and gas transmission path into the low-pressure oil and gas transmission path.

[0044] In this embodiment, in the early stage of waxy shale oil production, since the oil and gas pressure in each single well is at a relatively high state, the first oil and gas pipeline diameter and the second oil and gas pipeline diameter do not distinguish between high-pressure oil and gas transmission paths and low-pressure oil and gas transmission paths, and the oil and gas produced by each single well are directly transported to the centralized processing station through the nearest first oil and gas transmission path or the second oil and gas transmission path; in the stable production period of waxy shale oil, due to the rapid production decline, short stable production time and large changes in wellhead pressure of shale oil blocks, the production oil and gas pressure of some single wells in the well site gradually fluctuates greatly, and the production oil and gas pressure of a considerable number of single wells is at low pressure. At this time, according to the distribution of all low-pressure wells and the optimal transmission path, the first oil and gas transmission path or the second oil and gas transmission path is selected as the low-pressure oil and gas transmission path, and the remaining path is used as the high-pressure oil and gas transmission path. Subsequently, the medium pressure in the low-pressure oil and gas transmission path is tested. When the pressure is too low, the intermediate two-way connecting path is opened to introduce the oil and gas part of the high-pressure oil and gas transmission path into the low-pressure oil and gas transmission path. The high-pressure oil and gas are used to disturb the flow of low-pressure shale oil and gas in the low-pressure oil and gas transmission path, avoiding wax deposition and extending the pipe cleaning cycle.

[0045] Based on the above measures, this system uses dual oil gathering and transportation pipelines from the well site / platform to the centralized processing station to adapt to full-life cycle production. In the early stages of waxy shale oil production, high-pressure and low-pressure oil and gas transportation paths are not distinguished. The first and second oil and gas transportation paths are produced in parallel to adapt to the maximum production capacity scale and reach the peak. During the stable production period of waxy shale oil, the oil and gas produced by high-pressure single wells and low-pressure single wells are separated for production, improving the oil and gas transportation efficiency from the well site / platform to the centralized processing station. An intermediate two-way connecting path is also set up to partially guide the high-pressure oil and gas into the low-pressure oil and gas transportation path to avoid the low flow rate and easy wax precipitation in the low-pressure oil and gas transportation path. Taking full advantage of the good low-temperature flow properties of waxy shale oil, it improves the efficiency of the gathering and transportation pipelines and saves energy. It achieves energy consumption and cost reduction throughout the life cycle of the waxy shale oil gathering and transportation system, which is of great significance to the efficient development of shale oil and gas resources.

[0046] Example 2

[0047] The structure and principle of Example 2 are similar to those of Example 1, except that a layout method of a high-pressure oil and gas transmission path and a low-pressure transmission path is provided, and the selection of the transmission path is determined by the distribution position of the oil and gas output of a single well in a well site or platform in a low-pressure state.

[0048] Specifically, a number of single wells 1-1 are provided in the well site or platform, and the output pipelines of the single wells are simultaneously connected to the first oil and gas transmission path and the second oil and gas transmission path; a pressure detector is provided in the output pipeline 1-2 of each single well, and the single well is selected to be connected to the first oil and gas transmission path or the second oil and gas transmission path according to the oil and gas pressure produced by each single well.

[0049] Example 3

[0050] The structure and principle of Example 3 are similar to those of Example 2, except that a preferred arrangement of the first oil and gas delivery path and the second oil and gas delivery path is provided.

[0051] The first oil and gas transmission path consists of several first oil outlet lines 3-1, first oil gathering manifolds 3-2, and a first gathering trunk line 3-3. The output pipeline of each single well is connected to a first oil outlet line. The other end of all first oil outlet lines is connected to one end of the gathering trunk line through the first oil gathering manifold. The other end of the first gathering trunk line is connected to the centralized processing station.

[0052] The second oil and gas transmission path consists of several second oil outlet lines 4-1, second oil gathering manifolds 4-2, and a second gathering trunk line 4-3. The output pipeline of each single well is connected to a second oil outlet line. The other end of all second oil outlet lines is connected to one end of the gathering trunk line through the second oil gathering manifold. The other end of the second gathering trunk line is connected to the centralized processing station.

[0053] The output pipeline of a single well is connected to the first oil outlet line or the second oil outlet line according to demand, and the intermediate two-way communication path is connected between the first oil collecting manifold and the second oil collecting manifold.

[0054] In this embodiment, the output pipeline of each single well is connected to the first oil flow line pipe and the second oil flow line pipe at the same time. A plurality of first oil flow line pipes and second oil flow line pipes are provided to connect all the single wells to the first gathering and transportation trunk line and the second gathering and transportation trunk line.

[0055] In the above-mentioned embodiment 3, valves are provided at the connection between the first oil outlet line and the single-well oil outlet pipe, and at the connection between the second oil outlet line and the single-well oil outlet pipe. The valves open or close the valves at the connection between the first oil outlet line and the single-well oil outlet pipe, and at the connection between the second oil outlet line and the single-well oil outlet pipe according to the oil and gas pressure produced by the single well, and the situation in which the first oil and gas transmission path and the second oil and gas transmission path transmit high-pressure or low-pressure oil and gas.

[0056] In the aforementioned embodiment 3, a skid-mounted well selection and metering skid 6 is installed at the ends of both the first and second oil gathering manifolds near the individual wells. The first oil outflow line is connected to the inlet of the skid-mounted well selection and metering skid, and the first oil gathering manifold is connected to the outlet of the skid-mounted well selection and metering skid. The second oil outflow line is connected to the inlet of the skid-mounted well selection and metering skid, and the second oil gathering manifold is connected to the outlet of the skid-mounted well selection and metering skid. In this embodiment, the skid-mounted well selection and metering skid is a detachable structure.

[0057] Example 4

[0058] The structure and principle of Example 4 are similar to those of Example 2, except that: to facilitate the transportation of oil and gas output, oil and gas output above the set pressure is heated, and all oil and gas output is throttled and depressurized.

[0059] Specifically, a heating structure and a throttling structure are provided in the single-well output pipeline, and the throttling structure is located after the pressure detector; the heating device is used to heat the output pipeline with a production oil and gas pressure of aMPa and above, where the value range of a is above 10, and the throttling device is used to throttle the oil and gas in the output pipeline to reduce the pressure.

[0060] In Example 4, after heating, the temperature of the oil and gas output flowing out of the output pipeline is between 35°C and 45°C; it is necessary to ensure that the inlet temperature of the oil and gas output on the first oil and gas transportation path and the second oil and gas transportation path is controlled to be 3°C higher than the freezing point of shale oil.

[0061] The present invention also provides a waxy shale oil and gas dual-pipe gathering and transportation process, comprising the following steps:

[0062] In the initial stage of production, each single well is connected to the closest path between the first oil and gas transmission path and the second oil and gas transmission path;

[0063] Heat the output pipeline of a single well with a production oil and gas pressure greater than aMPa, and adjust the heating temperature so that the temperature of the oil and gas output entering the centralized processing station is 3°C higher than the pour point of shale oil;

[0064] The oil and gas output of all single wells is throttled, and the pressure after throttling is maintained at 4MPa~5MPa.

[0065] During the stable production period, according to the pressure in the output pipeline of each single well, the optimal oil and gas transmission path is allocated according to the pressure, and the first oil and gas transmission path or the second oil and gas transmission path is set as the high-pressure oil and gas transmission path;

[0066] The output pipeline of a single well with a production oil and gas pressure greater than aMPa is heated, and the heating temperature is adjusted to match the oil and gas introduced from the high-pressure oil and gas transmission path to the low-pressure oil and gas transmission path, so that the temperature of the oil and gas output entering the centralized processing station from the first oil and gas transmission path and the second oil and gas transmission path is 3°C higher than the pour point of shale oil;

[0067] The oil and gas output of all single wells is throttled, and the pressure of the high-pressure oil and gas transmission path is maintained at 4Mpa~5Mpa, and the pressure of the low-pressure oil and gas transmission path is maintained at 1.5MPa~2.0MPa.

[0068] In this process, preferably, an electric valve is installed in the intermediate bidirectional communication path, and pressure sensors are installed in both the first and second oil and gas transmission paths. The opening and closing and opening degree of the electric valve are controlled based on the pressure in the low-pressure oil and gas transmission path detected by the pressure sensors. When the flow rate is too low, the pressure in the first or second oil and gas transmission path, which serves as the low-pressure oil and gas transmission path, will increase. Therefore, the pressure sensors are used to detect changes in flow rate.

[0069] Working principle of the present invention:

[0070] A dual-outlet oil gathering pipeline is used from a single well / platform to a centralized processing station to accommodate full life cycle production. Initial parallel production adapts to the maximum production capacity to reach peak levels, while production is separated at different pressures during the stable production period to improve pipeline transportation efficiency and avoid wax precipitation due to low flow rates. An intermediate two-way connecting path is used between the first oil and gas transportation path and the second oil and gas transportation path to control high-pressure oil and gas from entering the low-pressure pipeline, disrupting the flow of low-pressure shale oil and gas to avoid wax deposition and extend the pipe cleaning cycle.

[0071] The above are only preferred embodiments of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope of protection of the present invention.

Claims

1. A waxy shale oil and gas dual-pipe gathering and transportation system, comprising a well site or platform and a centralized processing station, characterized by: A first oil and gas transmission path and a second oil and gas transmission path connected in parallel with each other are provided between the well site and the platform, and an intermediate two-way communication path connecting the first oil and gas transmission path and the second oil and gas transmission path. Both ends of the first oil and gas transmission path and the second oil and gas transmission path are connected to the well site or the platform and the centralized processing station respectively. The first oil and gas transmission path and the second oil and gas transmission path are used for high-pressure oil and gas transmission and low-pressure oil and gas transmission respectively. According to the requirements of the pipeline layout, the first oil and gas transmission path or the second oil and gas transmission path is designated as the path for high-pressure oil and gas transmission. The intermediate two-way communication path is opened as required to guide the oil and gas portion of the high-pressure oil and gas transmission path into the low-pressure oil and gas transmission path. A plurality of single wells are provided in the well site or platform, and the output pipelines of the single wells are connected to the first oil and gas transmission path and the second oil and gas transmission path at the same time; a pressure detector is provided in the output pipeline of each single well, and the single well is selected to be connected to the first oil and gas transmission path or the second oil and gas transmission path according to the oil and gas pressure produced by each single well; A heating structure and a throttling structure are also provided in the single-well output pipeline. The throttling structure is located after the pressure detector. The heating device is used to heat the output pipeline with a production oil and gas pressure of aMPa or above, where the value of a is greater than 10, and the throttling device is used to throttle the oil and gas in the output pipeline to reduce the pressure. After heating, the temperature of the oil and gas output flowing out of the output pipeline is between 35°C and 45°C; it is necessary to ensure that the inlet temperature of the oil and gas output on the first oil and gas transportation path and the second oil and gas transportation path is controlled to be 3°C higher than the freezing point of shale oil.

2. The waxy shale oil and gas dual-pipe gathering and transportation system according to claim 1, characterized in that: The first oil and gas transmission path consists of a plurality of first oil outlet lines, a first oil gathering manifold, and a first gathering trunk line. The output pipeline of each single well is connected to a first oil outlet line. The other end of all first oil outlet lines is connected to one end of the gathering trunk line through the first oil gathering manifold. The other end of the first gathering trunk line is connected to a centralized processing station. The second oil and gas transmission path consists of several second oil outlet lines, a second oil gathering manifold, and a second gathering trunk line. The output pipeline of each single well is connected to a second oil outlet line. The other end of all second oil outlet lines is connected to one end of the gathering trunk line through the second oil gathering manifold. The other end of the second gathering trunk line is connected to the centralized processing station. The output pipeline of a single well is connected to the first oil outlet line or the second oil outlet line according to demand, and the intermediate two-way communication path is connected between the first oil collecting manifold and the second oil collecting manifold.

3. The waxy shale oil and gas dual-pipe gathering and transportation system according to claim 2, characterized in that: Valves are provided at the connection between the first oil outlet line and the single well oil outlet pipe, and at the connection between the second oil outlet line and the single well oil outlet pipe. The valves open or close the valves at the connection between the first oil outlet line and the single well oil outlet pipe, and at the connection between the second oil outlet line and the single well oil outlet pipe according to the oil and gas pressure produced by the single well, and the situation of high-pressure or low-pressure oil and gas transported by the first oil and gas transmission path and the second oil and gas transmission path.

4. The waxy shale oil and gas dual-pipe gathering and transportation system according to claim 2, characterized in that: A skid-mounted well selection and metering skid is installed at the end of the first oil gathering manifold and the second oil gathering manifold near the single well. The first oil outlet line is connected to the inlet of the skid-mounted well selection and metering skid, and the first oil gathering manifold is connected to the outlet of the skid-mounted well selection and metering skid; the second oil outlet line is connected to the inlet of the skid-mounted well selection and metering skid, and the second oil gathering manifold is connected to the outlet of the skid-mounted well selection and metering skid.

5. A waxy shale oil and gas dual-pipe gathering and transportation process, characterized by: The waxy shale oil and gas dual-pipe gathering and transportation system as claimed in any one of claims 1 to 4 comprises the following steps: In the initial stage of production, each single well is connected to the closest path between the first oil and gas transmission path and the second oil and gas transmission path; Heat the output pipeline of a single well with a production oil and gas pressure greater than aMPa, and adjust the heating temperature so that the temperature of the oil and gas output entering the centralized processing station is 3°C higher than the pour point of shale oil; Throttling of oil and gas output from all single wells, maintaining the pressure at 4MPa~5MPa after throttling; During the stable production period, according to the pressure in the output pipeline of each single well, the optimal oil and gas transmission path is allocated according to the pressure, and the first oil and gas transmission path or the second oil and gas transmission path is set as the high-pressure oil and gas transmission path; The output pipeline of a single well with a production oil and gas pressure greater than aMPa is heated, and the heating temperature is adjusted to match the oil and gas introduced from the high-pressure oil and gas transmission path to the low-pressure oil and gas transmission path, so that the temperature of the oil and gas output entering the centralized processing station from the first oil and gas transmission path and the second oil and gas transmission path is 3°C higher than the pour point of shale oil; The oil and gas output of all single wells is throttled, and the pressure of the high-pressure oil and gas transmission path is maintained at 4MPa~5Mpa, and the pressure of the low-pressure oil and gas transmission path is maintained at 1.5MPa~2.0MPa.

6. The waxy shale oil and gas dual-pipe gathering and transportation process according to claim 5, characterized in that: An electric valve is set in the middle two-way connecting path, and pressure sensors are provided in the first oil and gas transmission path and the second oil and gas transmission path. The opening and closing and opening degree of the electric valve are controlled according to the pressure in the low-pressure oil and gas transmission path detected by the pressure sensor.

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