Process Introduction

The multi-component thermal fluid huff-puff is a composite huff-puff recovery technology between steam (or hot water) and gas, and this technology adopts the burning spray mechanism used by the engine of space rocket, which takes the industrial diesel oil, crude oil or natural gas as the fuel, and then burns with the high-pressure air in the high-pressure combustion chamber of the rocket-power recovery equipment, and forms multi-component thermal fluid consisting of steam, CO2 and N2 for huff-puff recovery after adding injection water.

The synergistic effect of steam, gas or chemical agents, etc., is made full used for common offshore heavy oil, and it indicates that the productive results can up to 1.5 times of the conventional steam recovery through physical simulation and numeric simulation, and can up to more than 3 times of the conventional cold recovery capacity by applying multi-component thermal fluid huff-puff technology for offshore heavy oil.

Technical Applicability

Supporting Systems, Software and Tools

Supporting systems: Geological reservoir technology, thermal recovery and completion technology, thermal recovery technology design, ground equipment technology of thermal recovery, multi-component thermal fluid corrosion protection technology, gas channeling prevention and control technology, demulsification prevention and efficiency improvement technology;

Software: offshore heavy oil thermal recovery wellbore thermal parameter calculating software, optimization and design software for thermal recovery and injection string of multi-component thermal fluid, software for multi-component thermal fluid corrosion prediction, software for optimizing the thermal recovery and injection parameter of multi-component thermal fluid;

Tools: Down-hole safety control tool, injection-production two-way pollution prevention tool, high-performance insulation tool, uniform injection allocation tool at horizontal section.

Application

This technology has been implemented in some oilfield in Bohai Sea since 2008, including thermal recovery huff-puff of old wells, the primary, the secondary and the third round of thermal recovery huff-huff of new wells, with cumulative operation of 28 well-times, and the daily oil production is increased to 600 ton/day from less than 200 ton/day before cold recovery, with the recovery rate of up to 0.67%. The thermal recovery production capacity is increased by 1~2 times compared with that of cold recovery so as to develop the oilfields economically and efficiently.

Case Study

Some well in the southern area of N Oilfield is injected with 2,933 cubic meters of heat from May 9 to May 9, 2012, put into operation on May 27, which blew for 67 days, and the daily peak oil production reached 101 cubic meter/day, with cumulative oil production from open flow of 4,690 cubic meter; the thermal recovery capacity was 2.3 times of that achieved by the cold recovery at initial stage.

Process Introduction

The principle of the ultrasonic stimulation technology is indicated as follows: the power source of ultrasonic wave on the ground sends corresponding electrical power oscillation signal (electric pulse), transfers to the down-hole transducer via dedicated cable, and the transducer transfers the electrical power oscillation signal (electric pulse) into mechanical vibrational energy - ultrasonic wave. The mechanical vibration, cavatition and thermal function and others of the ultrasonic wave are utilized to eliminate the pollution at the immediate vicinity of the wellbore, improve the mobility of the crude oil, thus increasing the yield and the injection as well.

Technical Indicators

Technical Applicability

The technology has a wide range of applications, and is characterized by pollution-free to reservoir, low costs, simple to construct, short production time, and could cooperate to complete the conventional work-over operations, easy to operate and manage.

Process Introduction

The wellbore heating by electricity technology is to heat the wellbore crude oil by the "Skin Effect" of single-phase alternating current, and the technology would transfer the electric energy to the down-hole via steel armored cable, solves the problems in lifting the pump upward and the difficulty of heavy oil into pump by "heating along the steel armored cable" as well as "intensive heating by downhole electric heater" according to actual needs of oil well; relying on the auxiliary construction equipment, carry out electric heating for plugging removal without halt for a short period and long-term wellbore heating by electricity according to the production of oil well.

This technology is characterized by low costs, shorter working time, little occupation of land by equipment, quick results, etc, so it has better prospect of application for offshore oilfield.

Technical Indicators

Technical Applicability

Difficulty in wellbore lifting for recovery of heavy oil with “Three Highs”(high viscosity, high freezing point and high paraffin content).

Application

The wellbore heating by electricity has been used in some oilfields successively since 1990s, and has obtained better economic benefits.

Case Study

Well Z-12 (Mechanical recovery well with difficulty in pumping):

After this well adopts intensive heating at the horizontal section, the daily fluid output reaches 19.7 tons, water content of 67%, and daily oil production of 6.50 tons. After heating the horizontal section, as the temperature rise changes the oil-water mobility ratio at the immediate vicinity of wellbore, resulting in a decrease in water content and an increase in oil production, thus attaining the target of controlling the water-cut and improving the production.

Well S-14 (Flowing well with high freezing point and high paraffin content):

After this well adopts electric heater, the daily fluid production reaches 11.4 tons and daily oil production of 9.2 tons, preventing the crude oil from paraffin precipitation, and the oil well could maintain normal production steadily. This well maintains flowing continuously for 4 months and then changes to mechanical recovery.

Process Introduction

The superconducting thermal washing technology refers to a technique that uses superconducting heating device to heat the output fluid of oilfield, fresh water or sewage, seawater and other media, then inject into the oil well to flush the well in a cycle manner, remove the plugging of string, such as paraffin, etc., or inject the thermal fluid into reservoir directly to reduce the viscosity or eliminate the pollution at the immediate vicinity of wellbore. The heating temperature depends on the target well-hole and process design, which can be heated to 80～180℃.

The superconducting heating device is the key equipment for superconducting thermal washing technology, and the energy-efficient thermal superconducting technology adopted internally is a new environmental protection and energy-saving thermal transfer technology, which takes the new superconducting material as the heat-transfer medium, has overcome many drawbacks in the heat-transfer technology that takes the water as the carrier of heat transfer.

Technical Indicators

Technical Applicability

It is applicable to the oil wells plugged by organic matters and with wellbore shrinkage, such as plugging by gum asphaltic, paraffin precipitation, etc.

It can be applied to the oil wells plugged and polluted by organic matters at the immediate vicinity of wellbore.

Application

Currently, the superconducting thermal washing technology has gradually replaced the ordinary one, and has been widely applied.

Case Study

The CX Oilfield introduced the superconducting thermal washing technology in 2008, which took the output fluid of the oil well as the thermal washing medium for "non-destructive" thermal washing, and it has improved the thermal washing performance significantly, as there is no drainage period for oil well after the thermal washing, it could avoid pollution and secondary damages to the reservoir as well.

Process Introduction

The heavy-oil enhanced cold recovery refers to a series of stimulation technology performed in such manner that combines gas and chemicals on the basis of conventional heavy-oil cold recovery and water flooding, including chemical huff-puff, chemical viscosity reduction of wellbore, CHOPS, Vapex method, chemical flooding, CO2 injection method, flue gas injection method, etc.

Take the chemical huff-puff technology as an example, this technology squeezes a great amount of chemical huff-puff fluid into the reservoir, which could turn the oil emulsion into low-viscosity oil-in-water emulsion, reduce the oil-water interfacial tension and resistance of thin tubes, stimulate the flow of the deep heavy oil, and improve the rock surface wettability of the reservoir as well. The prevention and removal of the plug at the immediate vicinity of wellbore resulting from deposition of heavy organic matters could not only improve the yield of the oil well and the pump efficiency, but also play a role in absorption and wetting on the surface of the reservoir rocks, and prolong the period of validity for the chemical huff-puff viscosity reduction.

Technical Indicators

Technical Applicability

It is applicable to heavy oil well or heavy oil oilfield.

Application

Currently, the technology has been applied in Bohai Oilfields and some blocks of South China Sea.

Case Study

The Well AX implemented chemical huff-puff viscosity reduction in 2017, the oil production was 69.5 cubic meters/day after putting into operation, with an increase of 15.9 cubic meters/day over that before taking the measures, with an increasing rate of 29.94%; the daily fluid production was also improved by about 23.9 cubic meters/day as compared with that before taking the measures, with an increase rate of 42.9%, so the viscosity reduction measures have obtained a better stimulation results.

Process Introduction

The multi-component thermal fluid yield and performance improvement technology could dissolve the dissoluble paraffin, colloid, asphaltene and other organic deposition by the thermal-gas-chemical "plugging removal" and "performance improvement" of the multi-component thermal fluid, thus eliminating the shrinkage of oil pipe due to the organic deposition like paraffin, etc., as well as removing the pump-down plugging and the organic plugging of the sieve tube or at the immediate vicinity of the wellbore; meanwhile, the injected multi-component thermal fluid could reduce the viscosity of the crude oil effectively, improve its liquidity, make up energy for the formation, thus improving the production of low producing wells.

By studying and applying the yield and performance improvement technology, it could improve the production of offshore low producing wells by cold recovery, and enlarge the application of multi-component thermal fluid thermal recovery technology in Bohai Oilfields.

Technical Indicators

The oil production of a single well within a cycle is increased by more than 30% during the implementation on site, with the input-output ratio of more than 1:4.

Technical Applicability

It is applicable to low-viscosity stimulation well, the old oilfields with potentials, low-production and low efficiency wells.

Application

Complete technology program design for a total of 5 wells in Bohai Oilfield;

Complete the site operation for 1 well in Bohai Oilfields.

Case Study

The implementation of the yield and performance improvement technology in Well A-1 in Bohai Oilfield, verified that the multi-component thermal fluid yield and performance improvement technology could be implemented in old fields. No piercing-caused leakage occurred to the wellhead equipment during the thermal injection of this technology, and the string and tools could function properly, and the casing pipes were not prolonged due to heat, etc.; the electric pump could be started up smoothly, the output elements do not affect the demulsification on the rig/utilization of associated gas after the thermal injection.