Northeast oil and gas tight clastic gas reservoir wells have consecutively achieved productivity breakthroughs

China Petroleum and Chemical News.
com recently, following the North 217-4HF well in the volcanic rock gas reservoir of the Northeast Oil and Gas Longfengshan Gas Field, which achieved a daily production capacity of 100,000 cubic meters, the tight clastic gas reservoir wells in the gas field have also achieved production breakthroughs
.

Among them, the North 201-32HF well produced 66,000 cubic meters of natural gas and 21 cubic meters of condensate per day after fracturing, which was the highest productivity gas well in the Yingsansha Formation; the North 210-7HF well produced 184,000 cubic meters of natural gas and condensate per day after fracturing.

Finely depict the sand body, optimize the well trajectory, and increase the drilling encounter rate of the reservoir

The clastic gas reservoir in Longfengshan Gas Field has complex structures, well-developed faults, rapid lateral changes in sand bodies, and strong heterogeneity
.

In the early stage, horizontal wells deployed under the "group-section-sand group-small layer" stratigraphic framework were short horizontal sections, low effective reservoir drilling rate, and failed productivity tests, which could not meet the requirements for efficient development of tight clastic thin gas layers.

The technicians have finely described sand bodies from multiple sets to single sets, deeply studied the development characteristics of clastic sand bodies, explored the development rules of single sand bodies between wells and the interlayers between sand bodies and sand bodies, and refined the connection relationship of sand bodies.
Delimit a favorable single sand body
.

At the same time, they used the 3D geological modeling technology under the constraint of the inversion volume to realize the single-sandbody plane prediction, and focused on the deployment idea of ​​“fewer wells and high production”, and deployed the North 201-32HF well and the North 210-7HF in the predominant facies zone.

In the process of horizontal well drilling and tracking, technicians aim at the geological difficulties of the two wells, according to the top and bottom surface boundaries of the gas reservoir, use GR pseudo-acoustic while drilling technology and formation true thickness correction technology to correct the geological model of the positive drilling and guide the wellbore The trajectory is optimized and adjusted so that the target half-height does not exceed 1 meter, the target half-width does not exceed 5 meters, and the deviation angle of the well does not exceed 0.
5 degrees
.

By leveraging the advantages of integrated and coordinated research, the actual drilling of Well Bei 201-32HF made a total of two trajectory adjustments, with a reservoir drilling rate of 71%, and Well Bei 210-7HF made a total of 1 trajectory adjustment, with a reservoir drilling rate of 78.
%, to lay a solid foundation for subsequent fracturing reconstruction
.

　　Strengthen technical research, improve process details, and ensure safe and rapid drilling

　　Drilling construction in clastic gas reservoirs has problems such as slow drilling speed, long cycle, easy leakage, and large friction.
In addition, the surface conditions of the Longfengshan gas field are complex, and some horizontal wells need to be greatly twisted
.

Geological engineering and technical personnel closely combined, and carried out targeted speed-up series based on high-efficiency PDC shearing and breaking rock, drilling fluid leakage prevention and plugging, water-based drilling fluid lubrication capacity optimization, and dual two-dimensional horizontal well bore trajectory design And other technical research

　　In the stage of single well optimization design, they predicted the possible complex situations during drilling construction, changed "encounter battle" into "position battle", strengthened on-site real-time tracking, and carried out technical clarifications on site before complex situations occurred, and refined the differences.
Countermeasures under leakage conditions
.

In order to better adapt to the clastic reservoirs, they continuously improved the technical details of the engineering technology, increased the bending angle of the horizontal section power drilling tool from 1.

　　A total of 5 losses occurred during the drilling of Well Bei 201-32HF, including 3 permeability losses and 2 reversion losses.
The technicians combined the loss mechanism of clastic rock reservoirs with supporting leakage plugging while drilling + bridging plugging.
Technology, successfully plugging the leaks all at once
.

They also promoted the application of "dual two-dimensional" well trajectory, which solved the problem of complex surface conditions and ensured the degree of reserves control; designed vegetable oil + mineral oil mixed lubrication technology, the lubrication coefficient was increased by 24.

　　In Well Bei 210-7HF, technicians used high-efficiency PDC drill bits with 5 blades, 3 rows of teeth, and special-shaped teeth to solve the problem of premature failure of PDC drill bits; changed the speed-up thinking and matched high-torque screws to provide torque for high-efficiency drill bits; adopted large parameters The drilling technology guarantees the rock-carrying capacity of large wellbore drilling.
The average mechanical drilling speed of the whole well is 8.
2 m/h, and the drilling and completion period is 75.
4 days
.

　　Iterative optimization experience, supporting superior technologies, and fully releasing gas reservoir productivity

　　The tight clastic reservoirs in the Longfengshan Gas Field have long brought huge challenges to reservoir reconstruction, such as large differences in single well productivity and insufficient capacity for stable production after fracturing
.

　　According to the situation of the reservoir drilling, the technicians iteratively optimize the previous fracturing experience, based on the principle of controlling the maximum reserves and the best benefit, applying the "sweet spot" quantitative identification technology of geological engineering, and adopting "dense cutting + imposing" in combination with different reservoir types.
The "sand + W joints" transformation process enhances the transformation effect of heterogeneous reservoirs
.

　　The logging display of Well North 201-32HF is dominated by oil traces and fluorescence, accounting for 80% of the oil and gas display section, and it is predicted that the condensate oil content is high
.

The technicians combined with the main control factors of geological engineering of the Yingsansha Group condensate gas reservoir, focused on "maximizing the volume of transformation + reducing retrograde condensate damage", innovatively applied the pre-carbon dioxide fracturing technology, and used carbon dioxide to "cool down, break the rock," The technical advantages of "enhancement and extraction", especially its effect on condensate extraction and miscible viscosity reduction, greatly enhance the fluid flow capacity of the reservoir and reduce the damage to the formation caused by the condensate accumulated at the bottom of the well

　　The North 210-7HF well has dense lithology but good material foundation, dominated by matrix seepage, and does not have the conditions for fracture network formation
.

The technicians select the combination of fracturing fluid system and proppant, supporting "temporary blockage in fractures, unequal perforation in fractures, real-time parameter adjustment" technology, and carry out multiple rounds of optimization for different reservoir types and reconstruction difficulties