Effect analysis and main attack direction of comprehensive treatment of "double low" units in Shengli Oilfield

The changes and present situation of "double low" units (oil production rate less than 1% and recovery ratio less than 10%) in Shengli Oilfield since the Eighth Five-Year Plan are analyzed and studied. This paper summarizes the main practices and effects of "double low" unit management of different types of reservoirs during the Ninth Five-Year Plan period, and analyzes the potential of "double low" unit management. The governance plan and objectives of the "double low" unit during the tenth five-year plan period are deployed, and the main direction of the tenth five-year plan is defined, which is of great significance to improving the development effect of the "double low" unit and improving the overall development level of the oilfield.

Keywords: "Double Low" unit and "Double Low" unit treatment effect evaluation in Shengli Oilfield

I. Introduction

Since the Eighth Five-Year Plan, the number of "double low" units in Shengli Oilfield has increased year by year, which has seriously affected the development effect of the whole oilfield and restricted the development level of the oilfield. Since 1996, the oilfield has set up special funds to carry out special comprehensive management of "double low" units, and the effect is obvious. Summarize the main methods of "double-low" unit management, analyze the potential of "double-low" unit at present, and put forward the main direction of further improving the development effect of "double-low" unit, which is of great significance to strengthen the stable production foundation of oilfield, improve oil recovery, improve the development effect of oilfield and realize a virtuous cycle of oilfield development.

Two. Changes of "Double Low" Units in Shengli Oilfield since the Eighth Five-Year Plan

Since 1990, the number of "double low" units in Shengli Oilfield has increased year by year, from 7 1 in 1990 to 163 in 1999. In terms of investment and development time, 87 new "double low" units have been newly invested and developed since the Eighth Five-Year Plan, and their reserves account for 33.7% of the newly built onshore production blocks since the Eighth Five-Year Plan, which are mainly caused by low geological understanding, poor reserve grade, lagging water injection work, imperfect injection-production well pattern and untimely adjustment. 163 "double low" unit, the produced reserves are 5 1664× 104t, accounting for 16.0% of the produced reserves in Shengli Oilfield. * * * Oil well 18 13, oil well116, the daily oil production is 4675t, the average daily oil production of a single well is 4.2t, the comprehensive water cut is 77.8%, and the annual oil production is184×/. There are 529 water injection wells, 28 1 well, the utilization rate of oil and water wells is 59.6%, and the injection-production well ratio is1:3; The average oil recovery rate is 0.35% and the average oil recovery rate is 5.44%. The "double low" unit has the characteristics of low oil recovery rate and recovery degree, high single well controlled reserves, poor reserves production and imperfect injection-production well pattern, which also shows that it has great potential to improve development effect.

163 "double low" units are distributed in 10 oil production plants except Haiyang and Qinghe, among which Binnan, Hekou, Chunliang and Xianhe have higher absolute reserves (table 1).

Table 1 Distribution of "Double Low" Devices in Oil Production Plant

Three, "Nine Five" period "double low" unit comprehensive management effect evaluation

During the Ninth Five-Year Plan period, * * * handled 63 "double low" units with a reserve of 2.8357× 108t. This paper mainly analyzes and evaluates 50 units dealt with in the first four years of the Ninth Five-Year Plan. These units are distributed in 28 oilfields, including Shengtuo, Dongxin, Bonan, Pan Lin and Niuzhuang, which are mainly heavy oil reservoirs with sand production, low permeability and complex fault blocks. The overall treatment effect of "double low" unit is obvious. The oil recovery rate is increased from 0.59% before treatment to 0.83% after treatment, the recoverable reserves are increased by 738× 104t, the oil recovery is increased by 3.2%, and the crude oil production capacity is expanded by 75× 104t. 17 unit has completely got rid of the "double low".

1. Treatment and effect of "double low" units in different types of reservoirs

During the ninth five-year plan period, the overall measures for comprehensive management of "double low" units are to implement project management, strengthen organizational operation and ensure orderly and efficient management; Deepen the study of reservoir geology and make preparations for the management of "double low" units; Improve comprehensive management technology and highlight the role of technology in "double low" management; According to reservoir types, targeted control measures are taken: sand control and viscosity reduction measures are taken for heavy oil sand-producing reservoirs, injection water quality is mainly improved for low permeability reservoirs, and injection-production well pattern is mainly improved for complex fault-block reservoirs.

1) heavy oil sand production reservoir

In the first four years of the Ninth Five-Year Plan, a total of 8 heavy oil sand-producing reservoir units/kloc-0 were treated, such as Guanxia in the west of Chengdong Oilfield and Dongsan in Shengsan District of Shengtuo Oilfield. These "double-low" units mainly produce Guantao Formation (Ng) and Dongying Formation (Ed), which have the characteristics of shallow reservoir burial (1000 ~ 1500m), weak compaction, poor consolidation lithology, loose reservoir cementation and thick crude oil properties. However, the lack of understanding of its geology, especially its structure, makes it difficult to perfect the injection-production system. Therefore, deepening the geological understanding of fault block reservoirs, especially the structural understanding, is the premise of achieving good governance results.

(1) Make full use of 3D seismic technology, deepen reservoir understanding, and make early preparations for making adjustment plan.

In the process of fault block reservoir processing, make full use of 3D seismic data, combined with drilling, logging and production performance data to carry out fine geological research, especially structural research, establish fine geological model, and determine the structure and reserves. According to the comprehensive interpretation results of three-dimensional data, we have a new understanding of the structure and reserves of Ying 66 fault block in Dongxin Oilfield. It is considered that the internal structure of the fault block is relatively simple, and there are only two south-dipping faults near the waist, and the high points are discontinuous and not well controlled. Due to the structural changes in this block, the oil-bearing area has expanded to the southwest by 0.5km2, and the geological reserves have increased by 70× 104t. These new geological understandings have laid a foundation for the compilation of the adjustment scheme. Jiangyan Practice and effect analysis of comprehensive management of British 66 double-low unit. 2000。

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(2) Improve the injection-production system and increase the utilization degree of reserves.

After further understanding the structural form, reservoir development and fluid distribution of fault-block reservoirs, the treatment scheme is deployed, the injection-production system is improved, and the reserve utilization degree is improved. Based on the new geological understanding, two new wells were drilled 12 at the microstructure high point of Ying 66 block in Dongxin Oilfield, and the average initial daily oil production of the new wells was 18. 1t, and the old downhole electric pump was used to lift the fluid, which improved the production intensity. These measures have obviously improved the development effect. The oil recovery rate increased from 0.4% before treatment to 2.86%, and the recoverable reserves increased by 68× 104t.

During the treatment of complex fault-block reservoirs, the structure and reserves were confirmed by strengthening the previous geological research, and the treatment effect was obvious. The oil recovery rate increased from 0.38% before treatment to 0.62% after treatment, the cumulative oil production increased by 52× 104t, the recoverable reserves increased by 260× 104t, and the oil recovery increased by 4.3%.

2. Analysis and evaluation of economic benefits

The economic post-evaluation of 1996 and 1997 "double low" governance units was carried out by incremental method. Judging from the evaluation results, among 1996 treatment units, there are 13 units with internal rate of return greater than 12%, and the reserves account for 95.5%; In 1997, there are five units with internal rate of return greater than 12%, accounting for 94.5% of the reserves. Most governance units have obvious economic benefits. But there are also some inefficient blocks, mainly because the proportion of new wells and inefficient wells in these inefficient units is too high, which is 29%.

In addition, from the comparison of million-ton capacity construction investment, the million-ton capacity investment of 1996 "double low" governance unit is 6. 1× 108 yuan, while the million-ton capacity investment of the new district is 18.5× 108 yuan in the same period, so it is necessary to Through the analysis of investment composition, there is little difference between drilling investment and public works investment, mainly because the "double low" governance unit of ground construction investment and public works investment is far lower than that of productivity construction block in the new district.

Four, "double low" unit comprehensive management potential analysis and main direction

On the basis of summarizing the comprehensive management practice of "double low" units since the Ninth Five-Year Plan, according to the principle of "analysis has potential, technology is guaranteed, and management is beneficial", Shengli Oilfield 163 "double low" units are screened and evaluated, their potentials are analyzed, and the main measures and main directions for further improving the development effect of "double low" units are put forward.

1. The "double low" unit has great potential in the Tenth Five-Year Plan.

According to the analysis, there are 92 "double low" units that can be treated at the end of 1999, with a reserve of 2.3445× 108t. During the Tenth Five-Year Plan period, 73 processing units will be arranged with a reserve of 1.93× 108t. It is estimated that the recoverable reserves will increase by 460× 104t and the production capacity will increase by 45× 104t. Among them, there are 35 units in complex fault block reservoir, with reserves of 78 19× 104t and recoverable reserves of 200×104t; Increased; There are 17 units in heavy oil sand production reservoir, with a reserve of 6405× 104t, which increases the recoverable reserve of160×104t; The low permeability reservoir is 2 1 unit, with a reserve of 5056× 104t, and the recoverable reserve is increased by100x104t.

2. The main direction of comprehensive management of "double low" units

1) heavy oil sand production reservoir

This kind of reservoir occupies a large proportion in the "double low" unit. Sand production of heavy oil is the difficult point and key direction of this kind of reservoir management.

Study on sand production mechanism of (1) enhanced reservoir

The reservoir types and rock types in Shengli Oilfield are complex, and the sand production situation is different in different reservoirs, sedimentary facies belts, different horizons, different completion methods and different water cut periods, and the sand production mechanism of oil layers is complex. According to the sand production characteristics of heavy oil sand production reservoir, the sand production mechanism of different sandstone types (fine sandstone and loose sandstone) is studied. According to the well conditions, the sand production mechanism of different well conditions, different sedimentary facies zones and different water-cut periods (especially high water-cut periods) are studied.

(2) Improve the matching technology of sand control and thickening.

On the basis of the existing technical level, the combination of geology and technology, reservoir-bottom hole-wellbore-surface, further improve the matching technology of sand control and thickening, and improve the application level of this kind of reservoir technology from multiple levels and directions, such as oil layer perforation, bottom hole plugging removal, sand control, rod pump thickening, wellbore viscosity reduction and surface gathering and transportation.

(3) Develop low-cost and high-efficiency sand control technology.

The coated sand and PS sand control technology developed in recent years have good sand control effect, but the cost of the measures is high, which restricts the popularization and application to some extent. To develop low-cost and high-efficiency sand control technology, it is necessary to extend the validity period of sand control measures and reduce the cost of sand control.

(4) Research on sand control and liquid extraction technology.

At present, after sand control in oil wells, there is a widespread problem of fluid production intensity decline, which affects the single well production and unit production effect. The research on sand control technology with high liquid production strength is carried out, and it is found that the liquid production strength will not decrease, but will increase, forming a non-liquid-proof sand control technology, which improves the oil production speed of heavy oil sand-producing reservoirs.

2) Low permeability reservoir

This kind of reservoir mainly focuses on improving the injection capacity of water injection wells and oil recovery. The specific work has the following four aspects. First, deepen the study of seepage mechanism in low permeability reservoirs. Carry out theoretical research on low-speed nonlinear seepage, double-medium seepage law, reasonable driving pressure gradient and well pattern adaptability, seek ways to solve the problem of "no injection and no production", and provide theoretical basis for improving the development effect of low-permeability "double low" units at present. Second, strengthen the refined treatment of water quality. For the "double low" unit of sewage reinjection, multi-stage fine filtration (using fine filtration device) should be carried out to make the solid content, particle size and oil content of suspended solids meet the ministerial standards; Strengthen the compatibility study between injected water and formation, and take anti-swelling measures for water-sensitive formation to prevent formation damage. Third, gradually improve the supporting technology of high-pressure water injection. While solving the problem of injected water quality, we will gradually improve the matching technology of high-pressure water injection and improve the injection capacity of water injection wells by means of trunk line pressurization (upgrading of pumping stations), wellhead pressurization (single booster pump), reservoir reconstruction (acidizing fracturing) and injection enhancement technology. Combining fine water quality treatment technology with high-pressure injection enhancement technology, giving full play to the overall advantages, strengthening water injection, restoring formation energy, and completely solving the water injection problem in low-permeability reservoirs. Fourth, make full use of reservoir protection, reservoir reconstruction and horizontal well technology. Oil and water wells should take reservoir protection measures in the whole process of drilling, oil production, operation and water injection to reduce the pollution of external factors to the formation, and adopt technologies such as reservoir reconstruction and horizontal well to improve the injection-production capacity of the reservoir.

3) Complex fault block reservoir

Complex fault block reservoir is characterized by many faults, small fault blocks and complex structure, which is limited by geological understanding means. Many complex fault-block reservoirs put into development in the early stage have problems such as incomplete structure and unclear reservoir understanding. We should make full use of three-dimensional seismic technology, strengthen fine geological research and deepen the geological understanding of reservoirs.

For small fault-block reservoirs whose injection-production system is difficult to be perfected, CO2 injection and single well huff and puff test can be carried out to improve the reserve utilization degree and tap the potential of such reservoirs. For fault-block reservoirs with many oil-bearing series, long oil-bearing well sections, large production difference between layers and unbalanced injection and production, series technologies of layered water injection and subdivision development can be adopted to improve the development effect of water flooding.

Verb (abbreviation of verb) conclusion

During the Ninth Five-Year Plan period, the management effect of "double low" units was obvious, and the growth trend of "double low" reserves in oil areas was controlled. At present, the new "double low" produced reserves and upgraded reserves are basically balanced.

Different types of reservoirs should take targeted control measures to improve the control effect. The main purpose of heavy oil sand production reservoir is to select and apply sand control and thickening matching technologies. The low permeability reservoir is mainly to strengthen the fine treatment of water quality, high pressure water injection, prevent swelling and plug removal, improve the injection-production well pattern and improve the injection-production capacity. Complex fault block reservoirs are mainly to deepen geological understanding, confirm structure and reserves, improve injection-production system and improve reserves utilization.

Main references

Li Xingguo. Deposition and microstructure of continental reservoirs. Beijing: Petroleum Industry Press, 2000: 106 ~ 107.

Wang Ping, Li Jifu, Li Youqiong. Fine exploration and development of complex fault block oilfield. Beijing: Petroleum Industry Press, 1994: 8 ~ 9.

Cheng Shiming, Zhang Furen. Dongxin complex fault block reservoir. Beijing: Petroleum Industry Press, 1997: 3 ~ 7.