General situation of gas field, development target and scheme

(1) Gas Field Overview and Development Target

The study area is a gas field in the west of China, and the study area is Block A and Block B.. This gas field is an Upper Paleozoic gas field in a basin in the west. According to the basic proven reserves data, its natural gas reserves exceed 10 12m3, which is the largest gas field in China at present, and it is also a typical "three lows" gas field with low permeability, low pressure and low abundance, so it is difficult to develop. The gas source mainly comes from the mud shale of Carboniferous and Lower Permian, and the delta sedimentary system sandstone above the source rock is the main reservoir. It is an atmospheric field with good preservation conditions and large natural gas reserves.

According to the Regulations on Natural Gas Exploitation, gas fields with natural gas reserves of more than 50× 108m3 are exploited at the exploitation rate of 3% ~ 5%, and the stable production period is 10 year. Combined with the actual situation of this gas field, by analyzing the law of natural decline of production year by year, the stable production development plan is designed comprehensively. According to the gas field development plan, two wells will be completed in 20 10, with an annual output of natural gas 15× 108m3. At present, the capacity construction of this gas field has reached the designed production scale, that is, the annual output of natural gas 15× 108m3. In production, production wells were built in the first year and put into production in the second year. In order to make up for the natural decline in production, extra wells are needed every year to maintain stable production.

According to the overall goal of annual gas production 15× 108m3, two specific exploration and development schemes are put forward: the first scheme has a stable production period of 8 years and a declining period of 7 years; Scheme 2, the stable production period is 10 year, and the decline period is 6 years. During drilling, the gas gathering stations required by each scheme shall be built according to the ratio of original well to gas gathering station. The specific contents of the two development schemes are as follows.

(II) Scheme I

1. Total number of wells and total footage

It is planned to build 625 exploration and development wells with a total footage of 2 189535 meters.

2. The total number of wells and footage in each block.

(a) Area A: 302 development wells with total drilling footage1050960m are deployed.

Area B: 323 development wells with total footage1138,575m are deployed.

3. Development plan

After the development of capital construction, the annual natural gas production will reach 15× 108m3, and the annual natural gas production will decrease at the rate of 16. 1%. In order to make the stable production period of this block reach 8 years, more wells are needed in the first 7 years (20 12 ~ 20 19), and the annual gas production capacity is expected to be maintained 15× 108m3. After that, the annual gas production will naturally decrease at the rate of 16. 1% until the average gas production of a single well falls below the abandoned production. See table 9- 14 for drilling deployment.

Table 9- 14 Drilling Deployment Plan of Scheme I

(III) Scheme II

1. Total number of wells and total footage

792 exploration and development wells were completed with a total footage of 2,774,520 meters.

2. The total number of wells and footage in each block.

(a) Area A: 384 exploration and development wells are deployed, with a total drilling footage of 65,438+0,336,320m.

Area B: 408 exploration and development wells are deployed with total footage1438,200m.

3. Development plan

The annual output of natural gas will reach 15× 108m3 after the capital construction year, and will decrease at the rate of 16. 1% in the future. In order to make the stable production period of this block reach 10 year, additional drilling is needed in the first 9 years (20 12 ~ 202 1 year), and it is estimated that the annual production capacity will be maintained at about 15× 108 m3. After that, the annual output will naturally decrease at the rate of 16. 1% until the average output of a single well falls below the abandoned output. See table 9- 15 for drilling deployment.

Table 9- 15 Drilling Deployment Plan of Scheme II