Northwest Oilfield Scientific Research Team Multi-disciplinary Fusion Fine Review of Old Wells

Sinopec News Network reported on June 30 that the low-yield and low-efficiency well AT1-7 was operated through refilling and layer-changing measures, with a daily output of 34 tons of crude oil
.

This well was able to resume work because the scientific researchers "talked" with the oil well, "dialogue" with the formation, and formulated the best measures after understanding the real situation
.

Since the beginning of this year, Northwest Oilfield has implemented the "100 Wells and Thousand Tons" plan for suspended wells, which means that 100 suspended, low-yield, and low-efficiency oil and gas wells can restore 1,000 tons of production capacity per day
.

The scientific research team integrates multiple disciplines to finely review old wells, understand the oil-bearing information of the strata through which the well passes, and extract the oil and gas hidden in the reservoir in a targeted manner

Let old wells reveal the "new" sound and find new oil-bearing formations

This year, the TK7202 has been "emotional"
.

Its original target layer was an Ordovician carbonate reservoir with a depth of 5,500 meters, and later returned to the production of clastic reservoirs, but recently it "strikes"

Researchers communicated with it using logging data, and obtained the gamma curve, spontaneous potential curve, and caliper curve, which is the "Morse code" for cracking the lithology of the formation
.

The clastic reservoirs in the Northwest Oilfield are buried deep and have many layers.
Sandstone and mudstone are wrapped around each other, like a sheet cake.
With the help of this set of codes, the reservoir sand body can be clearly depicted from the mudstone pile
.

"If you want to make the formation'tell the truth' and make it clear whether it contains water or oil, you need to identify it through the resistivity curve
.

" said Zou Rong, a researcher at the Institute of Logging Technology, Northwest Oilfield Exploration and Development Research Institute

Through in-depth "talking", Well TK7202 "confessed": when the new well was muddled, oil and gas displays were missed in the 5236m to 5239m interval of the Carboniferous.
In addition, there were seven layers with oil and gas displays
.

Zou Rong continued to use density logging, neutron logging and sonic logging curves to communicate in depth with the reservoir, determine their true porosity, and grasp how much space the reservoir can hold for oil and gas
.

On this basis, the scientific research team determined that the TK7202 well still has a reserve potential of 20,000 tons of crude oil and 40 million cubic meters of natural gas.

Transition production is a good way to treat suspended wells and low-yield and low-efficiency wells
.

Sometimes, discovering a new horizon in an old well may bring about a new productivity position

Well S105-1 was drilled to a depth of 6021 meters, and the target layer was an Ordovician carbonate reservoir
.

At that time, when the new well was drilling and logging, there was no oil and gas display in many formations

Let the "isolated" strata open up and release oil and gas through reservoir modification

The Ordovician carbonate reservoir well TK1124 has been suspended for many years
.

Researchers used conventional logging, logging, and reservoir geological data, added special project nuclear magnetic resonance logging, established logging interpretation templates for complex reservoirs, and found oil and gas layers hidden 5,000 meters underground

Researchers used Archie's formula to determine the bottom of the reservoir and found that although the Carboniferous well has an oil saturation of less than 50%, there are still 30,000 tons of reserves available for exploitation
.

　　"The Carboniferous reservoir of this well is'isolated'.
The oil and gas are trapped in the stratum rock fractures and it is difficult to flow
.

" Zhang Xiaoming, director of the Institute of Logging Technology, said that they therefore designed a sand fracturing plan.

　　Since the beginning of this year, the scientific research team has deep "dialogue" with more than 200 parked wells, and found that 15 wells meet the reservoir reform standards
.

　　The transformation of the "solitary" formation started in 2015 in Well T902C
.
The target layer of this well is the Carboniferous, but the three layers of the Carboniferous are all poor layers, with small storage space and low oil saturation.
After drilling, only more than 1,000 tons of oil were produced
.

　　Well T902C expressed dissatisfaction through logging interpretation: "It's not that I can't, but that it needs special care
.
"

　　Researchers learned that the reservoir pores of this well contained calcium carbonate cements, so they were acidified and reformed to liberate oil and gas, increasing the total oil by more than 2,100 tons
.
In 2017, scientific researchers implemented sand fracturing reforms on this well, increasing oil production by 2100 tons again
.

　　Identify true and false oil-bearing reservoirs through "electrocardiogram" polygraph detection

　　On March 28 this year, the TK915-5X well, which was shut down well, was able to produce 15 tons of oil and 40,000 cubic meters of gas per day after the implementation of refilling and layer reforming measures
.

　　When this well was drilled, mud logging focused on identifying the Ordovician and taking into account the Carboniferous
.
Due to the weak Carboniferous oil and gas display, the well stopped lying after the Ordovician produced 24,500 tons of oil and 28.
66 million cubic meters of gas in the main producing layer
.

　　The scientific research team used the logging curve to “talk” with the oil well and found that the clastic reservoir has 8 layers, but only the Carboniferous contains oil and gas, and the other layers are water and dry layers.
The production risk of returning to the Carboniferous is relatively high.

.

　　The Northwest Oilfield Exploration and Development Research Institute unites the oil production plant to form a multidisciplinary joint research team of geology, geophysical prospecting, well logging, and reservoir engineering
.
Under the strong offensive of the joint team, the Carboniferous finally said the "truth": its top sand body is inclined upward, and there is a huge thick mudstone as the cap layer, which can form a favorable storage space, and the oil and gas fall along the fault from the source rock.
It migrates towards the sand body and is filled into the sand body, which can be enriched and accumulated
.
Therefore, they can rest assured that the Carboniferous reservoir of this well will be refilled and reformed
.

　　Since the beginning of this year, the Northwest Oilfield Institute has combined a total of 550 suspended wells and low-yield and low-efficiency wells.
More than 80 wells have been found to have potential formations.
At present, measures have been implemented for 30 well-times and a cumulative oil increase of 55,000 tons
.

　　Oil wells and formations sometimes "lie"
.
The resistivity of the Triassic upper oil group in Well S7203 reached the standard for oil and gas-bearing layers.
The oil production plant assigned an "expert" to ask whether it could perforate the upper Triassic upper oil group for production
.

　　The scientific research team analyzed in detail and found that the logging curve like the “ECG” of an oil well was abnormal.
Because of its low porosity and insufficient oil and gas charging, it created the illusion that the resistivity index was high and the measures were risky
.

　　In this review of the old wells, the scientific research team identified a total of 12 parked wells that "lied" to avoid invalid operation costs of 10 million yuan
.

　　(Zhang Yang Sun Zhaohui)