1. Complex fishing technology with ESP string

Well DH-xx in 2001: there were 6 different types of fish in the well, which were alternately soft and hard and affected each other; all the fish in the well was fished out using right-hand thread drilling tools to mill the broken cable and tubing annuls; After the fishing was completed, acid fracturing operations were carried out, and the oil production of the well was increased by 4 times compared with that before the workover.

2. Corroded and broken tubing treatment technology

(Broken tubing out of the well)

Well TH-xx in 2014: through timely exploration on site, a high-efficiency milling tool was developed to mill and fish the corroded and broken tubing, and the fishing task was completed within 70 days.

3. Multi-stage permanent packer string and open-hole staged string fishing technology

Well GS-xx in 2012: Using the RCT cutting technology, the downhole string was divided into four parts, and the 4 permanent packers and 5 bridge plugs were fished out by means of step-by-step staged milling and fishing, thus providing good wellbore conditions for the recompletion.

Well MX-xx in 2020: the casing packer and open-hole packer were fished out using left–hand thread drilling tools to carry out step-by-step continuous milling, back-off, washover and fishing. Efficient wellbore cleaning has created conditions for open hole sidetracking. Through the implementation of recompletion, the resumption and high production of the well have been ensured.

4. Casing deformation repair and unfreezing and fishing technology

Well YD-xx in 2014: the 9-5/8”P110*10.36 casing with reduced diameter due to deformation was thoroughly made unobstructed using the milling technology and the unfreezing-fishing RTTS leak testing string; in the later stage, the 7″ casings was partially tied back for cementing, so as to ensure the smooth completion and commissioning of the well.

5. Downhole problem treatment technology with coiled tubing

Well YB-xx in 2014: downhole problems were treated using coiled tubing. Main operation contents: liquid nitrogen induced flow, steel ball fishing with tailor-made external fishing grabs, milling and diameter enlargement of ball seat, ball seat fishing with tailor-made male coupling taps, negative pressure bailing with Venturi tubes, through tubing perforation, acidizing, fracturing and production restoration, etc. The fishing operation depth reached 6876m. The operation effect of the well was highly affirmed by Party A.

6. Slim hole fishing technology with perforation-testing combination string

(The 89mm perforating gun fished out of the 5″ casing by milling)

Well M4 in 2016: It was discovered that the RTTS perforation-testing combination string was stuck during workover. A special milling tool was designed; all the fish including testing tools, perforating guns, etc. was fished out using the left-hand thread drilling tools and the milling tool to carry out milling/washover/back-off. The success of this well has won SinoPetroleum a good reputation in the Northwest Bureau.

7. Rotary geosteering device unfreezing and fishing technology

Schematic diagram of fish

Schematic diagram of the rotary geosteering system

Screw rotor and drive shaft fished out of the well

Bit and rotary geosteering device fished out of the well

Well Lu-203xx in 2020: a fishing tool was flexibly designed on site; all the stuck fish including drum rotor, drive shaft, rotary geosteering system, etc. was fished out through precise treatment and operation; the treatment time was 19 days.

8. Leakage stoppage and repair technology for casing damage shale gas wells

Well N209xx in 2021: Due to the influence of various factors such as sensed earthquakes and large-scale hydraulic fracturing in southern Sichuan, some high-steel-grade thick-walled casing in some shale gas wells has been damaged. In view of the fact that the shale reservoirs cannot be fractured due to casing damage and leakage, a high pressure-bearing plugging agent LTSD has been developed. In the later stage of squeezing and plugging construction, the plugging agent withstood multi-stage continuous high-pressure construction, with a maximum pressure of 77MPa; the plugging effect was remarkable. This well was the first attempt of chemical plugging in shale gas wells with damaged casing, and has a good prospect of popularization and application.