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Water Control Project

 Mesozoic Andesite block is a dome and fault-nose structure with complicated faults, the main fault extends along north-east direction, with features of large fault displacement (100-300m) and long extension distance, dividing the whole block into two sub-block: north block and south block. The north block is graben dome structure and south block is fault-nose structure.

The development zone is dual porosity media fractured igneous rock in Mesozoic Erathem.
 
(1)High Geological Reserve Abundance
Oil bearing area of target zone is 1.2km2, pay zone thickness is 60m, geological reserves is 331.21×104 tons, with high reserves abundance.
(2)Lithological Characteristics
Pure rock with stable and homogeneous lithology. It mainly consists of intermediate Andesite rock. The rock is dense and hard with good fragility; fracture extends long distance in longitudinal direction with good connectivity.
(3)Single Well Productivity
In the early production, the production is about tens of tons, even some up to 100 tons. Therefore, the single well has a very high productivity.
(4)Remaining Reserves
The recoverable reserves is 35.06×104 tons,  remaining recoverable reserves is 14.45×104  tons,  with abundant remaining recoverable reserves.
(5)Predictive Productivity and Water Cut
The horizontal well predictive productivity is 15-18 tons with early stage water cut is about 60%.
(6)Bottom Water Characteristics
The bottom water is active, there is a high water productive zone below WOC with strong energy.

The fracture of Andesite north block is well developed with good connectivity in vertical and horizontal directions, so it is prone to bottom water coning rapidly.
 
 
Well Data

Well Name XXX Well Type Oil Producer Well Model Horizontal
Geographical Location Cang County, Hebei Province
Structure Location Andesite North Block
VD 2947.25 m Target zone Mesozoic Completion Method Screen completion
 
Casing Program
Casing Procedure Wellbore Size
mm
Casing Size
mm
Casing Depth
m
Screen Depth
m
Surface Casing 444.5 339.7 270 /
Intermediate Casing 311.1 244.5 1560 /
Production Casing 215.9 139.7 3289 /
Sand Screen / 3289-3587
 
 
Reservoir Simulation Parameters

Reservoir Pressure (Mpa) 30-32 Crude Density (formation) (g/cm3 ) 0.86-0.88
Formation Temperature(℃) 87-93 Crude Viscosity (formation) (cP) 26-42
Horizontal/reservoir interval(m) 298 Pay Zone Thickness(m) 60
Early Production(m3/d) 15-18 Early Water Cut(%) 60
 
 
ICD Segmented Water Control Completion
 
 


Liquid Production Simulation Comparison and ICD Design
 

 
Reservoir Analysis and Water Control Proposal

 1. Reservoir information:
The whole interval is 3289-3591m, of which there are 302m is pay zones and water control zones.

 2. Target well water production factors analysis
(1)Reservoir fracture is subject to water coning rapidly along well-developed facture belt, leading to partial water breakthrough, this should be highly preventative.
(2)Irregular well trajectory may cause lower water barrier height to earliest water breakthrough at the lower part of horizontal well.

3. Logging interpretation shows
(1)The middle interval (3362-3407m)  of horizontal well is a well-developed fracture belt, is the key point to restrict water, which calls Water Control Interval 1;
(2)The middle and lower interval (3474-3521m) of horizontal well is a developed fracture belt, is the second point to restrict water, which calls Water Control Interval 2;
(3)The toe of horizontal well is the lowest point of water barrier height, need to moderately  control water, which calls Water Control Interval 3.
So, the design is to run in hole four packers to build five pressure compartments. This can balance the formation heterogeneity through different nozzles controlling different flow rates of these compartments.

4. Geological analysis and simulation result
Water Control Interval 1
: adopt only ONE nozzle to restrict water; Water Control Interval 2: use TWO nozzles to restrict water; Water Control Interval 3: utilize FOUR nozzles to moderately restrict water.
 
 
Effects
Compared with adjoining well, it shows:
•    Two wells close with each other and can be comparative with similar production cycle.
•     Water cut rate increase slowly for Well XX and composite water cut reaching 64% after 3 years while adjoining well up to 93% within 3 months, which shows great difference between water control and non-water control.