Original title: Prescription for shale oil and gas pulse diagnosis
——State Key Laboratory of Shale Oil and Gas Enrichment Mechanism and Effective Development
Our reporter Cheng Lipei Correspondent Wang Haitao Ren Lili Liu Jiayi
With the rapid development of my country's national economy and the increasing dependence on foreign oil and gas, the discovery and acquisition of more oil and gas resources has become a major national strategic need.
In November 2015, the State Key Laboratory of Shale Oil and Gas Enrichment Mechanism and Effective Development was established in Beijing, jointly constructed by the Sinopec Petroleum Exploration and Development Research Institute and the Petroleum Engineering Technology Research Institute.
The laboratory pays close attention to the key technologies of shale oil and gas exploration and development, and carries out basic theoretical research with shale oil and gas enrichment, flow and formation mechanism of shale fracture network as the core, and innovative research with integrated exploration and development engineering technology as the main content.
Realize scale economic development of marine shale gas in southern China, deep marine shale gas, atmospheric marine shale gas in structurally complex areas, and marine-continent transitional facies-continental shale gas development, and continental shale oil at low oil prices Fruitful research results have been achieved in exploration and development, and won 2 first prizes for national scientific and technological progress and 3 second prizes for technological inventions.
"Frontline Laboratory" built on the well site
Shale oil is a petroleum resource that is stored in the pores and micro-fractures of shale.
It is difficult to produce and has not received attention for a long time.
Around 2010, after more than 30 years of long exploration in the United States, breakthroughs were made in the field of marine shale oil, bringing about a global energy revolution.
The successful exploration and development of shale oil and gas in the United States has triggered a global oil and gas technology revolution.
The laboratory director and academician of the Chinese Academy of Sciences Jin Zhijun said: "The transformation of shale oil and gas exploration and development from conventional search for traps to unconventional search for large-area continuous shale reservoirs has overturned the traditional trap oil and gas accumulation theory.
Although my country's terrestrial shale oil has a huge resource potential, it is not like the "natural beauty" of American marine shale oil, and it is difficult to apply the ocean theory.
Because continental shale oil is mainly deposited by lakes, the sediments vary greatly laterally, making them more viscous and difficult to flow, and the shale texture is relatively soft and difficult to fracturing.
Li Maowen, deputy director of the laboratory and senior expert of the group company, said: "The above characteristics have brought three problems to researchers: one is where there is more oil, the other is where the oil is easier to flow, and the third is where the formation is easier to fracture.
The most important experimental analysis object is the core, but there was no mature standard for sampling, storage, and analysis of shale oil core before, and everything had to be studied from scratch.
Because the light hydrocarbon substances and gases in the shale oil core are extremely easy to lose, the team moved the laboratory to the side of the well site, established a set of sampling specifications, independently developed experimental instruments, and turned the "hot" core into fresh Reliable data.
The team's self-developed frozen airtight pyrolysis device can be cryopreserved with liquid nitrogen at minus 200 degrees Celsius when the core is just drilled, and it can effectively preserve the light hydrocarbon gas in the pores even if high temperatures are generated during the core crushing process.
The self-developed magnetic fluid rock volume tester realizes the automation of the measurement process.
The volume has changed from a big guy that can only be carried by five or six people into a "suitcase", which has been produced and applied in many exploration areas in China.
Due to the need to take cores the first time they drill out, stationing at the well site and taking cores in the early morning has become commonplace for team members.
The team also strengthened the research on the occurrence, flow and enrichment mechanism of shale oil, formed a series of quantitative evaluation methods for shale oil resources classification and a sweet geological and geophysical prediction software platform, established a selection evaluation index system, and clarified the next step for shale oil exploration Focus and technology roadmap.
"The Occurrence Mechanism and Resource Classification and Evaluation Method of Terrestrial Shale Oil" won the first prize of the 2019 Sinopec Fundamental Prospective Research Achievement.
Open the "code lock" for efficient development of shale gas
In November 2012, with the gas flow from Well Jiaoye 1HF, my country's shale gas exploration and development progress was accelerated.
But at this time, the fine description and development technology research of shale gas reservoirs is almost blank in China, and a new path must be found.
In the past, the total porosity was only calculated in domestic and foreign logging interpretation, the method was simple but the result was not accurate enough.
After repeated experiments and research, the team innovatively proposed the "four-pore geological model" in which shale gas reservoirs develop organic pores, brittle mineral pores, clay mineral pores and micro-fractures.
Based on this theory, they developed the logging "four-pore components" Interpretation models, adopting different models to more accurately explain the content of free gas and adsorbed gas.
At the same time, a series of special processing and interpretation technologies for seismic data have been developed, which can carry out "geological-engineering double sweet spots" evaluation, and carry out fracture and fracture interpretation on different scales, especially horizontal fracture prediction.
Based on the fine description of shale gas reservoirs, a set of geological modeling technology has been established to perform fine description and three-dimensional characterization of shale gas reservoirs like CT.
A very important issue in shale gas development is how to accurately predict the productivity of gas wells and predict the production trend of gas wells.
This is the basis for demonstrating shale gas reservoir development plans and the key to scientific and profitable development of shale gas fields.
The laboratory organized research on the flow mechanism of shale gas development gas reservoirs, and finally established a set of unstable well test analysis, productivity evaluation and prediction, production performance analysis, and development technology reflecting the complex seepage characteristics of shale gas multi-stage fractured horizontal wells Policies, numerical simulation and other technical methods, independently developed a numerical simulation software (COMPASS) with shale gas and other unconventional oil and gas reservoir development simulation as the main feature while taking into account conventional oil and gas reservoirs, and applied it on site.
Yongchuan and other shale gas field development plans, capacity construction and production management provide strong technical support.
The equipment is the basis of the experiment.
The laboratory has independently developed 8 sets of experimental equipment, and at the same time introduced and developed high-precision equipment such as nano-CT and focused ion beam, integrated and established a set of high-precision shale gas geology-development-engineering experimental technology.
Among them, shale reservoir micro-nano mineral composition, pore structure and physical property analysis instruments are the observation "artifacts", which can clearly detect and show the minerals of very fine particles that cannot be seen by conventional microscopes, and pores as small as a few nanometers.
Distribution and connectivity characteristics; the shale field gas content analyzer has the characteristics of batch processing and high automation, which effectively avoids the loss of gas caused by the core being left for too long.
The full-diameter shale gas adsorption, desorption and depletion development physical simulation device can maintain the original structure of the core sample and simulate the shale gas flow process under the real formation temperature and pressure under the high temperature and high pressure of 70 MPa and 150 degrees Celsius.
Manual "high-speed channels" dredge the "underground road network"
Compared with conventional natural gas resources, southern my country’s marine shale gas reservoirs are deeper, older and more remodeled, and the surface is more complex.
The development technology is a world-class problem.
In recent years, through unremitting efforts, the laboratory has developed horizontal well drilling and completion and staged fracturing technologies with independent intellectual property rights and a full technology chain.
"From a microscopic point of view, a shale gas reservoir is equivalent to a dark chamber, with many dead ends and narrow passages.
It is difficult for the gas blocked in it to find a way out.
" The researcher told reporters, "Hydraulic fracturing is undoubtedly the most direct An effective mining method is to create an artificial “high-speed channel” to form an underground intricate “road network”, which provides a long-term stable high-speed channel for shale gas production and flow.
” Facing the huge changes in shale gas geological conditions, experiments The chamber takes the formation of multi-scale complex fracture network as the core and maximizes the effective reconstruction volume as the goal.
It adopts the overall idea of physical model + digital model, indoor + site, and launched a technology to greatly improve the effective reconstruction volume of shale multi-scale hydraulic fractures.
Tackling key research, innovative research and application in the identification and quantitative description of shale sweet spots, multi-cluster fracture equilibrium control, "well factory" parameter optimization, single well multi-scale fracture optimization, low-cost fracturing materials, and real-time rapid fracturing assessment, etc.
It has fully supported Sinopec's efficient development of shale gas.
Since 2016, relevant research results have guided the fracturing design and construction of 179 wells in the Fuling block, 3744 sections.
The process success rate is as high as 100%.
The cumulative increase of natural gas is 3.
763 billion cubic meters, which has achieved remarkable results in reducing costs and increasing efficiency; Deep and complex structural blocks such as Yongchuan, Dingshan-Dongxi, and Nanchuan have carried out field applications in multiple wells, and the process success rate has reached 100%.
Especially in the past two years, the laboratory has formed a new generation of shale gas high-efficiency fracturing technology with "multi-cluster dense cutting perforation + multi-stage temporary plugging + high-strength sanding" as the main body.
A number of advanced indicators have been achieved in the fracturing engineering of deep and infill adjustment wells, and a series of high-tech indicators for fracturing shale gas horizontal wells have been created, and the daily production of 310,000 cubic meters of deep shale gas wells with a vertical depth of more than 4,200 meters has been tested after compression.